THE MERSEY GATEWAY PROJECT DELIVERY PHASE · the Mersey Gateway Project. EIA is required under...
Transcript of THE MERSEY GATEWAY PROJECT DELIVERY PHASE · the Mersey Gateway Project. EIA is required under...
Report No. MG_REP_EIA_009
November 2011 Revision B
ENVIRONMENTAL IMPACT ASSESSMENT
CONTAMINATION OF SOILS, SEDIMENTS AND GROUNDWATER
TECHNICAL ANNEX
THE MERSEY GATEWAY PROJECT
DELIVERY PHASE
The Mersey Gateway Project Gifford
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Technical Annex
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THE MERSEY GATEWAY PROJECT
ENVIRONMENTAL IMPACT ASSESSMENT
CONTAMINATION OF SOILS, SEDIMENTS AND GROUNDWATER
TECHNICAL ANNEX
C O N T E N T S
1. INTRODUCTION ................................................................................................................. 1
2. PROPOSED CONSTRUCTION WORKS ........................................................................... 3
3. PLANNING POLICY ......................................................................................................... 12
4. METHOD STATEMENT .................................................................................................... 30
5. REVIEW OF DESK STUDY INFORMATION ................................................................... 87
6. BASELINE ...................................................................................................................... 145
7. RISK ASSESSMENT ...................................................................................................... 242
8. MITIGATION AND ENHANCEMENT MEASURES........................................................ 271
9. MONITORING REQUIREMENTS ................................................................................... 307
10. SUMMARY ...................................................................................................................... 308
11. REFERENCES ................................................................................................................ 326
FIGURES
Figure 3.1 Group A and B Priority Sites: Widnes
Figure 3.2 Group A and B Priority Sites: Runcorn
Figure 3.3 Updated Priority Sites: Widnes
Figure 3.4 Updated Priority Sites: Astmoor Industrial Estate
Figure 4.1 Comparison of Results Obtained for Dissolved and Total Metal Analysis in
Groundwater
Figure 5.1 Groundwater Source Protection Zones
Figure 6.1 Variation in Groundwater Levels with Time for the Sherwood Sandstone in
Widnes
Figure 6.2 Variation in Groundwater Levels over Time for the Sherwood Sandstone in
Runcorn
Figure 6.3 Variation in Groundwater Level over Time for the Glacial Deposits
Figure 6.4 Variation in Groundwater Level over Time for the Estuarine Alluvium
Figure 6.5 Variation in Groundwater Level over Time for the Made Ground
Figure 6.6 Tidal Influence with Distance from the Estuary in Widnes
Figure 6.7 Concentrations of Conductivity, Sodium and Chloride in the Sherwood Sandstone
Figure 6.8 Conceptualisation of Scouring and Sediment Mixing
Figure 6.9 Comparison of 95th Percentile Metal Concentrations to ISQG and PEL
Figure 6.10 Comparison of 95th Percentile PAH Concentrations to ISQG and PEL
Figure 6.11 Variation in Metal Concentrations Over Time for Different Groundwater Horizons
Figure 6.12 Variation in Chlorinated Hydrocarbon Concentrations over Time in BH1003
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DRAWINGS
MG_REP_EIA_009/001 Site Location Plan
MG_REP_EIA_009/002 Reference Design
MG_REP_EIA_009/003 Mersey Gateway Project Areas
MG_REP_EIA_009/004 Gifford Exploratory Hole Location Plans Phase 1, 2 & 3
MG_REP_EIA_009/005 Gifford Exploratory Hole Location Plans Phase 4 & 4a
MG_REP_EIA_009/006 Gifford Exploratory Hole Location Plans Phase 5
MG_REP_EIA_009/007 Gifford Exploratory Hole Location Plans Phase 6 (Widnes)
MG_REP_EIA_009/008 Gifford Exploratory Hole Location Plans Phase 6 (Bridgewater Junction)
MG_REP_EIA_009/009 Gifford Exploratory Hole Location Plans Phase 6 (Central Expressway)
MG_REP_EIA_009/010 Monitoring Well Locations
MG_REP_EIA_009/011 Shallow Monitoring Well Installation
MG_REP_EIA_009/012 Deep Monitoring Well Installation
MG_REP_EIA_009/013 Extract from BGS Geological Map - Drift
MG_REP_EIA_009/014 Extract from BGS Geological Map - Solid
MG_REP_EIA_009/015 Extract from Environment Agency Groundwater Vulnerability Map
MG_REP_EIA_009/016 Former ICI Widnes Experimental Site Drainage Plan
MG_REP_EIA_009/017 Historical Exploratory Hole Location Plan
MG_REP_EIA_009/018 St Michaels Golf Course, Southern Route Geological Cross Section A-A
MG_REP_EIA_009/019 St Michaels Golf Course, Southern Route Geological Cross Section B-B
MG_REP_EIA_009/020 Ditton Junction to Victoria Interchange Geological Cross Section C-C
MG_REP_EIA_009/021 Anglo Blackwell to Gussion Transport Geological Cross Section C2-C2
MG_REP_EIA_009/022 Victoria Interchange to St Helens Canal Geological Cross Section D-D
MG_REP_EIA_009/023 Catalyst Trade Park North-South Geological Cross Section D2-D2
MG_REP_EIA_009/024 Catalyst Trade Park Southern Boundary Geological Cross Section D3-
D3
MG_REP_EIA_009/025 St Helens Canal to Widnes Warth, Geological Cross Section E-E
MG_REP_EIA_009/026 Mersey Estuary Geological Cross Section F-F
MG_REP_EIA_009/027 Runcorn Saltmarsh to Manchester Ship Canal Geological Cross Section
G-G
MG_REP_EIA_009/028 Manchester Ship Canal to Bridgewater Junction Geological Cross
Section H-H
MG_REP_EIA_009/029 Remote Junctions Central Expressway Geological Cross Section J-J
MG_REP_EIA_009/030 Remote Junctions Weston Link Junction and M56 Junction 12
Geological Cross Section K-K & L-L
MG_REP_EIA_009/031 Conceptual Ground Model Widnes
MG_REP_EIA_009/032 Conceptual Ground Model Runcorn
MG_REP_EIA_009/033 Groundwater Flow Direction in the Alluvium
MG_REP_EIA_009/034 Groundwater Flow Direction in the Sandstone
MG_REP_EIA_009/035 Exceedances of GAC for Arsenic in Soil
MG_REP_EIA_009/036 Exceedances of GAC for Lead in Soil
MG_REP_EIA_009/037 Soil pH
MG_REP_EIA_009/038 Exceedances of GAC for Water Soluble Sulphate in Soil
MG_REP_EIA_009/039 Sulphide Concentrations >50mg/kg in Soil
MG_REP_EIA_009/040 Concentrations of Ammoniacal Nitrogen in Soil
MG_REP_EIA_009/041 Total Petroleum Hydrocarbons above 50mg/kg in Soils
MG_REP_EIA_009/042 Tetrachloroethene Concentrations in Soil
MG_REP_EIA_009/043 Trichloroethene Concentrations in Soil
MG_REP_EIA_009/044 1,1,1-Trichloroethane Concentrations in Soil
MG_REP_EIA_009/045 1,2-Dichloroethane Concentrations in Soil
MG_REP_EIA_009/046 Chloroform Concentrations in Soils
MG_REP_EIA_009/047 Carbon Tetrachloride Concentrations in Soils
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MG_REP_EIA_009/048 Hexachlorobutadiene Concentrations in Soils
MG_REP_EIA_009/049 Hexachloroethane Concentrations in Soils
MG_REP_EIA_009/050 Exceedances of ISQG for Arsenic in Soils
MG_REP_EIA_009/051 Exceedances of ISQG for Cadmium in Soils
MG_REP_EIA_009/052 Exceedances of ISQG for Chromium in Soils
MG_REP_EIA_009/053 Exceedances of ISQG for Copper in Soils
MG_REP_EIA_009/054 Exceedances of ISQG for Lead in Soils
MG_REP_EIA_009/055 Exceedances of ISQG for Zinc in Soils
MG_REP_EIA_009/056 Elevated Concentrations of Arsenic in Groundwater
MG_REP_EIA_009/057 Elevated Concentrations of Iron in Groundwater
MG_REP_EIA_009/058 Elevated Concentrations of Vanadium in Groundwater
MG_REP_EIA_009/059 Elevated Concentrations of Zinc in Groundwater
MG_REP_EIA_009/060 Elevated Concentrations of Antimony in Groundwater
MG_REP_EIA_009/061 Elevated Concentrations of Cadmium in Groundwater
MG_REP_EIA_009/062 Elevated Concentrations of Copper in Groundwater
MG_REP_EIA_009/063 Elevated Concentrations of Mercury in Groundwater
MG_REP_EIA_009/064 Elevated Concentrations of Chromium in Groundwater
MG_REP_EIA_009/065 Elevated Concentrations of Lead in Groundwater
MG_REP_EIA_009/066 Elevated Concentrations of Nickel in Groundwater
MG_REP_EIA_009/067 pH Concentrations in Groundwater
MG_REP_EIA_009/068 Chloride Levels >40% above the Seawater Standard in Groundwater
MG_REP_EIA_009/069 Distribution of Ammonia in Groundwater
MG_REP_EIA_009/070 Benzene Concentrations above the EQS in Groundwater
MG_REP_EIA_009/071 Toluene Concentrations above the EQS in Groundwater
MG_REP_EIA_009/072 Xylene Concentrations above the EQS in Groundwater
MG_REP_EIA_009/073 Petroleum Hydrocarbons Exceeding DWS in Groundwater
MG_REP_EIA_009/074 Locations of LNAPL
MG_REP_EIA_009/075 Carbon Disulphide in Groundwater
MG_REP_EIA_009/076 1,2-Dichloroethane in Groundwater above the DWS
MG_REP_EIA_009/077 Sum of PCE and TCE Concentrations above the DWS in Groundwater
MG_REP_EIA_009/078 Carbon Tetrachloride Concentration above the DWS in Groundwater
MG_REP_EIA_009/079 Trihalomethane Concentrations above the DWS in Groundwater
MG_REP_EIA_009/080 Vinyl Chloride Concentrations above the DWS in Groundwater
MG_REP_EIA_009/081 1,1,1-Trichloroethane Concentrations above EQS in Groundwater
MG_REP_EIA_009/082 1,1,2-Trichloroethane Concentrations above EQS in Groundwater
MG_REP_EIA_009/083 1,2-Dichloroethane Concentrations above EQS in Groundwater
MG_REP_EIA_009/084 Carbon Tetrachloride Concentrations above EQS in Groundwater
MG_REP_EIA_009/085 Chloroform Exceeding Concentrations in Groundwater Exceeding EQS
in Groundwater
MG_REP_EIA_009/086 Hexachlorobutadiene Concentrations in Groundwater Exceeding EQS in
Groundwater
MG_REP_EIA_009/087 Tetrachloroethene in Groundwater Exceeding EQS in Groundwater
MG_REP_EIA_009/088 Trichloroethene in Groundwater Exceeding EQS in Groundwater
MG_REP_EIA_009/089 Free Phase DNAPL in Groundwater
MG_REP_EIA_009/090 PAH Exceeding 1.2µg/l in Groundwater
MG_REP_EIA_009/091 Total Pesticides in Groundwater
MG_REP_EIA_009/092 Soil PID Readings
MG_REP_EIA_009/093 Conceptual Site Model – St Michaels Golf Course
MG_REP_EIA_009/094 Conceptual Site Model – Gussion Transport
MG_REP_EIA_009/095 Conceptual Site Model – Catalyst Trade Park
MG_REP_EIA_009/096 Conceptual Site Model – Astmoor Industrial Estate and Wigg Island
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APPENDICES
Appendix A Halton Borough Council St Michaels Golf Course (North) Part IIA Determination
Appendix B Minutes of Meetings with Environment Agency and Local Authority Contaminated Land
Officer
Appendix C Reynolds Geoscience Geophysical Report
Appendix D BACTEC UXO Desk Top Threat Assessment
Appendix R BAE Systems Risk Assessment for UXO
Appendix S Radman Associates Documentary Review on Potential for Radiological Contamination
Appendix T Information on former Chemical Weapons Facility at Randle Island
Appendix E Norwest Holst Soil Engineering Ltd Report on a Ground Investigation for the New
Mersey Crossing Factual Report (Phase 1 & 2 Site Investigation)
Appendix F Geotechnics Ltd Runcorn Sands Site Investigation Factual Report (Phase 3)
Appendix G Soil Mechanics Phase 4 Site Investigation Factual Report
Appendix H Soil Mechanics Phase 4A Site Investigation Factual Report
Appendix I Fugro Seacore Phase 5 Marine Site Investigation Factual Report
Appendix J Soil Mechanics Phase 6 Site Investigation Factual Report
Appendix U AEG Phase 7 Site Investigation Factual Report
Appendix K Historical Ordnance Survey Maps and Envirocheck Reports
Appendix L Results of Chemical Testing
Appendix M Contamination Assessment Criteria
Appendix V Detailed Quantitative Risk Assessment for Controlled Waters
Appendix N Results of Groundwater Level Monitoring
Appendix O Results of Ground Gas Monitoring
Appendix P Review of Alternative Foundation Measures for Embankments
Appendix Q Preliminary Remediation Options Appraisal
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1. INTRODUCTION
1.1.1 An Environmental Impact Assessment (EIA) was undertaken in 2008 to support the proposal for
the Mersey Gateway Project. EIA is required under European law by Council Directive
99/337/EEC and in United Kingdom law by a variety of legislation including the Town and
Country Planning (Environmental Impact Assessment) (England and Wales) Regulations 1999.
The site location plan is included as Drawing Number MG_REP_EIA_009/001.
1.1.2 As explained in Chapter 1 of the Further Application Environmental Statement the Council is
now advancing the Project including the Proposals to its delivery phase and in order to prepare
the Project for procurement of the Project Company and in response to consultation with the
Department for Transport, some modifications to the Reference Design proposals have been
made which are the subject of the Further Application. This Technical Annexe has been
updated to reflect these modificaitions.
1.1.3 This report forms provides technical environmental information to support and elaborate on the
Environmental Statement (ES). The ES summarises the outcome of the EIA process, which
included work to compile this document.
1.1.4 Information on historical land uses, environmental setting and previous investigations was
obtained for review. This information was used to design a series of site investigations within
the Project area (as defined by the ES) in order to identify the ground conditions and the
presence, or otherwise, of contamination.
1.1.5 This report presents the findings of the information review and site investigations and, in
particular comments on the ground conditions encountered. An assessment of the likely
significance of the contamination that was found was undertaken along with a review of
potentially viable mitigation measures. This report includes additional information arising from
research, monitoring, site investigation and assessment undertaken since the 2008
Environmental Statement (Orders ES), including data obtained for the Public Inquiry in 2009.
1.1.6 The work undertaken was intended to provide sufficient information to allow an assessment of
ground conditions and potential risks arising from contamination to be undertaken for the EIA
process. Further investigation will be required to provide design criteria and enable the design
and any mitigation measures to be finalised. This assessment enables the feasibility of
mitigation measures to be considered but not to conclude that a given solution is necessarily the
most appropriate. The information obtained has also formed the basis for the remedial
measures currently being developed as part of the advanced works.
1.1.7 The site investigations were undertaken as combined geotechnical and contaminated land
investigations. The overall approach to the investigation works has been in accordance with
BS5930 (1999) Code of Practice for Site Investigation (and amendments in 2010), and
BS10175 (2001) Code of Practice for the Investigation of Potentially Contaminated Sites (and
subsequent revision dated 2011) together with other relevant guidance. The work has been
undertaken with reasonable skill, care and diligence.
1.1.8 The assessment has been based on information obtained from exploratory holes located at
positions based on information obtained on the history of the study area, the proposals for the
Mersey Gateway Project including the Proposals and the standards current at the time each
phase of investigation was designed. However, ground conditions are only known in detail at
each exploratory hole location. The conditions between holes have been interpolated and,
therefore, the actual nature of the ground may differ from the interpretation in this document.
Similarly, chemical analysis has only been undertaken on samples recovered at the exploratory
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hole positions and it is possible that further areas of contamination are present between the
exploratory holes. This approach is entirely appropriate for an assessment of this nature.
1.1.9 In line with current UK best practice the contamination assessments made in this report are risk
based and the proposed end uses on which these are based are defined in the report. If
proposals for the project change or alternative construction methods are proposed then the
levels of risk and impacts outlined in this report could vary.
1.1.10 The findings and opinions in this report are based upon information derived from a variety of
sources that can reasonably be assumed to be reliable. Information has been derived from the
public register using various databases that allow data to be accessed quickly and cost
effectively. Information sources for the database include the Environment Agency and other
statutory authorities.
1.1.11 It will be necessary for the findings of this report to be reviewed prior to construction
commencing to ensure that they remain valid. Whilst the levels of most soil contaminants are
unlikely to change significantly, the potential remains for there to be changes in the
concentrations of contaminants in groundwater over time. This will ensure that the mitigation
measures being deployed remain appropriate. In order to reflect this, a programme of
groundwater monitoring has been carried out. This has been updated by monitoring of key
wells as part of the preparation of the Further Applications ES.
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2. PROPOSED CONSTRUCTION WORKS
2.1 Introduction
2.1.1 This section provides a review of the construction proposals and methods with particular
referene to where these require consideration of ground conditions.
2.1.2 Detailed information on construction proposals is contained within the Mersey Gateway Project
Construction Methods Report which is appended to Chapter 2 of the Environmental Statement.
The following text has been updated to include amendments from the Construction Methods
Report prepared for the Further Applications ES (referred to as the Project including the
Proposals), concluding with a summary of the residual effects following mitigation.
2.1.3 The proposals under the Further Applications can be summarised as follows:
a. Adoption of Open Road Tolling Technology from opening, as opposed the barrier tolling
authorised by the Permissions and Orders;
b. Redesign of the on and off slips at the formerly proposed Widnes Loops Junction to
remove the loops configuration from the proposals and provide a grade separated
roundabout junction;
c. Changes to the vertical alignment of the mainline of the Project as a result of other design
changes;
d. Adjustments to the alignment at Lodge Lane Junction to remove the need to replace the
existing busway bridge; and
e. Adoption of urban highways standards in some locations where rural standards had been
used.
2.1.4 A description of the Proposals is provided in Chapter 2 of the ES: those relevant to
Contamination of Soils, Sediments and Groundwater are summarised in the following table:
Area Summary of Proposals
A – Speke Road a. Toll plazas removed;
b. Extent of overall works reduced to reflect removal of toll plazas;
c. Slip roads and embankments re-designed to reflect removal of toll plaza, low
retaining wall added on northern off slip; and
d. The reduced extent of the works means there will be no requirement for any
works that might affect either Stewards Brook or the Old Lane Subway.
B - Ditton Junction to
Freight Line
a. Toll plazas removed;
b. Slip roads and embankments re-designed to reflect removal of toll plazas;
c. Main alignment shifted north to reduce adverse effects during construction in
terms of disruption to road users; and
d. Providing flexibility in approach to structure design
C - Freight Line to St
Helens Canal
including the Widnes
Loops Junction
a. Toll plazas removed;
b. Junction, slip road and embankments re-designed (as roundabout) to reflect the
removal of the toll plazas;
c. Alternative construction of embankment / structures at Victoria Road;
d. Revisions to the alignment to take account of the changes including a reduction in
the vertical alignment and moving of the horizontal alignment to the south; and
e. Providing flexibility in approach to structure design.
D - Mersey Gateway
Bridge
a. Provision of greater flexibility in design details of the New Bridge covering the
deck design and cable arrangements including removal of potential provision for
future light rapid transit;
b. Revision to the northern abutment and the New bridge to tie into the lower
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Area Summary of Proposals
vertical alignment in Area C. This revision does not affect the navigational
clearances and the clearance over St Helens Canal's canal is maintained.
c. Re-location of the northern abutment to avoid high pressure gas main on the
southern side of St Helens Canal, this will involve the abutment moving to the
south east (towards the salt marsh) and alteration to the extent of the narrowing of
the canal;
d. Alternative construction of St Helens Canal Bridge; and
e. Providing flexibility in approach viaduct design.
E - Astmoor Viaduct a. Provision of greater flexibility in design details of the New Bridge covering the
deck design; and
b. Providing flexibility in approach viaduct design.
F - Bridgewater
Junction
a. Minor re-alignment of slip roads and associated embankments;
b. Extent of slip road works reduced; and
c. Providing flexibility in approach to structure design.
G - Central
Expressway, Lodge
Lane and Weston
Link Junction
a. Re-alignment of Calvers Road omitted;
b. Merge / diverge to Halton Lea reinstated;
c. Addition of retaining walls and traffic signals at Central Expressway slips to
accommodate design developments;
d. Existing Busway bridge retained with adjustments in line / level to fit alignment
through existing bridge;
e. Simplified route for footway/bridleway at Weston Link Junction; and
f. Overall extent of slip road works reduced; and
g. Providing flexibility in approach to structure design.
H - M56 Junction 12 a. No changes to proposals.
I - Silver Jubilee
Bridge and Widnes
De-Linking
a. Removal of toll plazas; and
b. Queensway reduced to three lanes to accommodate cycle/footway over existing
structures
2.1.1 There are a series of structural options proposed as part of this Application and these are
detailed in Chapter 2. Those described at Victoria Road, Widnes Junction and St Helens Canal
are considered to be relevant to the Contamination of Soils, Sediments and Groundwater
chapter as they involve works in the ground where contamination is or could be present with the
potential to result in pollutant linkages being introduced, for example contact with contaminants
by construction workers or preferential pathways being introduced for contaminant migration.
2.1.2 Drawing No. MG_REP_EIA_009/002 shows the proposed Mersey Gateway Project including
the the new river crossing and the locations of new/improved road and junction layouts and the
location of the tolling plazas. These areas are outlined in Drawing No. MG_REP_EIA_009/003,
references to the areas outlined in the Construction Methods Report (CMR) have been included
in brackets.
2.2 Proposed Construction Methods
Area A - Main Toll Plaza St Michaels Golf Course Works to Existing A562 Speke Road
(CMR Area A)
2.2.1 It is proposed that the The Reference Design envisaged that the ground supporting the new
carriageways would could be improved by the installation of a grid of vibro-concrete columns
(VCCs). These would be installed on an approximate 2m x 2m grid to an average depth of 6m.
These VCCs would be installed by specialist piling rigs that sink a probe into the ground and
then inject concrete at pressure as the probe is withdrawn forming a column of concrete. Given
the reduced area of new carriageway within the Updated Reference Design other techniques
may be more appropriate/economical in this area.
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2.2.2 The resulting grid of VCCs would could be overlain by a load transfer platform comprising
geosynthetics and imported granular fill material.
2.2.3 The carriageway pavement could be constructed directly on top of this granular capping layer.
Because of anticipated near surface ground contamination, a strip of the existing topsoil is not
envisaged.
2.2.4 A low reinforced concrete retaining wall will be constructed alongside the eastbound offslip to
avoid the widening to the north. The wall will be a maximum of 2m high.
2.2.5 The construction of culvert extensions for Stewards Brook would involve some excavation of
potentially contaminated material.
2.2.6 The toll plaza area would require a drainage system to carry rainwater to the balancing ponds.
This would include concrete drainage channels on either side of the main carriageway; these
would be formed in situ with minimal excavation. Two balancing ponds would be formed to the
south of the new carriageway on either side of Stewards Brook to control the drainage water
outfall flow rate into the brook. This water would not be allowed to drain into the ground. A
drainage system to carry surface water run-off to the drainage outfalls will be required. This
could include concrete drainage channels on either side of the main carriageway which could be
formed in-situ with minimal excavation. A kerb gully system could be considered although this
would require more excavation.
2.2.7 New services would be required for the new tolling facilities.
2.2.8 Finishing works would include street lighting, road signs and gantries, construction of the tolling
booths and associated facilities. and the erection of the tolling canopies potentially requiring
excavations for the installation of foundations. It is understood there will be no tunnel access to
the toll booths. This text has been removed as the proposed construction works no longer
include toll booths.
2.2.9 Area A includes part of the southern section of St Michaels Golf Course. The extent of the
permanent works in Area A is small, however, it has been included in this assessment on the
basis this area could be used as a construction compound.
Areas B1 to B2 - Ditton Junction to Freight Line (CMR Area B)
2.2.10 The proposed bridge at Ditton Junction would be a conventional structure and the deck could be
in concrete or steel/concrete composite of either in-situ or precast construction. The
foundations for the new bridge at the Ditton Junction would either be piled or on a combined
system of spread foundations and ground improvement. The pile caps or spread foundations
would be below finished ground level and would require excavation and the construction of
reinforced concrete elements. The abutment walls and wing walls would be of reinforced
concrete.
2.2.11 The new carriageway will be constructed on the embankment. A drainage system to carry
surface water run-off to the attenuation measures in the vicinity of the proposed Ditton Junction
would be required.
2.2.12 The ground that would supporting the new embankments on either side of the new bridge would
could be improved by the installation of a grid of vibro-concrete columns (VCCs). The resulting
grid of VCCs would could then be overlaid with geosynthetics and imported granular fill material.
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2.2.13 Finishing works would will include street lighting, road marking, safety fencing, road signs and
gantries, installing communications equipment and construction of the tolling booths and
associated facilities., and the erection of the tolling canopies potentially requiring excavations for
the installation of foundations.
2.2.14 The re-aligned Ditton Road would will be constructed beneath the new bridge. Traffic signal
controlled junctions would will be formed with Ashley Way, Ditton Road and both of the new slip
roads. These works would will include major services diversions.
Area C - Freight Line to St Helens Canal (CMR Area C)
2.2.15 The elevated sections in this area would be formed by a combination of earthworks and
structures.
2.2.16 It is proposed assumed that the new bridge at the Freight Line would be a conventional portal
structure and the concrete deck beams cast integral with the reinforced concrete abutment
walls. Initially, railway protection fences would be erected to allow work to proceed safely
adjacent to the live railway. The foundations for this structure would be piled. The pile caps
would be below finished ground level and would require excavation and the construction of
reinforced concrete elements. The abutment walls and wing walls would also be of reinforced
concrete, constructed using excavators and a handling crane to move materials.
2.2.17 The Victoria Road Viaduct Bridge and embankments would share an abutment with between
the Bridge and the Freight Line Bridge would be phased to correspond with the availability of
the various sections of the site. Following site clearance, a piling platform would be formed at
each pier and abutment position and the piled foundations installed. The pile caps would then
be excavated and the piles would be broken down to the required cut off levels. The pile caps
and the viaduct columns would be of reinforced concrete.
2.2.18 The existing Victoria Road is a principal route for services between the centre of Widnes and
West Bank. Most of these should be able to remain in place, although protection measures may
be required during construction.
2.2.19 The section between the Freightline Bridge and Victoria Road could be formed using one of four
basic options:
i. Option 1: An embankment would be provided from the Freightline Bridge to the
edge of Victoria Road which would then be crossed by a two span bridge, landing on a
large abutment structure that separates the Victoria Road Bridge from the adjacent
Widnes Loops Junction.
ii. Option 2: A retained earth structure (such as reinforced earth walls or reinforced
concrete walls) would be provided from the Freightline Bridge to the edge of Victoria
Road which would then be crossed by a two span bridge, landing on a large abutment
structure that separates the Victoria Road Bridge from the adjacent Widnes Loops
Junction.
iii. Option 3: A cellular abutment would be formed on the east side of the freight line
bridge to support the end of a continuous viaduct that would extend eastward to cross
Victoria Road and land on a large abutment structure separating Victoria Road Bridge
from the adjacent Widnes Loops Junction.
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iv. Option 4: An embankment from the Freightline Bridge to the edge of Victoria Road
which would then be crossed by a multi span viaduct which would also cross the west
side of the roundabout at Widnes Loops Junction. This Option is a variation of Option 1
in which the large abutment between Victoria Road and Widnes Loops junction is
replaced by an elevation bridge span. It could also be combined with the configurations
described in Options 2 and 3.
2.2.20 Victoria Road Viaduct Bridge would terminate on an abutment to the east side of Victoria Road.
This structure would also act as the west abutment for the Widnes Loops West Bridge. It would
be a cellular structure, approximately 28m 20m square in plan and 10m 9m in height,
comprising piled foundations, pile caps, abutment walls and wing walls.
2.2.21 Widnes Loops West Bridge would is assumed to be a 78m two span bridge approximately 40m
long carrying the new highway over the low circulatory carriageway level on and off-slip roads of
the junction. The east abutment of the Widnes Loops West Bridge would be a reinforced
concrete abutment with wing walls founded on piled foundations. The west end support would
be provided by the large abutment common with the east end support of Victoria Road Bridge.
The east end support would be provided by a reinforced concrete bank seat at the top of a
sloping batter. Intermediate supports would be rectangular piers. All foundations would be
piled.
2.2.22 Towards the centre of the Widnes Loops Junction there would be two single span bridges
allowing the on-slip road to pass beneath the main carriageway of the new road (Widnes Loops
East Bridge) and the on-slip itself before it merges with the main carriageway (Widnes Loops
Slip Road Bridge). These would be box structures with spans of approximately 20m that would
eliminate the need to excavate deep foundations. These would be founded on ground that had
been improved using the techniques described above. Widnes Loops East Bridge would be a
single span bridge approximately 25m long carrying the new carriageway over the low level
circulatory carriageway to the east of the junction. This deck would be of similar form to the
adjacent Victoria Road Bridge and would be constructed in situ on a scaffold falsework. The
abutments of the Widnes Loops West Bridge would be a reinforced concrete abutment with
wing walls founded on piled foundations.
2.2.23 Widnes Loops East Bridge is assumed to be a two span bridge approximately 40m long carrying
the new carriageway over the low level circulatory carriageway to the east of the junction. The
west end support would comprise a reinforced concrete bank seat. The east end support would
be a reinforced concrete full height abutment and wing walls. Intermediate supports would be
rectangular piers. All foundations would be piled. All of these elements would be of reinforced
concrete requiring steel fixing, shuttering, concrete placement and compaction activities.
2.2.24 It is proposed the ground that supporting the Widnes Loops Junction embankments, including
the main line embankment up to the St Helens Canal Bridge would be improved by, this could
involve the installation of a grid of VCCs. The resulting grid of VCCs could be overlaid with
geosynthetics and imported granular fill material.
2.2.25 The new carriageway would could cross the St Helens Canal on a three-span structure,
terminating on the estuary side of the canal on the North Abutment of the Mersey Gateway
Bridge. Alternatively, the Widnes approach structure could be extended across St Helens Canal
if a different desk option were to be adopted. The St Helens Canal would be temporarily in-filled
during construction, although an allowance would be required for the maximum drainage flow
rate of the canal involving the provision of a large diameter bypass pipe. These works would
also involve the realignment of Bowers Brook into a new culvert passing through the spans of
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the new bridge.
2.2.26 The St Helens Canal Bridge would be founded on piled foundations. These would support
reinforced concrete pile caps and columns. It is assumed that abutments would need to be
situated on piles.
2.2.27 Finishing works would include street lighting, road marking, safety fencing, road signs and
gantries, installing communications equipment and construction of the tolling booths and
associated facilities., and the erection of the tolling canopies potentially requiring excavations for
the installation of foundations.
Area D – Mersey Gateway Bridge (CMR Area D)
Approach Viaducts
2.2.28 The approach viaduct piers would could be supported by groups of rotary bored cast in situ
concrete replacement piles. On the north bank, it is assumed that the piles would act in friction
founded in the glacial tills.
2.2.29 On the south bank, piles would could be taken to rockhead and the load would be carried
principally in end bearing. Although where rockhead is shallow enough, it may also be possible
to construct pad foundations within cofferdams. Based on the proposed pier spacings there
may be the need for one of the approach piers in this area to be would located on the eastern
edge of the Wigg Island Landfill.
2.2.30 The piled foundations for the approach viaducts would be groups of large diameter rotary bored
cast in situ concrete piles. In order to construct these, To construct the piles for the approach
piers, a stone piling platform would could be created at each pier position. Temporary pile
casings to support the excavation could be driven down, using vibration methods, to the level of
the glacial tills or the bedrock. The pile shaft could be excavated using an auger-piling rig. In
some locations, where a dry bore cannot be maintained, a supply of bentonite slurry is likely to
be required to support the excavation and to keep water out. The steel-reinforcing cage could
then be introduced followed by concreting of the pile using a tremmie pipe. Finally, the steel
casing could be withdrawn using vibration techniques.
2.2.31 Following completion of all piles in a group, a temporary cofferdam of steel sheet piles could be
installed to reduce the inflow of groundwater. These sheet piles could be installed by vibration
techniques. The cofferdam would are likely to be of minimum dimensions to allow the
construction of the pile caps, i.e. 12m by 14m, allowing as little as 1m working space around the
perimeter of the permanent pile cap. Groundwater would be pumped out of the cofferdam after
excavation and for the duration of the below ground works.
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2.2.32 Excavation would be to a level just below the underside of the pile cap; this could be 4m below
existing saltmarsh level to allow for a 3.5m pile cap and 0.5m cover of re-instated saltmarsh
material. A thin layer of blinding concrete could be laid and the piles would then be broken
down to cut-off level. The pile cap‟s reinforcement cage could then be fixed, the shutters fitted
and the concrete cast. Finally, the top and side surfaces of the pile cap would have a
waterproofing membrane applied before backfilling with estuary sands and removing the
cofferdam. Surplus excavated material could be incorporated into the main works where
possible.
Towers
2.2.33 The towers could be supported by large diameter piles or rectangular barrettes. Barrettes are
large rectangular piles formed using conventional diaphragm walling equipment and techniques,
which can accommodate high horizontal forces, moments and vertical loads. These barrettes
would be taken down to rockhead within a piled cofferdam. The cofferdams would comprise
steel sheet piles constructed with piling plant on the adjacent jetty piers. Initially, cofferdams
would be filled with sand to form a platform from which the barrette piling plant would operate.
Bentonite slurry would be used during the construction of the barrettes. The barrettes would be
excavated by either clam-shell grabs or by a down-the-hole self driving technique such as a
Hydrofraise. Similar techniques would be used in relation to a solution involving large diameter
piles.
2.2.34 Working areas would need to be created on the jetty piers adjacent to the cofferdams to permit
plant operation. Alternatively, the cofferdam could be formed by the foundation itself as a ring
diaphragm wall. Because of the need to minimise interference within the water column, the top
of pile cap level would be established below the lowest natural channel level within the estuary,
this is likely to be about 5m below the bed level of the channel. This would also require the
removal of any cofferdam by extracting the sheet piles once construction of the tower shaft is
completed. The cofferdam itself is likely assumed to be circular (approximately 30m diameter)
with the sheet piles taken deep enough to permit excavation to approx 5 8 metres below datum
(-5m -3m AOD). The cofferdam would need jetty piers adjacent to the top to allow space for
plant, material storage and working areas.
Area E – Astmoor Viaduct (CMR Area E)
2.2.35 Following site clearance, a piling platform would be formed at each pier position and the piled
foundations would be installed. The pile caps would can then be excavated and the piles would
be broken down to the required cut off levels. Piling excavation arisings and the arisings of the
pile caps would could be re-used in the works. The pile caps and the viaduct columns would be
of reinforced concrete requiring steel fixing, access scaffolding, shuttering and concrete
placement and compaction activities.
2.2.36 Finishing works would include fitting parapets, kerbing, carriageway construction, street lighting,
road marking, safety fencing and road signs potentially requiring excavations for the installation
of foundations.
2.2.37 Piled foundations have been assumed. However, where the bedrock is at shallow depth
beneath this viaduct it may be possible to use spread foundations bearing directly on the
bedrock.
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Area F – Bridgewater Junction (CMR Area F)
2.2.38 Piling platforms would be formed at each abutment and pier position of all three new bridges
and piled foundations would be installed. The pile caps would then be excavated and the piles
would be broken down to the required cut off levels. Cofferdams would be required for the
excavations adjacent to the Bridgewater Canal. Piling excavation arisings and the arisings of
the pile caps would be re-used in the works. The pile caps, abutments, wing walls and piers
would be of reinforced concrete construction.
2.2.39 The areas behind abutment and wing walls would be filled with imported granular fill material
prior to general embankment fill being placed and compacted.
Area G1 and G2 – Central Expressway, Local Distributor Roads, Lodge Lane Junction
and Weston Link Junction (CMR Area G)
2.2.40 The works along the Central Expressway would will be partial carriageway reconstruction works.
The existing hard shoulders would be excavated and a new carriageway would be constructed.
2.2.41 The replacement bridge for the footbridge is assumed to be formed using a long single span
steel structure on reinforced concrete abutments constructed within the cutting slopes.
2.2.42 At Lodge Lane Junction, a new bridge would be required. This would involve the formation of
either piled or spread foundations. Excavated material would be re-used in the works where
possible. The substructure would be of piled foundations and reinforced concrete piers. The
pile caps, abutments, wing walls and piers would be of reinforced concrete construction.
2.2.43 The road layout of Lodge Lane Junction would be modified to change the priority of the junction.
This would require earthworks in the formation of new embankments and highway carriageway
construction.
2.2.1 At Weston Link Junction the road layout would be modified to change the priority of the junction.
The free flow slip between Weston Link and southern leg of the Weston Point Expressway
would be widened and the straightened out to improve the alignment and capacity. A new link
would be constructed on the north side of the junction between the northern leg of the Weston
Point expressway and the Weston Link. These works would involve earthworks in the formation
of new embankments and highway carriageway construction. The existing bridge between
Weston Link and the northern leg of Weston Point Expressway would become redundant.
2.2.2 A new retaining wall would be required along the northern edge of this new slip road so that the
works would remain within the existing highway boundary. A new equestrian bridge would be
required across the new link on the north side of the junction to maintain an existing bridleway.
Also, a new retaining wall would be required along the northern edge of the new slip road so
that the works would remain within the existing highway boundary and mitigate impact on
existing services.
Area H – M56 Junction 12 (CMR Area H)
2.2.3 The new retaining wall on the south-east side of the existing roundabout would involve the
installation of a line of contiguous 750mm diameter bored concrete piles over a length of 75m
and 262m of inverted T concrete footing assumed to be 600mm wide by 150mm deep over a
length of 120m reinforced concrete retaining wall. The maximum retained height would be
approximately 11m8m. Also two embankments would be constructed with side slopes of 1 in 2
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at either end of the retaining wall. The exposed faces of the retaining wall would be cast in
panel lengths of up to 15m.
2.2.4 To undertake the piling, a piling platform would first need to be established for the piling rig to
operate on. The excavated arisings from the piling would be re-used as general fill in the works.
An area would be required to store reinforcement cages prior to them being installed into the
pile shafts. The piles would be constructed from concrete.
2.2.5 The main retaining wall stems would be constructed of in-situ reinforced pre-cast concrete
panels. The ground would be excavated to the level of the base and a layer of blinding
concrete would be laid to establish clean and firm working platform. The contiguous piles would
be broken down to cut-off level. The base reinforcing steel would be fixed and shutters fitted
and concreting of the element would follow. The buried surface of the retaining walls would be
waterproofed before backfilling with imported granular fill. The construction of the
embankments to the required carriageway levels would follow to complete the ends of the
retaining wall. A parapet would be attached on top of the wall along its entire length
2.2.6 The new carriageway arrangements would be constructed by excavating to formation level and
by laying and compacting the various levels of carriageway pavement construction.
Area I – Silver Jubille Bridge and Widnes De-linking (CMR Area I)
2.2.7 The tollbooths on Queensway would be installed on the existing carriageway. The northern part
of Area I is located in the Gussion Transport site adjacent to Area B2. The embankment and
viaduct linking to the Widnes Eastern Bypass would be removed by excavation and the use of
concrete breakers. The main link to Ditton Junction would be downgraded to a single
carriageway following the line of the existing northbound slip road to Ditton Junction.
2.2.8 The material excavated from the Widnes Eastern Bypass and Queensway embankments would
be re-used in the works where possible.
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3. PLANNING POLICY
3.1 Introduction
3.1.1 This section provides an overview and summary of the legislation and policies which have been
considered for the contaminated land assessment.
3.2 Legislation and Policies
3.2.1 This assessment takes into account the following local, regional and national policies and
legislation:
f. Part IIA of the Environmental Protection Act (EPA), 1990.
g. Water Framework Directive
h. The Water Resources Act
i. Groundwater Directive Environmental Permitting Regulations
j. Planning and Policy Statement 23 Planning Policy Statement 23: Planning and Pollution
Control. Annex 2 Development on Land Affected by Contamination. Office of the
Deputy Prime Minister
k. Draft National Planning Policy Framework
l. Regional Spatial Strategy Planning Guidance for the North West (RPG 13)
m. Halton Borough Council Contaminated Land Inspection Strategy
n. Halton Borough Council Unitary Development Plan (UDP)
3.2.2 A review of policy and legislation relating to waste management has not been included here as
this is considered within the Waste and Materials Chapter of the Environmental Statement.
3.2.3 The following review is based on information extracted from the respective legislation and policy
documents.
3.3 National Legislation and Policy
Part IIA of the Environmental Protection Act
3.3.1 Part IIA of the Environmental Protection Act provides a framework for the identification of
Statutory „Contaminated Land‟ and, where necessary, its remediation. Under Part IIA Local
Authorities are required:
a. to cause their areas to be inspected to identify contaminated land
b. to determine whether any particular site is contaminated land
c. to act as enforcing authority for all contaminated land which is not designated as a
„special site‟ (the Environment Agency are the enforcing authority for special sites)
3.3.2 The Environmental Protection Act provides the statutory definition of Contaminated Land for the
purposes of determining land that requires remedial action to be taken, as follows:
„Contaminated Land is any land which appears to the Local Authority in whose area it is
situated to be in such a condition, by reason of substances in, on or under the land, that:
Significant harm is being caused or there is a significant possibility of such harm being
caused; or
Pollution of controlled waters is being, or is likely to be, caused.‟
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3.3.3 These definitions are intended to allow the identification and remediation land that is causing
an „unacceptable risk‟ to human health or the wider environment. The approach is based upon
the principles of risk assessment, using the concept of a contaminant, a receptor and a
pathway, which combine to form a pollutant linkage. The presence of a significant pollutant
linkage forms the basis of a formal determination that land is contaminated. As well as being
defined in Part IIA, unacceptable risk and the principles of risk assessment in statutory guidance
are set out in Annex 3 to DEFRA Circular 01/2006 which was issued to take into account the
extension of Part IIA, principally to include radioactivity.
3.3.4 Under the provisions concerning liabilities, responsibility for paying for remediation will, where
feasible, follow the „polluter pays‟ principle. In the first instance, any persons who caused or
knowingly permitted the contaminating substances to be in, on or under the land will be the
appropriate person(s) to undertake the remediation and meet its costs. However, if it is not
possible to find any such person, responsibility will pass to the current owner or occupier
3.3.5 In July 2008 further guidance on the legal definition of Contaminated Land was provided by
DEFRA. This guidance notes that since Part IIA came into force there has been uncertainty
over the interpretation of the definition of statutory Contaminated Land centred on two issues.
a. In the absence of a precise legal definition, what constitutes a significant possibility of
significant harm and what does not
b. How should decisions be taken in cases where it is not scientifically possible to estimate
risks accurately
3.3.6 The July 2008 DEFRA guidance advocated a risk based, case by case approach to deciding
whether a significant possibility of significant harm exists. It relied on local authorities assessing
risks on individual sites and then deciding whether, in their view, a given site involves a
significant possibility of significant harm. On this basis the local authority is expected to decide
whether the land is Contaminated Land. The authority must decide what constitutes a
significant possibility of significant harm
3.3.7 In December 2010 DEFRA and the Welsh Assembly Government released a consultation
document on proposed changes to the Statutory Guidance which forms a key part of the
contaminated land regime under Part 2A. The main aim of the changes were to clarify various
aspects of the Statutory Guidance, particularly as it relates to the legal definition of
“contaminated land” and broad outcome the regime aims to achieve, and make it more effective
at prioritising higher risk sites. The consultation on proposed changes closed in March 2011
and no changes to the regime have been issued to date.
3.3.8 Information obtained from the Council‟s Contaminated Land Officer in September 2007 (and
contained in Appendix A) shows that the northern section of St Michaels Golf Course (located
immediately to the north of the proposed route alignment, north of Speke Road and west of
Dundalk Road) has been determined as „Contaminated Land‟, as defined by Part IIA of the
Environmental Protection Act (1990). This site is a Special Site as defined in the Environmental
Protection Act (1990).
3.3.9 The determination by the Council is located in Appendix A. Table 3.1 shows the significant
pollutant linkages that were identified by the Council:
Table 3.1 – Significant Pollutant Linkages at St Michaels Golf Course (North)
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Linkage No. Contaminant Pathway Receptor
001 Arsenic • Dermal Uptake • Ingestion of Soil
Golf Course User
002 Arsenic • Dermal Uptake • Ingestion of Soil
Golf Course Visitor
003 Arsenic • Dermal Uptake • Ingestion of Soil
Domestic Pets
004 Sulphates • Leaching from soil • Vertical Migration in Leachate • Lateral migration in groundwater
Stewards Brook
005 Sulphides • Leaching from soil • Vertical Migration in Leachate • Lateral migration in groundwater
Stewards Brook
006 Leachate Mixture • Leaching from soil • Vertical Migration in Leachate • Lateral migration in groundwater
Stewards Brook
007 Arsenic • Leaching from the soil • Vertical migration in Leachate • Lateral migration in groundwater
Minor Aquifer
008 Barium • Leaching from the soil • Vertical migration in Leachate • Lateral migration in groundwater
Minor Aquifer
009 Cadmium • Leaching from the soil • Vertical migration in Leachate • Lateral migration in groundwater
Minor Aquifer
010 Zinc • Leaching from the soil • Vertical migration in Leachate • Lateral migration in groundwater
Minor Aquifer
011 Sulphate • Leaching from the soil • Vertical migration in Leachate • Lateral migration in groundwater
Minor Aquifer
012 Sulphide • Leaching from the soil • Vertical migration in Leachate • Lateral migration in groundwater
Minor Aquifer
013 Iron • Leaching from the soil • Vertical migration in Leachate • Lateral migration in groundwater
Minor Aquifer
014 Leachate Mixture • Leaching from the soil • Vertical migration in Leachate • Lateral migration in groundwater
Minor Aquifer
3.3.10 Remediation has been undertaken on the northern section of St Michaels Golf Course to
improve the water quality in Stewards Brook and remove pathways from existing soil
contaminants to site users. The remediation works were completed 2010 and comprised
recapping using site won material from the re-alignment of Stewards Brook and imported
material to form a 350mm sand cap and 150mm topsoil. The former Stewards Brook alignment
is being used as a leachate collection facility with the periodic removal of leachate off-site.
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3.3.11 It is understood that pollutant linkages have also been identified by the Council on the southern
part of St Michaels Golf Course. However, determination of this part of the golf course as
statutory „Contaminated Land‟ has not been progressed on the basis that a review on the
outcome of remediation on the northern part of the golf course will be undertaken first.
Water Framework Directive
3.3.12 The EC Water Framework Directive came into force on 22 December 2000 and establishes a
new, integrated approach to the protection, improvement and sustainable use of Europe‟s
rivers, lakes, estuaries, coastal waters and groundwater.
3.3.13 The Directive introduces two key changes to the way the water environment must be managed
across the European Community.
3.3.14 The first change relates to the types of environmental objectives that must be delivered.
Previous European water legislation set objectives to protect particular uses of the water
environment from the effects of pollution and to protect the water environment itself from
especially dangerous chemical substances. These types of objectives are taken forward in the
Directive‟s provisions for Protected Areas and Priority Substances respectively.
3.3.15 However, the Directive also introduces new, broader ecological objectives, designed to protect
and, where necessary, restore the structure and function of aquatic ecosystems themselves,
and thereby safeguard the sustainable use of water resources. Future success in managing
Europe‟s water environment will be judged principally by the achievement of these ecological
goals.
3.3.16 The second key change is the introduction of a river basin management planning system. This
will be the key mechanism for ensuring the integrated management of groundwater, rivers,
canals, lakes, reservoirs, estuaries and other brackish waters, coastal waters, and the water
needs of terrestrial ecosystems that depend on groundwater, such as wetlands.
3.3.17 The planning system will provide the decision-making framework within which costs and
benefits can properly be taken into account when setting environmental objectives. It will
ensure that proportionate and cost-effective combinations of measures to achieve the objectives
can be designed and implemented.
3.3.18 The Water Framework Directive introduces a holistic approach to water management. In
particular it aims to help deal with diffuse pollution which remains a major issue, especially
following tighter controls being exercised on most significant point source discharges. By
rationalising and updating the current water legislation a number of existing European directives
will be replaced.
3.3.19 Replaced by the end of 2007:
a. Surface Water Abstraction Directive – 75/440/EEC
b. Exchange of Information on Surface Water Decision – 77/795/EEC
c. Surface Water Abstraction Measurement / Analysis Directive – 79/869/EEC
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3.3.20 Replaced by the end of 2013:
d. Freshwater Fish Directive – 78/659/EEC
e. Shellfish Waters Directive – 79/923/EEC
f. Groundwater Directive – 80/68/EEC
g. Dangerous Substances Directive – 76/464/EEC
The Water Resources Act
3.3.21 The Water Resources Act 1991 (WRA) came into effect in 1991 and replaced the corresponding
sections of the Water Act 1989.
3.3.22 The WRA sets out the responsibilities of the Environment Agency (formerly the National Rivers
Authority) in relation to water pollution, resource management, flood defence, fisheries, and in
some areas, navigation. The WRA regulates discharges to controlled waters, namely rivers,
estuaries, coastal waters, lakes and groundwater. This is distinct from the drainage of water or
trade effluent from trade premises into a sewer. Discharge to controlled waters is only permitted
with the consent of the Environment Agency. One of the aims of the Act is to ensure that the
polluter pays the cost of the consequences of their discharges.
3.3.23 Section 85 of the WRA states that „no person shall cause or knowingly permit any poisonous,
noxious or toxic material or solid waste to enter a controlled water‟. „Causing‟ means not only
deliberately releasing any polluting matter but also causing the pollution accidentally, by being
the operator of a plant or process.
3.3.24 Companies may also be liable for prosecution under Section 85, if they fail to take adequate
precautions to prevent unauthorised personnel discharging pollutants from the premises into
controlled waters. In addition to unauthorised discharges direct into controlled waters,
companies are held liable for an unauthorised discharge to controlled waters occurring via
surface water drains, or by discharge onto the land.
3.3.25 Failure to comply with the WRA is an offence subject to a fine not exceeding £20,000 and/or
imprisonment not exceeding three months if found guilty in a Magistrates Court. An unlimited
fine or prison sentence of up to two years may be imposed if the case is heard in a Crown
Court.
3.3.26 An offence is not committed where a discharge is made in accordance with a discharge
consent. The procedures for obtaining a consent from the Environment Agency are contained in
Schedule 10 of the Water Resources Act 1991 and the Control of Pollution (Applications,
Appeals, and Registers) Regulations 1996 – SI 1996/2971. Consents to discharge effluent are
subject to conditions such as biological oxygen demand, pH, temperature, concentration of
suspended solids and toxicity.
3.3.27 The abstraction of water from watercourses or groundwater is regulated under the WRA by the
Environment Agency. For a company or individual to abstract from controlled waters, a licence
has to be obtained from the Environment Agency. The procurement of a licence indemnifies the
company which is abstracting the water against any effect the authorised abstraction may have
on other existing rights to abstract water.
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3.3.28 The Anti-Pollution Works Regulations (1999) were enacted into Section 161A of the WRA, to
enable the Environment Agency to serve works notices on polluters or prospective polluters.
The purpose of the regulations is to provide the Agency with additional powers to prevent water
pollution. Works Notices may be served on anyone who has „caused or knowingly permitted‟ or
potentially may „allow‟ polluting matter to enter controlled waters.
3.3.29 The Environment Agency is entitled to recover the costs of any investigations needed, to
determine the source of the pollution from the person(s) on whom the notice was served. In
these situations the Environment Agency conducts a risk assessment to determine whether or
not a Works Notice should be served.
3.3.30 The Water Resources Act 1991 (Amendment) (England and Wales) Regulations 2009 amended
Section 93 and Section 161 of the 1991 Act, a summary of the changes has been provided as
follows:
a. Section 93: extending controls on activities to include those which could cause harm to
controlled waters in addition to activities which risk or cause pollution, designating water
protection zones to limit pollution caused by specified activities, and revoking nitrate
sensitive areas.
b. Section 161: extending controls on activities to include those which could cause harm to
controlled waters and enabling the Environment Agency to carry out works where the
condition of any hydromorphological quality element of any controlled waters is
unsatisfactory.
Groundwater Directive
3.3.31 The Groundwater Regulations were introduced in 1998 to complete the implementation of the
EC Groundwater Directive (Protection of Groundwater against Pollution Caused by Certain
Dangerous Substances 80/68/EEC).
3.3.32 Anyone who disposes of listed substances or materials containing listed substances needs to
apply to the Environment Agency for an authorisation. This requirement was introduced on 1
January 1999. The EA will consider the application and, where the disposal is acceptable, they
will issue an authorisation with appropriate conditions. Only then can disposal can take place. In
some cases it may be necessary to refuse the application because of the risks of groundwater
pollution. It is a criminal offence to intentionally dispose of such substances onto or into land,
unless a Groundwater Authorisation or other relevant permit is in place.
3.3.33 The substances controlled under the Regulations fall into two lists:
a. List 1 substances are the most toxic and must be prevented from entering groundwater.
They include pesticides, sheep dip, solvents, hydrocarbons, mercury, cadmium and
cyanide.
b. List 2 substances are less dangerous, but entry of these substances into groundwater
must be restricted to prevent pollution. This list also includes metal, pesticides, solvents.
3.3.34 This text has been removed as the requirements have been incorporated into the Environmental
Permitting (England and Wales) Regulations 2010 below.
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Environmental Permitting (England and Wales) Regulations 2010
3.3.35 The Environmental Permitting Regulations provided a consolidated system of permitting in
England Wales which affect all regulated facilities that are installations (outlined in Schedule 1
of the Regulations), mobile plant, waste operations (including mining waste operations),
radioactive substances activities, water discharge and groundwater activities.
3.3.36 Schedule 21 of the Regulations relates to water discharge activities discharge or entry to inland
freshwaters, coastal waters or relevant territorial waters of any poisonous, noxious or polluting
matter, waste matter,trade effluent or sewage effluent. Schedule 22 relates to discharge of
pollutants into groundwater. The pollutants controlled under the regulations fall into two lists:
a. Hazardous pollutants will need to be prevented from entering groundwater (unless
authorised). These comprising substances which are toxic, persistent and liable to bio-
accumulate including organohalogens, organophosphorous, organotin, cyanides,
arsenic, mercury and cadmium.
b. Non-hazardous are any pollutant capable of causing pollution other than a hazardous
substance. The input of these non-hazardous substances should be limited so as not to
cause pollution.
3.3.37 The Environmental Permitting Regulations amend and replace a number of previous regulations
which includes the system of consenting water discharges in the Water Resources Act 1991
and the groundwater permitting system in the Groundwater (England and Wales) Regulations
2009.
3.3.38 These regulations are enforced by the Environment Agency and Local Authorites.
Planning Policy Statement 23
3.3.39 Annex 2 of Planning Policy Statement 23 (PPS23) was issued in 2004 and provides guidance
on how the development of contaminated land is to be controlled through the planning process.
The document expands on the policy considerations the Government expects Regional
Planning Bodies and Local Planning Authorities to have regard to in preparing policies in
development plans and taking decisions on applications in relation to development on land
affected by contamination.
3.3.40 PPS23 is clear that the standard of remediation to be achieved through the granting of planning
permission for new development, including permission for land remediation activities, is the
removal of unacceptable risk and making the site suitable for use. As a minimum, after carrying
out the development and commencement of its use, the land should not be capable of being
determined as statutory „Contaminated Land‟ under Part IIA.
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Draft National Planning Policy Framework
3.3.41 In July 2011, The Government issued the Draft National Planning Policy Framework (NPPF).
This document is aimed at simplifying the existing national policy documents (Planning Policy
Statements (PPS) and Planning Policy Guidance (PPG)) into one document, with the aim of
make the planning system accessible for communities and to promote sustainable growth.
3.3.42 Advice from the planning inspectorate on the Draft NPPF is:
“It is a consultation document and, therefore, subject to potential amendment. It is capable of
being a material consideration, although the weight to be given to it will be a matter for the
decision maker in each particular case. The current Planning Policy Statements, Guidance
notes and Circulars remain in place until cancelled.”
3.3.43 Paragraph 171 of the NPPF relates to preventing unacceptable risks from pollution and land
instability. This states that local policies and decisions should ensure that:
a. New development is appropriate for its location, having regard to the effects of pollution
on health, the natural environment or general amenity, taking account of the potential
sensitivity of the area or proposed development to adverse effects from pollution.
b. The site is suitable for its new use taking account of ground conditions, pollution arising
from previous uses and any proposals for land remediation.
3.3.44 The footnote to Paragraph 171 states that as a minimum, the land should not be capable of
being determined as contaminated land under Part IIA of the Environmental Protection Act
1990.
3.4 Regional Policy
Regional Planning Guidance for the North West
3.4.1 The Regional Planning Guidance for the Northwest (RPG13) was prepared by the Government
Office for the Northwest in 2003. The main purpose of RPG13 is to provide a regional spatial
strategy within which local authority development plans and local transport plans can be
prepared. It provides the broad development framework for the Region, identifying the scale and
distribution of housing development and the priorities for the environment, transport,
infrastructure, economic development, agriculture, minerals and waste treatment and disposal.
By virtue of being a spatial strategy it also informs other strategies and programmes. In
particular, it provides the longer-term planning framework for the North West Development
Agency‟s Regional (Economic) Strategy (R(E)S).
3.4.2 Chapter 9 „Ensuring High Environmental Quality‟ of RPG13 focuses on the environmental
concerns associated with derelict and contaminated land; air and water quality; waste
management and radioactive waste. Policy EQ1 of Chapter 9 deals with derelict land and
contamination issues.
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Policy EQ1 Tackling Derelict Land and Contamination Issues
3.4.3 Policy EQ1 states that Local Authorities should work in partnership with the North West
Regional Assembly (NWRA), North West Development Agency (NWDA) and the Environment
Agency to identify and prioritise a major programme of schemes for the restoration and
remediation of derelict and contaminated sites. Wherever possible, priority should be given to
those sites which present the best opportunities to support urban renaissance and reduce
sources of pollution and environmental impact in the North West in line with the Core
Development Principles and in a manner that will support the Spatial Development Framework.
3.4.4 The North West‟s industrial heritage includes a legacy of derelict, contaminated and degraded
land and buildings. This derelict land – one quarter of that found in the country as a whole –
detracts from the image of an area, attracts crime and flytipping and discourages investment.
Reclamation and regeneration of such land can provide valuable land for housing, employment,
leisure, nature conservation and public open spaces, assist urban renaissance and vastly
improve the appearance of an area while easing pressure on greenfield sites and protecting
valuable environmental assets. Some areas classified as derelict may serve as important urban
green spaces and wildlife havens.
3.4.5 Part IIA of the Environment Protection Act 1990 provides a framework for local authorities and
the Environment Agency to ensure that unacceptable risks from land identified as contaminated
land in its current use are removed and to allocate and apportion the liability for the costs of
doing so.
3.4.6 The NWDA‟s Regional (Economic) Strategy includes a commitment to a review of land
reclamation in the North West. Programmes should be prioritised to return as much of this land
as possible to beneficial use.
Policy EQ3 Water Quality
3.4.7 Policy EQ3 states that measures to improve and sustain the quality of the Region‟s rivers,
canals, lakes and sea will be promoted. Local authorities and other regional agencies should
co-ordinate their strategies and programmes to:
a. maintain or improve the quality of groundwater, surface or coastal waters
b. avoid development that poses an unacceptable risk to the quality of groundwater,
surface or coastal water
c. ensure that adequate foul and surface water provision and infrastructure is available to
serve new development and minimise the environmental impact of discharges
d. ensure that adequate pollution control measures to reduce the risks of water pollution
are incorporated into new developments
e. discourage the proliferation of private sewage disposal facilities
f. locate development in locations where the necessary sewerage infrastructure will be
available or can be provided at an affordable cost and without environmental harm
g. discourage diffuse pollution of water from agriculture and from landfill sites
h. ensure that the construction of roads and other transport infrastructure does not
unnecessarily add to diffuse pollution.
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3.4.8 Policy EQ3 also states that while some stretches of water in the North West represent notable
beauty and conservation spots, other areas, particularly in the southern parts of the Region,
have become derelict and polluted by urbanisation and industrialisation and require
improvement. The Region historically suffers from some of the poorest surface water quality in
England and Wales due to farming practices, industrial discharges and, significantly, sewerage
and the sewage treatment infrastructure, some of which dates back to Victorian times.
3.4.9 Policy EQ3 states that some 13% of the Region‟s watercourses, mainly in the Mersey Basin, are
classified as „poor‟ or „bad‟. The Policy notes that the combined sewer overflows are
unsatisfactory and many of the major wastewater treatment works do not have „river needs‟
consents and will add considerably to pollution. Bathing waters are noted to be another cause of
concern and several of the Region‟s beaches currently fail to meet EU Directive standards.
3.4.10 Policy EQ3 states the Environment Agency‟s Local Environment Action Plans (LEAPs) have
identified areas where water quality problems exist and development must not proceed before
the sewerage systems are able to deal with increased loads.
3.4.11 Diffuse pollution, especially from agriculture, is noted in Policy EQ3 to be a major challenge to
water quality. This can affect both the chemical and ecological quality of water, including bathing
water. This is becoming a proportionately more important consideration as pollution from point
sources is improved. In addition to agriculture, diffuse pollution can arise from other sources,
including roads.
3.4.12 Policy EQ3 also considers that emphasis should be placed on protecting the quality of
groundwater resources as once contaminated they can be difficult or even impossible to
remediate. Water pollution can result from failure to install adequate measures such as oil
interceptor facilities or trapped gullies to surface water systems that serve industrial, highway,
residential or commercial schemes. Sustainable Drainage Systems (SuDS) can help to reduce
the problem. If private sewage treatment facilities are not properly maintained, pollution can
result and the proliferation of small package treatment plants and septic tanks should be
discouraged in favour of first time rural sewerage. This text has been removed as Regional
Planning Guidance for the Northwest RPG13 no longer exists.
Regional Spatial Strategy
3.4.13 The Regional Spatial Strategy (RSS) for North West England was prepared by the Government Office for the North West in 2008 and provides a framework for development and investment in the region. It establishes a broad vision for the region and its sub-regions, priorities for growth and regeneration, and policies to achieve sustainable development across a wide range of topics from jobs, housing and transport to climate change, waste and energy. The RSS is part of the statutory development plan for every local authority in the North West
3.4.14 The Coalition Government intends to abolish Regional Spatial Strategies (RSS) under powers of the Localism Act 2011 (s109). Until the Secretary of State issues relevant order, to revoke whole or parts of the RSS, the RSS for the North West remains part of the statutory development plan
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3.4.15 Policy DP7 relates to promoting Environmental Quality which states that environmental quality (including air, coastal and inland waters) should be protected and enhanced. This includes the following:
a. Reclaiming derelict land and remediaton contaminate land for end-uses to improve the
image of the region and use if land resources efficiently.
b. Maximising opportunities for the regeneration of derelict and dilapidated areas.
3.5 Local Policy
3.5.1 The Local Development Framework (LDF) is the overall name for the collection of planning documents that are currently being produced by the Council and which will eventually replace the Council‟s current statutory development plan, the Unitary Development Plan (UDP).
3.5.2 In May 2011, the Council published the Revised Proposed Submission Document and submitted it to Government for examination, which is scheduled for November 2011. The Core Strategy is not yet adopted, however given its advanced stage of development and the extent of public consultation in its preparation, it has been considered as being capable of carrying material weight.
3.5.3 The relevant sections of the saved UDP and Core Strategy have been discussed below:
Unitary Development Plan
3.5.4 Chapter 4 of the Council‟s Unitary Development Plan (UDP) covers Pollution and Risk, the
objectives outlined by the Council for this chapter comprise:
a. to reduce the potential of various land uses to cause continuing harm.
b. to improve the potential to create a safe, healthy and prosperous economy, environment
and society.
3.5.5 The UDP states „the quality of the environment in Halton Borough has improved dramatically in
recent years‟ and goes on to say „these improvements should not be jeopardised by allowing
new development which is likely to cause unacceptable pollution‟.
3.5.6 Part 2 of Chapter 4 in the UDP outlines the following Policies and Proposals relating to land
quality/contaminated land;
PR6 Land Quality
3.5.7 This policy states that “Development will not be permitted if it is likely to cause contamination of
the soil or sub-soil on a development site or on surrounding land uses as a result of pollution.
This includes consideration of:
a. The unacceptable effects of deposits and emissions.
b. Whether development, through its potential to pollute, is likely to have a serious impact
upon investment confidence.
c. The risk of damage to health”.
3.5.8 The justification provided for PR6 is that „it is essential to avoid the possibility of new land uses
which may themselves be a future source of land contamination‟.
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PR7 Development Near to Established Sources of Pollution
3.5.9 This policy states that “Development near to existing sources of pollution will not be permitted if
it is likely that those existing sources of pollution will have an unacceptable effect on the
proposed development and it is considered to be in the public interest that the interests of the
existing sources of pollution should prevail over those of the proposed development. Exceptions
may be permitted where the applicant submits satisfactory proposals to substantially mitigate
the effects of existing sources of pollution on the development proposal.”
PR13 Vacant and Derelict Land
3.5.10 This policy stated that “Development and reclamation of derelict and vacant land will not be
permitted unless all of the following criteria can be satisfied:
a. Reclamation/decontamination works are carried out to ensure the safety and health of
people and the environment on and around the land.
b. The proposal is a suitable after use of the site.
c. Any proposal complies with other relevant policies within the Plan including urban
regeneration initiatives by the Council.”
3.5.11 Information posted on the Council‟s website on 4th
April 2008 indicates that Policy PR13 expired
after 6th April 2008 and has not been saved and was not considered in this assessment. In
terms of the implications of removing Policy RP13, the requirements relating to ensuring the
safety and health of people and the environment from contamination are included in PPS23 and
Part IIA. Therefore, these have still been considered as part of this assessment.
PR14 Contaminated Land
3.5.12 This policy states that “before determining any planning applications for development on or
adjacent to land which is known or suspected to be contaminated, the applicant will be required
to satisfy all of the following:
a. Submit details to assess the nature and degree of contamination (type, degree and
extent of contamination).
b. Identify remedial measures required to deal with any hazard to safeguard future
development and neighbouring land uses.
c. Submit details of a programme of implementation for the roll out and completion of
mitigation measures to be agreed with the Council.”
3.5.13 The Council state the requirement to undertake the above work will be controlled by either
planning conditions or, where necessary, by planning obligations.
3.5.14 The justification stated for PR14 is that „many sites in the Borough are known to be
contaminated, e.g. historical chemical works/tip, former landfill sites‟. The justification in the
UDP goes on to say „development on or near to contaminated land can cause the release of
contaminants which may result in significant harm to the local environment and population‟.
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3.5.15 The UDP states that it is „therefore necessary to assess any risks and identify remediation
measures to make the land developable or to reduce harm to the existing environment, and so
that new receptors and pathways are not introduced‟. The UDP also states „The Council will
require that the implementation of mitigation measures is enforceable through either planning
conditions or by the forms of planning obligations‟.
PR15 Groundwater
3.5.16 This policy states that “Proposals that are likely to lead to an adverse impact on groundwater
resources in terms of their quantity, quality and ecological features they support will not be
permitted.”
3.5.17 The justification for PR15 is that „there are many developments that have the potential to pose a
direct or indirect threat to groundwater quality‟. PR15 states that „many of the types of
development likely to pose a risk to groundwater will fall under the requirements of the Town
and Country Planning (Environmental Impact Assessment) Regulations 1999. Where relevant,
environmental statements will fully address the potential impacts of any proposal upon the
groundwater environment. Wherever groundwater is vulnerable to land use activities the site-
specific considerations of both the geology and proposed operation controls must be considered
at the planning stage to ensure adequate protection‟.
3.5.18 The justification also notes „within the boundary of Halton a single major aquifer underlies
approximately two thirds of the area [Borough]. The groundwater is extensively exploited for
public and industrial supply and past over abstraction has led to saline intrusion from the
Mersey Estuary‟.
Core Strategy
3.5.19 Policy CS23 of the Core Strategy relates to managing pollution and risk. Part A“of Policy CS23 is about controlling development which may give rise to pollution and identifies the need to investigate potentially contaminated sites to identify the extent of contamination and risk to future uses. The policy states that development will only be permitted where the land has or will be made suitable for the proposed use. Where it is not possible to achieve the full remediation of a site, the policy states that the Council may seek soft-end or green uses.
Halton Borough Council Contaminated Land Inspection Strategy
3.5.20 Local Authorities are required undertake an assessment of contaminated land within their
administrative boundaries. This was intended to identify sites that potentially posed a risk and
to allow local authorities to rank them in terms of priority. On the basis of past site use, the
Council‟s Environmental Health Department have prioritised potentially contaminated sites for
inspection as to whether they should be determined as Contaminated Land, as defined in Part
IIA of the Environmental Protection Act (1990).
3.5.21 The Council‟s Contaminated Land Inspection Strategy was published in July 2001. The Strategy
sets out the broad characteristics of the Borough in terms of environmental setting, land use,
historical background and population. A review of the Contaminated Land Inspection Strategy
was published by the Council in 2006, which was the first formal review of the Strategy since its
publication in July 2001. Information contained within this 2006 review shows the following high
and medium priority sites within Runcorn and Widnes.
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Figure 3.1 – Group A and B Priority Sites: Widnes
Figure 3.2 – Group A and B Priority Sites: Runcorn
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3.5.22 Information obtained from the Council‟s Contaminated Land Officer in September 2007
indicates the sites within Astmoor Industrial Estate identified within the Contaminated Land
Inspection Strategy were based on historical mapping and their proximity to known receptors.
The Council have confirmed they hold no relevant site investigation data for this area.
3.5.23 The Council also indicate that the information within the published Contaminated Land
Inspection Strategy review document (2006) has been updated on their GIS database (and this
will continue to be updated as more information becomes available). The updated plan
obtained from the Council‟s GIS database for Widnes and Astmoor Industrial Estate in Runcorn
is as follows with the higher priority (Group A) sites shown in red and lower priority (Groups B
and C) sites in blue and green. It is understood that updates to these plans have not been
released since the Orders ES.
Figure 3.3 – Updated Priority Sites: Widnes
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Figure 3.4 – Updated Priority Sites: Astmoor Industrial Estate
3.5.24 No priority sites have been identified by the Council within the Project area to the south of the
Astmoor Industrial Estate in Runcorn.
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3.6 Consultations
3.6.1 Consultations have been undertaken with the following regulatory authorities regarding
contaminated land as part of the Mersey Gateway Project. Minutes produced by Gifford from
these meetings were copied to the regulators for comment, these minutes are included in
Appendix B.
a. Environment Agency (EA) Contaminated Land and Groundwater officers on:
19th September 2001
9th January 2002
6th November 2003
12th December 2006
30th January 2007
28th June 2007
7th August 2007
13th December 2007
5th November 2008
10th December 2008
20th March 2009
20th April 2010
20th July 2010
16th November 2010
16th December 2010
b. The Council‟s Contaminated Land Officer on:
26th September 2001
22nd
August 2006
3.6.2 The Contaminated Land Officer from the Council was also present at the meeting with the
Environment Agency on 13th December 2007 and 16
th December 2010.
3.6.3 Meetings have also been held with the Environment Agency and Council on 10th August 2011
and 20th September 2011 to provide updates on the progress of contaminated land
investigations and proposals for advanced works remediation.
3.6.4 Telephone and e-mail discussions have also been undertaken with the Contaminated Land
Officer at the Council as required to discuss issues relating to parts of Project area. The factual
data from the Phase 1 to 5 site investigations for the Mersey Gateway Project were sent to the
Council and Environment Agency in 2007.
3.6.5 The proposed locations and methodolody for the Phase 4 site investigation (which included the
locations for Phase 4A exploratory holes) were sent to the Environment Agency on 10th
September 2004 for comment. A copy of the Phase 4 exporatory holes were also e-mailed to
the Environment Agency on 20th January 2005. The proposals for the Phase 6 site investigation
were sent to the Council and the Environment Agency for comment prior to the site works
commencing. No comments were received on the proposals for either the Phase 4 or the
Phase 6 site investigations.
3.6.6 Electronic copies of all of the site investigation factual reports and chemical test data were sent
to the Environment Agency in 2007. No comments on the information submitted were received.
Regulators were also provided with the Orders ES and Technical Annex in 2008.
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3.6.7 Consultations were undertaken with Remediation Contractors in 2006 and 2007 2006/2007 and
in 2009. The information obtained is included in Section 8.
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4. METHOD STATEMENT
4.1 Introduction
4.1.1 This section provides a review of the methodologies adopted for the investigations and
assessments undertaken for the site investigations for the Mersey Gateway Project.
4.2 Methodology for EIA Assessment
4.2.1 The overall investigation strategy followed the guidance given in the following:
a. BS10175: 20012011. Investigation of Potentially Contaminated Sites – Code of
Practice.
b. BS5930: 1999. Code of Practice for Site Investigations (and amendments in 2010).
c. Highways Agency Design Manual for Roads and Bridges (DMRB).
d. Environment Agency, 2004. Contaminated Land Report (CLR) 11: Model Procedures
for the Management of Contaminated Land.
4.2.2 The overall strategy for the investigations involved the following:
a. Identifying and obtaining existing information on ground, groundwater and sediment
contamination held by the Council and third parties.
b. Establishing information gaps from historical investigations and obtaining additional
published information.
c. Preparation of Conceptual Models and undertaking of a Qualitative Risk Assessment.
d. Preparation of Health and Safety Plans for the Site Investigations.
e. Design of a phased intrusive investigation to fill information gaps and assess issues
identified during previous investigations.
f. Preparation of Contract Documents and tendering.
g. Undertaking Exploratory Site Investigations
h. Submitting samples for laboratory analysis and interpreting the results
i. Update of previous Conceptual Model and Qualitative Risk Assessment together with
Quantitative Risk Assessment where appropriate. A tiered approach has been adopted
for the risk assessment.
j. Assessing arisings from possible areas of excavation for hazardous waste.
k. Identifying potential mitigation measures.
l. Reporting via a Technical Annex to the Environmental Statement.
m. Monitoring of groundwater, ground gas and vapours during investigations with the
integration of new monitoring points into any ongoing monitoring programme as
appropriate.
4.2.3 The site investigations were undertaken to obtain information in order to establish the baseline
conditions in the Project area and to assess the potential impacts relating to the Project.
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4.3 Review of Desk Study Information
4.3.1 A review of published information obtained on historical site uses and ground conditions for the
Mersey Gateway Project area and information obtained from previous investigations has been
undertaken.
4.3.2 Information on site history was obtained from the following sources:
a. Historical Ordnance Survey Maps and Envirocheck Reports from Landmark
b. Public Records Office at Kew
c. Catalyst Museum in Widnes
d. Halton Borough Council
e. Cheshire County Council Records Office
4.3.3 Published information on ground conditions was obtained from the British Geological Survey
and Environment Agency and from previous reports. The previous reports were obtained from
the Council.
4.3.4 When there were ammendments to the Project area, for instance the addition of toll plazas at St
Michaels Golf Course, then the review was extended to include such areas.
4.3.5 A review of the historical land uses based historical ordnance survey (OS) maps and ground
conditions from previous reports is included in Section 5.
4.3.6 An updated Envirocheck Report was obtained for the Project area in 2011. However, the
historical OS maps previously obtained from Landmark were still considered to be appropriate
for providing information on previous land uses on and adjacent to the Project area. Further
research was undertaken during the preparation for the Public Inquiry in 2009 along with a
documentary survey on the potential for radiological contamination at the former ICI Works
(Area C) in 2011.
4.3.7 The objective of the desk based studies was to establish the nature of both previous and current
land uses in the Project area and the likelihood or otherwise that these might have given rise to
contamination. In addition, these studies were intended to identify the likely nature of the
contaminants that could be present depending on the processes and activities carried out on
the land in question. This information was used to inform the design of the subsequent
investigations and the laboratory analysis that was carried out.
4.4 Introduction to Site Investigations
4.4.1 The site investigations comprised geophysical exploration and intrusive site investigation
methods.
4.4.2 The locations of the exploratory holes and geophysical transits were chosen in order to
investigate ground conditions within the vicinity of the proposed route and areas of possible
contamination highlighted from the historical investigation, reports and plans. The investigations
took account of the information available at the time the investigation was designed. The site
investigations have been undertaken in phases to take into account developing proposals for
the Mersey Gateway Project and to take into account information obtained on ground conditions
from preceding phases.
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4.4.3 At the time that the Phase 1 to 3 intrusive investigations and geophysical works were designed,
it was acknowledged that the proposed route alignment was liable to change as more project
information, such as traffic information, ecology and population studies became available. The
methodology for these investigations was, therefore, designed such that the investigation could
consider a number of different alignments. For example, the sub-bottom geophysical profiling
along the southern channel of the estuary covered over 2km distance, from the existing Silver
Jubilee Bridge.
4.4.4 The geophysical and site investigations were undertaken in a series of stages, which allowed for
a review of data between each successive phase. The results from the site investigations were
used to improve the reliability of data interpretation from the geophysical surveys, and to provide
a reference to known ground conditions. An outline of the methodologies behind each type of
investigation is included below under the following headings:
a. Geophysical Investigation
b. UXO Desk Top Threat Assessment and Detailed Risk Assessment
c. Site Investigation
d. Groundwater, Ground Gas and Vapour Monitoring and Groundwater Sampling
4.4.5 The stages of the investigation works are summarised on Table 4.1 and 4.2:
Phase Objective Site
Investigation
Contractor’s
Reference
1 Saltmarsh Geophysical Investigation
To determine the depth and structure of bedrock beneath the areas of
saltmarsh on the banks of the Mersey Estuary
Phase 1
2 South Channel Geophysical Investigation
To determine the depth and structure of bedrock in the main southern
channel of the Mersey, between the key crossing points
Phase 2
3 Runcorn Sands Geophysical Investigation
To determine the depth to bedrock on the proposed crossing routes
over Runcorn Sands.
Phase 3
Table 4.1 – Phases of the Geophysical Investigation
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Phase Objective Site
Investigation
Contractor’s
Reference
1 Land Based Site Investigation (2002)
To determine the ground and groundwater conditions in the areas north
of St Helens Canal and south of the Manchester Ship Canal (MSC) to
the junction with the Bridgewater & Daresbury Expressway.
Phase 1
2 Saltmarsh Site Investigation (2002)
To determine the ground and groundwater conditions beneath the
saltmarsh areas.
Phase 2
3 Runcorn Sands Site Investigation (2002)
To determine the ground and groundwater conditions at shallow depth
within the inter-tidal area of the estuary.
Runcorn Sands
Site Investigation
(Phase 3)
4 Additional Site Investigation (2005)
To determine the route specific ground and groundwater conditions in
the areas north of St Helens Canal, on Wigg Island and beneath the
saltmarsh areas.
Phase 4
4A Additional Site Investigation (2006)
To determine the route specific ground and groundwater conditions for
the Catalyst Trade Park and Spike Island.
Phase 4A
Catalyst Trade
Park Site
Investigation
5 Additional Site Investigation (2006)
To determine the route specific ground conditions within the estuary.
Phase 5 Estuary
Investigation
6 Additional Site Investigation (2007)
To determine the route specific ground and groundwater conditions
based on reference design. The area between Ditton Roundabout and
Speke Road in Widnes was added to the project area by the Council in
2006.
Phase 6
7 Additional Site Investigation (2010)
To determine the ground and groundwater conditions on land north of
Hutchinson Street and on Spike Island in Widnes. The work at
Hutchinson Street was undertaken to inform the acquisition of this site
and at Spike Island to assess off-site migration of contaminants in
groundwater. This data obtained has been included in Section 6
(Baseline).
Phase 7
Table 4.2 Phases of Site Investigation
4.5 Geophysical Investigation
4.5.1 The geophysical investigation was sub divided into three sections as follows:
a. Phase 1 – To determine the depth and structure of bedrock beneath three areas of
saltmarsh on the banks of the Mersey Estuary.
b. Phase 2 – To determine the depth and structure of bedrock in main southern channel of
the Mersey, between the key crossing points.
c. Phase 3 – To determine the depth to bedrock across the proposed crossing routes on
Runcorn Sands.
4.5.2 Two corridors were surveyed, an eastern and a western corridor. The locations of these
corridors are discussed in Section 6.2.
4.5.3 The positions of the various geophysical investigations are shown in Appendix C.
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4.6 Methods employed for geophysical investigation
4.6.1 The following is a summary of the methods employed during the different phases of the
geophysical investigation. Further details are included in Appendix C.
4.6.2 Three main methods of geophysical surveying were used during the investigation, as follows:
a. Seismic Refraction Survey (Phases 1 & 3).
b. Seismic Reflection Survey (Phases 1 & 3).
c. Boomer Survey (Phase 2).
Seismic Refraction Survey
4.6.3 Seismic Refraction surveying relies on the contrasts in the acoustic transmissive properties of
earth materials to determine geological structure, with more dense materials exhibiting higher
seismic velocities. An energy source such an impacting hammer or explosive source (i.e.
Buffalo gun) was used to produce a shockwave, which travelled through the subsurface material
structure.
4.6.4 An array of geophones was then used to record the travel times of this wave from the source.
After processing, this information was used to provide a representation of the subsurface
geometry (known as the „seismic velocity structure‟).
Seismic Reflection Survey
4.6.5 The seismic reflection profiling used a similar approach to the refraction surveying, but the
results showed the physical structure of the subsurface materials rather than on the seismic
velocity structure.
4.6.6 The process relies on the capability to detect the reflected pulse, which requires a sufficiently
small attenuation of seismic energy. This method, therefore, can prove difficult where overlying
material causes deterioration of the energy pulse.
Boomer Survey
4.6.7 The Boomer Survey relates to the type of seismic source used for the marine geophysical
survey carried out in the southern channel of the estuary.
4.6.8 The acoustic pulse produced is from a „Boomer‟, using an electromotive plate or small capacity
airgun to produce a large acoustic source through the water column. The source is either hull
mounted or towed behind the survey vessel.
4.6.9 Instead of geophones being used to pick up the returning pulse, this method uses hydrophones,
towed behind the survey vessel in the water.
4.6.10 The profile produced utilises the principles of seismic reflection, producing a high-resolution
marine seismic reflection (or „sub-bottom‟) profile and can produce continuous sections to
depths of up to 100m beneath the riverbed.
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4.7 Extent of Geophysical Surveys
4.7.1 A total of 24 refraction profiles were acquired from Phases 1 and 3 of the geophysical
investigation. A minimum of seven individual shots were taken to form each profile line, this
was intended to ensure adequate subsurface coverage. Where depth to bedrock was greater,
the shots per line were increased to 11 to 19 to ensure sufficient information was obtained at
the profile margins.
4.7.2 Twelve reflection profiles were acquired from Phases 1 and 3 of the geophysical investigation.
The ground conditions on Widnes Warth (north of the River Mersey) were well suited to
reflection surveying, however, at Wigg Island the conditions were found to be less favourable,
probably due to the presence of organic material. Organic material rapidly attenuates the high
frequency signals required for reflection surveys and results in reduced accuracy and definition.
4.7.3 The Phase 2 Boomer survey was undertaken where there was sufficient water depth to allow
the survey vessel to operate, this limited the survey to the main, southern channel of the River
Mersey.
4.7.4 The main objective of the seismic surveys was the identification of the bedrock surface across
the estuary and saltmarshes. One of the significant observations was the variation in seismic
velocity at the rockhead. This is interpreted as the gradual transition from completely weathered
sandstone to competent rock, and was particularly noted on the southern side of the estuary.
This aspect is discussed further in the Geophysics Report in Appendix C.
4.7.5 The weathering profile of the rockhead, and the different physical properties of the ground
measured by the geophysical techniques resulted in an interpreted variation in the rockhead of
+2.0m across the survey area.
4.7.6 For the western corridor, the geophysical results were found to be in general agreement
between the main reflector surface and the top of the weathered rock profile. The marine profile
data did not record the top of solid rock to compare against the terrestrial data. This was
attributed to the attenuation of the boomer source within the weathered material.
4.7.7 A nominal accuracy of +2.0m was attributed to the rockhead elevations obtained by the
geophysical surveys, based on a comparison between the geophysical and intrusive
investigation results. In areas with no intrusive investigation and consequently no local
elevation control for the geophysical modelling software, this accuracy would likely decrease to
+2.0m.
4.8 Unexploded Ordnance (UXO)
4.8.1 Information was requested by Gifford from the British Army (33 Explosive Ordnance Disposal
Regiment in Salisbury) in 2002 as to whether they held any records of unexploded ordnance in
the project area between Bowers Business Park in Widnes and Astmoor Industrial Estate in
Runcorn (the project area under investigation for the Mersey Gateway in 2002). No records
were obtained within the Project area.
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4.8.2 A Desk Top Explosive Ordnance Threat Assessment was commissioned by the Council in 2006
prior to the Phase 5 Estuary investigation. This assessment was undertaken by BACTEC and
was based on the Mersey Gateway Project area between Junction 12, M56 and the proposal for
a new junction (Junction 11A) on the M56 in Runcorn and the Speke Road/St Michaels Golf
Course in Widnes. A copy of this report is located within Appendix D.
4.8.3 A detailed UXO risk assessment was prepared by BAE Systems in 2011 in accordance with
CIRIA C681 (2009) for the moderate risk areas identified by BACTEC for the construction
works. A copy of the BAE report is located within Appendix R.
4.9 Radiological Contamination
4.9.1 A review of the documentary evidence obtained relating to radiological contamination was
undertaken by Radman Associates for the former ICI Works in Area C. This was based on
identifying the historical work undertaken relating to radiological materials and the potential for
radiological contamination which included reviewing previous surveys. A copy of this report is
located within Appendix S.
4.10 Intrusive Site Investigations
4.10.1 The intrusive site investigations were undertaken to obtain information on the ground conditions,
the groundwater regime and the presence of contamination to establish the baseline ground
conditions within the study area and assess whether possible impacts could be introduced as
part of the proposed scheme. The factual reports from the site investigations are located in
Appendices E to J. The exploratory hole location plans for Phases 1 to 6 of the ground
investigation are shown on Drawing Nos. MG_REP_EIA_009/004 to MG_REP_EIA_009/009.
4.10.2 The site investigation works were undertaken by the following contractors and during the
following dates:
Table 4.3 – Contractors for the Site Investigations
Phase of Site Investigation Contractor Commencement
of Site Works
Completion of
Site Works
1 Land Based Intrusive Investigation Norwest Holst Soil
Engineering Ltd
30 April 2002 24 June2002
2 Saltmarsh Intrusive Investigation Norwest Holst Soil
Engineering Ltd
19 August 2002 21 September
2002
3 Runcorn Sands Site Investigation Geotechnics Ltd 1 October 2002
26 November
2002
10 October 2002
28 November
2002
4 Additional Site Investigation (2005) Soil Mechanics 10 January 2005 28 February 2005
4A Additional Site Investigation (2006) Soil Mechanics 16 January 2006 1 February 2006
5 Additional Site Investigation Fugro/Seacore 23 October 2006 11 November
2006
6 Additional Site Investigation Soil Mechanics 26 March 2007 22 May 2007
7 Additional Site Investigation Allied Exploration
and Geotechnics
Ltd
1 November 2010 5 November 2010
4.10.3 It had been intended the Phase 1 and 2 site investigations would commence during March 2002
within the land based areas and on the saltmarshes. However, concerns regarding the
possibility of disturbance to nesting birds meant the investigation was divided into two sections,
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with the saltmarsh work (Phase 2) being delayed until the end of the nesting period. Access to
the saltmarshes in Widnes and Runcorn was also required for the Phase 4 site investigation in
2005 and required that these exploratory holes be completed before the start of the bird
breeding season.
4.10.4 The Phase 3 Runcorn Sands investigation differed from the earlier phases of the intrusive
investigation in that the objective of this investigation was solely to gain information on the river
alluvium at shallow depths (less than 5.0m below bed level at the time of the investigation). The
aims of the Phase 3 investigation were to identify the possible presence of contaminants and
the grading of sediments.
4.10.5 Table 4.4 outlines the number and type of exploratory holes that were undertaken during each
phase of the intrusive investigations:
Table 4.4 – Extent of the Intrusive Investigations
Phase
No. Light Cable
Percussion
Boreholes
No. Rotary
Boreholes (as
follow-on)
No. Window
Samples
No. Trial
Pits/Trenches
1 & 2 39 13 3 25
3 - - 26 -
4 17 7 9 -
4A 8 - 8 -
5 5 5 2 -
6 89 8 35 -
7 6 - 4 -
4.10.1 In July 2008 an investigation was undertaken by the Council to the south and west of the
Project area to assess migration of the Dense Non-Aqueous Phase Liquid (DNAPL) that has
been encountered on the Catalyst Trade Park site. This investigation was not linked to the
Project but was a result of the Council‟s assessment strategy under Part IIA. This investigation
comprised six cable percussion boreholes at Spike Island and sites close to the Catalyst
Museum which were considered to be areas that could have been affected by DNAPL.
4.10.2 Groundwater testing was undertaken by the Council and the results obtained have been
considered in the baseline assessment (Section 6).
4.11 Site Supervision during Site Investigations
4.11.1 Site supervision was undertaken by Gifford during all of the intrusive site works to provide on-
site liaison during the works, review the arisings and provide decisions on obtaining samples for
testing.
4.11.2 Engineers from the site investigation Contractors were present throughout their respective site
works to provide descriptions of the arisings. Preliminary logs were prepared on-site, based on
the samples obtained from the exploratory holes with the exception of the Phase 1 and 2 site
investigations where the driller‟s records were provided to Gifford during the investigation. Final
exploratory hole logs were prepared following completion of the site works.
4.12 Phase 1, 4, 4a, and 6 and 7 – Land Based Site Investigations
4.12.1 These investigations covered the area of Widnes to the north of the St Helens Canal and
Runcorn to the south of the Manchester Ship Canal. They also included two areas of Wigg
Island (to the south of the River Mersey) located north of the Manchester Ship Canal.
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Investigations within the land based areas were undertaken during the Phase 1, 4, 4a and 6 and
7 site investigations.
4.12.2 The exploratory holes included light cable percussive boreholes (LCP), rotary boreholes and
windowless sampler holes to a maximum depth of 55.00m bgl (BH43 in Widnes drilled during
the Phase 4 investigation in 2005).
4.12.3 Trial pits and trenches were undertaken during the Phase 1 and 2 site investigations on Bowers
Business Park and the former ICI Muspratt Works as these areas of land were not in use at the
time of the investigation. Trial pits were also excavated towards the western boundary of
Thermphos, along with one adjacent to the Catalyst Trade Park and one between the Garston
to Timperly Rail Freight Line and the A557 Expressway. Two trial pits were excavated during
the Phase 2 investigation in an area of made ground located at the northern edge of Widnes
Warth. Trial pits were not undertaken during subsequent phases of the investigation to
minimise potential issues associated with re-instatement, particularly at operational sites and
allow for installing monitoring wells in exploratory holes.
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4.12.4 The exploratory holes carried out in Runcorn and Widnes were as follows:
Table 4.5 – Phase 1 (2002) Exploratory Hole Groupings in Widnes
Widnes
Exploratory Hole ID Present Land
Owner/s
Present Land Use/s Previous Land
Use/s
BH1 Halton Borough
Council
Road Verge,
Bowers Business Park
Various works
BH7, 10, 9, 10A
TP15, 16, 17, 18, 19
Broadthorn Ltd No current usage –
soils recycling (at time
of intrusive
investigation)
Chemical Works,
including alkali
and phosphorous
BH1001, TP1002, TP1004 Thermphos (formerly
Rhodia)
Manufacture of Food
Additives
Chemical Works,
(alkali &
phosphorous),
Gas Works,
Waste disposal
BH4, 6
TP6, 10, 11, 12, 13, 14
Halton Borough
Council
Bowers Business Park Railway Branch
Lines
BH1003 St Modwen
Properties Plc
Open Land
BH1004, BH1005 Broadthorn Ltd Saltmarsh Chemical Works
(BH1004) &
saltmarsh
BH41, WS07 Thermphos (formerly
Rhodia)
Manufacture of Food
Additives
Works
BH43 Fallon Brothers Scrap Yard Works
BH38 Fallon Brothers Metal Recycling Works.
BH39 S.Evans & Sons Scrap Yard Works
BH50, WS15 Halton Borough
Council
Road verge Works
BH52 Halton Borough
Council
Traffic Island Works
BH53 Halton Borough
Council
Roundabout
(landscaped area)
Works
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Table 4.6 – Phase 4 (2005) Exploratory Hole Groupings in Widnes
Exploratory Hole ID Present Land
Owner/s
Present Land Use/s Previous Land
Use/s
BH42, BH42A, BH42B,
BH44, BH45, BH46, BH47,
BH56, WS08, WS09,
WS10, WS10A, WS11,
WS12, WS13, WS14, WS21
St Modwen
Properties Plc
Business Park Works
BH55, BH57 Halton Borough
Council
Open Land Works
Table 4.7 – Phase 4A (2006) Exploratory Hole Groupings in Widnes
Exploratory Hole ID Present Land
Owner/s
Present Land Use/s Previous Land
Use/s
BH66, BH71 Thermphos (formerly
Rhodia)
Manufacture of Food
Additives
Works
BH65C, BH101 to BH108,
WS29 to WS47
St Modwen
Properties Plc
Business Park Chemical Works
BH100 Plumb Centre Car Park Works
BH97A BH99, Halton Borough
Council
BH95 Fallon Brothers Metal Recycling Works.
BH82 S. Evans & Sons Scrap Yard Works
BH79, BH81, BH83, BH85
to BH92, BH94, BH96,
BH98
Halton Borough
Council
Road Embankment/
verges
Railway, Works
BH51, BH54, BH58,
WS16A, WS17, WS20,
WS22
Gussion
Transport/Widnes
Tank Container
Services
Light industrial/
workshops, lorry and
container park
Works
BH59, BH60, WS23, WS24,
WS25
Former Anglo
Blackwell site - now
owned by the
Council
Storage – previously
used for metal Alloy
manufacture
Works
BH53A, BH77, BH78, BH80 Halton Borough
Council
Roundabout Works, railway
BH61 to BH64, BH67,
BH69, BH70, BH72 to
BH76, BH93, WS26, WS27
Halton Borough
Council
Roundabout, Road
Verge and Golf Course
Works
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Table 4.8 – Phase 6 (2007) Exploratory Hole Groupings in Widnes
Exploratory Hole ID Present Land
Owner/s
Present Land Use/s Previous Land
Use/s
BH146 to BH148, WS52 to
WS55
Halton Borough
Council
Reclamation Yard Railway
BH149 to BH151 Halton Borough
Council
Open landscaped area Chemical Works
Table 4.25 – Phase 7 (2010) Exploratory Hole Groupings in Widnes
Runcorn
Exploratory Hole ID Present Land
Owners
Present Land Use Previous Land
Use
BH 28, 29 Highways Authority Road Verge
BH 22, 24, 25, 27 Astmoor Industrial
Estate
Various including car
parking, warehousing
& pharmaceuticals
Greenfield
Table 4.9 – Phase 1 (2002) Exploratory Holes Groupings in Runcorn
Exploratory Hole ID Present Land
Owners
Present Land Use Previous Land
Use
BH31 Manchester Ship
Canal Company
Road Verge
BH32, WS01 – 04 Halton Borough
Council
Open landscaped
area
Landfill
(landraise)
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Table 4.10 – Phase 4 (2005) Exploratory Holes Groupings in Runcorn
Exploratory Hole ID Present Land
Owners
Present Land Use Previous Land
Use
BH30 Vantrunk Light industrial
(Astmoor Industrial
Estate)
Open land
BH84, BH113, BH117 Astmoor Industrial
Estate
Open land
BH68, BH119, BH120 Peel Holdings Bridgewater Canal
towpath
Bridgewater
Canal towpath
BH112, BH114, BH116,
BH118
Halton Borough
Council
Road and verges Road and verges
BH110, WS109 Halton Borough
Council Road verges Road verges
BH121 to BH126, WS48 to
WS51
Halton Borough
Council Road and verges Road and verges
BH127 to BH131 Halton Borough
Council Road verges Road verges
BH132 to BH135 Halton Borough
Council Road verges Road verges
BH136 to BH145 Halton Borough
Council, private land
Verges, field, garden
4.13 Overall Approach to Land Based Site Investigations
4.13.1 The exploratory holes were scheduled to reach sufficient depth in order to obtain information on
ground conditions relevant to that part of the proposed scheme.
4.14 Methodology for Boreholes – Light Cable Percussion (LCP)
4.14.1 All boreholes carried out during the Phase 1, 2, 4 to 67 site investigations were commenced
using LCP drilling techniques. These drilling rigs were trailer mounted and utilised cable-
operated tools to sample the soils encountered.
4.14.2 The sampling regime from boreholes comprised the following:
a. Disturbed samples (for geotechnical and contamination testing)
b. Bulk samples
c. U100 „undisturbed‟ tube samples
4.14.3 Samples were taken at intervals as directed by Gifford. Disturbed samples were obtained as
soon as each of the soil horizons was encountered and then at regular intervals throughout the
horizon, U100 tube samples were taken only in cohesive soils.
4.14.4 In granular soils, Standard Penetration Tests (SPT) were undertaken rather than U100 samples
to provide information on the in-situ density of the soil. Disturbed samples were also recovered
with each SPT.
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4.14.5 Groundwater samples were recovered from monitoring wells on completion rather than during
drilling (see Section 4.28).
4.14.6 The LCP boreholes were advanced to either a specified depth, to a specified horizon or to the
top level of bedrock, depending upon their location and the information required at each
position. Where the borehole was extended into bedrock using LCP, the material was proved
by means of „chiselling‟. Boreholes that were not installed with monitoring wells were backfilled
with grout upon completion and the spoil removed for off-site disposal.
4.15 Methodology for Boreholes – Rotary
4.15.1 Boreholes were extended in the bedrock by means of rotary coring to produce an intact core
sample of the rock material. This was primarily undertaken to ensure that bedrock had been
proved, i.e. the material was not a boulder in the glacial till and to install groundwater monitoring
wells into the bedrock.
4.15.2 Cores were recovered from rotary boreholes for geotechnical testing.
4.16 Methodology for Window Sample Holes
4.16.1 The window sampler holes were advanced up to 10m bgl. The starting diameter of the window
sample tube was sufficient to allow a reduction in diameter at the base of any encountered
made ground. The window sample holes that were not installed with monitoring wells were
backfilled with grout upon completion and the spoil removed for off-site disposal.
4.17 Methodology for Trial Pits
4.17.1 Trial pits were excavated in areas of suspected made ground during the Phase 1 and 2 site
investigations in Widnes to allow for a visual inspection of the materials excavated and exposed
within pit walls. These trial pits and trenches were of shallow depth, typically less than 4.00m
bgl.
4.17.2 The trial pits were generally 3 to 4m in length and excavated to the maximum reach of the
excavator used, which depending on the machine was approximately 3.8m to 4.2m bgl. The
trial trenches were very similar to the pits, but ranged from 5.5m to 18m in length.
4.17.3 Disturbed samples were taken at intervals specified by Gifford.
4.17.4 The material excavated from the trial pits was placed on plastic sheeting to prevent
contamination of the underlying soils. Most of the trial pits undertaken were carried out within
made ground and did not encounter natural ground. Where this was the case, arisings were
used for backfilling the pit. Natural ground was encountered in the base of six trial pits, and was
excavated to a maximum depth of 2.10m below the made ground. Where natural ground was
encountered, the arisings were kept separate from the made ground, the materials were then
backfilled in the same order in which they were excavated. Where natural ground was involved,
this was replaced in the correct horizon, with the made ground placed above it. Any material
that not be used for reinstatement was disposed off-site at a suitably licensed facility.
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4.18 Soil Sampling Methods
4.18.1 Samples for contamination testing were typically recovered from exploratory holes at 0.0-0.2m,
0.5m, 1.0m and then at 1m intervals or each change in horizon, unless specified by Gifford.
Samples were selected to be representative of the materials and/or contamination encountered.
When areas of contaminated materials were identified either by visual or olfactory means then
additional samples were recovered. Soil samples recovered for chemical testing were stored in
plastic tubs, glass amber jars and volatile organic compound (VOC) vials.
4.18.2 In accordance with BS10175 and chemical testing laboratory requirements (and later
requirements for MCERTS (see Section 4.18.3 below)) the Contractor was prepared a sample
report for each sample which was recorded on the laboratory Chain of Custody form. Copies of
the sample reports were maintained on site, and a copy of all sample reports was passed to the
Gifford site engineer at the end of each working day.
4.18.3 For the chemical testing of soil, where results are to be submitted to the Environment Agency
for regulatory purposes, it is a requirement that laboratories are accredited to the current version
of the European and international standard, ISO/IEC 17025 using the Monitoring Certification
Scheme (MCERTS) to deliver high quality environmental measurements. Accreditation of
MCERTS is undertaken by the United Kingdom Accreditation Service (UKAS). The MCERTS
performance standard was introduced in May 2003 for compliance by March 2005 and covers
performance targets, the selection and validation of methods, sampling pre-treatment and
preparation, participation in proficiency testing schemes, and the reporting of results and
information.
4.19 Cleaning of Equipment between Exploratory Holes and Sampling Events
4.19.1 The Contractor‟s method for forming exploratory holes was required to minimise the risks of
cross contamination between horizons, between exploratory holes and between samples.
4.19.2 The Contractor was required to wash all drilling and sampling equipment used in contaminated
ground between exploratory holes. The Contractor was also required to ensure that the
washing of equipment to prevent cross contamination did not result in any additional
contamination of soils or groundwater.
4.20 Prevention of Cross Contamination between Horizons
4.20.1 Where material suspected or known to be contaminated was encountered during the site
investigation the Contractor was required to immediately notify Gifford. Where the
contaminated material or suspected contaminated material was subsequently underlain by
material that may act as a barrier to the downward or lateral migration a bentonite seal was
installed before penetrating the barrier horizon. This approach required the use of multiple drill
string casing and the re-drilling of the bentonite seal.
4.20.2 If at any time concrete or other obstructions was encountered in made ground the Contractor
was required to inform Gifford.
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4.21 Protective Measures for Boreholes in Contaminated Ground.
4.21.1 The minimum diameter of any LCP borehole was 150mm. However, if made ground was
suspected or known to be present the minimum initial diameter was increased to 200mm, this
then in turn allowed for a reduction in diameter when natural ground was encountered. In this
way contaminated soils and/or groundwater could be sealed off from contact with deeper
horizons.
4.21.2 An allowance was made for installing a seal of bentonite at the reduction of casing if required.
The number of reductions in casing size in each material was left to the discretion of the
Contractor, provided the casing diameter was not less 200mm in made ground and 150mm in
natural ground.
4.21.3 The Contractor was required to report to the Gifford as soon as material considered to be made
ground was encountered and to report further when the base of any made ground was reached.
This allowed Gifford to make a judgement on whether boreholes should proceed beyond the
base of the made ground and the need for casing reductions and bentonite seals.
4.21.4 The reduction in casing upon reaching natural ground was undertaken to reduce the potential
for contaminants in the made ground being carried into the underlying natural ground and for
the opening up of pathways for the flow of contaminated groundwater.
4.21.5 Upon completing the borehole it was either grouted to surface using a cement/bentonite
mixture, or a groundwater/ground gas monitoring well was installed. Arisings from the
boreholes were not permitted to be used as backfill material.
4.21.6 This approach was adopted for land based boreholes and those on the saltmarshes.
4.22 Disposal and Security of Arisings
4.22.1 The Contractor was responsible for arranging the collection and disposal of all arisings and/or
waters obtained during the site investigation to suitably licensed waste disposal facilities.
4.22.2 Where it was known or suspected that arisings may be contaminated, the Contractor was
required to ensure these were secured at the end of each working day to prevent contact by the
public or site staff.
4.23 Permeability Testing Methodology
4.23.1 A total of 24 in-situ falling head permeability tests were undertaken during the Phase 6 site
investigation in Widnes.
4.23.2 These permeability tests were undertaken during the drilling of boreholes by adding a column of
at least 1m of water rapidly into the hole and then monitoring the rate of water dissipation. Such
tests are known as falling or variable head tests. The calculation of soil permeability was
undertaken using the approach outlined in Section 24.4.6 of BS5930:1999 for variable head
permeability tests.
4.23.3 The results of the permeability testing are located in Section 6.22 and in the Soil Mechanics
Phase 6 Site Investigation Factual Report in Appendix J.
4.24 Phase 2 and 4 – Saltmarsh Investigations
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4.24.1 Site investigations on the saltmarshes were undertaken during the Phase 2 and 4 site
investigations. The saltmarsh investigation methodology included LCP boreholes some of
which were advanced into the rock using a rotary rig, window samplers and the excavation of
trial pits into an area of made ground on Widnes Warth. The exploratory hole logs from the
Phase 2 and 4 investigations are located in Appendix E and G respectively. The saltmarsh
phase exploratory holes were as follows:
Table 4.12 – Phase 2 (2002) Saltmarsh Exploratory Holes in Widnes
Exploratory Hole ID Present Land
Owners
Present Use Previous Use
BH12, BH13, BH14,
BH1004, BH1005
TP20, TP21 WS1 to
WS3
Broadthorn Ltd Saltmarsh 1905 OS map shows BH1004 is
located on site of a former
chemical works
Table 4.13 – Phase 2 (2002) Saltmarsh Exploratory Holes in Runcorn
Exploratory Hole ID Present Land Owners
Present Use Previous Use
BH15, BH17, BH18A,
BH19-19C, BH20
Manchester Ship
Canal Company
(MSC) & Halton
Borough Council
Saltmarsh,
Public Open
Space
BH19 and BH20 located at a
former Chemical Works. BH18A
located on former Wigg Island
Landfill.
Table 4.14 – Phase 4 (2005) Saltmarsh Phase Exploratory Holes in Widnes
Exploratory Hole ID Present Land Owners
Present Use Previous Use
BH35 to BH40
WS5, WS6
Broadthorn Ltd Saltmarsh 1905 OS map shows BH40 and
WS6 located at site of a former
chemical works and tip
(respectively)
Table 4.15 – Phase 4 (2005) Saltmarsh Phase Exploratory Holes in Runcorn
Exploratory Hole ID Present Land
Owners
Present Use Previous Use
BH33, 34 (saltmarsh)
BH32
WS01-04 (Wigg
Island landfill)
MSC Company &
Halton Borough
Council
Saltmarsh,
Public Open
Space
Historical OS maps show BH32
and WS01-04 located at eastern
end of former tip associated with
former „Wigg Works‟ alkali
factory.
4.24.2 From the historical information obtained, the saltmarshes are thought to have had only very
limited use for industrial purposes so little made ground was expected. The possible exceptions
to this were two areas of raised ground on Widnes Warth located immediately south of St.
Helens Canal.
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4.24.3 In addition to this historical OS maps show the Wigg Works (Alkali) to the west of the route
alignment on Wigg Island in Runcorn. This works was located towards the existing swing bridge
access to Wigg Island. To the east of former Wigg Works and immediately north of the
Manchester Ship Canal, is the former Wigg Island Landfill (landraise) which is located on former
saltmarsh. At the eastern end of this landfill is the site of the former Kemet works. Between the
former Kemet Works and Wigg Island Landfill is a spur of the former Latchford Canal. A more
detailed review on the site history is located in Section 5.
4.24.4 The saltmarshes are a sensitive wildlife habitat so steps were taken during this phase of the
ground investigation to ensure that the possibility of any damage and disturbance was
minimised. These measures are detailed below.
Saltmarsh Exploratory Holes
4.24.5 The methodology for the boreholes, window sample holes and trial pits was the same as that
used for the investigation of the land based areas. The positions of the saltmarsh exploratory
holes are shown on Drawing Nos. MG_REP_EIA_009/004 and MG_REP_EIA_009/005.
4.24.6 To minimise damage to the saltmarshes along the routes to the boreholes, the rigs were moved
by hand along wooden boards during the Phase 2 investigation and a semi-amphibious six
wheel drive „Supacat‟ vehicle with wooden boards underlain by plastic sheeting. At each
borehole position, a work area was laid out on boards, with plastic sheeting placed on top. A
bund was formed beneath the plastic sheeting around the work area to retain run-off water
arising from the borehole.
4.24.7 The majority of shallow saltmarsh boreholes were cased using 150mm diameter casing from
ground level, as made ground was not anticipated. BH18A and BH1004 were commenced with
casing of 200mm diameter as these were located on raised areas of fill. All of the Phase 4 site
investigation boreholes on the saltmarshes were commenced using 200mm diameter casing,
reduced to 150mm during drilling, on order to reach the scheduled depth. The exception was
BH40 which commenced using 250mm diameter casing as this borehole was located on a
raised area of made ground and was required to reach bedrock which a previous phase of site
investigations (BH1004) indicated would be in the region of 40m bgl.
4.24.8 All of the boreholes carried out on the saltmarshes were completed by the installation of either a
shallow or deep monitoring well.
4.25 Phase 3 – Runcorn Sands Investigation
4.25.1 The Runcorn Sands Investigation was undertaken on the exposed sand banks of the River
Mersey, bounded by the two active channels at the northern and southern edges of the estuary.
The sand banks were accessed at low tide from the West Bank area in Widnes. A crane was
used to lift vehicles and drilling equipment onto the foreshore from the promenade.
Geotechnics Ltd factual report which includes the exploratory hole logs is located in Appendix F.
4.25.2 The investigation was undertaken using a semi-amphibious six wheel drive „Supacat‟ vehicle
and rigid inflatable boat (RIB) to carry personnel and equipment onto the sand banks. As the
sand bank and its access routes cover rapidly at high tide the state of the tides determined on
which days the investigation could be undertaken.
4.25.3 Between 1st October and 10
th October 2002, 16 exploratory holes were drilled. The method of
investigation comprised the following:
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a. Hand digging between 1.00 to 1.50m bgl followed by the installation of a plastic sleeve
to reduce potential for pit wall collapse;
b. Drilling by hand percussive boring, which allowed for the installation of casing to support
the sides of hole up to 3.00m bgl; and
c. Window sampling to depths of up to 5.00m bgl.
4.25.4 Dynamic sampling using window sampler tubes was used on the higher eastern end of the sand
bank as the sole method of drilling where ground conditions allowed. Each exploratory hole
was backfilled with arisings, although provision was made for material to be removed off-site
should olfactory or visual evidence of contamination be encountered.
4.25.5 Additional site investigation was undertaken between the 26th and 28
th November 2002 where a
further 10 exploratory holes were drilled. It was noted the sand banks had changed in profile
since undertaking the October 2002 site works; SS24 was now located on a low lying area
some 200m from the edge of a 2m high sand cliff on the north eastern end of the sand bank.
During the previous site works, the position of SS24 had been noted to be on the main sand
bank, within 10.00m of the sand bank cliff.
4.25.6 Access to the site in November 2002 was made using a rigid inflatable boat (RIB) to carry
personnel and the equipment to the sand banks each day. A hand held portable window
sampler was used to drill the exploratory holes.
4.25.7 Two exploratory holes were abandoned during the Phase 3 site investigation due to the
following reasons.
a. Extremely soft ground conditions at SS17.
b. SS23 was situated in an area covered by water at all states.
4.25.8 SS18 was relocated to SS18A due to the presence of very soft ground conditions at the original
location. SS25 to SS28 were moved from their original, proposed locations to coincide with
exposed sand banks during the site works. Therefore, SS25A to SS28A were relocated onto
low lying sand banks to the east, beyond the main channel.
4.25.9 The following samples were obtained:
a. Small disturbed samples were obtained for chemical analysis. These were typically
obtained from 0.20m bgl, 1.00m bgl, and then every 1.00m thereafter unless a change
in ground conditions was noted. Samples for chemical analysis were collected in both
1kg plastic tubs and also wide neck glass amber jars for organic analysis; and
b. Larger bulk samples were obtained mostly up to 1.00m bgl to undertake particle size
distribution (PSD) tests for the hydrodynamic modelling.
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4.26 Phase 5 – Estuary Investigation
4.26.1 The site works for the Phase 5 Estuary Site Investigation were undertaken between October
and November 2006. This investigation was undertaken to obtain information on ground
conditions within the estuary along the proposed alignment. This comprised the following:
a. 5 no. cable percussion boreholes with rotary coring (up to 51m bgl)
4.26.2 The works were carried out from a „Skate 1‟ jack up platform. Drilling tools and casing were
washed between exploratory holes to reduce potential for cross contamination. The washing
process involved using a bucket of water from the estuary to remove any visual signs of
material. A second bucket containing clean water (mains water)/detergent mix was then used
before a third bucket of clean water. Wash waters were removed off-site for disposal.
4.26.3 Water and sediment samples were obtained from the boreholes for chemical testing.
4.26.4 Each sediment sample comprised a plastic tub, 250g glass jar and a VOC vial which were
obtained from each borehole at every 1m or change in strata until bedrock was encountered.
4.27 Groundwater and Ground Gas Monitoring Wells in Exploratory Holes
4.27.1 Two types of well were installed in exploratory for the purpose of monitoring groundwater and
ground gas as follows:
a. shallow wells – installed into the made ground and drift material (50mm diameter, with
the exception of WS6 which was installed with 25mm diameter well screen during the
Phase 4 investigation); and
b. deep wells – installed into bedrock (50mm diameter, although 90mm diameter well
screens were used in deeper boreholes during the Phase 2 investigation).
4.27.2 The monitoring well locations are shown on Drawing No. MG_REP_EIA_010. Drawing Nos.
MG_REP_EIA_009/011 and MG_REP_EIA_009/012 show the details for the deep and shallow
monitoring wells respectively.
Monitoring Well Construction
4.27.3 Monitoring wells installed during the Phase 1, 2 and 4 investigations were constructed using
HDPE.
4.27.4 Due to the presence of potentially aggressive ground conditions noted in parts of Widnes during
earlier phases of the investigation and the requirement for long term monitoring the wells
installed in Widnes during the Phase 4A and 6 site investigations were constructed using
stainless steel. Monitoring wells in Runcorn were constructed using HDPE.
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Groundwater Monitoring Well Installations
4.27.5 The tables below shows the units into which each monitoring well was installed, along with the
depth to the base of the well screen as shown on the exploratory hole logs.
4.27.6 Phase 1 & 2 (2002) Site Investigation Monitoring Wells.
Table 4.16 – Formation and Depth of Monitoring Well Installations During Phase 1 & 2
Geological Unit & Borehole Descriptor Base of the Response Zone (m bgl)
Bedrock (Sandstone, except BH29)
BH1 37.50
BH14 40.90
BH15 23.50
BH22 16.00
BH24 20.00
BH25 18.00
BH1004 42.60
BH1005 24.80
BH29 (mudstone becoming siltstone) 6.40 (monitoring well dry)
Drift: Alluvium
BH7 10.00
BH10B 10.50
BH12 7.80
BH13 9.60
BH17 6.50
BH1003 10.00
Drift: Glacial
BH9 28.50
BH20 10.50
BH27 11.20
BH28 12.00
Made Ground
BH10A 3.00
BH18A 7.00 (monitoring well dry)
BH1001 4.00
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4.27.7 Phase 4 (2005) Site Investigation Monitoring Wells.
Table 4.17 – Formation and Depth of Monitoring Well Installations During Phase 4
Geological Unit & Borehole Descriptor Base of the Response Zone from Exploratory
Logs (m bgl)
Bedrock (Sandstone)
BH31 20.00
BH32 22.00
BH34 27.00
BH35 26.10
BH37 38.00
BH40 46.00
BH43 55.00
Drift: Alluvium
BH33 7.00
BH36 11.60
BH38 9.00
BH39 9.00
BH41 10.20
WS2 5.00
WS3 5.00
WS5B 4.00
WS6 7.00
Drift: Glacial
BH48 19.00
BH49 20.00
Made Ground
BH50 2.00
BH52 5.00
BH53 6.00
WS07 3.50
WS15 2.50(response zone includes glacial deposits)
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4.27.8 Phase 4a (2006) Site Investigation Monitoring Wells.
Table 4.18 – Formation and Depth of Monitoring Well Installations During Phase 4a
Geological Unit & Borehole Descriptor Base of the Response Zone from Exploratory
Logs (m bgl)
Drift: Alluvium
BH42 10.20
BH55 10.50
BH56 10.90
BH57 11.00
WS08 6.00
WS11A 5.50
Drift: Glacial
BH44 18.00
BH45 18.00
BH46 18.20
BH47 19.50
WS09 2.50
Made Ground
BH42B 3.00
WS10A 4.00
WS12 4.00
WS13 1.50 (response zone includes glacial clay)
WS14 2.00
WS21 1.50
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4.27.9 Phase 6 (2007) Site Investigation Monitoring Wells.
Table 4.19 – Formation and Depth of Monitoring Well Installations During Phase 6 (continued
overleaf)
Geological Unit & Borehole Descriptor Base of the Response Zone from Exploratory
Logs (m bgl)
Bedrock
BHRC30 28.00
BHRC121 11.00
BHRC123 26.00
BHRC124 (piezometer) 13.00
BH84 (piezometer) 17.10
BH114 (piezometer) 13.10
Drift: Alluvium
BH62 6.00 (includes made ground)
BH75 7.00
BH103 7.50
BH107 10.00
BH108 10.20
WS22 4.80
WS30 7.00
WS31 6.60
WS32 6.00 (includes made ground)
WS41 7.00 (includes made ground)
WS38 6.80
Drift: Glacial
BH54E 26.20
BH63 10.00
BH64 8.50
BH65C 15.60
BH66B (piezometer) 19.00
BH68A (piezometer) 9.80
BH71 (piezometer) 19.00
BH77 (piezometer) 20.50
BH80 (piezometer) 20.50
BH82 19.00
BH95 (piezometer) 18.00
BH99 17.50
BH100A (piezometer) 17.60
BH101 (piezometer) 20.00
BH102 (piezometer) 17.90
BH104 (piezometer) 16.20
BH106 16.95
BH117 (piezometer) 12.50
BH119 4.30
BH120 4.00
BH122 (piezometer) 5.00
BH131A 6.00
BH133 10.00
BH135A 6.00
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Table 4.20 (continued) – Formation and Depth of Monitoring Well Installations
During Phase 6
Geological Unit & Borehole Descriptor Base of the Response Zone from Exploratory
Logs (m bgl)
BH136 2.80
BH142 5.00
WS16A 3.00 (includes possible made gound)
WS50 5.00
WS51 6.00
Made Ground
BHRC140 6.30
BH53A 6.00
BH58 4.00
BH59 2.50
BH60 3.90
BH61 5.00
BH67A 5.00
BH69 7.00
BH70 9.00
BH72 9.00
BH73 7.00
BH74 5.00
BH76 5.00
BH78 5.50
BH93 4.00
BH97A 3.50
BH116 2.00
BH127 2.50
BH143 2.60 (includes glacial clay)
WS17 4.00
WS18 2.50
WS20 5.00
WS23 2.00
WS24 3.00
WS25 3.00
WS26 4.00
WS27 5.90
WS28 8.00
WS29 4.00
WS33 4.00
WS36 4.00
WS37B 3.00
WS40 4.00
WS42 4.00
WS43 3.00
WS44 3.00
WS46A 4.00
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Table 4.26 – Formation and Depth of Monitoring Well Installations During Phase 7
Geological Unit & Borehole Descriptor Base of the Response Zone from Exploratory
Logs (m bgl)
Drift: Alluvium
BH146 3.50
BH149 10.0
BH150 10.0
BH151 10.0
WS53 4.00 (includes made ground)
Drift: Glacial
BH147 20.0
Made Ground
WS52 1.50
WS54 1.80
WS55 1.80
4.28 Groundwater Sampling
4.28.1 The following rounds of groundwater level monitoring, sampling and testing have been
undertaken:
a. Round 1: September 2002
b. Round 2: January/February 2003
c. Round 3: March 2003
d. Round 4: January/February 2004
e. Round 5: September 2004
f. Round 6: December 2004
g. Round 7: July 2005
h. Round 8: December 2005
i. Round 9: February 2007
j. Round 10: May 2007
k. Round 11: October/November 2008
l. Round 12: December 2008
m. Round 13: August 2010
n. Round 14: October 2011
4.28.2 It should be noted that groundwater samples have not been obtained from all of the monitoring
wells during every round as sampling was targeted to areas where problems had been found.
4.28.3 In addition to the rounds of groundwater sampling outlined above, groundwater samples were
also obtained from monitoring wells installed as part of the following phases of site investigation:
a. Phase 4: February 2005
b. Phase 4A: February 2006
c. Phase 6: May/June 2007
d. Phase 7: November 2010
4.28.4 In addition to the groundwater sampling outlined above, the Council undertook four rounds of
sampling from monitoring wells installed during their July 2008 investigation at Spike Island.
4.28.5 Additional groundwater monitoring was undertaken by Gifford on the following dates to check
the findings of groundwater monitoring relating to free phase contamination obtained during the
Phase 6 site investigation:
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a. 23rd November 2007
b. 7th to 14th January 2008
4.28.6 A datalogger was installed by Gifford into various monitoring wells on and close to the
saltmarshes in Widnes and Runcorn in 2007 to measure changes in groundwater level over a
period of up to a week for each well. The data was correlated with tidal levels to assess the
impact of tidal changes upon the groundwater regime. Plots showing changes in groundwater
level are provided in Appendix N. The results are discussed in Section 6.19.
4.28.7 A total of 20 water samples were obtained for chemical testing during Round 14 from selected
wells in Area B, Area C, Area D (Widnes Warth and Spike Island) and Area I (reclamation yard
north of Hutchinson Street). These wells were selected to provide additional information in a
number of key areas for the baseline and to provide a second set of results for wells in Area I.
The Round 14 data has been considered within the baseline assessment.
4.29 Groundwater Sampling Methods
4.29.1 Groundwater samples were obtained during Round 1 by airlifting using a compressor. This was
method was not used during subsequent rounds due to the potential for cross contamination of
water samples by fuel or lubricants in the compressor. Groundwater samples were recovered
during Round 2 to 10 14 using a mechanically operated Waterra inertia pump (PP1 powerpack)
that was decontaminated between wells to reduce the potential for cross contamination
between sample locations. All purging and sampling was undertaken under the supervision of
Gifford. Groundwater levels were recorded prior to purging and sampling the wells.
4.29.2 The initial round of groundwater samples obtained from the monitoring wells installed during the
Phase 4 investigation were obtained using a Grundfos MP1 submersible pump. The exception
was WS06 on Widnes Warth which was installed with 25mm diameter standpipe with
piezometer tip it as it was not possible to install a 50mm diameter standpipe due to blowing
sand causing the hole to collapse when the casing was withdrawn. This exploratory hole was,
therefore, purged and sampled using waterra tubing.
4.29.3 A „Whale‟ pump was used during the Phase 6 site investigation to obtain water samples.
Although bailers were not normally permitted for obtaining groundwater samples, this method
was used on some monitoring wells installed during the Phase 6 investigation where only limited
quantity of groundwater was encountered and then only after attempts had been made to purge
and recover samples using the Whale pump.
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4.29.4 A trial using a low flow (or micropurging) method to obtain groundwater samples was
undertaken on BH1003 and BH1004 during Round 8 in 2006. Low flow methods have the
potential to reduce the amount of water removed from wells during purging. In addition to
obtaining groundwater samples using low flow, these wells were subsequently sampled using
the Waterra interia pump. The results obtained from the field monitoring and subsequent
chemical testing did not indicate that groundwater chemistry had stabilised within the 90
minutes that the low flow purging was undertaken on each well. Therefore, this approach was
not subsequently adopted for purging and obtaining groundwater samples. These results are
included in Appendix L.
4.29.5 Sampling for free phase LNAPL was undertaken by Gifford in November 2007 and January
2008. Purging was not undertaken prior to sampling during this work so as to preserve any
potential floating free product within the well. The sampling comprised a single check valve
transparent bailer being lowered into each well to between 0.5m and 0.8m below the water table
in order to recover samples from each well. Disposable bailers were used and a new bailer was
used for each exploratory hole. This sampling allowed a visual observation to be made of the
water at the top of these wells to confirm whether LNAPL was present or not. If present,
samples of the LNAPL were decanted into sealed glass containers and sent to the laboratory for
analysis. Ground gas and water level measurements, including using an interface probe to
monitor for the presence of free product were also undertaken prior to obtaining water samples
from each well.
4.29.6 It should be noted that the apparent thickness of LNAPL within the monitoring well will be
greater than the true thickness of LNAPL in the surrounding material. This is because the void
formed by the monitoring well causes a depression in the water table allowing free phase
LNAPL to accumulate (if present).
4.29.7 DNAPL sampling was also undertaken in November 2007 and January 2008. Again, purging
was not undertaken prior to sampling to preserve possible free product in the base of the well.
The sample was obtained using a double check valve transparent bailer lowered to the base of
the well. This type of bailer allows fluid to pass through whilst it is being lowered in the well.
When the bailer is raised it prevents fluid from draining from the base and also prevents fluid
from entering the top of the bailer. This method allows an undisturbed sample of fluid to be
obtained from the base of a monitoring well and a visual inspection as to whether DNAPL may
be present. Disposable bailers were used and a new bailer was used for each exploratory hole.
Sample from the base of the bailer were decanted into sealed glass container and sent to the
laboratory for analysis. Ground gas and water level measurements, including using an interface
probe to monitor for the presence of free product was also undertaken prior to obtaining water
samples from each well. These results are located in Appendix OT.
4.29.8 Cross contamination was identified from the results of the chemical testing during Round 11 and
12 as a number of organic contaminants were present at locations where they had not
previously been identified. Dedicated sampling equipment was installed in monitoring wells
during Round 13 in order to reduce the potential for cross contamination. However, the results
from Round 11 and 12 have not been included in the assessment of contamination results as
they are not considered representative of the groundwater conditions.
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4.30 Protocol for Developing/Purging of Monitoring Wells
4.30.1 All of the monitoring installations containing groundwater were „developed‟ where possible by
pumping to remove water associated with the drilling works, to reduce the effects of smearing
on the borehole wall and rotary flush deposition within aquifer materials. Development pumping
was undertaken for a minimum of 30 minutes or until clear water was obtained from the well.
4.30.2 Before any samples were recovered from monitoring wells, a check was undertaken for the
presence of Light Non-Aqueous Phase Liquids (LNAPLs) and Dense Non-Aqueous Liquids
(DNAPLs) using an interface meter and record the thickness of any free product. Probes were
cleaned between monitoring wells.
4.30.3 Prior to obtaining samples, each well was purged at a flow rate greater than that used for
sampling. Purging continued until at least three well volumes of water had been removed and
the pH, conductivity, dissolved oxygen and redox potential of the purged water had stabilised
(i.e. until three successive readings were within 10% of each other). The standard well volume
was defined as the volume of water within the standpipe and the gravel pack surround. The
purging of a minimum of three well volumes prior to obtaining a sample for testing has been
undertaken during all rounds of sampling from the Phase 1 site investigation onwards.
4.30.4 The Contractor was required to ensure that cross contamination between samples did not
occur. This comprised rinsing sampling equipment in clean water and suitable cleaning agent
between recovering individual samples.
4.30.5 The Contractor was required to prepare a sample report for each sample, with a copy of each
report being passed to Gifford at the end of each working day.
4.30.6 Groundwater arisings not sampled for analysis were collected for off-site disposal by the
Contractor to a licensed facility.
4.31 Soil and Water Sample Storage & Transportation
4.31.1 All soil and groundwater samples intended for contamination analysis were collected together in
cool boxes provided with frozen cool packs, a box was provided at each exploratory hole to
allow samples to be stored promptly. Samples were delivered to the analytical laboratory by
Gifford or collected from site on a daily basis by a courier.
4.31.2 Due to the warm weather during the Phase 2 and Phase 6 site investigations, samples were
stored in a refrigerator within the site portacabin until they could be collected by a courier.
Samples placed into glass jars for testing during Phase 4 and 5 site investigations were also
stored in a cool box and transferred to a refrigerator until collected from the site by a courier and
deliverd to the analytical laboratory.
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4.32 Methodology for Ground Gas and Vapour Monitoring
4.32.1 Ground gas monitoring was undertaken by Gifford using an infrared landfill gas analyser
(Geotechnical Instruments GA94 and GA2000) from January 2003 onwards. Groundwater level
monitoring was also undertaken during each visit. As site investigations have been undertaken
using a phased approach, the number of rounds of monitoring for each well has varied
depending on when it was installed. Ground gas monitoring was undertaken by Gifford on the
following dates:
a. January 2003
b. February 2003
c. March 2003
d. July 2003
e. January 2004
f. November to December 2004
g. February 2005
h. September to October 2005
i. February 2006
j. April 2006
k. July 2006
l. November 2006
m. January 2007
n. October 2008
o. April 2010
4.32.2 Ground gas monitoring comprised measuring methane (% volume/volume (v/v)), carbon dioxide
(%v/v), oxygen (%v/v) and atmospheric pressure (millibars (mb)) during each visit. Hydrogen
sulphide (parts per million (ppm)) was monitored during three rounds in 2003 and then from
September 2005 onwards, carbon monoxide (ppm) has been measured from December 2005
onwards. Since November 2004 flow rates (litres/hour) have been recorded during ground gas
monitoring. The results of this ground gas monitoring are located in Appendix PT.
4.32.3 Ground gas monitoring was also undertaken by the respective Contractors following the
installation of monitoring wells during the Phase 4, 4A, and 6 and 7 investigations and the
results of this monitoring are located in Appendix G, H and J respectively.
4.32.4 Monitoring for volatile vapours was undertaken by Soil Mechanics and AEG on soil arisings
during the Phase 6 and 7 site investigations respectively using a photo-ionisation detector (PID)
to record concentrations (in ppm). Soil samples to be checked for volatile vapours were placed
into tubs and the lids closed. These samples were stored in cool boxes for transporting back to
the site office for testing and to keep the sample cool. All soil samples were checked for volatile
vapours on the same day as they were obtained. To undertake the vapour assessment, only
part of the sample container was opened slightly and the PID probe inserted into the tub. The
peak reading obtained from each sample was recorded on the exploratory hole logs which are
located in Appendix J and U.
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4.32.5 Vapour monitoring was also undertaken by Gifford using a PID on monitoring wells installed
during the Phase 1 and 2 site investigation in March 2003 and subsequently on monitoring wells
installed at the Catalyst Trade Park during the Phase 4A site investigation in January 2006. To
undertake this monitoring, the PID was either connected to the gas tap on the monitoring well
using a narrow flexible pipe or a „needle‟ connected to the PID was inserted through the opened
gas tap. In both cases the aim was to obtain a seal between the PID and any vapours within
the monitoring well so as to obtain representative readings.
4.33 Radiological Screening Methodology
4.33.1 Radiological screening using a hand held scintillation counter was undertaken by the site
investigation contractor on made ground arisings by the site investigation contractor during the
Phase 4A and Phase 6 site investigations on exploratory holes located on and adjacent to the
Catalyst Trade Park. This was undertaken on the full depth of the made ground at all
exploratory hole locations within this area.
4.33.2 Following consultation with the Radiation Protection Advisor, Radman Associates, a limit of
twice background (as counts per second) was used to provide an indication of possible
radiological material. This was used as the level at which an exploratory hole would be
abandoned and relocated to minimise possible risks to site staff.
4.33.3 The background levels for the screnning were established in parts of the site where possible
radiological material or its use had not been identified from historical information (a review of
this historical information is contained in Section 5).
4.34 Soil and Water Contamination Analysis
4.34.1 The soil and groundwater samples obtained during the Phase 1 to 4 investigations and Round 1
to 7 groundwater sampling were submitted to Fugro Robertson Ltd (formerly Robertson
Research Laboratories) in Llandudno, North Wales for chemical analysis. A small number of
samples from the 2002 investigation and subsequent groundwater monitoring were forwarded
by Robertson to ALcontrol Laboratories (ALcontrol) in Chester at the request of Gifford for
analysis of specific determinands or to achieve specific detection limits.
4.34.2 Fugro-Robertson Ltd laboratories were acquired by ALcontrol on 7th July 2005 and the
contaminated land chemical testing laboratory in Llandudno was closed. Soil and water
samples obtained during the Phase 4A to 6 7 investigations and Round 8 to 10 13 groundwater
sampling were tested by ALcontrol in Chester.
4.34.3 Chain of Custody forms accompanied all soil and water samples sent to the laboratory.
4.34.4 Schedules of analysis were prepared by Gifford and forwarded to the relevant laboratory.
4.34.5 Analytical requirements were derived from a review of the materials encountered in the
exploratory hole combined with information obtained on the site history and ground conditions
for the specific area under consideration. Where there was no specific evidence of
contamination being present, or it was unlikely to be present on the basis of the sites past
history a generalised suite was adopted to cover metals, metalloids, non metals and organic
compounds.
4.34.6 In the Mersey Estuary and on the saltmarshes contamination was considered to be a possibility.
However, it was noted that this could have arisen from any one of the various contaminative
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land uses around the estuary. Therefore, a wide-ranging suite of determinands was adopted,
including elements such as Polychlorinated Biphenyls (PCB) and pesticides that historically
could have been discharged onto the saltmarsh and into the estuary from the surrounding
industrial processes.
4.34.7 As the site investigations have been undertaken between 2002 and 2007 using a phased
approach, the methods of analysis scheduled by Gifford for some parameters (such as the
change from „total‟ to „speciated‟ polyaromatic hydrocarbons) was changed to take into account
changes in contaminated land guidance and to obtain more detailed information to allow an
assessment of the possible risks to be undertaken.
4.34.8 The parameters scheduled for analysis were based on information obtained about the site
history, information from previous site investigations and observations during the site works to
identify possible contaminants of concern.
4.34.9 Where the same parameter had been tested for more than once from a single sample, data
from the more accurate method (e.g. GC-MS rather than GC-FID) has been used for
assessment purposes.
4.34.10 A number of the groundwater samples tested by ALcontrol during the Phase 6 site investigation
and Round 10 monitoring reported results as „no determination possible (NDP)‟. ALcontrol state
this was due to either insufficient sample being left for re-extraction, precipitation of the samples
to form a solid after a dilutent was added, or an unsuitable sample (in the case of WS17 which
was noted by ALcontrol as being oily).
4.34.11 The methods of analysis are included with the analytical results in Appendix L.
Soil Testing Parameters
4.34.12 Soil samples were scheduled for chemical testing based on the following parameters:
a. CLEA metals 1
b. Barium
c. Boron
d. Vanadium
e. Aluminium
f. pH
g. Water soluble sulphate
h. Acid soluble sulphide
i. Total sulphate
j. Total organic carbon
k. Total cyanide
l. Free cyanide
m. Ammoniacal Nitrogen (as N)
n. Ammonia (as NH4)
o. Asbestos screen
p. Phosphate
q. Phosphorous
r. Total PAHs
1 CLEA metals: arsenic, barium, beryllium, cadmium, chromium (total), copper, lead, mercury, nickel,
selenium, vanadium, zinc
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s. USEPA 16 PolyAromatic Hydrocarbons (PAHs)
t. Semi-Volatile Organic Compounds (SVOCs)
u. Volatile Organic Compounds (VOCs)
v. Total Petroleum Hydrocarbons (TPH)
w. Mineral Oils
x. TPH CWG (EC5-35) including BTEX and MTBE
y. TPH – Rapid Assessment Package (EC6-40)
z. Extractable Petroleum Hydrocarbons (EPH) (EC10-40)
aa. Gasoline Range Organics (GRO) (EC5-10)
bb. Polychlorinated biphenyls (PCBs)
cc. Organochlorine Pesticides
dd. Organophosphorous Pesticides
ee. Phenoxy Acid Herbicides
Soil Leachate Testing Parameters
4.34.13 Soil samples were scheduled for chemical testing based on the following parameters:
a. CLEA metals
b. Barium
c. Boron
d. Vanadium
e. Sulphate
f. Sulphide
g. pH
h. Hardness
i. EPH (EC10-EC40)
j. EPHCWG EC12-35
k. SVOCs
l. USEPA 16 PAH
Groundwater and Surface Water Testing Parameters
4.34.14 Water samples were scheduled for chemical testing based on the following parameters:
a. CLEA metals
b. Major Ions 2
c. Sulphide
d. Total organic carbon
e. pH
f. Conductivity
g. Barium
h. Boron
i. Vanadium
j. Iron
k. Manganese
l. Ammoniacal Nitrogen (as N)
m. Ammonia (as NH4)
n. Nitrate
o. Phosphate
p. Total PAHs
2 Major Ions: calcium, magnesium, sodium, potassium, bicarbonate, sulphate, chloride, nitrate.
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q. USEPA 16 PAHs
r. SVOCs including tentatively identified compounds
s. VOCs including tentatively identified compounds
t. Total TPH
u. TPH CWG (c5-c35)
v. EPH (c10-c40)
w. GRO (c6-c10)
x. Organochlorine Pesticides
y. Organophosphorous Pesticides
z. Phenoxy Acid Herbicides
aa. Particle Size Distribution (PSD)
Free Product Analysis
4.34.15 Samples of free product, or of liquids potentially containing free product, obtained in November
2007 and January 2008 were scheduled for chemical testing based on the following
parameters:
a. Qualitative tests 3
b. Density measurement
c. Addition of Sudan (IV) (hydrophobic dye)
d. Addition of anhydrous copper sulphate (dissolves in water)
e. Miscibility with water
f. VOCs
g. SVOCs
h. Whole Oil Analysis (LNAPL)
4.35 Review of Testing Methods for Inorganic Contaminants
Metals/Metalloids
4.35.1 Analysis for metals, metalloids and other inorganic compounds was based on elements and
compounds identified from the historical information obtained or identified as having the
potential to be present. In areas of known historical industrial use, additional elements and
compounds were added to reflect the previous use/s of sites.
4.35.2 Elevated levels of selenium were recorded in a number of the results from the first round of
groundwater analysis and it is considered this was due to cross contamination from the
sampling equipment or containers. These results were not repeated in any of the subsequent
rounds of groundwater testing.
3 These tests were devised following discussions between Gifford and the laboratory to devise an appropriate
schedule to determine if samples of fluid were water or DNAPL. Therefore, qualitative tests were not covered by laboratory UKAS accreditation due to the non-routine nature of the tests.
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4.35.3 Metals/metalloids in groundwater tested during the Phase 4A investigation and the Round 8 and
9 sampling visit were analysed for „total‟ metals rather than „dissolved‟ metals as during the
other rounds of testing. Information provided by ALcontrol indicates that samples tested for
„total‟ metals are subject to an acid digest which includes any sediment present within the
samples before being filtered, whereas sample tested for „dissolved‟ metals are filtered before
testing. The results for „total‟ metals can be significantly higher than for „dissolved‟ metals. The
results for „total‟ metals were not used in the assessment of the chemical test results as they
were not considered to be representative.
4.35.4 Some of the samples obtained from Round 9 field monitoring work were tested side by side for
both total and dissolved metals. Results were reported with those for Rounds 9 (total metals)
and 10 (dissolved metals) respectively and were used to assess the significance of using the
different methods. The concentrations of metal contaminants clearly show the results for „total‟
metals are significantly higher than those for „dissolved‟ metals, this is illustrated by results for a
selection of metals in Figure 4.1.
4.35.5 Following discussion with ALcontrol it has been established that the sample preparation method
would affect metal results only.
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Figure 4.1 – Comparison of Results Obtained from Dissolved and Total Metal Analysis
1
10
100
1000
10000
100000
1000000
BH
1003
BH
1005
BH
12
BH
14
BH
24
BH
27
BH
32
BH
34
BH
36
BH
38
BH
45
BH
47
WS
05B
WS
07
WS
09
WS
13
WS
15
WS
3
Co
ncen
trati
on
As-Total ug/l
As - Dissolved ug/l
1
10
100
1000
10000
BH
1003
BH
1005
BH
12
BH
14
BH
24
BH
27
BH
32
BH
34
BH
36
BH
38
BH
45
BH
47
WS
05B
WS
07
WS
09
WS
13
WS
15
WS
3
Co
nc
en
trati
on
Cr-Total ug/l
Cr - Dissolved ug/l
1
10
100
1000
10000
100000
1000000
BH
1003
BH
1005
BH
12
BH
14
BH
24
BH
27
BH
32
BH
34
BH
36
BH
38
BH
45
BH
47
WS
05B
WS
07
WS
09
WS
13
WS
15
WS
3
Co
ncen
trati
on
Fe-Total ug/l
Fe - Dissolved ug/l
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4.36 Review of Testing Methods for Organic Compounds
Organic Matter/Organic Carbon
4.36.1 In terms of organic compounds a number of Toluene Extractable Matter (TEM) tests and Total
Organic Carbon (TOC) were undertaken on samples from 2002 investigation. The TOC test
was used to indicate the total organic content of a sample. The TEM test is used to give an
approximate quantification of general hydrocarbons in a sample, but this is only a guide to the
possible presence of contamination since naturally occurring organic matter can contribute to
elevated results. All soil and sediment samples from the Phase 4 site investigation onwards
were screened for TOC as this information would be used within the risk assessment.
Volatile and Semi-Volatile Organic Compounds
4.36.2 Volatile organic compounds and semi volatile organic compounds (VOCs and SVOCs) suites of
contaminants were scheduled for testing on the basis of what was known of the site history and
from observations during the site investigations. In some cases additional compounds, carbon
disulphide for example, were subsequently added to analytical suites for specific sites where
further information became available or on the basis of findings in the field. The soil and water
analysis undertaken by ALcontrol Laboratories Ltd included carbon disulphide within the
standard list of VOCs.
Pesticides
4.36.3 A range of organochlorine pesticides were analysed for in soils and groundwater samples
obtained from the urban areas north of St Helens Canal, saltmarshes and the intertidal sand
bank. This suite was based on information obtained on the historical industrial processes
undertaken within the vicinity of the estuary, which included pesticide manufacture. Only the
near surface sediments from the saltmarshes were tested for these contaminants as this has a
high organic matter content and cohesive sediment fractions making this material likely to
concentrate contaminants.
4.36.4 Testing for organochlorine pesticides and phenoxy acid herbicides was included within the suite
of parameters during the Phase 6 site investigation and Round 9 and 10 14 groundwater
monitoring. This was based on information obtained on historical uses of the former ICI Widnes
Experimental Works on which the Catalyst Trade Park is located (ICI, 1996), which is discussed
in Section 5.
Polychlorinated Biphenyls (PCBs)
4.36.5 The PCB testing undertaken by Robertson comprised the total of the 7 most common
congeners, namely; 28, 52, 101, 118, 138, 153 and 180. Testing for PCBs by ALcontrol also
comprised the same seven congeners but reported as individual results rather than totals.
Polyaromatic Hydrocarbons
4.36.6 Samples tested as part of Phase 1 to 3 site investigations were tested for total Polyaromatic
Hydrocarbon (PAHs) to reflect contaminated land guidance current at that time (i.e. ICRCL
59/83, 1987 – this guidance was withdrawn in December 2002).
4.36.7 Due to changes in contaminated land guidance, speciated PAH were tested in samples
submitted during the Phase 4 to 6 investigations were tested for the United States
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Environmental Protection Agency (USEPA) Priority 16 PAHs or as part of a SVOC suite to
obtain information on the individual PAHs present in samples.
Petroleum Hydrocarbons
4.36.8 Petroleum Hydrocarbons were tested as „mineral oils‟ and „total petroleum hydrocarbons‟ (TPH)
during Phase 1 to 3 investigations based on contaminated land guidance current at that time
(i.e. ICRCL 59/83, 1987).
4.36.9 Due to changes in contaminated land guidance and to obtain more information on hydrocarbons
encountered, samples for testing during Phase 4 were scheduled for total diesel range organics
(DRO) and petrol range organics (PRO). Samples submitted to ALcontrol during Phase 4A
investigation were tested for DRO (as Extractable Petroleum Hydrocarbons or EPH) and
gasoline range organics (GRO) and separated into the following carbon bands:
a. GRO 5-8
b. GRO 8-12
c. EPH 10-12
d. EPH 12-16
e. EPH 16-21
f. EPH 21-35
4.36.10 Benzene, toluene, ethyl benzene and xylenes (BTEX) compounds were tested separately
during the Phase 4 and 4A investigations, and also included as part of the VOC suite during the
Phase 1, 2, 4 and 4A investigations.
4.36.11 Samples from the Phase 6 investigation were tested by ALcontrol for petroleum hydrocarbons
using either Risk Based Assessment Package (RBAP) or Total Petroleum Hydrocarbons
Criteria Working Group (TPHCWG) suite as these tests provide more detailed information on
the petroleum hydrocarbons present in samples. Both test methods are undertaken using a gas
chromatograph with a flame ionisation detector (GC-FID). These tests remove naturally
occurring organic matter such as humic acid from the sample being tested so the results
reported are petroleum compounds. These tests separate hydrocarbon fractions into the
following:
a. RBAP (C6-40) by GC-FID (EZ Flash) aliphatics/aromatic split with carbon bands C6-
8,>8-10,>10-12,>12-16,>16-21,>21-40.
b. TPHCWG (C5-35) aliphatic/aromatic split with aliphatic carbon bands 5-6,>6-8,>8-
10,>10-12,>12-16,>16-21,>21-35 and aromatic carbon bands >C6-7,>7-8,>8-10,>C10-
12,>12-16,>16-21,>21-35).
4.36.12 Soil and water samples from Phase 7 and Rounds 10 to 14 were tested for TPHCWG.
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4.37 Review of Groundwater Analysis – Specific Determinands
4.37.1 Three of the groundwater samples from Round 2 to 5 of the groundwater testing were sent to
ALcontrol for analysis to achieve lower detection limits for mercury and the United States
Environmental Protection Agency (USEPA) Priority 16 Polyaromatic Hydrocarbons (PAHs).
These samples were obtained from shallow monitoring wells installed in BH12, 13 and 17 on the
saltmarshes. An additional five samples from Rounds 2 to 5 of the groundwater sampling were
sent to ALcontrol for analysis of volatile organic compounds (VOCs) to analyse for the presence
of carbon disulphide which had been identified as a possible contaminant within the project
area.
4.38 Analytical Techniques
4.38.1 The analytical techniques used are shown on the certificates of analysis issued by Robertson
and Alcontrol. These methods can vary depending on the type of analysis requested for
individual parameters and analytical detection limits required.
4.39 Soil Leachate Testing Methodology
4.39.1 Leachate testing was undertaken on soil and sediment samples from the land based
investigations and saltmarshes using the method outlined by the former National Rivers
Authority (now Environment Agency R&D Note 301). The method comprises agitating 100 g of
soil (at natural moisture content) with 1000 ml of water for 24 hours (i.e. at a 1:10 ratio) and
filtering the subsequent leachate prior to specified analysis. This method is typically used for
inorganic or non/low volatility organics contaminants but not volatile compounds as these are
likely to be lost during the leachate preparation process.
4.39.2 Samples were selected for leachate testing on the basis of the initial soil testing results,
concentrating on samples tested which contained high levels of contamination.
4.39.3 The results of the chemical testing are included in Appendix L.
Leachate Testing on Saline Samples
4.39.4 The published information obtained for review indicates that salinity can affect metal solubility.
This is discussed in Section 5.4.
4.39.5 Discussions with the Environment Agency‟s laboratory indicated they could undertake soil
leachate testing using „standard‟ saline waters. However, this laboratory indicated there would
be problems calibrating the analytical machines for non-standard saline waters such as those
which could be encountered in the estuary.
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4.39.6 Therefore, in order to assess whether this was likely to be an issue for samples recovered from
the saltmarshes and estuary, salinity (in parts per thousand (ppt)) was derived from conductivity
values using the Practical Salinity Scale (PSS) equation (from Report of the National Park
Service Vital Signs Monitoring Marine/Estuarine Workgroup, 2003). The general equations for
the PSS are given by Lewis (1980), and for a temperature of 25 °C have been simplified by
Schemel (2001) as follows:
25
6
2
52
3
432
1
21 RKRKRKRKRKKS
Where K1 = 0.0120, K2 = –0.2174, K3 = 25.3283, K4 = 13.7714, K5 = –6.4788, K6 = 2.5842 and
R is the conductivity ratio of the sample specific conductance divided by that of standard
seawater salinity at the same temperature (53.087mS/cm at 25 °C).
4.39.7 The average conductivity and salinity values derived for each area were as follows:
Table 4.21 – Summary of Average Conductivity and Salinity Values Across Project Area
Determinand Estuary North Saltmarsh
(Widnes Warth)
South Saltmarsh
(Astmoor)
Conductivity mS/cm 4.17 5.00 6.05
Salinity ppt 2.20 2.68 3.28
4.39.8 Tsai et al (2003) indicate that the affects of salinity on metal leachability are minimal in low-
salinity environments, i.e. in the 0-5ppt salinity range. The average sediment salinity estimated
from measured conductivity for the estuary and saltmarshes falls within this range.
4.39.9 Therefore, the use of saline water from the estuary for leachate tests was not considered
necessary.
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4.40 Review of Potentially Hazardous Properties Associated with Contaminants Tested
4.40.1 The following table provides an overview of some of the hazardous properties associated with
the parameters tested. A review of particular issues relating to the parameters tested is outlined
in Section 4.34 to 4.37.
Table 4.22 – Summary of Possible Hazardous Properties
Contaminant Comments
Metals and
Metalloids
Metals/metalloids have the potential to cause harm to human health as they can be
toxic and some are carcinogenic. Some metals/metalloids are potentially ecotoxic
and they can also contaminate waters.
pH Acids and alkalis have the potential to cause harm to human health as they can
cause severe burns and can also be an irritant, harmful and toxic. pH can affect
buried concrete, and the environmental mobility of some contaminants. Acids and
alkalis can also be ecotoxic.
Sulphate and
Sulphide
Sulphate can affect the integrity of buried concrete. Some sulphate compounds can
cause harm to human health and be ecotoxic. Sulphides can be flammable and
very toxic if inhaled, they can also be excotoxic.
Cyanides Cyanides have the potential to cause harm to human health as they can be very
toxic. Cyanides can also contaminate waters, impact on buried plastic services and
water supplies and they are potentially ecotoxic.
Asbestos Asbestos has the potential to harm human health as they can be carcinogenic, they
can also be harmful and toxic.
Organic Carbon Organic carbon has the potential to affect the fate and transport of organic
contaminants. Materials with higher organic carbon can also produce ground gas.
Polyaromatic
Hydrocarbons
PAHs have the potential to cause harm to human health as they can be harmful,
carcinogenic, mutagenic, toxic for reproduction. PAHs can be ecotoxic, contaminate
waters, damage buried plastic services, and some can produce hazardous vapours.
Petroleum
Hydrocarbons
Petroleum hydrocarbons have potential to cause harm to human health as they can
be irritants, harmful, toxic, carcinogenic, toxic for reproduction, mutagenic and highly
flammable. They also have the potential to contaminate water, damage buried
plastic services, and they can produce ground gas and vapours.
SVOCs SVOCs have the potential to cause harm to human health as they can be irritants,
harmful, toxic and carcinogenic. Some SVOCs are ecotoxic. SVOCs can also
contaminate water, damage buried plastic services, and some can produce
hazardous vapours.
VOCs VOCs have the potential to cause harm to human health as they can be irritants,
harmful, toxic and carcinogenic. Some VOCs can be ecotoxic. VOCs can also
contaminate water, damage buried plastic services and water supplies, and they can
produce hazardous and flammable vapours.
PCBs PCBs can be harmful and very toxic to aquatic organisms and can cause long-term
adverse effects in the aquatic environment.
Pesticides and
herbicides
Pesticides and herbicides can be irritants, harmful, toxic, and some are carcinogenic
and they have the potential to cause harm to human health. Pesticides are also
ecotoxic and they can contaminate water.
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4.41 Background Information on Soil Contamination Assessment Criteria
Guideline Values for Contamination Assessment
4.41.1 The assessment of contaminated land in the UK is based on a „suitable for use‟ approach for a
defined end-use. Current guidance advocates using a tiered approach for assessing the risk
from soil contamination starting with an initial screening exercise (referred to as Generic
Assessment Criteria (GAC) in this report and also known as Tier 1). The purpose of the
screening exercise is to identify areas of contamination above generic guideline levels where it
may be necessary to undertake a site specific risk assessment (sometimes referred to as Tier 2
and 3) or implement mitigation measures.
4.41.2 On this basis the guideline values used for the Tier 1 assessment have been sourced from the
following:
a. Soil Guideline Values (SGVs) derived using Contaminated Land Science Report
(CLR)10 SR3/Contaminated Land Exposure Assessment (CLEA) Model and other
similarly derived soil assessment criteria
b. Environmental Quality Standards (EQS) for List I and II substances from the Dangerous
Substances Directive
c. UK Drinking Water Standards (UK DWS)
d. Interim UK Marine Special Areas of Conservation (SAC) Sediment Quality Guidelines
e. Building Research Establishment (BRE) Special Digest 1 (2005)
f. Ministry for Agriculture Fisheries and Food (MAFF) Soil Code (1998)
g. CIRIA C665 Assessing Risks posed by Hazardous Ground Gas (2007) – this text has
been removed as toll booths and offices are no longer proposed
h. Health and Safety Executive Workplace Exposure Limits
4.41.3 Details of the above guideline values are provided in the following sections.
4.41.4 For the purposes of assessing the soil, leachate and groundwater results, concentrations which
were reported below the lower analytical detection limit were set at the analytical detection limit.
This approach is considered to be conservative, particularly where analytical detection is close
to or exceeds the assessment criteria or where significant number of results are below detection
(i.e. results may appear as false positives). All of the soil, leachate and groundwater data used
in the assessments in Section 6 was checked against the validated results received from the
analytical laboratory.
4.42 Soil Assessment Criteria for Human Health
4.42.1 The following approach has been used when assessing the soil contamination results:
a. Screen soil contaminants against GAC for a commercial/industrial land use derived
using site specific numerical mean for TOC and pH in made ground (on basis this
material is near surface and is most likely to be exposed in excavations)
b. Screen soil contaminants against assessment criteria derived for construction workers
using site specific numerical mean for total organic carbon and pH in made ground (on
basis this material is most likely to be exposed in excavations)
c. Contaminants exceeding the GAC for a commercial/industrial land use will be assessed
using statistical methods to assess mean value and identify possible outliers
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4.42.2 Even where contaminants do not exceed the assessment criteria, particularly for construction
workers, consideration will need to be given during the works to possible risks from ingestion,
dermal contact and inhalation of contaminants in shallow groundwater in excavations.
4.42.3 The approach adopted is based on assessing whether potential impacts are likely to be
introduced during the construction and operational stages within the Mersey Gateway Project
area and do not necessarily represent remediation targets.
4.42.4 The soil assessment criteria for a commercial/industrial land use and construction workers has
been derived by entering data from the following sources into the CLEA UK version 1.06 model
(listed in order of preference and revised based on recent changes in guidance):
a. Published Soil Guideline Values (SGV)
b. Land Quality Management (LQM) Generic Assessment Criteria (GAC)
c. EIC/AGS/CL:AIRE GAC
d. Toxicological and fate and transport data derived from an internet based search and
following guidance outlined in CLR9 (2002) SR2 (2009)
4.42.5 The default exposure scenarions within the CLEA UK model has been used to derive the GAC
for a commercial/industrial land use (and site specific TOC and pH), a discussion on the use of
this approach is outlined in Section 4.43 below. The assessment criteria for construction
workers are discussed in Section 4.45 below. A more detailed discussion on the sources of
information listed above and derivation of the assessment criteria is included in Appendix MQ.
4.43 Basis for Using GAC for a Commercial/Industrial Land Use
Highways Agency Design Manual for Roads and Bridges (DMRB)
4.43.1 Guidance in Highways Agency Design Manual for Roads and Bridges (DMRB) Specification for
Highways Works Series 600 Earthworks Volume 1 (November 20062009 amendment) states
that unacceptable material (Class U1B) material excavated from within the site which unless
processed so that it meets the requirements (of Table 6/1 and Appendix 6/1) shall not be
included in the permanent works. Unacceptable material Class U2 shall not be used in the
permanent works.
4.43.2 Unacceptable material Class U1B is defined as contaminated materials, including controlled
wastes whose level of contamination is above that given in Appendix 6/14 or 6/15 of the Series
600 guidance but excluding all hazardous waste and radioactive waste. Class U2 material is
defined as hazardous waste and radioactive waste.
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4.43.3 Guidance in the DMRB Specification for Highways Works Series 600 Earthworks Volume 2
(November 2004) states the definition of contaminated materials Class U1B is based on the
concept of risk assessment and is in accordance with the definition of contaminated land in the
EPA 1990 Part IIA. This guidance states that a „site specific risk assessment should be
undertaken for each earthwork section as the degree of exposure to living organisms or the
hydrogeological conditions can vary significantly within the scheme. However, appropriate
generic guideline values, which are based on a risk assessment model may be used as default
values. For human health the series of SGVs published by DEFRA and the EA may provide
suitable default values. Generic guideline values have been adopted at this stage.
4.43.4 The DMRB states that for general fills, the limiting values for harm to human health should
normally be based on the commercial/industrial end use category of guideline values as there is
a very low risk of exposure to the public from any contaminants in the fill. For landscaping fills,
phytotoxicity (toxicity to plants) should be considered. This approach has been used to screen
soil contaminants within this report.
Soil Guideline Values and ‘Unacceptable Intake’
4.43.5 In March 2002, the Department for Environment, Food and Rural Affairs (DEFRA) and the
Environment Agency published a package of technical guidance relevant to the assessment of
human health risks arising from long-term exposure to contaminants in soil. This guidance
superseded earlier work in respect of human health published by the Interdepartmental
Committee on the Redevelopment of Contaminated Land (ICRCL), and in particular, the Trigger
Values set out in ICRCL 59/83 (1987).
4.43.6 The CLEA package consisted of the main CLR 7 – 10 reports, the CLEA 2002 software and Soil
Guideline Values (SGVs) for limited number of individual substances which were considered by
DEFRA to represent the key instruments for generic assessment of the health risks from land
contamination. The approach represented a cross-government consensus on the technical
approach to undertaking such assessments and was based on the latest scientific knowledge
and thinking.
4.43.7 Updates to the CLEA model in the form of four CLEA Briefing Notes (1 to 4) were released by
the Environment Agency between 2004 and 2005 (CLEA Briefing Note 1 was revised in March
2005).
4.43.8 On 1st September 2005 the Department for Environment Food and Rural Affairs (DEFRA)
published Contaminated Land Advice Note (CLAN) 2/05 on Soil Guideline Values (SGVs) and
the Determination of Land as Contaminated Land under Part IIA. One of the main purposes of
CLAN 2/05 was to restate the basis upon which SGVs have been derived to help ensure they
was not used uncritically by Local Authorities for the determination of land as contaminated land
on the grounds of „significant possibility of significant harm‟ to human health.
4.43.9 CLAN 2/05 states that from discussions within the Soil Guideline Values Task Force (SGVTF) it
was apparent that there was a wide body of opinion that such concentrations would not
necessarily satisfy that legal test. This remains the case where the site corresponds to the
generic model used to produce an SGV and this view would also apply to any assessment
criteria or site specific criteria generated (in the absence of an SGV) using a published Health
Criteria Value (HCV) and the CLEA software (or other exposure model).
4.43.10 It should be noted that CLR7-10 and the related toxicological (TOX) and SGV reports do not
state that exceedance of an SGV, properly applied, would meet the legal test for Part IIA. CLAN
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2/05 states that a key question is how far above an SGV the relevant soil concentration would
have to be to meet the „unacceptable intake‟ test. At the present time the published DEFRA/EA
technical guidance on risk assessment does not address this issue. This text has been
removed to reflect changes in guidance which are discussed below.
4.43.11 In November 2006, the DEFRA issued a discussion paper entitled Soil Guideline Values: The
Way Forward (DEFRA, 2006a). The paper sought views from key organisations and groups on
various ideas for how non-statutory technical guidance might be amended to make it more
useful to assessors carrying out risk assessments, and to make clearer when land qualifies as
contaminated land under Part 2A of the Environmental Protection Act 1990. This culminated in
DEFRA publishing the following documents:
a. Improvements to contaminated land guidance. Outcome of the “Way Forward” exercise
on Soil Guideline Values (DEFRA, 2008a);
b. Guidance on the legal definition of contaminated land (DEFRA, 2008b).
4.43.12 The EA produced new framework documents in 2009 that provided a methodology to help risk
assessors develop generic assessment criteria to evaluate whether a child or adult might be
exposed to harmful or potentially harmful levels of a chemical on a given site over a long period
of exposure. These comprised:
a. Updated technical background to the CLEA model (SR3) (EA, 2009a) which describes the technical principles of the Contaminated Land Exposure Assessment (CLEA) model, incorporating many of the updates to exposure assessment introduced in Soil Guideline Values: The Way Forward (Defra, 2006a) and other changes. SR3 replaces the former CLR10 (2002) report.
b. Human health toxicological assessment of contaminants in soil (SR2) (EA, 2009b) incorporates the updates to how the toxicity of chemicals in soil are assessed that were introduced in Guidance on the legal definition of contaminated land (Defra, 2008b) together with further guidance on chemical risk assessments for soil. SR2 replaces the former CLR8 (2002) report. Health Criteria Values (HCVs). HCVs describe a benchmark level of exposure to a chemical at which, unless stated otherwise, long-term human exposure to chemicals in soil is tolerable or poses a minimal risk.
c. CLEA software (version 1.06) and handbook (EA, 2009c, 2009d). The CLEA software is based on the modelling approach described in the framework report (Environment Agency, 2009a). The EA uses the CLEA software to derive SGVs. The software enables assessors to derive assessment criteria to assist in the evaluation of the risks posed to human health from chronic exposure to chemicals in soil in relation to land use.
4.43.13 SGVs are scientifically based generic assessment criteria that can be used to simplify the
assessment of human health risks arising from long-term and on-site exposure to chemical
contamination in soil. They do not, however, consider risks to construction workers or risks from
occupational exposure arising from activities in the work place.
4.43.14 SGVs are a screening tool for the generic quantitative risk assessment of land contamination.
They do not take account of other non soil based sources of contamination such as
contamination in groundwater, surface waters or drinking waters. They cannot be used to
evaluate risks to non-human receptors such as controlled waters, ecosystems, buildings and
services, domestic pets or garden plants.
4.43.15 SGVs are guidelines on the level of long-term human exposure to individual chemicals in soil
that, unless stated otherwise, are tolerable or pose a minimal risk to human health. They
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represent “trigger values” – indicators that soil concentrations above this level may pose a
possibility of significant harm to human health.
4.43.16 The EA (March 2009) state that SGVs do not of themselves represent the threshold at which
there is a significant possibility of significant harm (SPOSH) and nor do they automatically
represent an unacceptable intake in the context of Part IIA of the Environmental Protection Act
1990. However, they can be a useful starting point for such an assessment. SGVs are not
derived explicitly to be used as remediation standards.
Contaminated Land Exposure Assessment (CLEA) UK Model
4.43.17 In November 2005 the EA released a Beta version of the CLEA UK software for a period of user
evaluation prior to final release. This software provided a tool to develop assessment criteria
either generically or on a site specific basis. In October 2006 the Environment Agency issued
the following statement:
„The Environment Agency has formally withdrawn the CLEA 2002 software. Launched in 2002 with the
original CLR technical package, the software is no longer compliant with current technical guidance (for
example, Briefing Notes 1 to 4) and lacks the versatility of the more recent CLEA UK beta version 1.0.
Since its release in November 2005, feedback from CLEA UK beta users has suggested that this
software has performed effectively in the majority of cases. It is therefore recommended by the
Environment Agency for use in human health risk assessment in conjunction with advice found on our
CLEA web pages.
CLEA UK is an aid to decision-making and does not replace the need for sound professional judgement
in risk assessment.‟
4.43.18 The Environment Agency also stated they would consider the formal status of the CLEA UK
beta software following the review of Soil Guideline Values being undertaken by DEFRA and
that changes to the model may need to be made to the existing software to comply with the Way
Forward approach. A new version of the CLEA UK model is planned for release although a
copy of the programme has not been obtained by Gifford for review. This text has been
removed to reflect changes in the CLEA model which are discussed below.
4.43.19 In 2009 the Environment Agency released new CLEA software (version 1.03 beta) and withdrew
the Beta version of the CLEA UK model. Further revisions to the CLEA model were released by
the EA in 2009 following a three month period of evaluation on version 1.03. CLEA version 1.04
was released in January 2009, and superseded by version 1.05 and then the current version,
1.06, in September 2009.
4.43.20 The CLEA software is based on the modelling approach described in SR3 (EA, 2009a). The EA
uses the CLEA software to derive SGVs and the software enables assessors to derive
assessment criteria to assist in the evaluation of the risks posed to human health from chronic
exposure to chemicals in soil in relation to land use.
4.43.21 The beta version of CLEA UK version 1.06 models has been used in the development of the
assessment criteria for human health within this report.
DEFRA CLAN 6/06
4.43.22 In November 2006 DEFRA published the following consultation document:
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a. Assessing Risks from Land Contamination – a Proportionate Approach. Soil Guideline
Values: the Way Forward (CLAN 6/06).
4.43.23 CLAN 6/06 focuses on determination of land as contaminated land under the Park IIA regime
where there is a significant possibility of significant harm in relation to human health affects.
4.43.24 CLAN 6/06 states that „it has always been recognised that it may not be possible to provide a
complete set of generic guideline values for all contaminants outlined in CLR8‟ and that „some
contaminants will always require site specific evaluation of their particular behaviour and effect‟.
4.43.25 CLAN 6/06 also states „concerns were expressed about the limited number of SGVs and their
use. SGVs are intended to provide a means of assessing the impact of long term exposure to
contamination on human health‟. An additional concern was „current SGVs are not
proportionate or realistic – there is an overall perception across a number of different groups
that some, if not all of the published guideline values represent an overly stringent benchmark‟.
4.43.26 The guidance discussed and referred to in CLAN 6/06 was intended as an additional tool to
assist in the risk assessment process. CLAN 6/06 presented the emerging conclusions and
issues relating to the production of soil guideline values (SGVs). The purpose of the paper was
to allow wider stakeholder discussion on the emerging conclusions. The work focussed on the
way in which appropriate SGVs can be developed and used to facilitate the determination of
land as „contaminated land‟ under the Part IIA regime where there is a „significant possibility of
significant harm‟ (SPOSH) in relation to human health effects. DEFRA state there are no
proposals for developing SGVs for any other level of risk. CLAN 6/06 is only concerned with
potential risks to human health and does not relate to approaches taken for other wider
environmental risks such as pollution of controlled waters.
4.43.27 It is understood that the final outputs from the proposals outlined CLAN 6/06 were to include a
package of updated guidance documents and a number of the documents, or the scoping
exercises for the work involved and other preparatory work. CLAN 6/06 states „the aim is to
have completed improvements to current guidance by the end of December 2007, with
particular priority for the development and release of a new version of the CLEA UK software as
soon as possible‟. Gifford understand that draft versions of these updated guidance documents
have been released to a number of organisations for an initial review and comment. However,
copies of these documents have not been obtained by Gifford for review. It is understood there
has been a delay in publishing the response to CLAN6/06. This text has been removed to
reflect changes in guidance.
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4.44 Statistical Testing Method for Commercial/Industrial Land Use Assessment
4.44.1 CLR7 (2002) describes two statistical tests for use when assessing the results of contamination
testing; the mean value test (or „t-test‟) and the maximum value test. The mean value test
involves determining a value, 95% Upper Confidence Limit (UCL) (the upper 95th percentile
bound), that the true average concentration within an averaging area will be less than with a
95% confidence level. The maximum value test is carried out to determine if the maximum
value in the data set represents an outlier, and therefore a potential hotspot of contamination
(Nathanail, 1994).
4.44.2 The assumption behind the statistics in the mean and maximum value tests in CLR7 is that
each sample represents an equal fraction of the averaging area (Nathanail, 2004). Nathanail
(2004) also indicates there is an implicit underlying assumption that samples are located on a
square regular grid pattern with each sample having the same area of influence and where
samples are not evenly spaced this is not true. The mean value test in CLR7 assumes samples
are drawn from the same population. The CLR7 mean and maximum value tests do not apply
to sampling patterns that have been targeted to investigate specific features or which are based
on judgemental sampling. This text has been removed as CLR7 has been withdrawn by the
Environment Agency. The current method of statistical assessment is discussed below.
4.44.3 The approach adopted for soil sampling on the Mersey Gateway has been based on both
professional judgement and targeted sampling such as to investigate specific historical features,
to delineate contaminants encountered during previous phases of investigation or specific
features associated with the Mersey Gateway Project. The majority of sample locations do not
conform to a regular grid, this is due in part to the linear nature of the scheme. In addition, the
ground conditions encountered, and in particular the made ground, have been shown to be
highly variable in nature and this includes within the individual areas identified in Widnes for
assessing the chemical test results which were largely based on identified historical land uses.
4.44.4 The data obtained from the Mersey Gateway investigations, and particularly from the made
ground, does not typically follow a normal distribution even when zoning areas into similar
historical land uses and considering similar soil types. The mean and maximum value tests
outlined in CLR7 are not considered an appropriate method for assessing the soil contamination
test results.
4.44.5 Therefore, A mean value test and an outlier test was undertakenusing the one-sided version of
Chebyshev‟s Theorem, as outlined in Chartered Institute of Environmental Health (CIEH) (2008)
in the Statistics Calculator version 1 prepared by ESI Ltd (2008) and has been used to derive
the 95% UCL for the soil contamination results for contaminants in shallow soils (made ground)
exceeding their respective GAC for a commercial land use. Area D was not included in the
statistical assessment on the basis the scheme would be on piers in this area.
4.44.6 The mean value test involves determining a value, US95 (the upper 95th percentile), that is the
true average concentration of a contaminant within a particular averaging area. This means that
the concentration of the contaminant within that averaging area will be less than the US95 value
with a 95% confidence level. The outlier test is then carried out to determine if the maximum
value in the data set represents a statistical outlier, which could indicate a potential hotspot of
contamination
4.44.7 Chebyshev‟s Theorem was incorporated into a spreadsheet to undertake the statistical
assessment. This spreadsheet included several tests for normality of the data which was used
to confirm that the Chebyshev UCL was appropriate rather than the CLR7 mean value test.
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XLSTAT (Version 2007.06, released by Addinsoft Ltd) was used to produce the q-q‟ plots to
assess the normality of datasets. This text has been removed to reflect changes in the
approach used for the statistical assessment. However, Chebyshev‟s Thereom has been used
in the revised assessment as it is included within the ESI Statistics Calculator.
4.44.8 The statistical testing was applied areas where soil contaminants exceeded their respective
commercial/industrial GAC for human health. An assessment for outliers was also undertaken
on these parameters.
4.45 Basis of the Soil Assessment Criteria for Construction Workers
4.45.1 The human health risk assessment outlined above does not assess the possible risks
associated with exposure during the proposed construction works. The most potentially
exposed receptor was identified as a construction worker involved in ground works. No generic
UK guidelines for acceptable exposure to soil contaminants by construction workers have been
published. GAC for construction workers were derived using the CLEA UK model which has
now been withdrawn. The parameters used to derive the GAC were entered into the CLEA
version 1.06. However, it is not possible to directly enter all of the parameters from the CLEA
UK in CLEA version 1.06. The results obtained from the CLEA version 1.06 model are higher
for metals and a number of SVOCs, with significantly higher results derived for VOCs.
Therefore, the existing GAC have been retained on a precautionary basis as these are more
conservative.
4.45.2 The following assumptions have been used when assessing possible risks to construction
workers:
a. Exposed during construction activities only
b. Potential for high ingestion and inhalation exposures to surface and subsurface soil
contaminants
c. Short term exposure (from less than one year and up to three years)
4.45.3 The following pathways have been identified for construction workers involved in ground works:
a. Ingestion of soil and/or water
b. Dermal contact with soil and/or water
c. Inhalation of fugitive soil dust
d. Inhalation of vapours outside
4.45.4 The criteria for assessing potential risks to human health from ground gas are outlined in
Section 4.49 below. The following activities have been identified as likely to have the highest
potential to expose site workers to contamination:
a. Excavations for pile caps (including steel fixers)
b. Site strip and/or ground improvement
c. Laying of buried services
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4.45.5 In order to assess which activity is likely to result in the highest risk, assessment criteria have
been derived for all three scenarios and new exposure scenarios created in the CLEA UK
model. The lowest of the assessment criteria values derived has been compared against the
results of the investigation. The assessment indicates that workers are most likely to be at risk
from soil contamination during excavations for pile caps and also service trenches. The
assessment criteria for construction workers have been based on those derived for pile cap
excavations.
4.45.6 The former CLEA UK model is was based on chronic exposure. Although it is possible that
exposure by workers to soil contaminants could occur over shorter durations, for the purpose of
this assessment exposure has been averaged over one year.
4.45.7 Whilst the former CLEA UK model (and other commonly used contaminated land risk
assessment models) does not specifically assess the possible risks to a receptor within
excavations, and in particular with regards to the inhalation pathway, this model has been used
to provide an indication of where possible risks could be introduced from soil contamination.
The approach adopted is similar to that outlined in USEPA (2002) guidance for developing site
specific soil screening levels for a construction scenario The USEPA indicate that the
conservative nature of their model for construction workers (i.e. it assumes all the contamination
is at the surface) makes it sufficiently protective of exposure to volatiles. The USEPA note that
sub-chronic toxicological data should be used for construction workers rather than data relating
to chronic exspoures, however they go on to note that sub-chronic values are not as widely
available (sub-chronic exposure for Superfund sites is defined as lasting from between two
weeks and seven years). The use of chronic toxicological values in this assessment is more
likely to be conservative as these values tend to be lower than those for sub-chronic or acute
exposure.
4.45.8 It should be highlighted that the assessment criteria derived for construction workers are not
remediation levels and have only been used to assess possible areas of risk from soil
contamination. The construction works will need to take into account the Workplace Exposure
Limits (WEL) which are provided by the Health and Safety Executive in order to help protect the
health of workers. WELs are concentrations of hazardous substances in the air, averaged over
a specified period of time referred to as a time-weighted average (TWA).
4.45.9 Although it is considered more likely the construction workers would be male it is possible that
female workers would be present.
4.45.10 In addition to deriving assessment criteria for construction workers using the CLEA UK model,
additional assessment criteria for the following have been derived for this receptor as these
exposure scenarios are were not included within the CLEA UK model. These are discussed
further in Appendix M:
a. Shorter exposure to lead in soil
b. Acute ingestion of free and complex cyanides in soil
c. Acute inhalation of hydrogen cyanide from soils
d. Acute ingestion of arsenic in soil
4.45.11 The approach and assessment criteria for construction workers are outlined in Appendix M.
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4.46 Implications for Local Residents during Construction
4.46.1 Consideration has been given to the potential for fugitive emissions off-site of dusts and vapours
to impact on local residents or workers. Information obtained from Chapter 19 of the
Environmental Statement (Air Quality and Climate Change) indicates this is most likely to occur
within 200m of the construction works.
4.46.2 An assessment of the possible risks to local residents during the construction and operational
stages is discussed qualitatively in Section 7 of this report.
4.47 Other Soil Assessment Criteria
4.47.1 The following assessment criteria have been used to assess the risks to buried concrete,
potable plastic water pipes and plants in areas of soft landscaping:
a. Building Research Establishment (BRE) Special Digest 1 for concrete in aggressive
ground, Part 1: assessing the aggressive chemical environment (2005). This document
had been used to assess the significance aggressive ground conditions where concrete
is to be used. Special Digest 1 provides guidance on the specification of concrete for
installation in natural ground and in brownfield locations. Procedures are included for
ground assessment and concrete specification for sulphates, sulphides and acids.
b. Water Regulations Advisory Scheme (WRAS) Guidance on the Selection of Materials
for Water Supply Pipes to be laid in Contaminated Land (2002). United Utilities Water,
2011. Supplementary Guidance for the Selection of Water Pipes in Land Potentially
Affected by Contamination. This guidance note provides information for designers and
installers installating water supply pipes in land that may be contaminated and replaces
the former WRAS guidance previously used to assess these risks.
c. Ministry for Agriculture, Fisheries and Food (MAFF) 1998. The Soil Code (the Code of
Good Agricultural Practice for the Protection of Soil). This Code covers the possibility of
causing irreversible, or only slowly reversible physical, chemical or biological changes to
soils which would reduce their ability to grow plants for commercial, conservation or
recreational purposes and to support living organisms. On this basis it has been used
to assess risks to plants in areas of soft landscaping. The Code states that although
soils may be affected by a wide range of contaminants, problems usually arise from a
relatively small number of elements. Elements which can kill plants or reduce yields if
they are present in high concentrations include zinc, copper and nickel. These
contaminants are potentially phytotoxic.
Guidelines for Managing Water Quality Impacts within UK European Marine Sites
4.47.2 There are no standards for sediment quality in the UK with respect to ecological risk in an
estuarine environment. Therefore, the “Guidelines for managing water quality impacts within
UK European marine sites” outlined on the UK Marine SAC website
(www.ukmarinesac.org.uk/activities/water-quality/wq43.htm) have been used. These are based
on Canadian Guidelines and have been used make an initial assessment of risk from
concentrations of toxic substances in sediments to organisms. The guidelines comprise
threshold Interim Sediment Quality Guidelines (ISQGs) and Probable Effect Levels (PELs)
which were developed from the direct measurement of toxicity of sediments to a range of
aquatic organisms. A copy of the ISQGs and PELs are located in Appendix M.
4.47.3 The ISQG values are derived as a level at which effects may be observed in some sensitive
species, whereas the PEL is likely to cause adverse effects in a wider range of organisms. It
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should be noted that the guidelines have not been validated for use in the UK as a proportion of
the test species are not indigenous to the UK and there may be fundamental differences in
sediment geochemistry between Canada and the UK. However, in the absence of UK
standards, these guidelines have been used to make an initial assessment of risk to organisms
from toxic substances in sediments. This guidance is intended for use by nature conservation
agencies and organisations with duties for the management of marine sites.
4.47.4 A statistical assessment has been undertaken to assess the variability in contaminant
concentrations between the mobile sediments in the estuary and those that could be scoured at
the bridge tower locations. This assessment was undertaken using the one sample t-test as
outlined in CIEH (2008) (and also included in CLR7 (2002) which has now been withdrawn) to
derive UCL0.95 values for contaminants . The CLR7 (2002) methodology has been adopted for
the estuary due to the similarity in the alluvial sediments and spacing of the exploratory holes
from which the data was obtained.
4.48 Groundwater and Soil Leaching Tests Assessment Criteria
4.48.1 The results of the groundwater and soil leaching tests have been compared against the
following criteria on the basis that the River Mersey and the major aquifer associated with the
Sandstone bedrock are the main receptors in the Project area:
a. Environmental Quality Standards under the Dangerous Substances Directive
(76/464/EEC) for Coastal and Estuarine waters
b. UK Drinking Water Standards (obtained from the Water Supply (Water Quality)
Regulations, 2000 2010), this has been abbreviated to as the DWS where referred to in
the text.
4.48.2 Where an EQS or DWS have not been published, and in the absence of other appropriate UK
guidance, the following have been used:
a. The Surface Water (Abstraction for Drinking Water)(Classification) Regulations 1996 (SI
1996/3001), which have been abbreviated to the UK SDWS
4.48.3 Environmental Quality Standards (EQS) are levels that are used to assess the risk of chemical
pollutant effects on water quality to the health of aquatic plants and animals in freshwater and
marine waters.
4.48.4 The Dangerous Substances Directive classified substances as List I and List II. Standards for
List I substances have been defined in „daughter‟ Directives to the EC Dangerous Substances
Directive.
4.48.5 The Dangerous Substances Directive required that standards for List II substances are derived
by the member states. The UK has had set EQS for List II substances which have been were
derived by WRc. For each of the List II substances, reports were are available which
describeing the data used to derive the standards and any uncertainties in the derivation.
Where there were are uncertainties arising from a lack of information on effects on saltwater
organisms, larger safety factors had been used in the derivation of the EQS. The Water
Framework Directive (2000/60/EC) has superseded the List I and List II substances with
“hazardous substances” and “non-hazardous pollutants”.
4.49 Ground Gas and Volatile Vapour Assessment Criteria
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4.49.1 The concentrations of ground gas obtained from site monitoring visits have been compared with
the following guidance to provide an initial screen of the degree and extent of contaminants
present:
a. CIRIA Report C665: Assessing Risks Posed by Hazardous Ground Gases to Buildings
(2007)
4.49.2 This guidance has been used to assess risks from methane and carbon dioxide in areas where
toll plazas and offices are proposed. This assessment is based on multiplying the peak
methane and carbon dioxide readings against the peak borehole flow rate for each area to
obtain a Gas Screening Value to assess whether ground gas protection measures are likely to
be required for buildings: This text has been removed to reflect the removal of toll plazas and
offices from the proposed construction works.
a. HSE (2007) EH40/2005 Workplace Exposure Limits
4.49.3 These have been used to assess risks to construction workers from volatile vapours, carbon
dioxide, carbon monoxide and hydrogen sulphide within excavations. The long term (8 hour)
exposure limits have been used on the basis it is possible workers would be in excavations for
extended periods and these limits are lower than the short term (15 minute) exposure limits.
4.50 Detailed Quantititive Risk Assessment for Controlled Waters
4.50.1 A Detailed Quantitative Risk Assessment (DQRA) for controlled waters was undertaken in 2010
to assess the potential risks to surface water from free product identified in groundwater at
Gussion Transport (Area B2) and Catalyst Trade Park (Area C). This was based on
contaminants exceeding their assessment criteria or for which no appropriate assessment
criteria have been published.
4.50.2 The DQRA was undertaken using the Environment Agency‟s Remedial Targets Methodology
(2006) and Remedial Targets Worksheets (2006) to derive acceptable concentrations for
contaminants in the source areas based on a post-construction scenario for comparison against
the available chemical test results. The DQRA has been used to inform the requirement for
advance works remediation.
4.50.3 The DQRA has been included in Appendix V and a summary of the findings provided in Section
6.36.
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4.51 Methodolody for Deriving the Conceptual Site Model
4.51.1 On the basis of the information gathered from the review of published information, previous
investigations and the various phases of intrusive investigation a Conceptual Site Model was
developed. This model was used to identify potential Source – Pathway – Receptor linkages
across the Project area which were then carried forward to the risk assessment process detailed
below.
4.51.2 The Conceptual Site Model was developed under the following overall headings:
a. Environmental settting
b. Ground conditions
c. Contamination
d. Construction proposals
e. Sources
f. Receptors
g. Pathways
4.51.3 The Conceptual Site Model is described in Section 7.2.
4.52 Risk Assessment Methology
4.52.1 The assessment of risk from contaminants in soil and groundwater, and from ground gas and
volatile vapours is based on the guidance provided in CIRIA C552 (2001). At this stage a
qualitative risk assessment has been undertaken for the Do-Nothing, Construction and
Operational Stages. A description of the risk assessment criteria from CIRIA C552 is outlined in
Section 7.6.
4.52.2 The assessment of potential risks is shown on Tables 7.4 to 7.9 in Section 7.
4.53 Methodology for Assessing Possible Mitigation Measures
4.53.1 Mitigation and enhancement measures have been based on the Mitigation Hierarchy shown in
Table 4.23 below (DETR 1997), these range from the most favoured to least favoured options:
Table 4.23 – The Mitigation Hierarchy
Mitigation Hierarchy
Avoid at source
Minimise impacts at source
Abate impacts on site
Abate impacts at receptor
Repair impacts
Compensate in kind
Other compensation and enhancement
4.53.2 Options for mitigation from as high up the hierarchy as possible should be considered first,
working down the hierarchy until some form of successful mitigation can be achieved. This
should be undertaken for impacts created during the design, construction and operation stages
of the project.
4.53.3 In some cases mitigation measures may themselves have an impact on other disciplines, such
as air quality and waste management. Where this is the case these impacts would also need to
be identified and mitigated where possible.
Most Favoured
Least Favoured
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4.53.4 Mitigation is discussed in Section 8 and covers the following stages of the works:
a. Detailed Design.
b. Construction.
c. Operation.
Information on Remediation Techniques
4.53.5 A review was undertaken on remediation techniques that have previously been used within the
Project area or on adjacent sites where similar ground conditions and/or contaminants were
present. Information regarding remediation works at these sites has been obtained either
directly from the Council or from publicly available data sources, including the internet, CL:AIRE
and the University of Greenwich Centre for Contaminated Land Remediation. The use and
effectiveness of these remediation techniques have been considered within the Remediation
Technique Assessment.
4.53.6 Formal consultation was undertaken with remediation contractors in 2007 to establish the range
of techniques available in the UK market and the applicability of specific methods to the
Scheme. A second consultation was undertaken in 2009 with remediation contractors. This
was intended to build upon the findings of the first consultation and refine the estimated costs
and programme for remediation to inform the advanced works remediation in Area C.
4.53.7 The information obtained relating to remediaton techniques could also be used the Project
Company during the construction of the Project including the Proposals.
4.54 Assessment of Foundation Requirements
4.54.1 Information on foundations and proposed construction methods is required to inform the risk
assessment process, to identify whether remediation is required and to inform the waste
classification process.
4.54.2 The current plans for the Reference Design show foundations at structures to comprise piles
inserted by continuous flight auger (CFA) methods extending through the made ground or
alluvium to the glacial till or shallow bedrock. VCC are shown for areas of ground improvement.
However, it is possible different methods will be adopted by the Contractor or a combination of
methods adopted at different locations. It is possible that for embankment sections the
Concessionaire could adopt an approach that does not rely on ground improvement, such as
pre-consolidation or a lightweight embankment.
4.54.3 In order to undertake an assessment of potential risks from use of foundations or ground
improvement as part of the scheme and the potential for introducing preferential pathways, the
following guidance document has been used:
a. Environment Agency, 2001. Piling and Penetrative Ground Improvement Methods on
Land Affected by Contamination: Guidance on Pollution Prevention. Prepared by WS
Atkins for the Environment Agency National Groundwater and Contaminated Land
Centre (NC/99/73).
4.54.4 EA report (2001) outlines the following potential solutions for penetrative foundations in
contaminated land:
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Table 4.24 – Environment Agency Recommended Solutions for Penetrative Foundations in
Contaminated Land
Foundation Solution Methods
Penetrative Ground
Improvement
Vibro replacement
Vibro concrete column
Displacement Pre-formed hollow pile
Pre-formed solid pile
Displacement cast in-place pile
Non-Displacement/
Replacement
Non-displacement cast in-place pile
Partially pre-formed pile
Grout or concrete intruded pile
4.54.5 EA (2001) indicates that displacement piles involve the pile being formed by displacing soil
without the removal of soil to the ground surface (although some of the larger displacement
methods can lead to heave at ground level). Smaller displacement piles can comprise either H
section, I section, hollow tube sections or hybrids such as auger piles. Larger displacement
piles may consist of pre-cast concrete, closed end steel tube or cast in-situ inside a casing or
preformed void.
4.54.6 Non-displacement or replacement piling techniques involve the extraction of a core of soil and
its subsequent replacement by the pile. The pile is typically formed by casting concrete in situ.
Displacement of the soil surrounding the pile is minimised and there is minimal radial or vertical
soil movement or densification as a result of this method. Excavated soil is brought to the
ground surface in the form of arisings, sometimes mixed with grout or concrete from the pile
formation itself.
4.54.7 Since non-displacement piling methods involve the formation of an excavated hole in which the
pile is formed or placed, the temporary support of the hole prior to placing the pile is often
required. A variety of methods have been developed for providing this temporary support,
including temporary and permanent casings and the use of bentonite (DoE and CIRIA, 1977).
The installation of these casings can cause the same effects on the soil as for small
displacement piles.
4.54.8 Ground improvement generally involves the improvement of the physical characteristics related
to load bearing and settlement performance of the soil in order for it to form a competent
bearing material in its own right. Penetrative ground improvement methods involve penetration
of the full depth of soil to be improved by equipment used for the ground improvement; by
contrast non-penetrative methods involve the application of compactive effort at the ground
surface.
4.54.9 The physical properties of the ground may be improved by densification alone, or by a
combination of densification and introduction of granular material which improves the stiffness of
the ground. Introducing columns of granular material can also speed up settlement as the length
of the drainage path is reduced thereby allowing faster dissipation of excess soil pore water
pressures. A comparatively recent development is the introduction of concrete, rather than
granular material, a method that may be considered a hybrid between ground improvement and
displacement piling.
4.54.10 For the purposes of this assessment it is assumed that foundations would comprise
replacement piles such as continuous flight auger (CFA) piles due to the anticipated working
loads. Ground improvement is also likely to be required and on the basis that vibro-concrete
columns are less likely than vibro-stone columns to introduce preferential pathways in
contaminated areas, these have been taken forward for consideration at this stage.
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4.55 Methodology for Assessing Alternative Foundation Measures for Embankments
4.55.1 Alternative methods to VCC foundations have been considered as part of the embankment
construction in terms of engineering solutions. Alternative methods would need to consider
the potential for compression/consolidation of soft made ground and/or alluvial material
underlying the Project area as this could result in the „squeezing‟ out of a finite volume of
groundwater from under embankments. Such compression/consolidation also has the
potential to result in horizontal compression and hence heave of the ground adjacent to the
embankment. Where alternative solutions are proposed, it would be necessary to ensure
these would not lead to preferential pathways for contaminant migration being introduced
or risk inducing contaminant migration.
4.55.2 The assessment of alternative foundations for embankments is included within Appendix P.
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5. REVIEW OF DESK STUDY INFORMATION
5.1 Introduction
5.1.1 This section provides a review of the information obtained on ground conditions, hydrogeology,
landfills and waste management, historical land uses and information on the Mersey Estuary for
the Mersey Gateway Project area derived from published information and previous
investigations.
5.1.2 The results from the chemical testing and monitoring undertaken as part of the Gifford site
investigations for the Mersey Gateway Project are discussed in Section 6 (Baseline). Much of
the information obtained for the Orders ES remains relevant. Where additional information has
been obtained this has been included in the text.
5.2 Published Information on Ground Conditions
5.2.1 This section provides a review of published information on ground conditions.
5.2.2 The ground conditions for the Project area have been obtained from the 1:50,000 scale British
Geological Survey (BGS) Solid and Drift editions, Sheet 97, which shows the area to be
underlain by Quaternary Drift deposits which overlie bedrock of the Triassic Sherwood
Sandstone Group. An extract of the map is shown on Drawing Nos. MG_REP_EIA_009/013
(Drift) and MG_REP_EIA_009/014 (Solid).
5.2.3 The underlying stratigraphy for the study area is outlined in Table 5.1:
Table 5.1 – General Stratigraphy for the Study Area
Strata Type Group/Formation Age Period
Recent
Deposits Made Ground & Fill Recent Recent
Drift Deposits
Marine & Estuarine Alluvium
Shirdley Hill Sand
Glacial Till
Flandrian to Recent
Flandrian
Devensian
Quaternary
Solid Strata
Lower Keuper Marl
Keuper Waterstones
Mercia
Mudstone
Group Scythian Triassic
Upper
Mottled Sandstone
Pebble Beds
Sherwood
Sandstone
Group
Solid Geology
5.2.4 The BGS solid geology map shows that Area A to G is underlain by sandstone bedrock from the
Upper Mottled Sandstone and Pebble Beds. Mudstones and siltstones of the Keuper
Waterstones are shown at the Central Expressway in Area G. Mudstones of the Lower Keuper
Marl are shown from the Lodge Lane Junction to M56 Junction 12 in Areas G and H in Runcorn.
5.2.5 The geological map shows the strata to have a general south easterly dip at a relatively shallow
angle of approximately 15 degrees.
5.2.6 There are two prominent faults within the Project area with further subsidiary faults to the south
of the Project area. The two larger sets of faults are shown to trend approximately north-south
and are positioned as follows:
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a. Weston & Cronton Faults: Three sets of faults shown approximately at the existing
Silver Jubilee Bridge and eastern end of St Michaels Golf Course in Widnes.
b. Halton Fault: shown passing through the western end of Wigg Island (Runcorn) and the
former ICI Muspratt site (Widnes).
5.2.7 The locations of these faults are shown on Drawing No. MG_REP_EIA_009/014.
5.2.8 A buried channel of the River Mersey is shown on the BGS map cut into the sandstone bedrock.
This feature lies to the north of West Bank and is shown to present in parts of Areas A, B and C
and is the result of glacial erosion.
Drift Deposits
5.2.9 The BGS drift geology map shows Glacial Till (formerly known as Boulder Clay) overlying the
bedrock across much of the Project area. The glacial till is described as comprising clay
interbedded with discontinuous horizons of sand or sand and gravel. This is shown to form an
extensive sheet, which varies in thickness from the north to south side of the river. North of the
Mersey the glacial deposits are shown to be up to 40m thick although it is noted in the published
information that they may be thicker still in glacially eroded channels in the bedrock.
5.2.10 The BGS map shows the glacial till is likely to be present near surface in Widnes in the northern
part of Area A, beneath the northern part of the former Anglo Blackwell site in Area B2 and
beneath the Catalyst Trade Park in Area C. In Runcorn the BGS drift map indicates that the
glacial till is likely to be present near surface beneath the former Wigg East Works (also known
as the Kemet Works) on Wigg Island in Area D, and the area between the Astmoor Industrial
Estate and Bridgewater Junction in Areas E and F.
5.2.11 To the south of the River Mersey the bedrock is shown as being typically overlain by 10m to
20m of glacial till.
5.2.12 Glacial sand and gravel are shown at the surface on the BGS drift geology map around M56
Junction 12 in Area H.
5.2.13 The glacial deposits are shown as being overlain by marine and estuarine alluvium on the BGS
drift geology map. In the Project area in Widnes, alluvium is shown beneath Areas A to D on
Widnes Warth saltmarsh, the existing Thermphos UK Ltd site and the southern part of Catalyst
Trade Park, Gussion Transport and the southern part of the former Anglo Blackwell site, Ditton
Junction and St Michaels Golf Course (within Areas A to C). This alluvium in Widnes relates to
a previous course of the River Mersey which flowed to the north of West Bank. Alluvium is also
shown beneath Astmoor saltmarsh in Area D in Runcorn.
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Made Ground
5.2.14 Made ground is material that has been placed by man and can be divided into those composed of reworked natural soils and those composed of man-made materials. The BGS maps do not show made ground within the Project area. However, information from historical OS maps and previous investigations indicates extensive past industrial development in parts of Runcorn and Widnes and, therefore, the possibility of similarly extensive deposits of made ground.
Galligu
5.2.15 Information obtained from the Council‟s website (www2.halton.gov.uk/
content/environment/environmentalhealth/contaminatedland/galligu?a=541) indicates that
„galligu‟ is the term given to waste deposits generated by the Leblanc Process (process
patented by Nicolas Leblanc in 1791). The Leblanc Process was used extensively within the
Borough during the late 19th and early 20
th century for the synthetic production of sodium
carbonate, which was an important compound used in the rapidly expanding alkali chemical
industry.
5.2.16 The Council indicate the Leblanc process involved the heating of sodium chloride (salt) and
sulphuric acid to form sodium sulphate, with the resulting product known as „salt cake‟. The salt
cake was then heated with coal and calcium carbonate (in the form of chalk or crushed
limestone) to produce a material known as „black ash‟.
5.2.17 The black ash reaction was a mixture of sodium carbonate, calcium sulphide and unreacted
coal. This material was then leached with warm water to extract the soda ash (essentially
sodium carbonate) which was then concentrated through evaporation. It was the material left
after the leaching process that was termed galligu. This was a mixture of calcium sulphide, with
lesser fractions of unburnt coal, coal ash and sodium sulphide.
5.2.18 The Leblanc process was inherently wasteful. It is known that for every tonne of soda ash
produced, two tonnes of waste material (galligu) were generated and three quarters of a tonne
of hydrochloric acid vapour was discharged to the atmosphere. For every tonne of salt used in
the process, three tonnes of coal were burned. The Council indicate that it has been estimated
that one million tonnes of coal were being burned annually at the height of Leblanc production.
5.2.19 The Council indicate that an estimated 10 million tonnes of galligu were tipped in Widnes
throughout the period when the Leblanc process operated. The galligu was disposed of in an
uncontrolled manner in the areas surrounding the factories, and was often used to level the land
and to fill in ditches and watercourses. The atmospheric hydrochloric acid vapour precipitated
out on the surrounding land and had a damaging effect on the nearby countryside and
buildings. The action of the hydrochloric acid on the galligu deposits also had the effect of
generating hydrogen sulphide gas (toxic in significant concentrations), with an unpleasant odour
of rotten eggs.
5.2.20 The Council indicate that further problems lay with the production of sulphuric acid that was
used in the salt cake manufacturing stage of the Leblanc process. Rather than using raw
elemental sulphur which was costly, iron pyrites was used. The sulphur was derived from
burning arsenopyrites which lead to the liberation of arsenic vapour and some galligu waste
deposits had elevated concentrations of arsenic. Owing to impurities in the raw materials used
in the Leblanc process other heavy metals were also left in the waste deposits.
5.3 Published Information on the Mersey Estuary
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5.3.1 A review of the published information indicates that the present course of the River Mersey is
not that which it followed during previous interglacial and glacial periods. At that time, much of
the area would have consisted of exposed rock with an expanding ice sheet, thought to have
formed from the west. A combination of ice movement and glacial river flows is believed to
have directly eroded the rock forming deep valleys, now filled as „buried channels‟. D.E. Owen,
(1950) shows the suggested original course of the Mersey together with proven depths to
rockhead. It has been proposed that the greater depths to rockhead show the location of the
channel in pre-glacial and glacial periods. Although the ancient Mersey generally followed a
similar path to the present day river there is a significant postulated variation where the river
flowed north of West Bank rather than through the existing Runcorn Gap. Immediately west of
this point it then joined a wide confluence with the River Weaver (flowing from the south) before
flowing towards the present day Irish Sea.
5.3.2 T.A. Jones (1943) showed tentatively the ancient river course with the depths of rockhead
adjusted into metres. The former channel is shown within the proposed route alignment at
approximately the position of the St. Helens Canal. If this drawing is superimposed over the
exploratory hole location plan for the current investigation, the lower rockhead elevations used
by Jones as the basis for determining the ancient river course would be approximately 400m
south of those noted during investigations by Gifford (refer to Section 6).
5.3.3 D.E. Owen (1950) and R. Kay Gresswell (1964) suggested a greater width for the proposed
valley of the ancient Mersey. Owen (1950) shows the southern boundary approximately at
West Bank area of Widnes, where T.A. Jones marked his channel, with the northern boundary
approximately 1 mile to the north. The southern edge of this channel extends eastwards across
the study area passing through Randle Island (Runcorn), and along the southern edge of the
Fiddlers Ferry Power Station lagoons. The northern edge of this channel extends north of the
St Helens Canal into Widnes. These papers make numerous references to an irregular rock
head profile in this area.
5.4 Contaminant Distribution in Estuaries
5.4.1 The complex and dynamic nature of estuarine systems can influence contaminant distributions.
Therefore, a consideration has been given to recent research on estuaries and patterns of metal
contamination within their sediments.
5.4.2 Estuaries tend to form repositories for contamination (Loring et al, 1992 and Loring, 1990), and
heavy metal concentrations in sediment samples taken from around England and Wales were
found to be higher near the coast than offshore (Rowlatt et al, 1994). The cause of this is their
nature and position, having been the focal point for a wide variety of human activities (Ridgeway
et al, 2002), and also due to natural processes where mixing of saline and fresh waters occurs.
5.4.3 As a consequence of contaminant sorption and complexation by clays, oxyhdyroxides and
organic matter, there is a frequent association of contaminants with the fine-grained sediment
fraction (Ridgeway et al, 2002).
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5.4.4 In high energy environments, where the sediments are reworked these tend to be coarse
grained and non-cohesive with little sorptive capacity and low depositional rates. In low energy
environments, a significant deposition of fine-grained sediments exists, providing a high sorptive
capacity for contaminants (Kersten et al, 2002). In addition to this, fluvial and estuarine
sediments become coated with micro-algal filaments, with different degrees of thickness
according to flow rate.
5.4.5 Trace metals and other chemicals adsorbed to these algal films and particles can become
desorbed and re-suspended in the water column, depending upon the energy of the system
(Schuwerak, 2007). Tsai et al (2003) notes that larger particles tend to have a smaller organic
matter content and, therefore, a lower potential for adsorbing contaminants.
5.4.6 The highest contaminant contents are found in the more quiescent reaches where sediments
are finer grained are less reworked by physical disturbance (Ridgeway et al, 2002).
5.4.7 Metal distribution in estuaries is a function of sediment type, i.e. the hydrodynamics of the
system, and does not reflect major input zones of metals. High concentrations of metals do not
denote source areas (Taylor, 1986).
5.4.8 Saltmarshes and shorelines are examples of low energy systems and consist largely of silts
whilst the intertidal zone of the estuary provides a high energy environment with coarser grained
sediments and a greater degree of sediment reworking.
5.5 Previous Studies in the Mersey Estuary
5.5.1 Previous studies on the Mersey Estuary have determined that sediments are affected by
elevated concentrations of metals (Rowlatt, 1988).
5.5.2 A high and consistent degree of inter-correlation between the silt fraction, organic carbon
content and concentrations of metals was observed from Mersey Estuary data by Taylor (1985),
although this relationship may only be accurate for total metals and not for individual species.
Later studies by Rowlatt (1988) also confirmed that the degree of contamination is a
consequence of the fines content in the sediments.
5.5.3 The increased concentration of contaminants in cohesive materials is considered to be
attributed at least in part to the greater surface area of these unconsolidated sediments (Taylor,
1974), but could also relate to complexation by organic matter (Taylor, 1986).
5.5.4 Taylor (1985) observed elevated metal concentrations within the top 2m of saltmarsh areas of
the Mersey Estuary with no evidence that benthic infauna were being affected by these elevated
metal concentrations. However, the precise area of study of benthic organisms is unknown.
5.5.5 Temporal variations assessed by Taylor (1986) using normalisation to eliminate the fines
content effects have shown, with the exception of chromium, an overall decline in metal
concentrations over time in the Mersey Estuary.
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5.5.6 It is apparent that previous studies have proven a relationship between fines content and metal
concentrations, and that in the Mersey Estuary contaminant levels are greatest in the finer
grained sediments, and in particular the saltmarshes. However, over time the degree of metal
contamination in sediments has declined.
5.6 Hydrogeological Conditions
Groundwater Vulnerability
5.6.1 The Environment Agency 1:100,000 groundwater vulnerability map (Drawing No.
MG_REP_EIA_009/015) shows much of the route alignment in Widnes is directly underlain by a
minor aquifer with a major aquifer immediately to the north. Wigg Island is also shown as being
directly underlain by a minor aquifer as is the area around M56 Junction 12. A major aquifer is
shown near surface beneath the area at Astmoor Industrial Estate and Bridgewater Junction (in
Area E and F). A non-aquifer is shown near surface from the Central Expressway (in Area G1)
to the Weston Link Junction (in Area G2). The major aquifer represents the Sherwood
Sandstone and the minor and non-aquifers relate to drift geology. The major aquifer underlies
the minor aquifer.
5.6.2 A major aquifer is defined by the Environment Agency to be highly permeable formations
usually with a known or probable presence of significant fracturing. They are usually highly
productive and able to support large abstractions for public drinking water supply and
substantial industrial purposes.
5.6.3 Minor aquifers are defined as rocks which do not have a high primary permeability or as
formations of variable permeability. Although these aquifers seldom produce large quantities of
water for abstraction, they are important for local supplies and supplying base flow to rivers.
Non-aquifers are defined as formations which are generally regarded as containing insignificant
quantities of groundwater.
5.6.4 Overlying the major and minor aquifer the Groundwater Vulnerability maps shows drift deposits
of high leaching potential. These are defined by the Environment Agency as soils with little
ability to attenuate diffuse source pollutants and in which non-adsorbed diffuse source
pollutants and liquid discharges have the potential to move rapidly to underlying strata or to
shallow groundwater. However, the soils overlying the minor aquifer outside of Widnes Warth
and Wigg Island, and those overlying the major Sherwood Sandstone aquifer are shown as
urban areas where a worst case is assumed and soil information is based on fewer
observations. Low permeability drift is also shown on the groundwater vulnerability map at the
surface overlying the major aquifer within the proposed route alignment.
5.6.5 From April 2010 onwards the EA has revised the aquifer designations so that they are
consistent with the Water Framework Directive.
5.6.6 The revised aquifer classifications show much of the route alignment in Widnes to be directly
underlain by a Secondary (undifferentiated) aquifer with a Principal aquifer immediately to the
north in Area B. Wigg Island in Area D is shown as being directly underlain by a Secondary
(undifferentiated) aquifer. Secondary A and Secondary (undifferentiated) aquifers are shown in
the area around M56 Junction 12 in Area H. A Principal aquifer is shown near surface beneath
the area at Astmoor Industrial Estate and Bridgewater Junction in Areas E and F. The Central
Expressway to the area around M56 Junction 12 in Area H is shown as being underlain by a
Secondary B aquifer.
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5.6.7 The Principal aquifer represents the Sherwood Sandstone bedrock, the Secondary B aquifer
mudstone bedrock, the Secondary A relates to glacial sand and gravel and the Secondary
(undifferentiated) aquifer to alluvium. Areas where aquifers are not shown are either
unproductive strata or areas where no drift is present, although the presence of glacial deposits
indicates they are likely to be unproductive strata in the Project area.
5.6.8 The Environment Agency provide the following definitions for the revised aquifer classifications:
a. Principal aquifers:layers of rock or drift deposits that gave high intergranular and/or
fracture permeability. They may support water supply and/or river base flow on a
strategic scale. In most cases, principal aquifers are previously designated as major
aquifers.
b. Secondary A aquifers: permeable layers capable of supporting water supplies at a local
rather than strategic scale, and in some cases forming an important source of base flow
to rivers. These are generally aquifers formerly classified as minor aquifers.
c. Secondary B aquifers: predominantly lower permeability layers which may store and
yield limited amounts of groundwater due to localised features such as fissures, thin
permeable horizons and weathering. These are generally the water bearing parts of the
former non-aquifers
d. Secondary (undifferentiated) aquifers: have been assigned in cases where it has not
been possible to attribute either category A or B. In most cases, this means that the
layer in question has previously been designated as both minor and non-aquifer in
different locations due to the variable characteristics of the rock type.
e. Unproductive strata: these are rock layers or drift deposits with low permeability that
have negligible significance for water supply or river base flow.
Aquifer Units
5.6.9 The following information has been obtained on the physical characteristics of the aquifers
within the Mersey Gateway Project area.
Sherwood Sandstone
5.6.10 The Sherwood Sandstone Group comprises the Helsby and Wilmslow Sandstone Formations
within the study area and as noted above, it is classed by the EA as a major aquifer.
5.6.11 In the study area, the Sherwood Sandstone aquifer comprises the layered Helsby Sandstone
over Wilmslow Sandstone Formations. The aquifer as such can be considered to consist of an
upper anisotropic dual porosity zone to -200mAOD (Helsby Sandstone) which is relatively
permeable and fractured, and a lower zone of lower hydraulic conductivity (Wilmslow
Sandstone) with only minor fracturing (University of Birmingham, 1981; Brassington, 1992; Allen
et al, 1997).
5.6.12 The Sherwood Sandstone Group forms the second most important UK aquifer, and is the most
important source of groundwater in northwest England. Groundwater is pumped from a number
of extraction wells, for the purposes of industrial and potable supply. Mukherjee et al (2005)
notes that where the water table falls below sea level, saline water flows into the aquifer.
Made Ground and Drift Deposits
5.6.13 Drift deposits in the project area comprise marine and estuarine alluvium together with glacial
sand, gravel and clay.
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5.6.14 ICI (1999) indicate the glacial drift deposits of the study area do not form an aquifer of
importance and there are no records of its use for water supply in the vicinity of the Runcorn
Peninsula. However, ICI considered that these deposits do have an important hydrogeological
role since they largely determine the degree of hydraulic connectivity between the Permo-
Triassic Sherwood Sandstone aquifer and surface waters.
5.6.15 Hydraulic properties of the drift are reported to be highly variable. The glacial till was
considered by ICI (1999) to be effectively impermeable, and therefore inhibited recharge to the
sandstone aquifer where present in a significant unweathered thickness.
5.6.16 ICI considered the sands and gravels in the glacial drift to be of variable permeability and
porosity. Sand also constitutes lenses within the glacial till. The poorly sorted
fluvial/fluvioglacial deposits with high clay content are of low permeability. The cleaner, well
sorted deposits were considered to have greater potential to form horizons with high hydraulic
conductivity.
5.6.17 Shallow groundwater exists within the alluvial deposits of the proposed route alignment. These
deposits and the localised water tables associated with them are likely to be in hydraulic
continuity with surrounding watercourses, of which the most significant is the tidal estuary of the
River Mersey.
Fault Systems
5.6.18 Mohammed et al (2006) used groundwater chemistry to reveal different compartments of the
Sherwood Sandstone aquifer in the Liverpool area. As noted above the north-northwest to
south-southeast orientated faults (with vertical displacements of up to 300m) traverse the
Triassic and represent vertical margins of the discrete aquifer compartments.
5.6.19 Fault breccias could provide highly transmissive conduits, although the fault itself may be less
permeable and the surrounding rock may act as a barrier to groundwater flow perpendicular to
the fault (Allen et al, 1997).
5.6.20 Within the Permo-Triassic sandstone aquifer, faulting appears to have divided the aquifer into a
series of interconnected blocks, with restricted groundwater flow between the blocks due to the
juxtapositions of differing lithologies, granulation seams and fault-plane infill. The effects of
faulting have only become apparent when the aquifer has been subject to abstraction stress
(Seymour et al, 2006).
5.6.21 Mukherjee et al (2005) notes the dominant fault trend in this area to be approximately north-
south thus allowing saline intrusion in a northwards direction from the Mersey Estuary near to
Widnes. Mohammed et al (2006) have shown that where faults are approximately
perpendicular to the coastline (as in the Project area), the landward invasion by seawater is
more extensive.
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Source Protection Zones
5.6.22 Source Protection Zones (SPZs) are zones designated by the EA around public water supply
abstractions and other sensitive receptors and are intended to protect groundwater resources
from potentially polluting activities.
5.6.23 The Environment Agency define the Zone 2 outer protection zone as an area where
groundwater takes up to 400 days to travel to the borehole, or 25% of the total catchment area
(whichever area is the greater). This travel time is the minimum amount of time the
Environment Agency considers pollutants need to be diluted, reduced in strength or delayed by
the time they reach the borehole.
5.6.24 The Zone 3 (total catchment) is considered by the Environment Agency as the total area
needed to support removal of water from the borehole, and to support any discharge from the
borehole. Although not located in the Project area, a Zone 1 (inner protection zone) is classed
by the Environment Agency as being the area where any pollution can travel to the abstraction
borehole within 50 days from any point. This applies at and below the water table. This zone
also has a minimum 50 metre protection radius around the borehole.
5.6.25 The Environment Agency website shows that the area from Catalyst Trade Park in Area C to St
Michaels Golf Course in Area A is located in a Zone 3 SPZ (total catchment), and the western
most part of the scheme at St Michaels Golf Course is located in a Zone 2 SPZ (outer protection
zone). The total and outer catchment zones identified relate to a series of abstraction boreholes
in the sandstone bedrock to the north of the scheme north of Widnes. Figure 5.1 shows the
source protection zones in Runcorn and Widnes from the Environment Agency website: This
text has been deleted to reflect current information provided on the EA‟s website relating to
SPZs.
5.6.26 Figure 5.1 below shows updated information from the Environment Agency website (accessed
in October 2011) which does not show the project area to be located in a SPZ.
Figure 5.1 – Groundwater Source Protection Zones (Updated)
Inner zone Outer zone Total catchment
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Groundwater Abstractions
5.6.27 A number of abstraction boreholes have been identified from the updated Envirocheck Report
obtained in 2011 within 500m of the proposed scheme. These relate to abstraction of water for
industrial use. These are as follows:
Widnes
a. McKechnie Ltd to the south of Ditton Road (south of St Michaels Golf Course in Area
A). License status is listed as lapsed. The groundwater horizon abstracted is not listed.
b. Albright & Wilson Ltd (now Thermphos in Area C). License status is listed as revoked.
The groundwater horizon abstracted is not listed.
c. Fisons Ltd at West Bank Dock Estate (south of Area A and west of Area I). The license
is listed as lapsed. The groundwater horizon abstracted is not listed.
Runcorn
a. Two abstraction licences are operated by ICI Chemicals and Polymers Ltd and Ineos
Chlor Ltd, abstracting groundwater from the Rocksavage Works.
b. British Waterways Board from Weston Canal at Sutton Weaver. License status is listed
as revoked. Located approximately 500m south of the eastbound slip road at Junction
12 on the M56. This text has been removed as this information is not longer shown in
the updated Envirocheck Report.
5.6.28 The nearest groundwater abstraction identified from the Environment Agency website for
existing public or potable water supplies is 3km northwest of St Michael‟s Golf Course in Area A
near Upton in Widnes in the Sandstone bedrock.
5.6.29 Historical groundwater abstraction from the bedrock particularly for industrial purposes in the
Widnes area during the 1930s-1950s resulted in a substantial drawdown of the water table in
this unit. This may have formed an effective barrier to contaminant transport in the sandstone
bedrock towards public supply boreholes further north. Since the decline of industrial activities
in the 1970s-1990s and associated groundwater pumping, groundwater levels have rebounded
(ICI, 1999). It is also possible that groundwater levels in the bedrock were affected by coal
mining to the north of Widnes.
5.6.30 A number of Environment Agency monitoring wells have been identified within the sandstone
aquifer in the Widnes and Runcorn, although none are located within the Project area.
Groundwater sampling data from these monitoring wells was obtained from the Environment
Agency for review to determine existing groundwater quality in the sandstone. The data
obtained for review received includes the period between 1959 and 2007.
5.6.31 The data from the closest monitoring wells to the project area in Widnes has been assessed,
along with the data from the existing Rocksavage works in Runcorn. Three of these wells are
located close together approximately 1.5km to the east of the Catalyst Trade Park in Area C in
Widnes, and a further three are located between 0.8km and 1km to the south of St. Michaels
Golf Course.
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5.6.32 The chemical test results for chlorinated solvents from these monitoring wells showed the
following:
a. The maximum concentration of trichloroethene (TCE) observed from this data was
6.06μg/l at a monitoring well at the Croda Bowman Works in Widnes (to the south of St
Michaels Golf Course) in December 2000. This concentration was below the UK DWS
of 10μg/l. Other chlorinated solvents identified at this location between 1967 and 2007
included tetrachloroethane, tetrachloroethene, carbon tetrachloride, chloroform, 1,1,1-
trichloroethane and cis-1,2-dichloroethene. The concentrations of these solvents were
all less than the concentrations for TCE. The most recent data shows a concentration
of 1.96μg/l for TCE from this location in July 2007.
b. Other Environment Agency monitoring wells located near the Croda Bowman Works did
not show any impact from chlorinated solvents, although TCE was identified by the
Environment Agency at another monitoring well at the Croda Bowman Works in 1993
(1.4μg/l).
c. None of the monitoring wells to the north east of Catalyst Trade Park have shown
chlorinated solvents to be present above the lower analytical detection limit, although
chloroform (1.9μg/l) was observed from monitoring undertaken at the ICI Mond site in
1993.
d. The maximum concentration of TCE observed beneath Runcorn was 7,160μg/l in 1995
at the „ICI Runcorn‟ site. However, the most recent observation in 2007 at this location
was 1,260μg/l.
e. This data shows the maximum TCE concentration of 2,800μg/l (in 1998) at the Kessler
Works in Runcorn.
f. For Runcorn, the most recent concentrations of TCE are below the highest
concentrations recorded previously.
5.6.33 The information obtained indicates the major aquifer (now referred to as a principal aquifer) in
the sandstone bedrock in parts of Widnes and Runcorn has been impacted by solvents derived
from historical activities. This data indicates the current level of impact by solvents within the
sandstone aquifer to be less than previously observed. However, there appears to still be some
impact within the bedrock to the south of St. Michaels Golf Course. There is no evidence in the
EA data of chlorinated solvents impact in the sandstone aquifer within monitoring wells located
approximately 1km from Catalyst Trade Park.
5.7 Landfills and Waste Management
5.7.1 This section outlines information obtained on existing and former landfills and waste
management sites within 500m of the project area. This section has been updated to reflect
more recent information provided within the updated Envirocheck Report obtained in 2011. The
changes shown relate to updates in the data provided in the Envirocheck Report.
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5.7.2 The updated Envirocheck Report indicates that the southern section of St Michaels Golf Course
in Area A extending to boundary with Ditton Junction in Area B1 is a former registered landfill
site with licenses having been held by the Council and McKechnie Chemicals Ltd. This landfill
extends beyond the Project area boundary. The licenses for this site were surrendered in 1981
and 1979 respectively. The Envirocheck Report indicates these the sites was were licensed to
accept calcium sulphate, construction and demolition wastes, leblanc waste, mine and quarry
waste, distillation residues, industrial non-hazardous and inert waste, non-flammable waste,
potentially combustible waste, industrial effluent treatment sludge and used filter materials.
Ditton Junction in Area B1 is shown as being undertlain by a historical landfill which extends to
the east beneath the former Anglo Blackwell site in Area B2.
5.7.3 The Envirocheck Report shows part of the northern section of St Michaels Golf Course to be a
recorded landfill site, where deposited waste included inert, industrial, commercial and special
waste.
5.7.4 A former special waste transfer station site is shown to the west of St Michaels Road (approximately 200m west of Area A). This site was operated by Cleanaway Ltd and the license was surrendered in September 2002. Again, no further information is provided in the Envirocheck Report. This site accepted a wide range of waste types including household, commercial, inert, industrial non-hazardous.
5.7.5 A small former landfill is shown south of St Michaels Golf Course at the Alumina Factory. This
site accepted inert, industrial, special waste and liquid waste. The site last accepted waste in 1992.
5.7.6 With the exception of the landfills at St Michaels Golf Course, the Envirocheck Reports does not
have any records of landfills within 500m of the Project area in Widnes
5.7.7 The updated Envirocheck Report shows the former Anglo Blackwell site, Gussion Transport and
S Evans & Sons Scrapyard (Area B2) as being located in an area of historical landfill where
deposited waste included industrial waste.
5.7.8 S Evans and Sons Scrapyard in Area B2 is listed as a registered waste treatment or disposal site for electrical equipment, ferrous metals, fridges, gas cylinders, internal combustion engines, non-ferrous metals and vehicles.
5.7.9 The Fallon Bros site to the north of Hutchinson Street in the northwest of Area C is listed as a
licensed waste management facility for metal recycling site (vehicle dismantlers). The former Widnes Experimental Site in Area C (now Cataylst Trade Park) is shown as a former waste treatment site (for aqueous acidic and organic mixtures) and former Integrated Pollution Control site.
5.7.10 A former landfill is shown in the area south of Hutchinson Street (Area I) which is labelled as the
ICI Coal Stockyard. Deposited waste included industrial waste and liquid sludge. This part of Area I is also listed as having a mobile plant license issued to Powerbetter in 2003 which is understood to relate to soil treatment works
5.7.11 A historical landfill is shown to the west of Area I (west of MacDermott Road) at West Bank
Dock Estate where inert, industrial, commercial and household waste was deposited. The last input date is shown as 1979.
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5.7.12 A former landfill shown as the ICI C and P Muspratt site is located in the northeast of Area C,
which extends eastwards beneath the Thermpos factory. This site is shown as having accepted industrial waste from 1852, although no completion date has been provided.
5.7.13 A former landfill is shown adjacent to Catalyst Trade Park (Area C) which extends south along
St Helens Canal. No information is provided on the waste accepted or when the site operated.
5.7.14 In Runcorn approach viaduct piers would be located on Wigg Island Landfill in Area D. This is listed in the Council‟s Contaminated Land Strategy (2001) as being part of the Wigg Works Tip which was opertated by ICI for inert process solids. The Contaminated Land Inspection Strategy also lists the area to west of the route alignment in Area D (towards the west of Wigg Island Community Park) as having operated between 1869 and 1960, with deposited wastes including inert and industrial waste.
5.7.15 The former Kemet Works, to the east of Wigg Island Landfill is also shown as an area of landfill
although no information is provided on the waste deposited.
5.7.16 The Envirocheck Report has records for another historical landfill site in Area D. The location is
shown on the Envirocheck Report immediately south of the former Kemet Works. The records
provided indicate this site operated between 1869 and 1960 and deposited material included
industrial waste. Another record in the Envirocheck Report for this location indicates the landfill
was licensed to ICI Ltd Mond Division for waste produced on-site. The status of the landfill is
shown as „record superseded‟. The records indicate the maximum input rate was greater than
250,000 tonnes per year and the authorised waste comprised the following:
a. Construction demolition wastes
b. Mainly calcium sulphate
c. Mercury contaminated waste
d. PVC
e. Razorite
f. Sludge containing 5% vermiculite foam
g. Spent catalyst (including chromium oxide)
h. Sulphur bearing debris and filter cake
i. Traces of chemical contamination from own operations
5.7.17 The Randle Island Landfill is located approximately 400m east of Area D and is also on Wigg
Island in Runcorn. The Envirocheck Report indicates this is an active site operated by Ineos
Chlor which is licensed to accept Special Waste and also material excluding inert waste.
Information on the EA website (www.environment-
agency.gov.uk/commondata/103601/haz_landfills_677379.xls) indicates the Randle Island
Landfill site is permitted to accept treated hazardous wastes arising from the chemical
manufacturing process. Information on the Ineos Chlor website
(http://www.ineoschlor.com/productinformation/hazardouswaste.shtml) indicates that Randle
Island is licensed to accept hazardous waste.
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5.7.18 The updated Envirocheck Report shows all of Astmoor saltmarsh as being a former landfill
which operated from 1869 to 1960. No information has been provided on the waste accepted.
However, with the exception of the sites discussed above, the information relating to landfills in
the Envirocheck Report is not consistent with the historical records for this area. One of the
references in the Envirocheck Report for the Astmoor saltmarsh relates to the ICI Mond Division
for the Randle Island landfill which is located 400m east of Wigg Island in Area D. The status of
the landfill is shown as „record superseded‟. The records indicate the maximum input rate was
greater than 250,000 tonnes per year and the authorised waste comprised the following:
j. Construction demolition wastes
k. Mainly calcium sulphate
l. Mercury contaminated waste
m. PVC
n. Razorite
o. Sludge containing 5% vermiculite foam
p. Spent catalyst (including chromium oxide)
q. Sulphur bearing debris and filter cake
r. Traces of chemical contamination from own operations
5.7.19 The updated Envirocheck Report indicates this the Randle Island Landfill is still an active site
operated by Ineos Chlor which is licensed to accept Special Waste (hazardous waste)
5.7.20 The Envirocheck Report has records of a registered waste transfer site and a waste treatment
or disposal site on Astmoor Industrial Estate, licenses for both sites are shown as being
lapsed/cancelled/surrendered. The waste transfer site was located immediately north of the
Project area and the Daresbury Expressway on Chadwick Road. This license holder was
Autochem Ltd and the authorised wastes were solvents. No date for the issue or surrender of
the licence is provided in the Envirocheck Report. The waste treatment or disposal site was
located west of the Project area on Davy Road and the authorised waste comprised plastics
only. This license was issued in 1990 but no date for the surrender of the licence is provided in
the Envirocheck Report.
5.7.21 The updated Envirocheck Report has a record for a licensed waste management facility on
Astmoor Industrial Estate in Area E which relates to Statham Tyres & Co at Goddard Road.
The site is classed as a transfer station and the license was issued in 2008. A metal recycling
facility is also located at JFC Plastics on Hardwick Road at Astmoor Industrial Estate.
5.7.22 The Envirocheck Report has one record for a historical landfill on Astmoor Road to the west of
Area E at Astmoor Industrial Estate. This relates to the deposits of alum waste and the last
recorded use was in 1968.
5.7.23 The Envirocheck Report shows a landfill to the west of M56 Junction 12 in Area H which was
first used in 1962. This is shown as No.3 Lagoon although no other information was provided.
Additional lagoons are shown to the west of the Weaver Navigation, approximately 250m from
the Project area, which were operated by ICI Chemicals & Polymers Ltd. The licenses for these
sites are not shown as having been surrendered.
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5.8 Contaminated Land Register Entries
5.8.1 This section has been inserted using information provided within the updated Envirocheck
Report obtained in 2011.
5.8.2 The Envirocheck Report shows the northern section of St Michaels Golf Course to be a Special
Site under Part IIA of the Environmental Protection Act 1990.
5.8.3 Consultation with the Contaminated Land Officer at the Council in 2011 indicates that
remediation works have been undertaken on the northern section of St Michaels Golf Course to
improve the water quality in Stewards Brook and remove pathways from existing soil
contaminants to site users which were completed 2010.
5.9 Pollution Incidents
5.9.1 This section has been inserted using information provided within the updated Envirocheck
Report obtained in 2011.
5.9.2 A number of pollution incidents are shown in the Envirocheck Report on or close to the Project
Area.
5.9.3 In Area A to C, the majority of these are Category 3 – minor incidents which relate to sewage.
In Area C there is a reference to spillage of industrial effluent in 1992 into Bowers Brook. In the
surrounding area there are also a number of references to leachate from the northern section of
St Michaels Golf Course, along with oils and chemicals in surface water.
5.9.4 On Widnes Warth in Area D there is reference to a Category 3 – minor incident involving
industrial effluent from spillage into Johnsons Brook.
5.9.5 To the south the River Mersey, there are a number of records of pollution incidents into the
Manchester Ship Canal involving chemicals, oil and sewage. On Astmoor Industrial Estate in
Area E, in addition to sewage, there are records of Category 3 – minor incidents involving
chemicals (paints/dyes) and solvents. There is also one record at Astmoor Indsutrial Estate of a
prosecution for contaminated water entering a nearby watercourse (hearing date is shown as
November 2005), although no further information has been provided.
5.9.6 At the Weston Link Junction in Area G2, there is one record for pollution of Weston Canal with
diesel following a road traffic accident in 1997. There are also two records of incidents involving
diesel in Area H both of which occurred in 1995.
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5.10 Site Inspections
5.10.1 Site inspections were undertaken prior to each phase of investigation to assess the existing
land usage, ground cover and exploratory hole locations. The following land uses were
observed during the site inspections:
Widnes
a. Area A – closed golf course (St Michaels Golf Course) where ground cover comprised
grass with trees around the site boundary. A subway/tunnel is located to the west of
Area A below the Speke Road connected the northern and southern parts of the golf
course, although this has been blocked to prevent access.
b. Area B1 – Ditton Roundabout and access roads. Ground cover on the roundabout
predominantly comprised grass with hard surfacing for the access roads.
c. Area B2 – road tanker/container park (Gussion Transport) and industrial units (Widnes
Tanker Services), scrapyard (S.Evans & Sons). Ground cover at Gussion Transport
and the scrapyard comprised compacted hardcore with hardstanding only present
around the industrial units.
d. Area C – scrapyard with rough ground cover (Fallon Brothers), roads, light industrial
units (Catalyst Trade Park) and grassed area with an open culverted section of Bowers
Brook at Thermphos.
e. Area D – saltmarsh (Widnes Warth). Cover comprised saltmarsh vegetation, drainage
ditches and a canalised drainage channel (outfall to Bowers Brook).
f. Area I – highway embankments (A533 and A557), railway lines.
Runcorn
a. Area D – saltmarsh (Astmoor Saltmarsh). Cover comprised saltmarsh vegetation and
two areas of landraise towards the south of this area (Wigg Island Landfill and former
Kemet Works) separated by a surface water feature (spur to former Latchford Canal).
The Manchester Ship Canal was noted to the south of this area. The Wigg Island
Landfill forms part of a community park which extends west of this area.
b. Area E – industrial estate and access roads (Astmoor Industrial Estate).
c. Area F to H – highways (Bridgewater Junction to M56 Junction 12).
5.10.2 The Project area in Widnes and Runcorn is separated by inter-tidal sandbanks (Runcorn Sands)
in Area D. Alluvial silt deposits were noted where the River Mersey and saltmarshes meet.
5.10.3 The following areas have been identified within the route alignment with the potential to have
resulted in land contamination based on their current land uses:
a. Area A – former landfill at St Michaels Golf Course.
b. Area B2 – former Anglo Blackwell site, Gussion Transport, S.Evans & Sons Scrapyard,
Solar Petroleum (immediately east of Project area and the S.Evans & Sons Scrapyard).
c. Area C – Railway lines, Fallon Brothers Scrapyard, Catalyst Trade Park (ERF Building),
Thermphos.
d. Area D – former landfill at Wigg Island and Kemet Works.
e. Area E – Astmoor Industrial Estate.
5.10.4 No outcrops of bedrock were observed within the Project area. However, sandstone bedrock is
visible on the south bank of the Manchester Ship Canal near Guinness Berth in Runcorn (to the
west of the route alignment) and at the foreshore during lower tides at West Bank in Widnes.
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5.10.5 St Michaels Golf Course in Widnes is currently closed to the public, a sign on the entrance gate
adjacent to Ditton Road indicated that the site was closed to the public due to contamination
although this area has not been secured to prevent access.
5.10.6 A spring with a white residue/precipitate was noted on the south bank of a tidal drainage
channel on Astmoor Saltmarsh. This spring was located adjacent to the north of the eastern
end of the Wigg Island Landfill approximately 20m west of the proposed route alignment.
During a walkover to determine exploratory hole locations for the Phase 4 investigation in 2004,
a small area of subsidence was noted in the cap on the Wigg Island Landfill. This was located
to the west of the route alignment and exposed black chemical waste underlying a clay cap
5.10.7 Whilst no additional formal site walkovers have been undertaken, visits have been undertaken
to parts of the Project area during meetings, monitoring visits and additional site investigation.
5.11 Review of Historical OS Maps
5.11.1 This section provides a review of the historical Ordance Survey (OS) maps obtained from
Landmark for the Project area. These historical maps are included in Appendix K.
5.11.2 The information on site history is discussed on the basis of the „areas‟ shown on Drawing No.
MG_REP_EIA_009/003.
Widnes
Area A & B1 – St Michaels Golf Course
5.11.3 St Michaels Golf Course was added to the Project area in 2006. Ditton Junction is located to
the east of the Golf Course. A review of historical OS maps dating from 1880 to 2004 obtained
from the Landmark Information Group has identified the following land uses on and adjacent to
the southern part of St Michaels Golf Course, Speke Road and Ditton Junction.
5.11.4 The 1849 OS map shows the site of St Michaels Golf Course to be fields. Marsh End Farm is
shown in the northern part of the existing golf course, with Birch House to the east of the site.
Ditton Marsh and Widnes Marsh are shown to the south of the site. Stewards Brook is shown
flowing through the site St Michaels Golf Course in an approximate north-northeast to south-
southwest direction. Stewards Brook is located outside of the Project Area, west of Area A.
The Brook appears to be culverted to the north of the site.
5.11.5 The 1893 (1:2,500) and 1894 – 1896 (1: 10,560) maps show the Sheffield and Midland Joint
Railway crossing the northern part of the site. A possible pond is shown to the south of the
railway. A north-south track/road is shown between Ditton Road and Marsh End Farm passing
beneath the railway line in the approximate location of the existing subway/tunnel connecting
the northern and southern parts of what is now St Michaels Golf Course. The area around the
existing Ditton Junction is shown as an area of possible fill.
5.11.6 The Liver Alkali Works is shown towards the southwest of Area A (adjacent to Ditton Road and
possibly extending to the south of the road), with Ditton Copper Works and a Vitriol Works
shown south of Ditton Road. An Alkali Works is shown in the area to the south west of the
existing Ditton Roundabout (south east of Area A). Further to the east and south east in Widnes
the area is shown as having been developed with railway lines, chemical works and housing.
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5.11.7 The 1907 (1:2,500) OS maps shows water a course entering the site from the north before
turning to flow to the south east, this is in the approximate location of the existing Stewards
Brook.
5.11.8 The 1908 OS maps shows areas of possible fill as changes in slope in the west of the site and
also to the north in the northern part of what is now St Michaels Golf Course. A „Gasometer
(Disused)‟ is shown at the site of the Liver Alkali Works in the south west of Area A; the label for
this works is now shown to annotate the buildings to the south of the road together with two
Gasometers. The Vitriol Works to the south of Ditton Road is no longer labelled although
buildings remain. The Alkali Works to the south west of the existing Ditton Roundabout is now a
Metal Works, immediately to the west of this the Widnes Iron Works is marked.
5.11.9 No significant changes are shown on the 1911 OS map. The 1927 (1:2,500) OS maps show
areas of fill to the west of the current Stewards Brook, to the east of this Area A is shown as
marshy ground. To the south of the existing golf course site and north of Ditton Road, two
unlabelled buildings are shown along with fill material. Ditton Junction is also shown as fill.
5.11.10 The 1928 OS map shows an Alumina Works at the location of the former Vitriol Works, with
Newfoundland Timberyard to the west at the site of the former Liver Alkali Works. Fill material
is shown towards the west of the site and in the northern part of the existing golf course (west of
Marsh End Farm). Areas of fill are shown to the east of the existing Ditton Roundabout along
with a Corporation Depot. Fill is shown east of the railway lines located to the east of Area A.
5.11.11 The 1937 (1:2,500) OS maps shows fill material in the area between the north-south track/road
to Marsh End Farm and an unlabelled water course at the site (now Stewards Brook). The fill to
the east of Stewards Brook is more extensive and sludge beds are shown. The 1954 – 1956
OS maps do not show any significant changes.
5.11.12 The 1958-1959 (1:2,500) OS maps show a „works‟ on the area of fill to the east of Stewards
Brook/north of Ditton Road, on the area where two buildings were previously shown on the 1927
OS map. More extensive filling is shown to the east and west of Stewards Brook. A „Pit
(carbonate of lime)‟, timber yard and depot are shown towards the west of Area A. The possible
pond identified on the 1893 OS map is now labelled as a pond. More extensive filling is shown
in the northern part of what is now the golf course.
5.11.13 The 1964 OS map shows a smaller roundabout at the site of the existing Ditton Junction. The
existing northbound sliproad from Queensway to the Ditton Roundabout is shown leading to this
roundabout.
5.11.14 The 1967/1968/1969 (1:2,500) Composite OS map shows that the works to the south of Area A
is now a chemical works, „tanks‟ are labelled towards its northern and northwestern boundaries.
The southeast trending water course is now labelled as Stewards Brook; the previously labelled
water course is no longer shown. Ponds are shown to the east and west of Stewards Brook.
The A562 Speke Road is shown along the northern site boundary. Sludge beds and refuse tips
are shown on Area A; one of these sludge beds is on the site of the former pond. A dismantled
railway, slag heaps and refuse tip are shown in the northern part of what is now the golf course.
The north-south path is labelled as „old lane (path)‟ and passes beneath the Speke Road the
subway/tunnel.
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5.11.15 The 1970/1977 OS map shows a timber yard, lime pits and a depot in the western part of Area
A.
5.11.16 The 1979 (1:2,500) OS map shows Area A to be a refuse tip, a pond is shown towards the
northern boundary of Area A at the location of a former sludge bed. The land to the north of
Speke Road is labelled as a golf course.
5.11.17 The 1984/1987/ 1990/1994 Composite OS map shows the western part of the site is now also
part of the golf course (1990 OS section). Fill material is shown to the east of the site extending
towards the Speke Road and Ditton Roundabout (on the 1987 OS section).
5.11.18 The 1988 (1:1,250) OS map shows the smaller roundabout previously identified has been
replaced by the existing Ditton Junction.
5.11.19 The 1993 (1:2,500) OS map shows Area A to be part of a golf course. The 2004 OS maps also
shows this area to be a golf course, the land to the east of Area A (and west of Ditton Junction)
is shown as open land.
Area B2 and I1– Ditton Junction to Freight Rail Line
5.11.20 This assessment is based on the area currently occupied by Ditton Roundabout, Gussion
Transport, former Anglo Blackwell site and S. Evans and Sons Scrapyard.
5.11.21 The 1893 (1:2,500) OS map shows the Project area was occupied by an Alkali & Sulphur Works
located towards the west of the existing Gussion Transport site, with a Chemical Works
occupying the centre and east of the Gussion site. A Caustic Drum Works and an Oil and
Grease Works are shown to the east of the existing S.Evans and Sons Scrapyard which is
shown as open land (possible area of fill). Railway lines are shown to the south of these sites.
To the south of these railway lines a Manure Works, the Viaduct Chemical Works and the
Mersey Copper Works are shown. Residential buildings are shown along Victoria Road.
5.11.22 The 1907 (1:2,500) OS map shows that the majority of the buildings previously shown on the
site of the former Alkali & Sulphur Works and Chemical Works are no longer present. A
chimney and two possible tanks are shown beneath the existing A533 Queensway road
embankment. The existing former Anglo Blackwell site is shown as open land to the north of
Ditton Road. A foundry is shown to the west of the iron and steel works (immediately east of the
existing S.Evans and Sons Scrapyard). An iron and steel works is shown on the site previously
occupied by the caustic drum works. The Manure Works to the south is shown as the Victoria
Chemical Works.
5.11.23 The 1927 (1:2,500) OS map shows a Corrugated Iron Works (Hay Gordons & Birmingham Iron
Company) on the site of the former Alkali & Sulphur Works and a Steel Alloy Works on the site
of the former Chemical Works at the existing Gussion Transport site. Buildings are shown on
the existing S.Evans & Sons scrapyard but their use is not shown. The former existing Anglo
Blackwell site is also shown as an area of fill. The former iron and steel works is now shown as
an iron keg and drum works. The Victoria Chemical Works to the south is shown as a
Corrugated Iron Works.
5.11.24 The 1937 (1:2,500) OS map shows the buildings at the existing S.Evans & Sons scrapyard to
be an Engineering Works. Two rectangular buildings are shown to the north of Ditton Road at
the former Anglo Blackwell site, the area around these buildings is still shown as fill. The
Corrugated Iron Works to the south is shown as being disused.
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5.11.25 The 1958 and 1959 (1:2,500) OS maps shows all of the sites identified from the previous OS
maps as Works. Additional buildings are shown at the existing former Anglo Blackwell site. The
disused Corrugated Iron Works to the south of the site is no longer shown.
5.11.26 The OS map covering 1964, 1968 and 1971 shows the sites to the east of the S. Evans and
Sons Scrapyard as, from west to east, metal drum works, coal yard, engineering works and
motor oil works respectively.
5.11.27 The 1988 (1:1,250) OS map shows the area to be similar to the current land use. Many of the
railway lines/sidings to the south of the existing freight rail line have been removed, although
some are still present and this area is shown as a depot. A scrapyard is shown at the site of the
existing Fallon Brothers Scrapyard extending west to Victoria Road.
Area C
West of Victoria Road
5.11.28 This area currently comprises a reclamation yard in the western part (Area I2) with Fallon
Brothers Scrap Yard to the east in Area C.
5.11.29 The 1849 (1:10,560) OS map shows this area was unoccupied at this time. A railway line,
which is later recorded as the L & N W Railway Widnes Deviation, is shown along the northern
boundary.
5.11.30 Historical maps published between 1893 and 1971 show that the area was occupied by a
number of railway sidings and a goods station. Various residential and/or commercial
properties are also shown along Hutchinson Street and Victoria Road.
5.11.31 A number of railway sidings appear to have been removed from the site before 1988, when
historical maps show that the site was occupied by depot in the south and a scrap yard in the
north (which extended eastwards to Victoria Road). A garage and small depot are shown to
north of Hutchinson Street.
5.11.32 Ordnance survey plans of the area published in 1994 indicate that at the time of survey railway
sidings were no longer present on the site. The 1999 Ordnance Survey Plan shows the existing
A557 Widnes Bypass crossing the site on an embankment. Only the western end of the existing
Fallon Brothers Scrapyard is shown (to the west of the A557) on this map.
East of Victoria Road
5.11.33 This area is currently occupied by the Catalyst Trade Park and comprises a series of light
industrial units separated by hard landscaping (roads and car parking) and soft landscaping
(predominately grass and gravel). Within the route alignment at the Thermphos site the land
comprises predominantely grass cover, with Bowers Brook flowing through an enclosed channel
along the southern boundary. The existing Thermphos chemical works is located immediately
north of the route alignment.
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Catalyst Trade Park
5.11.34 The 1849 1:10,000 scale OS map shows this area to be mostly fields with Widnes Oil Works is
shown adjacent to the existing swing bridge over the St Helens Canal.
5.11.35 The 1893 OS map shows the majority of this area to be occupied by a Chemical Works with
associated railway lines/sidings. A Resin Works is shown in the approximate area of the former
Widnes Oil Works. Railway lines are shown in the approximate location of the existing A557
Expressway beyond which are buildings associated with a Chemical Works.
5.11.36 The 1907 OS maps show the Chemical Works at the current Catalyst Trade Park to be the
Woodend Chemical Works. The former Resin Works is now shown as a Manure Works.
5.11.37 The 1927 OS map shows the former Woodend Chemical Works as the Gaskell Deacon Works
(Chemical) with the former Manure Works shown as an Alum Works. The land use appears
similar on the 1937 OS map although the buildings are not labelled.
5.11.38 The 1958 and 1959 OS maps show the large building towards the centre/south of the Gaskell
Deacon Works to have been removed and replaced by a number of smaller buildings. Railway
lines are still shown at the site.
5.11.39 The 1971 OS map shows the site to be occupied by a Chemical Works although much of the
site appears to be open land. A number of tanks are shown towards the west of the site. The
former railway lines are shown as dismantled. The Chemical Works is still shown to the north of
the current A557 Expressway.
5.11.40 The 1988 OS map shows additional buildings towards the west of the current site with more
tanks labelled towards the centre and east of the existing Catalyst Trade Park. The former
chemical works to the north of the site is no longer shown. The existing copse of trees between
the eastern end of the Catalyst Trade Park and St Helens Canal is now shown.
Thermphos
5.11.41 Immediately to the east of the Catalyst Trade Park is Thermphos UK Ltd which produces
speciality phosphates for use in a variety of applications. The former ICI Muspratt site is located
immediately to the east of Thermphos and Area C.
5.11.42 The 1849 OS map shows a chemical works in the southern part of the existing Thermphos site
with east-west orientated railway lines which cross the Thermphos site to the south of the
existing buildings.
5.11.43 The 1893 OS map shows an expansion of the chemical works and a gasometer in the south
west corner of the site surrounded by a possible area of fill. The site is labelled as the Muspratt
Works (Chemical) with an increased number of tanks and buildings shown on the 1907 OS map
where it is labelled as the Muspratt Works (No.1) (Chemical).
5.11.44 A significant number of buildings and tanks at the current Thermphos site are shown as having
been cleared on the 1927 OS map.
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5.11.45 Alkali Works are shown occupying the western part of the former ICI Muspratt site immediately
to east of the current Thermphos site on the 1895 OS map. This site is shown as the Muspratt
Works No.2 on the 1928 OS map. The former Muspratt No.2 works site is shown to have
largely been cleared on the 1982 OS map.
Area D - Widnes Warth
5.11.46 Widnes Warth currently comprises saltmarshes, with Bowers Brook flowing in a north-south
open channel towards the Mersey Estuary. No developments are located in this area.
5.11.47 The 1893 OS map shows a building in the northwest corner of Widnes Warth. An area of fill is
shown to the east of this building on from the 1927 OS map onwards at the location of the
proposed northern abutment (immediately adjacent to the St Helens Canal). An area of fill is
also shown adjacent to the St Helens Canal to the east of the route alignment (and east of
Bowers Brook) from the 1895 OS map onwards. Bowers Brook appears on the 1982 OS map
although none of the 1:10,000 scale maps dating back to the 1960‟s show this area.
Runcorn
Area D to F - Astmoor Saltmarsh to Bridgewater Junction
5.11.48 Wigg Island Landfill forms part of the Wigg Island Community Park. No developments are
currently located within Area D to the north of Manchester Ship Canal. To the south of the
Manchester Ship Canal is the Astmoor Industrial Estate in Area E which comprises mostly light
industrial units, to the south of which is an existing junction to the A533 Expressway in Area F.
5.11.49 The 1881/1882 OS map (10:560) shows the area north of the existing Manchester Ship Canal
(which has not been constructed at that time) to be predominantly saltmarsh („Astmoor Salt
Marsh‟). The Latchford Canal is shown. The Old Quay Works (copper and alkali) is shown to
west of the Project area in Area D, towards the west of Wigg Island. Marsh Farm is shown east
of the Project area at the Astmoor Industrial Estate although the majority of this is shown as
open fields. The Astmoor Tannery is shown within the Project area along the north bank of the
Bridgewater Canal east of the Bridgewater Junction.
5.11.50 The 1899 OS map shows the Manchester Ship Canal in the approximate location of the former
Latchford Canal. A spur to the Latchford Canal in the project area is still shown, to the south of
this is a triangular area of land which appears to have been tipped on (this extends to the east
of the project area). Astmoor Salt Marsh is shown as “liable to floods”. The former Old Quay
Works is now shown as the Wigg Works (Alkali) with a limited area of tipping to the east of the
works. Finches Ferry is shown south of the Manchester Ship Canal and west of the Project
area.
5.11.51 The 1908 OS map shows the existing Latchford Canal spur as Canal (Disused). The former
Finches Ferry is now shown as Point Turn Bridge Ferry (Private).
5.11.52 The 1928 OS maps shows the area of tipping adjacent to the Wigg Works to have extended
eastwards although not into the Project area. The Point Turn Bridge Ferry is no longer shown.
The building at Astmoor Tannery is shown to have expanded northwards.
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5.11.53 The 1938 OS map shows extensive development in the area between the Latchford Canal spur
and Manchester Ship Canal. The Point Turn Bridge Ferry (Private) is now shown again.
5.11.54 The 1954 OS map shows the development noted immediately north of the Manchester Ship
Canal to be the Kemet Chemical Factory. The tipping east of Wigg Works has extended
eastwards slightly further. A filter bed is shown north of Marsh Farm in the area of the existing
Astmoor Industrial Estate. Buildings (possible houses) are shown east of Marsh Farm.
5.11.55 The 1962 and 1963 OS maps (1:2,500) shows that the area of tipping noted to the east of the
Wigg Works has extended closer to the Project area. Development is shown to the east of the
Kemet Factory at Randle Island. An outfall is shown in the Project area extending from the site
of the Kemet Factory, over the Latchford Canal and into a drain on the saltmarsh. Halton Brook
is shown flowing northwest from the filter beds identified in the area of the Astmoor Industrial
Estate and towards the Manchester Ship Canal.
5.11.56 The 1968 OS map shows numerous buildings at Randle Island, the closest of which are
approximately 700m east of the Project area. The use of these buildings is not shown. The
land surrounding the works at Randle Island is approximately 380m east of the Project area at
its closest point.
5.11.57 The 1982 OS map shows a „refuse tip‟ in the Project area to the south of Astmoor Saltmarsh (at
the existing Wigg Island Community Park). The former Kemet Works is no longer shown. Part
of the Latchford Canal spur to the east of the Project area appears to have been infilled. The
former Wigg Works has been removed and a Warehouse is shown. The buildings at Randle
Island are shown as being „works (disused)‟ with the majority of the buildings having been
removed. To the south of the Manchester Ship Canal, the Astmoor Industrial Estate is shown
along with the Bridgewater Junction (the carriageway west of the Bridgewater Junction has not
been constructed at this stage). The former Astmoor Tannery and Marsh Farm are no longer
shown.
5.11.58 The 1994 OS map shows trees at the former refuse tip at the existing Wigg Island Community
Park and at the Kemet Factory. The area of the former works at Randle Island is shown as an
area of tipping with a series of possible lagoons or ponds towards the south of the site. The
tipping at Randle Island is shown approximately 380m east of the Project at its closest point.
Further development is shown at the Astmoor Industrial Estate. The A533 Daresbury
Expressway is shown to the west of the Bridgewater Junction.
Area G to H - A533 Central Expressway to M56 Junction 12
5.11.59 A review of the historical OS maps up to and including 1962 shows the majority of the Project
area to be fields. The existing road network is first shown on the 1974 OS map (1:2,500) with
the adjacent housing developments at Beechwood and Southgate shown on the 1980 OS maps
onwards.
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5.12 Review of Information from Previous Investigations
Widnes
Area A and B1 – St Michaels Golf Course (South) and Ditton Junction
5.12.1 St Michaels Golf Course was added to the proposed Mersey Gateway Project area in 2006.
The information below on St Michaels Golf Course was obtained from a review of ground
conditions undertaken by Gifford for the Council in July 2006.
5.12.2 Information on ground conditions was obtained from the following:
Table 5.2 – Sources of Information on Ground Conditions
Title Author Date Client
Investigations of Contaminated Land at McKechnie
Site, Widnes
Environmental
Advisory Unit
June 1980 Cheshire County
Council
Report of Soils and Foundation Conditions Soils & Materials
Testing Ltd
September 1980 Cheshire County
Council
Report on a Ground Investigation at proposed
Industrial Development at McKechnies Land
Reclamation Scheme Phase II, Dutton Lane, Widnes
Sub Soil Surveys
Ltd
March 1982 Cheshire County
Council
Contamination Assessment: St Michael‟s Golf
Course, Widnes
EAC December 2003 Halton Borough
Council
Results of Ground Investigation at Widnes
Galvanising, Widnes
Sub Soils
Surveys Ltd
May 2004 Fleming Smith
Associates
St Michael‟s Golf Course, Widnes: Environment
Agency B.20(a) Documentary Review. Draft Report
Volumes 1 to 3
Atkins July 2005 Environment
Agency
Factual information comprising exploratory hole
location plan, logs and chemical test results (no
report)
AMEC August 2006 Halton Borough
Council
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Ground Conditions at St Michaels Golf Course (South)
5.12.3 The information from the previous investigations indicates the ground conditions within the
proposed route alignment comprise the following:
Table 5.3 – Ground Conditions Identified from Previous Investigations
Strata Depth of Strata (m
bgl)
Description Groundwater levels
(m bgl)
Made Ground Top: Ground Level
Base: 3.8 – 8.0
(base not proved in
any trial pit to 0.6+
to 3.7+)
General infill, brick rubble, evidence of
„metallic‟ layers, Leblanc waste
Very soft to firm sandy clay with brick, soil,
stones, ash, wood and chemical waste with a
lower area of chemical waste
Widnes Galvanising Report (May 2004):
Concrete and sub-base (stone ash, sand,
brick and concrete) over slightly clayey to
clayey sandy chemical waste (galligu) with
occasional brick and stone
1.4 – 6.2 (not
encountered in all
exploratory holes)
Glacial Till Top: 3.8 – 8.0
Base: 15.2+
(base not proved at
any location)
Slightly sandy to sandy CLAY
Occasional organic sandy CLAY near
surface
11.2
5.12.4 None of the trial pits undertaken by the Environmental Advisory Unit (1980) within this area
proved the base of the made ground.
5.12.5 EAC (2003) indicated that groundwater in the locality of the northern area of golf course is
believed to flow to the north under the influence of industrial abstractions but did not state which
horizon they were referring to. EAC also note that “hydraulic gradients in the northern area
generally show migration out from the centre of the fill mass to the periphery and into the
northern part of Stewards Brook”. EAC considered that shallow groundwater in the made
ground was in hydraulic connection with surface water in Stewards Brook.
Atkins (2005) Documentary Review
5.12.6 The documentary review by Atkins (2005) identified the following potentially contaminating
historical activities in the southern part of St Michael‟s Golf Course:
a. LeBlanc wastes (galligu) from the manufacture of saltcake (main contaminants:
sulphide, sulphate, arsenic and acidity/alkalinity)
b. Pyrites waste from the manufacture of sulphuric acid (main contaminants: metals
including iron, copper and arsenic, acidity)
c. Barytes waste from the manufacture of bleaches (main contaminants: barium salts)
d. Ash waste from coal fired boilers (main contaminants: metals, sulphates)
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5.12.7 The review by Atkins identified the following wastes as having been deposited in the southern
part of St Michael‟s Golf Course:
a. In the western area: LeBlanc and lime wastes
b. In the eastern area: sludges and other wastes from metal refining
5.12.8 The review by Atkins identified the following contaminants as having been encountered in soils
within the southern area from the „limited‟ investigations undertaken at that time:
a. High pH (alkalinity), sulphide, ammoniacal nitrogen, arsenic, barium, cadmium, copper,
lead and zinc
5.12.9 Atkins considered that the following chemicals of concern could be present in the northern part
of St Michael‟s Golf Course:
a. Boron, chromium, iron, lead, mercury, nickel, selenium, sulphate and chloride
5.12.10 Atkins considered that the following contaminants could be present in the dissolved phase
(groundwater and leachate):
a. ammoniacal nitrogen, chloride, sulphates, sulphides, arsenic, barium, cadmium,
chromium, copper, lead, mercury, nickel, selenium and zinc.
5.12.11 Atkins considered that hydrogen sulphide, carbon dioxide, methane and arsine gases could also
be present but no monitoring was undertaken to confirm this.
AMEC (2006) Factual Information
5.12.12 Factual information has been obtained from the Council from a site investigation undertaken at
St Michaels Golf Course in August 2006 by AMEC. This investigation comprised 15 cable
percussion boreholes that were drilled within the southern part of St Michaels Golf Course, of
which 11 were located on or adjacent to the proposed highways and toll plazas in the Project
area. These boreholes were drilled to a maximum depth of 10m bgl.
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5.12.13 Ground conditions were reported as being made ground, peat, alluvium and glacial clay (base
not proved), a summary of the ground conditions is shown below.
Table 5.4 – Ground Conditions from AMEC (2006) Ground Investigation
Strata Depth of Strata (m
bgl)
Description Groundwater Strikes
(m bgl)
Made Ground Top: Ground Level
Base: 3.2 to 7.5
Variable CLAY, SILT SAND, GRAVEL, ASH
with inclusions of brick, ash, pottery, slag,
sandstone, plastic, glass, metal, wood
2.0 to 7.0
Alluvium Top: 3.0 to 7.5
Base: 4.0+ to 8.7
Base not proved in
BH10B
Soft to stiff organic CLAY, SILT or SAND
pseudofibrous plant matter, clay with
rootlets, slightly gravely or slightly to very
sandy.
Peat in BHS09
Alluvium not encountered in BHS04
4.0 to 4.9
Glacial Till Top: 3.8
Base: 7.0+
(base not proved)
Firm to stiff slightly sandy slightly gravely to
gravely CLAY
Not proved in BH10B
-
5.12.14 A total of 12 soil samples from three boreholes located on/adjacent to the proposed scheme
were subjected to a range of contamination testing. No assessment of the chemical testing
results by AMEC was included. A review of the soil testing results by Gifford indicates the
following potential contaminants of concern present above the lower analytical detection limit in
the made ground; arsenic, lead, zinc, total sulphate, sulphide and hydrocarbons.
5.12.15 „Availability‟ testing was undertaken on the soil samples to assess risks to plants from
metals/metalloids. The results of this testing indicate the concentrations of „available‟
metals/metalloids to be significantly lower than those of the „total‟ metals.
5.12.16 Groundwater samples from 10 monitoring wells installed on/adjacent to the proposed scheme
were tested by AMEC. No assessment of the chemical testing results by AMEC was included.
A review of the groundwater test results by Gifford indicates that indicates the following potential
contaminants of concern were above the lower analytical detection limit in the made ground;
arsenic, zinc, barium, sulphate, chemical/biochemical oxygen demand, pH and ammoniacal
nitrogen.
Sub Soil Surveys (1982) - McKechnie Chemicals
5.12.17 This investigation covered the McKechnie Chemicals site immediately east of the golf course
and west of Ditton Junction. The historical OS maps obtained by Gifford do not show any
previous development on this site, although it is shown as an area of fill on the 1987 OS map.
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5.12.18 The ground conditions identified within the proposed route alignment can be summarised as
follows:
Table 5.5 – Ground Conditions Identified from Previous Investigations
Strata Depth of Strata (m bgl) Description
Made Ground Top: Ground Level
Base:1.8+ to 3.8
Soft to very soft sandy clay with bricks, soil, stone
ashes, wood to black clayey chemical waste with ashes
and white bands.
Glacial Till Top: 3.8
Base: 7.0+
(base not proved)
Firm to stiff slightly sandy slightly gravely CLAY to
sandy CLAY. Becoming stiff to very stiff sandy and
gravelly CLAY at depth.
Medium dense to dense slightly to very silty slightly
gravely fine to medium SAND
Interbedded Glacial Sand & Gravels and Glacial Till
5.12.19 Limited testing of soil and groundwater was undertaken as part of the Sub Soil Surveys
investigation, no samples were tested by Sub Soil Surveys from the trial pits. However, Sub
Soil Surveys obtained elevated concentrations of sulphate, sulphide, chloride, zinc, pH
(alkalinity) were obtained from made ground in BH4 which was located within the Mersey
Gateway Project area.
Area B2 & I1 – Ditton Junction to Freight Line
5.12.20 This Area comprises the existing sites of Anglo Blackwell (now owned by the Council), Gussion
Transport and S.Evans Scrapyard.
5.12.21 Additional information on the site history has been obtained from Hardie (1950) and the Catalyst
Museum in Widnes.
5.12.22 Historical OS maps published between 1893 and 1896 show the area to the south of Ditton
Road to have been occupied by an Alkali and Sulphur Works and a Chemical Works. The Alkali
and Sulphur Works was initially operated by the Desoto Alkali Company. It appears from the
records in the Catalyst Museum that the original intentions of the firm included soda-making, but
in 1873 the Directors thought it desirable, owing to the decreased demand for soda ash, to
restrict their activities to caustic soda, the works capacity for this material then being 130 tons
per month. A non-chemical activity of the firm on this site was brick making (Hardie, 1950).
5.12.23 The Desoto Alkali Company was wound up in 1886 and operations were carried on by the
Lancashire Alkali and Sulphur Company until 1981. Historical maps published in 1907 appear
to indicate that all buildings associated with the works were cleared from the site, with the
exception of two chimneys, two large circular tanks and several smaller tanks.
5.12.24 The Gussion Transport site was previously occupied by a Steel Alloy Works operated by High
Speed Steel Alloys Ltd (HSSA). The historical OS maps indicate the centre of former HSSA site
(shown as a Steel Alloy Works) would have been located towards the centre and east of the
existing Gussion Transport site. The record notes that the site was constructed in 1914 to
facilitate the production of tungsten metal powder for use in the manufacture of war munitions.
The first six years of operation were centred on the production of tungsten powder. A short term
increase in demand between 1919 and 1920 led to the extension of existing departments,
erection of new buildings and the installation of additional plant.
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5.12.25 A review of information held by The Catalyst Museum in Widnes revealed a limited number of
historical records relating to High Speed Steel Alloys Ltd. Table 5.6 below provides a
description of the processes undertaken in the manufacture of Tungsten and Vanadium alloys
within each department.
5.12.26 Raw materials comprised “ore, fuel, alkali and acid”, although the exact specification of these
materials is not given. Raw materials were delivered to the site by rail, although by 1934 an
increasing use of road transport was being made. All ore and material received was stored
within a warehouse located in the north western corner of the site.
5.12.27 The original laboratory constructed in 1914 was extended in 1916 to accommodate the
technical needs of the site. A proportion of laboratory staff were engaged in analytical work
including the checking of raw materials, sampling and weighing of process intermediates and
the calculation of output efficiency. In addition to analytical work, the laboratory was also used
for research and investigative purposes. Facilities within the laboratory included a high
temperature furnace, a small ball mill, hydraulic press and equipment for the measurement of
hydrogen-ion concentration and electrolytic potential.
5.12.28 The information obtained indicates the works water supply was taken from a 250ft deep
borehole located within the centre of the site. This well is not shown on the historical OS maps.
Steam for boiling, blowing and agitating purposes was generated by two hand-fired Galloway
Boilers and was distributed to the various departments by a wrought iron steam main.
Table 5.6 – Description of HSSA Works, 1934 (continued overleaf)
Department Process
Mill Tungsten ores were crushed and concentrated by magnetic separation,
which also recovered any tin ore that was present. The refined concentrates
were ground in ball mills for subsequent treatment in the production of
tungsten metal and ferro tungsten.
Ores for the manufacture of vanadium compounds were calcined in a rotary
calciner and reverberatoy furnace.
A Ground tungsten ores were blended and mixed with soda.
Calcined vanadium ores were ground in ball mills and mixed with soda.
B The mixtures produced in Dept. A were heated in reverberatory furnaces.
C The tungsten ore melt from the furnance in Dept. B was broken in jaw
crushers and ground in ball mills before being conveyed to the next
department by small worm conveyors.
The vanadium ore melt was crushed and ground before being sent forward
to Dept. D.
D The ground tungsten ore melt was fed into “Montejus Dissolvers” which were
capable of boiling solutions under pressure. The tungsten was separated
from other constituents of the ore by filtering and the solution of tungstate of
soda was concentrated in tubular evaporators.
Vanadate of soda was obtained using a similar method.
E Tungsten trioxide was obtained by the addition of acid to the tungstate of
soda solution. The oxide was washed and excess water was removed
mechanically.
F Tungsten trioxide was dried, calcined and ground in a disintegrator before
being mixed with carbon.
Calcination of molybdenum ore also took place within this department, in
three „reverberatory‟ furnaces.
G Dept. G housed a small experimental furnace which comprised an
electrically heated rotary furnace. The lining and attached fittings were all
made of austenitic nickel chrome steel.
H The crude metal tungsten from the tunnel furnace was picked, ground
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Department Process
washed and dried. The finished product was packed in drums for dispatch.
H1 Various grades of sodium tungstate were produced within this building.
E2 Vanadate of soda from Dept. D was pumped into precipitating vats. The
oxide was precipitated by acid and was washed, filtered, dried and ground
before being sent for reduction in the Ferro Dept.
Acid Plant The acid plant processed vanadiferous ores and residues which were more
readily attacked by acid then alkali in the preliminary stages of manufacture.
Fine Chemicals Various salts of metals of a greater degree of purity than that required for
metallurgical processes were manufactured within the „Fine Chemical No.1
and No.2 Depts‟.
Ferro Ferro vanadium, ferro tungsten, ferro molybdenum and alloys manufactured
using the „thermit‟ process were manufacture within this department. The
ores were mixed with different reducing agents and transferred to the „firing
section‟ where they were fired in special pots lined with magnesite. The
fused mass of slag and metal was allowed to cool before the pots were
emptied and blocks of metal cleaned before being returned to the mill where
they were crushed to the required size and packed for dispatch.
Electric
Furnace
The Electric Furnace Department consisted of a 35KVA High Frequency
Furnace and a small Arc Furnace, both used for experimental work.
Crucible Dept. The Crucible Dept. was installed for the manufacture of crucibles using
fireclay, Plumbago and “grog” (clay which has been fired and ground).
Tunnel Furnace
House
In the final stages in the manufacture of tungsten metal, tungsten trioxide
and the carbon mixture from Dept. F were fired in the tunnel furnace. Crude
metal from the fired product was then picked washed and dried.
The tunnel furnace was put into operation in 1917 to replace the use of open
kilns. The brick built furnace was heated by gas and was designed to allow
continuous working. Crucibles were carried though the furnace on firebrick
structures mounted on bogies which ran on rails.
5.12.29 Metals, alloys and compounds produced at the HSSA site in 1934 are listed in Table 5.7:
Table 5.7 – Metals, Alloys and Compounds Produced by HSSA, 1934
Metals Tungsten Powder, Chromium, Manganese, Molybdenum Powder,
Vanadium.
Alloys Ferro Tungsten, Ferro Vanadium, Ferro Molybdenum, Ferro
Chromium, Ferro Titanium, Cupro Manganese, Cupro Vanadium
Other Tungsten Carbides, Molyte, Calcium Molybdate.
Fine Chemicals Tungsten Tungsten Oxide, Tungsten Acid, Sodium
Tungstate, Sodium Para-Tungstate, Ammonium
Para-Tungstate, Calcium Tungstate, Lead
Tungstate, Barium Tungstate.
Vanadium Vanadic Acid, Vanadic Oxide, Vanadium
Pentoxide, Ammonium Meta-Vanadate, Sodium
Vanadate, Vanadyl Sulphate, Vanadyl Chloride.
Molybdenum Molybdic Acid, Molybdic Oxide, Ammonium
Molybdate, Sodium Molybdate, Calcium
Molybdate.
5.12.30 The 1937 historical OS map illustrates an additional Steel Alloy Works to the North of Ditton
Road, suggesting an expansion of the HSSA site on to the site currently occupied by the former
Anglo Blackwell site. Further buildings and structures are illustrated on historical maps
published between 1958 and 1971.
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5.12.31 The British Steel Corporation (BSC) became the largest shareholders of High Speed Steel
Alloys Limited after the Second World War. In 1969 these shares were purchased by the British
Oxygen Company (BOC).
5.12.32 In 1975 BOC took over Blackwell Metallurgical of Garston, Liverpool, and Anglo Metallurgical of
Sheffield. The operations of both firms were transferred to the Widnes site, forming Anglo
Blackwell Ltd, and the remaining High Speed Steel Alloys chemical processes were transferred
to Murex in Rainham, Essex. The only process to remain at the site was the roasting of
molybdenum ore, the rest related to the production of aluminium alloys.
5.12.33 Historical maps published in 1982 indicate that the majority of works buildings previously
associated with HSSA had been cleared from the area to the south of Ditton Road. This
suggests that the formation of Anglo Blackwell Limited was accompanied by a reduction in the
extent of the site, with operations probably being transferred to the site to the north of Ditton
Road, where the former Anglo Blackwell is presently located.
5.12.34 The site located to the north of Ditton Road is currently occupied by the former Anglo Blackwell
works. A company leaflet dating from May 1982 stated that the products at that time included:
a. Grain refining alloys (Aluminium, Titanium, Boron)
b. Metal treatment alloys (aluminium, Silicon, Strontium etc)
c. Aluminium Master alloys
d. Alloys for the Copper industry
e. Alloys for the magnet, nickel, iron and steel industries (Ferro compounds etc)
5.12.35 The former Anglo Blackwell website stateds that they specialised in alloys for the aluminium
industry, and this includes a grain refiners, hardeners and speciality products such as
Aluminium Strontium and Aluminium Boron alloys.
5.12.36 The part of the site to the south of Ditton Road is now occupied by Gussion Transport and
Widnes Tank Container Services (referred to as the Gussion Transport site in this report).
High Speed Steel Alloys Ltd (1936) Historical Site Layout Plan
5.12.37 This plan was obtained from Cheshire Records Office and shows the former High Speed Steel
Alloys (HSSA) works which was located at the existing Gussion Transport site. A number of the
buildings shown in the north of this plan appear similar in outline to existing buildings at the
Gussion Transport site.
5.12.38 The buildings labelled on this plan include warehouses, mills, „ferro dept‟, fine chemicals dept, a
boiler house, a calcining house and calcium tungstate storage. A 500 gallon petrol tank and
600 gallon diesel oil storage tank are shown towards the northwest of the former HSSA site,
with a 340 gallon and two 600 gallon fuel oil storage tanks towards the south of the site.
Settling pits and acid wells are shown towards the south and east of the former HSSA site.
5.12.39 A 25,000 gallon water tower is shown towards the centre of the former HSSA site (south of the
buildings currently used by Widnes Tank Container Services). A circular feature is shown at the
south east corner of the water tower which, although not labelled, could be the former works
water well.
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Previous Site Investigation Reports
Dames & Moore (July 1994)
5.12.40 The report covers a site investigation undertaken at the now former existing Anglo Blackwell site
to the north of Ditton Road in Widnes in 1994. This report was prepared for Anglo Blackwell Ltd
and is dated July 1994. The report notes that Anglo Blackwells‟ owners SKW, were looking to
divest the site and that Dames and Moore (D&M) had been commissioned to carry out a
preliminary environmental assessment.
5.12.41 D&M indicate the existing facility originally formed the No.2 site of the Anglo Blackwells
operations. The main plant (No.1site) at which the bulk of the process operations took place
was recorded as being located immediately south of Ditton Road (as noted above).
5.12.42 D&M noted that the site itself remained relatively undeveloped until the 1900s when the London
North Eastern Railway was constructed on an embankment on the northern boundary of the
site.
5.12.43 D&M noted that the main phase of the development of the site had taken place in 1913 when
High Speed Steels was established, producing tungsten and vanadium alloys primarily for
wartime armaments usage. The 1927 OS county series plan shows two buildings in the centre
of the No.2 site with a chimney on the western boundary. D&M noted that the site development
appeared to have occurred progressively from 1940 onwards with the establishment of the
meltshop on the western boundary, extension and addition of the two central buildings,
construction in the eastern part of the site and in 1950, an extension to the molybdenum plant
area in the centre of the site. D&M also indicated that High Speed Steels later sold the site to
BOC in 1960 when many former site activities were curtailed. The report indicates that BOC
merged three local aluminium companies in 1970 to form Anglo Blackwell‟s and that SKW of
Bavaria acquired the facility from BOC in 1980. This is consistent with information obtained by
Gifford. This site was extended in 1984 when Anglo Blackwell‟s purchased a strip of land to the
north of the site between the existing facility and Ashley Way (location of the former railway line)
from Cheshire County Council.
5.12.44 D&M noted that process operations originally undertaken at the site included molybdenum,
tungsten and vanadium processing. This involved a number of smelting and chemical
processes, the details of which were not fully known, to produce the various alloys required.
Smelting is understood to have generally been undertaken in the meltshop area in the western
part of the site and wet and dry vanadium and molybdenum processing in the central areas.
D&M noted that molybdenum processing ceased in 1991 and vanadium and tungsten at some
date prior to that.
5.12.45 The D&M report does not state the source of the historical information.
5.12.46 The D&M intrusive investigation comprised nine boreholes to depths of between 0.9m and 4.0m
bgl using a hand held window sampler. Six trial pits were also excavated to depths of between
1.7m and 2.4m bgl.
5.12.47 Galligu was encountered by D&M in TP1 to TP6, these were located towards the north of the
site.
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5.12.48 D&M compared the results of the chemical testing to the ICRCL guidelines which were current
at the time. The main issues identified by D&M comprised localised contamination by
hydrocarbons and heavy metals, in particular arsenic, tungsten, vanadium and molybdenum.
Soils & Materials Testing Ltd (June 1989)
5.12.49 Exploratory hole logs for two boreholes drilled at the Gussion Transport site by Soils & Material
Testing in 1989 were obtained from the Council. The investigation comprised two boreholes to
a depth of 10.00m bgl to obtain geotechnical information for a proposed workshop extension at
Gussion Transport. This workshop is located in the northwest corner of this site.
5.12.50 Black silt sized chemical waste was described on both borehole logs from 1.50m to 4.00m bgl
overlying glacial clay. No information on contamination testing was included with the
information.
Ditton Road East, Widnes
5.12.51 This comprises the area south of Ditton Road and to the east of Gussion Transport, and
includes S.Evans and Sons Scrapyard with Premier Security, Fairview (windows, doors and
conservatories), Solar Lubricants and Renard Systems to the east of this scrapyard and just
outside of the Project area in Area B2.
Previous Reports – Solar Lubricants
Strata Surveys Ltd (April 1992)
5.12.52 Strata Surveys Ltd (SSL) state this report was undertaken on behalf of Cheshire County Council
for proposed reclamation of derelict land known as the Q8 Site on Ditton Road. This is now the
site of Solar Lubricants. The site investigation comprised eight boreholes drilled to depths of
6.0m to 10.10m bgl.
5.12.53 „Chemical odours‟ were noted on the borehole logs within the made ground and shallow glacial
deposits. Groundwater was encountered within the made ground.
5.12.54 Chemical testing was undertaken on seven groundwater samples and 26 soil samples. No
discussion on the results for groundwater was included in the report obtained. The results show
that elevated concentrations of sulphate were encountered in groundwater when compared to
the UK drinking water standards and EQS. All other results were at or below analytical
detection limit with the exception of phenol (3.3mg/l) and lead (0.2mg/l) in individual samples.
5.12.55 Locally elevated concentrations of sulphate (when compared to BRE Digest 250) and arsenic
were encountered in soil samples when compared by SSL to the ICRCL 59/83 threshold levels
which was current guidance at the time of the investigation. SSL noted „patchy contamination‟
with regards to nickel, copper and zinc which they indicate are phytotoxic. SSL considered 30%
of the samples tested for PAHs to be „uncontaminated‟, and the maximum value of 196mg/kg
was considered to be slightly contaminated but „well within the ICRCL action level of 500mg/kg‟.
During the review it was noted the peak concentration of arsenic was 1,028mg/kg which is twice
the current SGV for a commercial/industrial land use.
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Caleb Brett Environmental (1999)
5.12.56 This report was based on samples obtained from the existing site of Solar Lubricants where
chemical testing was undertaken on six soil samples obtained from three boreholes at between
1.0m and 3.5m bgl. Caleb Brett Environmental (CBE) reported that the results showed locally
slightly elevated phenol and arsenic above the ICRCL 59/83 threshold levels and alkaline soils
along with elevated levels of sulphate. ICRCL 59/83 guidance was current at the time of the
investigation. The majority of the elevated toluene extractable matter encountered in one
borehole (BH3) was attributed to mineral oils by CBE.
5.12.57 CBE noted they were not supplied with the borehole logs or locations so a correlation of the
chemical test results with the ground conditions and site uses could not be undertaken.
Area C – Widnes Loops
Catalyst Trade Park and Widnes Eastern Bypass, Widnes
5.12.58 This area is currently occupied by the Catalyst Trade Park (owned by St Modwen Properties
Plc). This was the former site of the ICI Widnes Experimental Site (WES), which formed part of
the Gaskell Marsh group of works in Widnes. Information on the site history has been obtained
from Hardie (1950) and ICI (1996).
5.12.59 In 1855 Henry Deacon and Holbrook Gaskell entered into partnership to produce soda ash by
the Leblanc process (forming the Gaskell Deacon company). By 1865 the works were
decomposing 7,800 tonnes of salt per annum. ICI (1996) reported the site was first used as a
„chemical dump (galligu)‟ between 1849 and 1865 before which it was a „green field site‟.
5.12.60 The site was associated with scientific innovation including the development of the Weldon
process (1866) that contributed significantly to the production of bleaching powder. Gaskell
Deacon produced over a quarter of the bleaching powder in Widnes.
5.12.61 The Deacon process was also developed on this site. This process involved a more efficient
process of chlorine recovery; using hydrochloric acid passed over heated copper salts.
5.12.62 In 1890 the Gaskell Deacon Company joined approximately forty other alkali manufacturers in
forming the United Alkali Company and in 1891 the Central Laboratory or Hurter Laboratory was
founded at the site.
5.12.63 The Central Laboratory was located in the north and northwest of the existing Catalyst Trade
Park, beneath the existing A557 Expressway. In 1908 the United Alkali Company constructed a
Chief Engineers office in a new building behind the central laboratory, where all the principal
engineering functions of the company were centralised.
5.12.64 The Chief Engineers Office was closed in 1926, with the formation of ICI, to provide further
space for the Research Department. Further expansion of the research facility was undertaken
before World War II. A new “Main Building” was built in four stages; three before the war and
the fourth, the analytical laboratories, during the war. New semi-technical laboratories,
workshops and stores were also built and some of the existing buildings from Gaskell Deacon
works were adapted for research purposes.
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5.12.65 Hardie (1950) notes that on 14th January 1930, the Gaskell-Deacon and Marsh Works were
amalgamated into one administrative unit named Gaskell Marsh. This source also notes that
the factories of the Gaskell-Marsh unit were primarily concerned with the production of sulphuric
acid and that a considerable amount of saltcake was produced as a by-product of the formic
acid process carried on at the Gaskell-Deacon Works. The Gaskell Marsh factories also
manufactured sodium sulphide, sulphite, bisulphite, thiosulphate, and „a number of other
products‟.
5.12.66 The Central laboratory was bombed on 10th August 1942 when a substantial part of the new
Main Building was demolished. A second bomb fell on the railway line close to the Victoria
Road level-crossing. Although it missed the laboratory, the fabric of the building was severely
damaged by the blast. Temporary repairs were made to allow the laboratory to continue
operating until the end of the war when permanent repairs were made.
Works Water Well
5.12.67 ICI (1996) note that a works water well was constructed prior to 1927 and was drilled to a depth
of 207m into the underlying Sherwood Sandstone aquifer. ICI state the well was disused and
the abstraction cancelled in 1961 probably as a results of high chloride concentrations in the
water (5,529mg/l in 1958 and 2,249mg/l in 1959). ICI indicated this well was either covered or
capped in the 1960s. ICI‟s plans show that it was located north of the Pioneer Building (now
Unit 3) but no details were available at the site or from Environment Agency on the capping of
the borehole. A site inspection by ICI in 1996 noted no evidence of this well at the surface.
5.12.68 Plans for the Mersey Gateway Project indicate this water well would be located beneath the
western edge of the proposed Widnes Loops embankment and associated structures.
Central Laboratory – Chemical Processes
5.12.69 Processes carried out in the Central Laboratory between 1891 and 1927 are thought to have
included (ICI, 1996):
a. Production of carbon tetrachloride from carbon disulphide and chlorine
b. Preparation of sodium nitrite
c. Evaluation of electrolytic cells, including the Castner, the Hargreaves–Bird and the
Ashcroft Cells.
d. Liquid chlorine
e. Production of chlorine from hydrochloric acid by electrolysis
f. Manufacture of alumina from bauxite
g. Electrolytic chlorates
h. Gas purification by Weldon mud
i. Manufacture of sulphur from hydrogen sulphide
j. Preparation of strontium hydroxide
k. The general chemistry of the Le Blanc Process
l. Extraction of bismuth from flue dust
m. Production of caustic soda from saltcake and oxalic acid
n. Preparation of manganates and permanganates
o. Preparation of ferrocyanides, sulphocyanides and cyanides
p. Electrolysis of fused zinc chloride
q. Production of sodium-lead alloy by electrolysis
r. Preparation of sodium hypochlorite
s. Sulphur recovery
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t. Production of sulphur trioxide from sulphur dioxide and oxygen using platinised
asbestos
u. Copper refining by electrolysis
v. Manufacture of caustic soda from sodium carbonate by reaction with iron oxide
w. Reaction of calcium fluoride and silica at high temperatures
x. Electrolytic bismuth
y. Improved Solvay cell
z. Preparation of chlorine from sulphur dioxide, salt and air
aa. Lead acetate
bb. Extraction of vanadium values from ore
cc. Extraction of metallic tungsten from Wolfram ore
dd. Purification of caustic soda
ee. Preparation of lithophone
5.12.70 Records of processes investigated on a larger scale within the works are limited. However, ICI
(1996) note that prior to the formation of ICI in 1927 a number of processes were investigated
and developed within the Central Laboratory and then carried out on site. Details of these
processes are provided in Table 5.8 below:
Table 5.8 – Processes developed within the Central Laboratory and implemented within
the Gaskell Deacon site (ICI, 1996)
Process Date Plant location
Sodium cyanide from carbon
disulphide, ammonia, lime, and nitric
acid using the Raschen Process.
1894 – 1900 Site of existing Unit 3 of the
Catalyst Trading Estate.
Manufacture of formic acid by the
addition of sulphuric acid to hot sodium
formate.
1913 – 1960 Site of existing Unit 3 of the
Catalyst Trading Estate.
Acetone production Plant demolished by
1935
Between the sites of the
existing Unit 2 and Unit 3 of
the Catalyst Trading Estate.
Aluminium chloride manufactured
via the direct chlorination of molten
aluminium
Unknown Unknown
Chloroform manufacture from acetone
and bleach
Site to the NE of the existing
Unit 3 of the Catalyst
Trading Estate.
Manufacture of chlorinate rubber 1918 – 1928 Unknown
Acetic acid plant. Materials delivered by
rail included calcium acetate and
sulphuric acid
1896 – 1930 Unknown
Manufacture of formic acid Unknown Unknown
Manufacture of carbon tetrachloride Unknown Unknown
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World War I
5.12.71 ICI note that work at the was not well documented during the first World War. Processes known
to have been dealt with on site at this time include (ICI, 1996):
a. Chlorosulphonic acid made for smoke generators and also used in the manufacture of
saccharine.
b. Sulphuric acid for the manufacture of explosives.
c. Dinitrophenol from chlorobenzene via dinitrochlorobenzene.
d. Ammonium perchlorate by electrolysis of sodium chlorate.
e. „War gases‟: chlorine, phosgene, arsenic trichloride, mustard gas and its intermediates
(in particular sodium sulphide, thionyl chloride, sulphure chloride etc), chlorhydrine and
thionyl.
World War II
5.12.72 During the period 1939 to 1945 ICI (1996) indicate that it is believed a number of „Ministry of
Defence‟ Classified projects were carried out on the site. Although ICI records of wartime
arrangements with the MoD have been destroyed or are not free for examination (ICI, 1996),
limited details are available with respect to the “Tube Alloy Project”, which involved early
development work for atomic energy and the atomic bomb.
5.12.73 Early work carried out between 1940 and 1945 included uranium extraction and metal
production processes which eventually led to the production of the rods used to fuel the first
atomic reactor pile at Harwell. These activities were carried out in the Central Laboratory and
Semi-Tech buildings, although the majority of the larger scale uranium extraction / production
was carried out in the former warehouse 2 which was located along the southern boundary of
the existing Catalyst Trade Park (between the existing Unit 6 and ERF building).
5.12.74 The extraction process involved the production of Uranium hexafluoride from Uranium ore and
subsequent separation of the Uranium-235 F6 (0.7%) and Uranium-238 F6 (99.3%)
components and then the subsequent recovery of the pure Uranium-235 metal from the gas.
The Uranium products, intermediates and raw materials were all brightly coloured and the
former employees who worked on the Uranium extraction on site talked of a blue dust (UF4)
which „covered everything and everybody who worked in the building‟ (ICI, 1996).
5.12.75 ICI note that „war gases were developed and manufactured throughout the Second World War‟.
ICI was the Governments largest industrial agent and the largest investment of all was in the
research, development and manufacture of war gases. The gases developed by ICI during
World War II were bromobenzylcyanide, diphenylchloroarsine, diphenylcyanoarsine,
phenylarsinic acid and thiodiglycol (for use in mustard gas) but ICI state there was „no
confirmation that any of these gases were developed at this site‟ and that „no shells were filled
with poisonous gas at this site‟.
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Historical Effluent Management
5.12.76 ICI (1996) records indicate that effluent from the site was historically discharged directly to site
drains with little or no treatment. ICI (1996) make reference to various written records which
note the discharge of methanol from the chlorinated polymers plant and discharge of chloroform
and carbon tetrachloride to the River Mersey from their Widnes Works (which included the
Widnes Experimental Site and the Pilkington Sullivan Works located approximately 750m to the
east of the Catalyst Trade Park). The ICI (1996) report includes a plan showing site drains
associated with the former ICI Widnes Experimental Site, a copy of this plan is shown on
Drawing MG_REP_EIA_009/016.
5.12.77 ICI (1996) note that discussions with previous employees of the site revealed that it was
common practice for operators to dispose of waste material by pouring it onto unmade ground.
Former employees also recalled the use of soakaways within the site to dispose of the „full
range‟ of liquid wastes. ICI considered the positions of one of these soakaways to be to the
north-west of the Pioneer Building which it is thought relates to the existing Unit 3 in Catalyst
Trade Park.
5.12.78 The ICI (1996) report included records of a site walkover and „present site layout‟ plan. The site
layout plan showed a drum storage area, waste drum storage and empty drum storage and
solvent trap towards the western end and „tanks‟ (EDC or 1,2-dichloroethane) towards the
eastern end of the existing Unit 6. To the west of Unit 6 was the Semi Tech building. The
former Warehouse No.2 is shown to the east of Unit 6. To the east of Warehouse No.2 were
two tanks and to the north was an area of oil storage, a boiler house and a compressor house
(located east of the car park to Unit 6). A pressurised drum store was shown near the existing
ERF Building. Numerous buildings are shown at the site.
5.12.79 A site inspection was undertaken by ICI in 1996. Evidence of spills onto unprotected ground
were noted around the boiler and compressor houses and spills at the oil loading point had filled
the sump and spread onto a stoned area. ICI noted that drums of waste materials were stored
on paved areas at the No.3 lab (north of Unit 6) and Semi Tech building. No bund was present
at the empty drum storage compound and large cracks were noted in the bund to the tanks
formerly located towards the eastern end of Unit 6. ICI noted signs of leaks and corrosion to a
concrete slab south of the „Pioneer building‟ (now Unit 3).
5.12.80 ICI noted that trench excavations of up to 1m depth were undertaken in March 1996 across the
central section of the site (close to the former Gaskell Avenue) for the diversion of domestic
effluent. The trenches were excavated in made ground which comprised gravel, ash, brick,
concrete and galligu. The yellow colour of the made ground was considered by ICI to probably
have been caused by sulphides in the galligu. These excavations uncovered old brick and
concrete foundations considered by ICI to be from demolished plant, redundant drains and an
old brick culvert.
Previous Site Investigations
5.12.81 Information has been obtained from following site investigations previously carried out at the
site.
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Tracero (1990) Radiological Survey
5.12.82 In March 1990 Tracero surveyed a proportion of the floor of the No. 2 Warehouse, the site of the
previous Uranium extraction plant, which was located to the east of the existing Unit 6 at
Catalyst Trade Park. The results of the investigation were not considered significant by
Tracero, no readings of Uranium-238 greater than the regulatory limit of 0.4Bq/cm2 were
recorded. Further work by Tracero highlighted radioactive „hotspots‟ on the site of the previous
„on-site car park, on the concreted area by the boundary fence‟, although the levels of radiation
recorded are not included within the ICI report.
5.12.83 ICI (1996) identified a number of further locations where radioactive contamination was
understood to exist within the site:
a. Thorium contamination was recorded within the surface layer of the sandstone wall
which bordered the public pathway know as „Soapwaste Walk‟.
b. Soil contamination comprising Thorium-232 (and daughters) and Uranium-238 (and
daughters) was identified to the south of the Semi Tech Building on the site of the
Thorium settling tank that was demolished in 1976. These Semi Tech buildings were
located towards the western end of Unit 6 at Catalyst Trade Park and are outside the
Project area.
Allot and Lomax (1990) Ground Investigation
5.12.84 In April 1990, Allott and Lomax (A&L) investigated the ground to the north of the Catalyst Trade
Park as part of works associated with construction of the Widnes Eastern Bypass. Phenols,
sulphide, lead, cadmium, mercury, arsenic and other heavy metals were identified within the
soils, although A&L noted that analysis of groundwater suggested that heavy metals were not
leaching from the soil. Uranium contaminated bricks were also excavated during the
investigation. ICI (1996) noted that uranium contaminated bricks were excavated during
preparation work by the Department of Transport (DoT) for the new by-pass (A557
Expressway), but that this area was sold to the DoT and was no longer part of the former ICI
Widnes Experimental Site.
5.12.85 Due to the nature and history of the site, A&L considered that metal contamination would be
highly likely to be present across the whole site. Further soil samples taken during excavation
works in the north-east of the site were found to contain various metals including mercury, lead,
arsenic and cadmium. „Chromia‟ catalyst contamination was also identified and strong
hydrocarbon smells were noted during excavation work along the main site road, which was
formerly the site of the Garston and Warrington Railway Line that passed through the site.
ABB Impell Ltd (1993) Survey of Bowers Brook
5.12.86 ICI (1996) make reference to a survey of Bowers Brook carried out by ABB Impell Ltd in
October 1993 which found „considerable radioactive contaminated material in silt‟ and that this
silt resulted in the blocking of part of the original culvert immediately upstream of the Widnes
Experimental Site outfall (Y drain) and the re-routing of a surface water drain from the Widnes
bypass. ICI considered the radioactive contamination came from the Thorium Ltd works located
downstream of the former ICI Widnes Experimental Site outfall.
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5.12.87 Gifford note that Bowers Brook is tidal in the area between the outfall to the River Mersey
(located adjacent to the lock gates for the St Helens Canal at Spike Island) and the Catalyst
Trade Park. Manhole covers to Bowers Brook between the outfall and Catalyst Trade Park
have been sealed and/or covered and are no longer readily accessible. Further information on
Bowers Brook is contained within the Surface Water Quality Chapter of the Environmental
Statement (Gifford Ref: MG_REP_EIA_007).
Allot and Lomax (1994) Ground Investigation
5.12.88 Two factual geotechnical reports relating to the A557 Widnes Eastern Bypass prepared by Allot
& Lomax (1994) for the Highways Agency were reviewed. A radiological survey was
undertaken by IRAS in 1992 as part of these works, which included screening areas around
boreholes and the arisings. The monitoring was conducted to protect the site workers.
5.12.89 With the exception of BH S108, this report notes that dose rates at all locations were considered
„normal‟, and „did not identify material with significantly elevated levels of radioactivity‟.
Investigation of the area surrounding BH S108 identified „elevated levels of naturally occurring
radioactivity‟ within the bricks used between the former ICI visitor car park and public footpath.
These bricks are reported to have been subsequently removed. One other sample from this
borehole at 2.00m bgl was found to give elevated readings, around twice background. IRAS
considered this to be insignificant for short term exposures.
Ian Farmer Associates Ltd (2001) Ground Investigation
5.12.90 A site investigation was undertaken by Ian Farmer Associates Ltd (IFA) (July 2001) at the
request of the Halcrow Group Ltd and on behalf of Redman Heenan Properties Ltd on the
eastern end of the former ICI experimental works for the proposed HGV park (currently used by
ERF).
5.12.91 The site works comprised eight cable percussion boreholes to depths of between 10.45m and
20.45m bgl, two rotary augered boreholes to 9.00m bgl, and eight trial pits to depths of between
1.45m and 3.20m bgl to obtain samples for chemical analysis. Combined gas and groundwater
standpipes were installed in all boreholes with the exception of BH8. Ground conditions
comprised made ground over alluvium and glacial till, although the alluvium was not
encountered at all of the exploratory hole locations. The made ground was encountered at
depths of up to 5.40m bgl (in BH6, located in the south west corner of the site).
5.12.92 As this was a factual report a review of the chemical test results was not undertaken by IFA.
However, the results of the chemical analysis indicate that arsenic, copper, and zinc were
encountered above the lower analytical detetion limit in the made ground. Analysis for VOCs in
soil samples from boreholes showed the presence of trichloroethene, 1,1,1,2-tetrachloroethane,
1,1,2,2-tetrachloroethane, 1,2,3-trichloropropane, and 1,1,2-trichloroethane in the made ground
and in the underlying natural soils. The highest levels were 21mg/kg of 1,1,2-trichloroethane in
BH10 at 4.00m bgl, and 14mg/kg of 1,1,2,2-tetrachloroethane in BH9 at 7.00m bgl.
5.12.93 Samples from the trial pits showed elevated concentrations of arsenic, cadmium, lead, zinc, and
sulphate. The sample obtained from TP4 at 0.80m bgl contained 1,200mg/kg of cadmium,
9,600mg/kg of copper, 61,000mg/kg of zinc, and 21,000mg/kg of sulphate. The sample from
TP5 at 0.70m bgl showed 4,700mg/kg of diesel range organic hydrocarbons and 7,300mg/kg of
„heavy‟ hydrocarbons (no information was included on the carbon range covered by this
parameter).
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5.12.94 Analysis of groundwater samples from BH4, BH6, BH7, BH8 and TP4 showed the presence of
total petroleum hydrocarbons (TPH) in the C20 to C40 range, with the highest concentration of
0.2mg/l, obtained from BH1.
Halcrow UK (2000) Factual Report on Ground Investigation
5.12.95 This report was prepared on behalf of St. Modwen Developments Ltd and comprises factual
information obtained from three phases of ground investigation undertaken at the location of the
existing Unit 6 at Catalyst Trade Park prior to its construction:
a. Phase I: Two boreholes and six trial pits (BH1, BH2, TP1 to TP6) on 12th and 13
th June
2000.
b. Phase II: Eleven trial pits (TPA to TPK) on 5th July 2000.
c. Phase III: Seven trial pits (TP2 to TP7b) on 24th July 2000.
5.12.96 As this was a factual report, a review of the chemical test results was not included by Halcrow
although the ICRCL 59/83 values were included with the test results for comparison. This
guidance was current at the time of this investigation.
Halcrow UK (2000) Factual Report on Ground Investigation - Phase I
5.12.97 Chemical testing for the Phase I investigation comprised an „ICRCL‟ suite and „VOC‟ suite
undertaken on five soil samples. NRA leachability and water testing were undertaken on five
samples (two leachate and three groundwater). The two boreholes were located towards the
south west (BH1) and east (BH2) of the existing Unit 6. Trial pits were undertaken within the
footprint of the proposed building. Made ground was encountered at all of the sample locations
with the following visual and/or olfactory evidence of contamination noted by Gifford from the
Halcrow exploratory hole logs:
a. Odour of „diesel‟ in the made ground and alluvium between 1.5m and 5.5m bgl in BH1
and 2.2m and 10.10m bgl.
b. TP3 recorded a seepage of „solvents‟ between 0.65m and 0.75m bgl, „strong odour of
solvents‟ between 1.4m and 2.40m bgl and an „odour of PAH‟ between 2.4m and 2.80m
bgl within the made ground.
5.12.98 When compared to the ICRCL values listed by Halcrow for playing fields, open spaces and
buildings locally elevated concentrations of arsenic, lead, copper, selenium, pH, total cyanide,
total sulphate and thiocyanate were noted. Testing of VOCs was undertaken on two samples of
made ground from TP3. Concentrations of VOCs (and in particular chlorinated solvents) above
lower detection were recorded, the highest concentrations were 6.2 and 8.2mg/kg of 1,2,4-
trichlorobenzene, and 2.9mg/kg of 1,2-dibromo-3-chloropropane and 1,1,1,2-trichloroethane in
TP3 at 2.8m bgl.
5.12.99 Water standards listed with the test results in the report are shown as the „NRA Upper Tame‟.
Comparison of the results against these standards shows exceedances of pH (TP3), sulphate,
arsenic, cadmium, selenium and zinc. No assessment criteria for VOC were included in the
report although the highest concentrations of VOCs were 1mg/l of 1,1,1,2-trichloroethane,1,1,2-
trichloroethane and 1,2-dibromo-3-chloropropane.
5.12.100 Halcrow noted that BH2 installed during the Phase I investigation was destroyed during
building construction. Only one round of monitoring was undertaken on BH1 in July 2000,
although Halcrow indicated they did not detect any ground gas.
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Halcrow UK (2000) Factual Report on Ground Investigation - Phase II
5.12.101 Chemical testing for the Phase II investigation comprised an „ICRCL‟ suite, NRA leachability
suite and a „VOC‟ suite on eight soil samples along with the testing of five water samples
obtained from the interceptor pit, cooling towers, a drain (which Halcrow state is „of unknown
location‟), and groundwater from two trial pits. Made ground was encountered at all of the
sample locations and the following visual and/or olfactory evidence of contamination was noted
on the exploratory hole logs:
a. Seepage of „viscous light brown fluid‟ at 1.5m, groundwater ingress at 2.5m with
„extremely strong PAH odour‟, „occasional light to dark blue coating‟ on gravel in TPB
b. „Heavy ingress of orange coloured groundwater‟ at 1.3m (noted to be ruptured drain)
and „oil film on groundwater‟ in TPG
c. „Strong odour‟ to „extremely strong odours of PAH‟ were noted in TPA, TPC, TPD, TPE,
TPF, TPG, TPI and TPJ
5.12.102 When compared to the ICRCL values listed by Halcrow for playing fields, open spaces and
buildings elevated concentrations of arsenic, lead, copper, mercury, selenium, zinc, total
sulphate boron, sulphide and free sulphur were noted.
5.12.103 Concentrations of VOCs (and in particular chlorinated solvents) above lower detection were
recorded in all of the eight samples. The highest individual concentrations were 87mg/kg for
1,1,1,2-trichloroethane and 62mg/kg for hexachlorobutadiene in TPI (the sample depth is not
stated).
5.12.104 Water standards listed with the test results in the Halcrow report are shown as the „NRA
Upper Tame‟. Comparison of the results against these standards shows exceedances of pH,
sulphate, arsenic, chromium, copper, mercury, selenium, zinc, phenols, PAHs and ammonia in
groundwater and water obtained from the interceptor pit, cooling tower and a drain. No
assessment criteria were included for VOCs, although the highest concentrations of VOCs were
1.2mg/l of chloroform from the interceptor pit followed by 0.52mg/l of cis-1,2-dichloroethene
from TPA.
Halcrow UK (2000) Factual Report on Ground Investigation - Phase III
5.12.105 The Phase III investigation included testing of a „VOC‟ suite, NRA leachability suite, pH and
sulphate on nine soil samples and three water samples. Made ground was encountered at all of
the sample locations with the following visual and/or olfactory evidence of contamination noted
by Gifford on the exploratory hole logs:
a. „Strong‟ and „very strong odour of PAH‟ noted in TP2, TP5, T5A, TP6, TP7A and TP7B.
5.12.106 When compared to the ICRCL values listed by Halcrow for playing fields, open spaces and
buildings one elevated concentration sulphate from TP6 at 1.7m was noted. No assessment
criteria for VOCs were shown in the report although the highest concentration of VOCs to be
1,100mg/kg of 1,1,2,2-trichloroethane in TP5A at 0.6m bgl.
5.12.107 Comparison of the water results against the „NRA Upper Tame‟ water standards listed by
Halcrow in the report indicates elevated sulphate, arsenic, ammonia, total PAHs and Diesel
Range Organics. Although no water standards were included for VOCs, Gifford note the
highest concentrations to be 12mg/l of 1,1,1,2-tetrachloroethane in TP5A from a water sample
obtained at 2.3m bgl (made ground).
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Halcrow UK Factual Report (2000) Drain Sampling
5.12.108 Drain sampling was carried out at Catalyst Industrial Estate by Halcrow on behalf of St
Modwen Developments Ltd. This report is dated August 2000. Halcrow note the aim of the
investigation was to sample and test the contents of the drains beneath the site for
contamination as part of the ongoing discharge consent. Halcrow noted this report was purely
factual and that no interpretation or conclusions had been made.
5.12.109 City Analytical Services collected the samples and tested them for a range of heavy metals
and „halocarbons‟ on two occasions in March and April. The plan provided in the report
indicates the drains sampled comprise the main drain, along with drains feeding into this, which
then appear to discharge into the X and Y outfalls from the former ICI Widnes Experimental Site
at Catalyst Trade Park.
5.12.110 Although no interpretation of the results was included in the report obtained, it was noted that
elevated concentrations of arsenic, copper, zinc were present when compared to the EQS for
coastal and estuarine waters. Consistently elevated concentrations of arsenic were noted with
the peak concentration being 0.7mg/l from Halcrow reference drain W6A5A1 (which appears to
be located near Unit 3).
5.12.111 Elevated concentrations of „halocarbons‟ above lower analytical detection were also
encountered including chloroform, carbon tetrachloride, 1,1,1-trichloroehane, trichloroethene,
1,1,2-trichloroethane, tetrachlorothene, 1,1,2,2-tetrachloroethane and 1,2-dichlorobenzene.
The highest individual „halocarbon‟ concentration was 1,1,2-trichloroethane (1.1mg/l) from drain
sample X1 which appears to have been obtained near to the existing site boundary and close to
the south west corner of Unit 6.
Halcrow Group Limited (2004) Ground Investigation
5.12.112 A ground investigation was undertaken in December 2003 on Unit 5 of Catalyst Industrial
Park for Redman Heenan Properties Ltd. The report is dated January 2004. The site
investigation comprised four boreholes to depths of 10.00m bgl. Ground conditions comprised
made ground which was encountered in all boreholes to between 1.7m and 2.0m bgl overlying
glacial clay to the base of the borehole (10m bgl).
5.12.113 The results of the soil testing were compared to the CLEA derived SGVs and Dutch
Threshold Values. Elevated concentrations of heavy metals such as lead, copper and zinc,
phenol and PAHs were encountered
5.12.114 The concentrations of heavy metals in groundwater were in the majority of cases below the
Water Supply Regulations (2000) and EQS except for a single arsenic, two ammonia and two
iron concentrations.
5.12.115 No visual or olfactory evidence of hydrocarbon or solvent contamination was recorded by
Halcrow for any of the soil samples.
Ian Farmer Associates (2002) Ground Investigation
5.12.116 Ian Farmer Associates Ltd (IFA), on the instruction of Halcrow Group Limited, undertook a
site investigation for Redman Heenan Properties Ltd at Catalyst Industrial Estate for Proposed
Nursery Units. This investigation was undertaken on the central and northern part of the
Catalyst Trade Park for proposed nursery units, the report obtained comprises factual
information. This report is dated May 2002.
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5.12.117 The site investigation comprised four light cable percussion boreholes to depths of between
10.00m and 15.00m bgl and 10 window sample holes to depths of between 1.00m and 3.00m
bgl. Eight soil samples and two leachate samples were tested for the „ICRCL‟ suite along with
one soil TPH test and ammonia, BOD, COD and chloride on the leachate samples. The ICRCL
59/83 guidance was current as the time of the investigation.
5.12.118 Ground conditions comprised made ground over glacial clay. The base of the made ground
was encountered at depths of between 0.7m and 2.4m bgl. No visual or olfactory evidence of
contamination was encountered with the exception of a hydrocarbon odour and sheen in the
made ground from WS7 between 1.0m and 2.0m (base of hole).
5.12.119 No interpretation was included within the report, although elevated arsenic, lead and zinc
were noted in the soil samples when compared against soil guideline values for a residential
without plant uptake land use and phytotoxicity (zinc). Concentrations of lead, copper, nickel
and zinc in the leachate samples exceeded the EQS for coastal and estuarine waters.
Ian Farmer Associates (2004) Ground Investigation
5.12.120 A site investigation was undertaken by Ian Farmer Associates Ltd (IFA) for a new sub-station
adjacent to Unit 3 at Catalyst Trade Park on the 30th September on behalf of Bespoke
Construction Services Ltd. This report is dated October 2004. The investigation was
undertaken to determine the ground conditions and enable an assessment of contamination and
its risk in the short term to groundworkers excavating service trenches. The site works
comprised the excavation of five trial pits using a mechanical excavator to obtained soil samples
from the pits and two existing spoil heaps. A radiological survey was also undertaken on
excavations and existing spoil heaps by Radman Associates, no readings above background
were encountered.
5.12.121 Trial pits were excavated to 0.9m bgl and encountered concrete at the surface (in TP1 and
TP2) over made ground to the base of the trial pits. IFA noted strong odours of sulphur and
solvent in TP4 (between 0.35 and 0.9m bgl) and TP5 (between 0.7m and 0.9m bgl).
5.12.122 Chemical testing was undertaken on 10 soil samples and six soil leachate samples for
metals, USEPA 16 PAHs, cyanides, sulphates, sulphides, VOCs and SVOCs.
5.12.123 IFA compared the results of the chemical testing to CLEA derived SGVs (for a
commercial/industrial land use) and soil screening values (SSVs) determined by IFA or
internationally recognised guidance (USEPA Preliminary Remediation Goal). IFA noted
exceedances from trial pits and stockpiled material for arsenic (maximum of 7300mg/kg), lead
(maximum of 41,000mg/kg) and PAHs. Concentrations of PAHs in soil sample 3 (report does
not state which location this relates to) were significantly higher than the other samples tested
including 160mg/kg of benzo(a)pyrene, 480mg/kg of phenanthrene and fluoranthene, 400mg/kg
of pyrene, 190mg/kg of benzo(a)anthracene and 81mg/kg of naphthalene. Sample tested for
VOCs were all reported to be below analytical detection.
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NSG Environmental Ltd (1999) Preliminary Radiological Survey
5.12.124 NSG Environmental Ltd (NSG), on the instruction of Halcrow UK, undertook a preliminary
radiological survey of the ICI Widnes Experimental Site. This report was dated October 1999.
Samples of silt and water were obtained from the X and Y drains leading to Bowers Brook,
these samples were noted by NSG as being generally from the upper (and most recent) layers
of silt in the manholes. Walk over surveys were undertaken by NSG using a mini-monitor Type
44A in the former Warehouse No.2 (east of Unit 6), the area adjacent to Soapwaste Walk and
the Northern Boundary fence.
5.12.125 The count rates were not considered significant by NSG with respect to statutory
requirements or health considerations at Warehouse No.2. However, NSG considered that the
mild steel plates could shield areas of higher activity especially as the highest count rates were
observed in the interface between the concrete floor and the steel plates.
5.12.126 The count rates were not significant with respect to statutory requirements or health
considerations in the Wall adjacent to Soapwaste Walk. However, the presence of one area
giving elevated readings suggested that other areas of activity could exist and the elevated
areas on the stone wall indicated traces of radioactive material. This wall was located at the
south west boundary of Catalyst Trade Park and outside of the Project area.
5.12.127 NSG considered the presence of stone chippings over the majority of the boundary fence
meant the count rate was low and that radioactive contamination could exist below the
chippings. The background count rate (5 counts per second) rose where the chippings were not
present and 80 counts per second was recorded in a „region of tarmac and railway lines‟ which
NSG considered was possibly due to slag used as filler within the tarmac. The location of this
survey is not shown in the NSG report.
5.12.128 NSG noted the count rates in the manholes were higher than the background at the surface,
although the levels were consistent with natural radiation from soil and brickwork. Elevated
readings (40 counts per second) were recorded in Manhole X1 which NSG considered indicated
possible radioactive contamination in the silt.
5.12.129 The levels of activity detected in the manholes were considered by NSG to be „below
regulatory levels‟. However, NSG considered that it was possible that if material were
excavated for removal then historical layers with higher levels of activity could be disturbed.
5.12.130 NSG considered the results of the analysis for uranium and thorium decay chains to be
„consistent with general background concentrations in natural soil‟ with the exception of X1 and
X3 although NSG considered these results to be significantly below levels requiring regulatory
control. Concentrations of caesium, cobalt and americium were detected close, but below the
regulatory control limit of 0.4Bq/g for these radionuclides (as outlined in the Radioactive
Substances Act, 1993).
Halton Borough Council - A557 Expressway
5.12.131 Anecdotal information obtained from Halton Borough Council in 2008 on the construction of
the A557 in the north of Area C indicates that at least some radioactive material from the former
ICI Widnes Experimental Site was encapsulated in concrete at depth during the construction of
the east abutment at Victoria Road.
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5.12.132 Additional anecdotal information obtained in 2011 from a former Highways Agency project
engineer for the A557 indicates that radioactive material encountered at the former ICI Widnes
Experimental Site during the construction of the A557 could have been buried within the road
embankment. The material encountered is understood to have contained low levels of
radiation.
5.12.133 A summary of the findings from a review of documentary information by Radman Associates
relating to radiological contamination has been provided in Section 6.4 and included in
Appendix S.
Thermphos and Former ICI Muspratt Site, Widnes
5.12.134 Immediately to the east of the Catalyst Trade Park is the area is currently occupied by
Thermphos UK Ltd. The Thermphos plant is located immediately north and east of Area C.
The former ICI Muspratt site is located immediately east of Thermphos and east of Area C.
Previous reports
ICI (1995) Historical Review
5.12.135 Information on site history has been obtained from ICI C&P (1995) and Hardie (1950).
5.12.136 The ICI (1995) report was undertaken site to assess the type and extent of contamination
resulting from past site operations and subsequent effects.
5.12.137 The former Muspratt site was used for the manufacture of chemicals from about 1854 until
1968 and during this period the works manufactured a variety of chemicals including caustic
soda, bleaching powder and sodium sulphide. From 1968, ICI indicated that the site was
occupied by Tarmac Ltd and at the time of ICI preparing their report (1995) the site was leased
to Summerfield and Lang for the storage and handling of blast furnace slag and stone. At this
stage it was no longer used for chemical production with all process plant and most buildings
having been demolished.
5.12.138 The ICI (1995) report also describes operations on the eastern part of the adjacent Albright
and Wilson Works (now within Thermphos) which historically formed part of these works.
5.12.139 The production of chemicals on the Muspratt site began around 1865 when the site was
known as the Widnes Alkali Works (former Muspratt site), the main products manufactured were
caustic soda and bleaching powder. In 1868/69 some 2,500 tons of caustic were manufactured
and by the late 1880s this had risen to 40,000 tones per year with over 10,000 tons of bleaching
powder. ICI noted that Charles Lambert carried out copper smelting and vitriol manufacture in
the vicinity of the site in 1850, the vitriol area was leased to the works in 1878.
5.12.140 The manufacture of soda by the LeBlanc process began at the Wood End Works
(immediately west of Widnes Alkali Works) in 1851. This works subsequently became the
Muspratt No.1 Works and later Albright and Wilson (now Thermphos). It is considered possible
that waste from Wood End Works was tipped locally, possibly on the site previously occupied
Widnes Alkali Works (now former Muspratt site to east of Thermphos).
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5.12.141 Chlorine gas was used for the manufacture of bleaching powder and also for potassium
chlorate. By 1890, Widnes Alkali Works were making 290 tons per year of potassium chlorate
and the Muspratt Wood End Works were making 70 tons per year in 1870 and 500 tons in 1890
along with 100 tons of sodium chlorate. ICI note that chlorate was a powerful oxidising agent
and frequently caused fires, the Muspratt works had a chlorate fire in 1870 and a serious
explosion in 1912, Widnes Alkali works had a chlorate fire in 1895.
5.12.142 ICI note that Widnes Alkali Works had about two miles of internal railway and small
locomotives were used for transporting chemicals around the works.
5.12.143 Plants to recover sulphur from the LeBlanc process had been installed at both works by
1890. In 1915/16 the production of sodium sulphide began at the Widnes Alkali Works. By
1921 soda and chlorine manufacture had ceased at the Muspratt and Widnes Alkali Works and
only two of the revolvers manufacturing sodium sulphide remained at Widnes Alkali Works.
5.12.144 In 1919 the Muspratt Wood End and Widnes Alkali Works combined becoming Muspratt
No.1 and No.2 respectively. In 1930 the Muspratt Works were amalgamated with the Gaskell
Marsh Works. Gaskell Marsh works made sodium sulphide, sulphite, bisulphite, thiosulphite
and a number of other products. In 1933 Albright and Wilson started the manufacture of
phosphorous on the Muspratt No.1 site.
5.12.145 The sodium sulphide plant was located at the eastern end of the Muspratt No.2 site. The
carbon disulphide plant was located at the west end of the Muspratt No.2 site in an area owned
and occupied at the time by Albright and Wilson (and now Thermphos car park), this plant was
shut down around 1968. ICI noted that carbon disulphide is heavier than water and found its
way into Bowers Brook where it reacted with acid to give off hydrogen sulphide. ICI records
indicate that carbon disulphide was stored in drums in the south east corner of the site. ICI also
noted that carbon disulphide is prone to explosion and an explosion was noted in a March 1953
site investigation borehole log from under the transformer house (the location of which is not
known, though ICI thought it was likely to have been located in the west area which formed part
of Albright and Wilson and is now part of Thermphos and outside of the Project area).
5.12.146 The chemicals identified by ICI as having been used and manufactured at the former ICI
Muspratt Site are as follows:
a. Carbon disulphide (or bisulphide)
b. Caustic soda
c. Sulphuric acid
d. Hydrochloric acid
e. Copper
f. Copper chloride
g. Arsenic
h. Nickel
i. Chromium
j. Benzene (ICI considered this was not likely to be present in significant quantities or
concentrations)
k. Thiophene (sulphur containing aromatic compound; C4H4S. ICI also considered this
was not likely to be present in significant quantities or concentrations)
l. Sodium cyanide (ICI had no records of its use but noted that it was added at some
sodium sulphide plants)
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5.12.147 ICI indicated there was little information at the site regarding locations of chemical use,
storage, handling and waste disposal and it was therefore assumed the majority of sources of
contamination could be present in most areas of the site within the made ground or alluvium.
ICI (1995) Intrusive Investigation
5.12.148 Historical information on the ground conditions has been obtained from the following:
a. ICI C&P, July 1995. Muspratt Site, Widnes Soil and Groundwater Contamination
Assessment Stage II – Site Investigation Report (ref: 79759/13/02)
b. ICI C&P, July 1995. Muspratt Site, Widnes Soil and Groundwater Contamination
Assessment Stage III – Hazard Assessment (ref: 79759/13/03)
5.12.149 A site investigation was undertaken by ICI at the site of the former ICI Muspratt Site in 1995.
This site comprises the site previously occupied by Widnes Alkali Works and the Muspratt No.2
Works.
5.12.150 The ICI site investigation comprised samples of soils and groundwater from 11 trial pits up to
3.0m bgl, 34 surface scrapes, three samples of standing water, nine samples from Bowers
Brook, and 10 passive soil vapour probes with samples obtained being analysed for a range of
metals, sulphate, sulphide, cyanide, VOCs and total organic carbon (TOC). The soil vapour
probes were to assess carbon disulphide levels.
5.12.151 The base of the made ground was not proved in any of the trial pits. The possible presence
of Galligu and hydrogen sulphide odours are recorded on the trial pit logs. Shallow groundwater
was encountered between 0.9m and 2.9m bgl in eight of the 11 trial pits.
5.12.152 ICI compared the results of the soil testing to trigger concentrations in ICRCL 59/83 (1987)
and the water samples to Environmental Quality Standards. The ICRCL guidance was current
at the time of the investigation. ICI encountered elevated levels of soil contaminants in surface
scrape samples and trial pits, which included arsenic, barium, copper, lead, zinc, and TOC. The
ICI report noted that elevated total organic carbon (TOC) was likely to be associated with ash or
cinders in made ground, large amounts of unchanged coal in galligu, or locations where coal or
charcoal could be present, e.g. rail sidings or charcoal store. Localised elevated concentrations
of cadmium and mercury were also noted in samples from the trial pits.
5.12.153 Elevated levels of sulphate were recorded within groundwater samples, which ICI considered
to be associated with products historically used or manufactured on the site. Elevated
concentrations of arsenic, copper, nickel, zinc and cyanide were also recorded. Carbon
disulphide was encountered above analytical detection limit (<0.005mg/l) in one of the five
groundwater samples tested (TH3 at 0.135mg/l). ICI considered the groundwater contamination
to be fairly localised as the water in Bowers Brook had not been adversely affected by
groundwater. This section of Bowers Brook is located outside of the Project area.
5.12.154 ICI considered the concentrations of benzene and carbon disulphide in soil vapour were low.
5.12.155 It was noted that groundwater samples were obtained from trial pits by ICI. It is possible the
results obtained may not be representative of the ground conditions due to the potential for
cross contamination when obtaining the sample and due to the loss of possible volatile
contaminants from water during the trial pit excavation and subsequent sampling.
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5.12.156 The ICI Stage I Historical Review (1995) noted the former carbon disulphide plant (now
located within Thermphos) was shut down around 1968. ICI noted that „carbon disulphide is
heavier than water and found its way into Bowers Brook„ and that „it settled in the hollows in the
invert of the Brook where it reacted with acid to give off hydrogen sulphide.
Halton Borough Council - Thermphos
5.12.157 Anecdotal evidence from the Council indicates that a carbon tetrachloride plant may
historically have been present in the south west of the Thermphos site. No information has
been obtained to confirm this, although a number of unnamed buildings were identified in this
area on the historical OS maps.
5.12.158 Anecdotal evidence has been obtained from Thermphos on the location of the carbon
tetrachloride plant. This indicates that it was located in the south of the site (within the Project
area). It is understood the location of this plant corresponds with a series of structures shown in
the south of the site on the 1958 and 1959 OS maps, which was located between railway lines
(no longer present) and Bowers Brook.
Bowers Brook
5.12.159 Information obtained from the Council (Mersey River Board drawing W.26.B) on Bowers
Brook indicates this is partly in a brick lined culvert and partly in an open channel. The Brook
flows in culvert in a general southerly direction through Bowers Business Park and the former
ICI Muspratt site towards the St Helens Canal. It passes beneath the canal (tumbling chamber)
and then flows in an open channel across the salt marshes to join the River Mersey. A further
section of the brook is present as an open channel/culvert is present between the south west of
corner of the former ICI Muspratt site (the existing Thermphos site) and the lock gates to the St
Helens Canal at Spike Island. The water in this part of Bowers Brook flows in an easterly
direction along the southern boundary of Thermphos and then joins the Brook and flows out
through the channel in the salt marshes to the Mersey. Another channel of the Brook flows in a
westerly direction from Catalyst Trade Park to Spike Island where it outfalls into the Mersey.
This information also indicates that the base of Bowers Brook, to the south of the Catalyst Trade
Park, would be located within the cohesive alluvial deposits.
5.12.160 The plans show the levels for Bowers Brook culvert to the south of the former ICI Muspratt
site at the tumbling chamber where it flows beneath the St Helens Canal. This information
indicates the base of St Helens Canal is approximately 4.56m AOD. Comparison of this level
against the ground conditions identified for BH10B (which was located adjacent to bowers Brook
and St Helens Canal at the former ICI Muspratt site) indicates the base of the St Helens Canal
would be located on or within alluvial clay deposits.
5.12.161 As noted previously, there are records of drains beneath the Catalyst Trade Park (Area C)
that link to Bowers Brook.
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St Helens Canal
5.12.162 Area C is situated immediately to the north of the St Helens Canal. The ICI (1995) report for
the Muspratt site notes that St Helens Canal was opened to commercial traffic in 1757, over 100
years prior to the start of operations at the Muspratt site. The canal was noted by ICI has
having been built on embankment above the level of the surrounding estuarial marshes.
Information within Starkey (1998) contradicts this and notes that whilst the Sankey Canal (St
Helens Canal) was complete by the end of 1757, the Sankey or St Helens Canal was only
extended to Woodend (Widnes) at the Runcorn Gap in 1833.
5.12.163 The House of Commons Journal (1830) states that „Lord Stanley presented a Bill (The
Sankey Brook Navigation Bill) to consolidate and amend the Acts relating to the Sankey Brook
Navigation, in the County of Lancaster, and to make a navigable Canal from the said Navigation
at Fidler‟s Ferry, to communicate with the River Mersey at Widnes Wharf, near Westbank, in the
Township of Widnes‟. It is not known whether the St Helens Canal is lined, although it is
understood the use of puddle clay as a lining for canals dates from the late 1700s onwards.
Runcorn
Area D – Wigg Island and Astmoor Saltmarsh
5.12.164 The land occupied by the Wigg Island Community Park has a history of industrial land use,
which commenced in the late 19th Century. Historical OS maps published in 1881 show that a
copper and alkali works, known as Old Quay Works, was located in the west of Wigg Island.
Extensions to the works are illustrated on historical OS maps published between 1899 and
1908.
5.12.165 Intrusive investigations have been undertaken at this site by Exploration Associates, WS
Atkins and the Environmental Advisory Unit on the areas of Wigg Island, south of the River
Mersey and formerly occupied by the Wigg Works Alkali Factory, an associated tip (Wigg Island
Landfill) and a Chemical Works with known names including „Wigg East Works‟, „Kemet‟ or
„Kemsol‟.
5.12.166 The reports obtained for review comprised the following:
a. Exploration Associates, July 1993. Factual report on Ground Investigation: Wigg Island,
Runcorn. Prepared for Commission for the New Towns, Warrington.
b. Exploration Associates, February 1994. Factual report on Ground Investigation: Wigg
Island, Runcorn. Prepared for Commission for the New Towns, Warrington.
c. WS Atkins Environment, November 1995. Assessment of Near Surface Soil and Water
Contamination at Wigg Island, Runcorn. Prepared for Commission for the New Towns,
Warrington.
d. Environmental Advice Centre, September 2000. Further Contamination Assessment,
Wigg Island. Prepared for Halton Borough Council
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5.12.167 A brief review of these reports is included below:
Exploration Associates (1993) Ground Investigation
5.12.168 The investigation was undertaken by Exploration Associates to assess the nature of the fill
material on the Wigg Island Landfill and former Kemet Works on Wigg Island. The fieldwork
comprised 12 cable percussion boreholes to depths of between 2.00m and 15.00m bgl to obtain
soil and water samples for chemical analysis, combined gas and groundwater monitoring wells
were installed at six of the locations into made ground.
5.12.169 Ground conditions were described as comprising topsoil over clay fill with inclusions of wood,
brick, ash, clinker, plastic and occasional „chemical waste pockets‟ from 0.50m to 6.00m bgl.
Specific descriptions of the fill material included white, blue, grey or orange crystalline chemical
waste, dark brown or black very sandy clay or clayey sand often with an oily or greasy lustre.
Exploration Associates noted the „boundary between the made and natural ground was often
difficult to distinguish as leaching of contaminants into natural ground has almost certainly
occurred‟. Exporation Associates considered that natural ground was encountered in two
boreholes at 9.0m bgl (0.74m AOD) and 7.80m bgl (0.78m AOD) where the material
encountered was described as alluvial silty fine sands or soft silty clay.
5.12.170 Borehole logs show that groundwater was encountered in the made ground during drilling
mostly as „slight seepages‟. Groundwater ingress was noted in one borehole during site works
at 9.00m bgl rising to 7.00m bgl after 20 minutes. Monitoring wells were installed towards the
base of the fill materials or within natural ground (alluvium). Standing water was present in all
wells during a subsequent monitoring visit „three to four weeks‟ after installation where it had
risen to be within the waste materials.
5.12.171 The results of the chemical testing were not included in the factual report provided to Gifford.
5.12.172 Borehole 11287 was drilled closest to the proposed bridge piers on Wigg Island Landfill.
Exploration Associates noted that made ground was encountered to the base of the borehole at
15m bgl. This comprised blue-grey mottled white silty sandy gravel of crystalline chemical
waste to 10.70m bgl. Underlying this, the made ground was described as clayey sandy silt of
chemical waste (10.70 to 12m bgl), soft black fibrous peaty clay with some gravels of chemical
waste (to 12.0 to 13.0m bgl) and very silty sand (13.0 to 15.0m bgl, base of hole). However, it is
likely that at least some of the material described as made ground by Exploration Associates is
alluvium with inclusions of the overlying made ground, possibly from 10.70m bgl.
5.12.173 No groundwater was noted within the made ground in Borehole 11287 during drilling. Two
50mm diameter monitoring wells were installed into Borehole 11287; one with slotted well sceen
from 1.7m to 10.7m bgl (made ground) and the second with slotted well screen from 12m to
15m bgl (alluvium). A 1.7m bentonite seal was installed to separate the two monitoring wells.
Subsequent monitoring by Exploration Associates encountered identical or almost groundwater
levels in both wells during two of the three visits. This indicates the gap between the two slotted
well screens is unlikely to have been adequately sealed and, therefore, it is not possible to
assess which horizon this groundwater is associated with.
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Exploration Associates (1994) Ground Investigation
5.12.174 A second investigation by Exploration Associates was undertaken in December 1993, and a
factual report prepared in February 1994.
5.12.175 This investigation comprised eight cable percussion boreholes in the same area as their
previous site works to depths of between 7.50m bgl and 18.00m bgl. Monitoring wells were
installed in all of the boreholes. The ground conditions included a thin layer of topsoil over fill
material. The fill comprised wood, brick, ash, clinker, plastic, concrete and occasional chemical
waste pockets. This deposit was encountered from 1.80m to 8.40m bgl. In four of the
boreholes (P1 to P4) below the fill a firm to stiff silty sandy clay (glacial till) was found, and in the
other four (P5 to P8) a soft to firm grey to dark grey silty to very silty clay was noted. Bedrock
was encountered in all boreholes beneath the fill and drift deposits, at depths ranging from
6.90m to 17.60m bgl. This comprised highly weathered sandstone.
5.12.176 These exploratory holes were located to the west of the Project area on the Wigg Island
Landfill. However, Borehole P4 was located close to the approach viaduct piers at the former
Kemet Works. Ground conditions in P4 comprised made ground to 5.8m bgl described as a
sandy clay with gravels of brick and concrete. Underlying the made ground was glacial clay
which was described as stiff sandy clay, with sandstone rockhead encountered at 10.50m bgl.
5.12.177 Groundwater ingress was recorded by Exploration Associates in six boreholes in the made
ground and alluvium. Groundwater was described as black by Exploration Associates in P5 and
P6 at 9.0m and 11.0m bgl respectively, both of which relate to groundwater in the alluvium. P5
and P6 were located approximately 400m and 700m west of the route alignment at Wigg Island.
The groundwater strike in P4 was encountered in the made ground at 4.8m bgl and rose to
3.5m bgl after 20 minutes.
5.12.178 Again, the results of the chemical testing were not included in the factual report obtained by
Gifford.
WS Atkins (1995) Ground Investigation
5.12.179 This report was commissioned to assess the contamination status in the shallow soils and
surface waters on Wigg Island. The WS Atkins (WSA) investigation comprised the former Wigg
Works Alkali Factory, the tipping area and the area formerly occupied by the Kemet Chemical
Factory.
5.12.180 A total of 208 sample locations were selected based on obtaining one sample every 25m, i.e.
a 25m by 25m grid, with the site sub-divided into five areas; Areas A to E. WSA indicated that
soil samples were obtained by hand using a spade and trowel. A square of turf was removed at
each location and samples of the soil immediately below the turf were obtained.
5.12.181 The results of the analysis showed that elevated concentrations of arsenic, copper, zinc,
sulphide, sulphur and phenol were present in soils when compared to the ICRCL 59/83 (1987)
threshold and action trigger values for parks, playing fields and open spaces (current at the time
of this investigation), supplemented by soil assessment criteria issued by the former Greater
London Council. The ICRCL guidance was current at the time of the investigation. Elevated
concentrations of sulphide were widespread across the whole site. Areas A to C did not have
significantly elevated levels of the 11 metals and metalloids tested.
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5.12.182 However, hotspots of contamination were noted by WSA at the site of the former Kemet
Chemical Factory with respect to arsenic, copper and zinc. After inspection of these hotspots
by WSA, it was noted that these appeared to be associated with areas of rutting caused by
motorcyclists mixing topsoil with underlying fill.
5.12.183 Elevated levels of metals and metalloids, including arsenic, copper, zinc were reported from
the former Wigg Works site.
5.12.184 Surface water samples were taken from the „disused canal spur‟ (former Latchford Canal)
which lies north of the former Kemet Chemical Factory, where a pH of 2.75 was obtained from
the eastern end of the spur. WSA considered it likely that other contaminants existed in the silt
within this water body. Samples of a water seep entering a surface water ditch to the north of
the site were recorded to be alkaline, with pH of 10.95 and 11.12. The pH from samples of the
water within the ditch itself ranged between 9.15 and 11.36, with one of the samples (W5) also
having elevated concentrations of arsenic, cadmium and chromium.
Environmental Advice Centre (2000) Ground Investigation
5.12.185 The Environmental Advice Centre (EAC) were commissioned by the Council to undertake
further intrusive investigations across the area formerly occupied by the Wigg Works Alkali
Factory, the tipping area and the area of the Kemet Chemical Factory on Wigg Island. This was
due to information gaps considered to be present in previous investigations including:
a. Lack of data relating to the contamination at depths greater than 0.50m.
b. No data relating to contamination in materials underlying areas of dense planting.
c. Insufficient data to describe the distribution of asbestos found on site.
5.12.186 The EAC investigation comprised 69 trial pits, 10 cable percussion boreholes and 65 window
sample holes to visually assess ground conditions and obtain samples for chemical analysis.
The trial pits were extended to 3.0m bgl where possible, the boreholes were extended to prove
natural ground and combined gas and groundwater standpipes were installed in all of them.
The window sample holes were positioned in areas of dense vegetation, where no previous
investigation had been undertaken.
5.12.187 EAC report the thickness of the made ground from 20 borehole logs to be between 2.0m and
12.8m. EAC report that made ground was underlain by alluvial sands and silts in 12 boreholes,
and glacial till in seven boreholes. Sandstone bedrock was proven in 12 boreholes at depths
ranging from 6.90m to 17.60m bgl (6.83m to –1.63m relative to OD). None of boreholes
encountered made ground directly overlying bedrock. EAC noted that the area under
investigation had been capped with clay fill, although this was variable in thickness, being less
than 0.30m in places.
5.12.188 The results of the chemical testing were compared by EAC against levels identified in
uncontaminated soils and with the ICRCL guidelines which were current at the time of the
investigation.
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5.12.189 Contamination associated with made ground included:
a. Very high concentrations of cyanide and arsenic found in a blue silty material
immediately beneath the capping layer.
b. Very high concentrations of heavy metals including arsenic, copper, lead and zinc
associated with a purple ash material encountered at varying depths
c. Localised areas of white „chemical waste‟ contaminated with elevated metals, which
was widespread across the site and is considered to be related to the historical alkali
and copper works.
d. No visible asbestos was noted during these site works, analysis showed <0.01%
chrysotile in two samples of the 43 tested (neither located along the route alignment).
5.12.190 Maximum concentrations of contaminants noted within the made ground beneath the
capping layer included arsenic (1,816mg/kg), copper (19,000mg/kg), cadmium (611mg/kg),
cyanide (8,820mg/kg), lead (74,000mg/kg), mercury (300mg/kg), zinc (19,000mg/kg) and
sulphide (20,000mg/kg).
5.12.191 Groundwater samples were obtained from six monitoring wells located in made ground and
natural ground, none were located within the proposed route alignment. Borehole 4, located in
Kemet Works was the closest monitoring to the proposed route. The plan provided indicates
that BH4 would have been located approximately 50m north east of the proposed bridge piers in
this part of the project. The made ground in BH4 was noted as being „moist‟ during drilling
towards the base of the made ground at 7.0m bgl. Glacial clay was encountered in BH4 at 8.0m
bgl.
5.12.192 The groundwater analysis from this investigation indicated that concentrations of metals,
sulphide and total cyanides were all below analytical detection limits, except for locally elevated
concentrations of metals at two locations.
5.12.193 EAC indicated that there was variation between the gas concentrations obtained by
Exploration Associates in June 1993 and their investigation. They state that locally elevated
concentrations of methane (max. of 55.45%) and carbon dioxide (max. of 11.1%) were present,
along with reduced concentrations of oxygen (0.6%).
Wigg East Works (1995) Historical Plan
5.12.194 This site is also known as the former Kemet or Kemsol Works. The following plan has been
obtained which shows the usage of buildings at the site:
a. ICI Ltd, General Chemical Division. Wigg East Works – Plan showing underground
cables. Drawing Number SD 14326 (1955).
5.12.195 Two garages are shown in the south western part of the site along with a petrol pump. The
nearest features to the proposed piers shown in this area are labelled as HCL loading, stage,
loading bay, oil tank store (located adjacent to the existing Randle Island haulage road), and a
pipe compound.
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5.12.196 The main part of the former Wigg East Works is shown to have been located to the east and
northeast of the Project area and was occupied by processes associated with the following:
a. Ammonia building
b. Saltcake furnace and storage
c. Kemsol Store
d. Sulphuric acid plant and storage
e. Hydrochloric Acid storage
f. Sodium bi-sulphite plant
g. Red Lead Building
h. Boiler Plant and power house
i. Spent oxide furnace and storage
j. Sulphur storage
k. Gelatine storage, grinding and plant
l. Osseine plant
m. Bone storage
n. Incinerators
o. Drum storage
p. Various railway lines and pipelines
Randle Island – Former Chemical Weapons Production Facility
5.12.197 Information provided in Soilleux et al (2001) indicates there was a chemical weapon
production facility located at Wigg Island on the southern bank of the River Mersey to the north
of Runcorn and that this was the site of a purpose built production facility dating from the late
1930s. This plant produced principally mustard gas until the end of the World War II although
the plant was kept in an operational condition until 1956. This information also indicates that
during the 1950s the plant was used to manufacture ethylene glycol. Randle was also used for
the destruction of 6000 tons of mustard and other vesicants during the late 1950s in an
incineration plant.
5.12.198 The information obtained from historical OS maps and BACTEC (2006) indicates the closest
site boundary at this facility would have been approximately 380m east of the proposed
approach viaduct, with the nearest buildings at approximately 700m. This site is now the
Randle Island Landfill operated by Ineos Chlor Ltd. A summary of the information obtained from
BACTEC (2006) together with the outcome from additional documentary research for the Public
Inquiry in 2009 has been included in Section 6.3.
Area E – Astmoor Industrial Estate, Runcorn
Exploration Associates (1984) Ground Investigation
5.12.199 A factual report was received for a site investigation at Astmoor 18 carried out for the
Warrington & Runcorn Development Corporation by Exploration Associates in 1984. The area
of this investigation is located south of the Manchester Ship Canal almost opposite the former
Kemet works site. The site works comprised 11 cable percussion boreholes drilled to depths
ranging from 5.30m to 7.00m bgl, and a total of 13 trial pits excavated to a maximum depth of
3.00m bgl to obtain information on geotechnical properties (only) for a proposed industrial
development.
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5.12.200 Ground conditions comprised topsoil over made ground, glacial sand and glacial till, with the
greatest thicknesses of made ground in the western part of the site and associated with a sewer
along the northern edge of the site. The ground conditions comprised:
a. Made ground divided into two types; the first associated with the sewer was essentially
remoulded glacial till, and the second (across the majority of the site) was a silty sandy
gravely clay with inclusions of brick and wood.
b. Glacial sand was encountered overlying the glacial till and comprised an orange brown
silty fine to medium sand with varying proportions of clay and organic material.
c. Glacial till extended to the base of the boreholes, and comprised stiff silty sandy gravely
clay with occasional sand horizons. The thickness of the sand horizons varied from
0.10m to over 1.30m.
d. Bedrock was not encountered.
5.12.201 No chemical testing was undertaken during the investigation by Exploration Associates.
Dames & Moore April 1998 Phase 1 Environmental Assessment
5.12.202 Dames & Moore undertook a Phase 1 Environmental Assessment report on behalf of
Courtaulds Plc (now Solutia) which is located in the south of Astmoor Industrial Estate, adjacent
to the Bridgewater Junction. The Dames & Moore report provides the following information on
the site history:
a. The site was initially developed in 1971 for the manufacture of brass fittings and cables
and could have included the use of solvents for degreasing and cutting and lubricating
oils for machining;
b. From 1986 to 1988 the site was empty; and
c. In 1988 Courtaulds started at the site manufacturing coated films, constructing the boiler
house in 1989. The warehouse immediately to the south was acquired in 1997 before
this it was used for the storage of plasterboard.
5.12.203 Potentially contaminating land uses identified at the site by Dames & Moore in 1998
associated with the Courtaulds site comprised the following:
a. Use of “solvents” – methyl ethyl ketone (MEK), isopropylalcohol, acrylic acid, butyl
acetate, resin;
b. Drum storage;
c. Five above ground storage tanks within the drum storage area; 2 x 3,500 litre capacity
for MEK, 1 x 4,000 litre for industrial methylated spirits and 1 x 4,000 litre for petroleum
based solvent, all tanks were constructed from steel with concrete bunds. The
remaining tank is constructed from steel with a breeze block bund, comprising 1,500
litre capacity for storing diesel;
d. Former electrical sub-station - at the time of preparing their report in 1998, Dames and
Moore indicate a new substation was under construction;
e. Small engineering workshop; and
f. Asbestos cement roof on the main factory, lagging on a small water tank and some wall
cladding panels in the same room as the water tank.
5.12.204 A 12,000 litre capacity underground sump was installed in 1997 and constructed from
concrete with an impermeable lining to collect spills and leaks from the yard and also surface
water run-off. Dames & Moore reported that the sump was allowed to overflow into nearby
surface drains, which were believed to drain into the Manchester Ship Canal.
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5.12.205 Small quantities of chemicals including resins and powders were also stored in a concrete
bunded floor building in the drum yard. Other chemicals include small quantities of biocides and
rust inhibitors used in the boiler and cooling waters. Dames & Moore indicate the boiler house
was gas fired.
5.12.206 Dames & Moore indicate a spill comprising 1000 litres of industrial methylated spirits
occurred in the early 1990s onto a concrete surface from one of the above ground storage tanks
due to a gasket failing. Most of the solvent (800 litres) was reported to have been collected with
the remaining being washed away to foul sewer by the fire brigade.
Sirius Geotechnical & Environmental Ltd, 2010
5.12.207 Investigation was undertaken by Sirius Geotechnical & Environmental Ltd (Sirius) in 2010 at
the south east corner of the Solutia site in the area where storage tanks and the sump were
located.
5.12.208 Ground conditions comprised made ground overlying glacial deposits. Beneath area of
concrete and limestone hardcore, made ground comprised soft and firm red brown sandy
gravelly clay with a fine to coarse and angular gravel of brick and concrete and occasional
cobble sized fragments of brick. The glacial deposits were described as firm and stiff, becoming
very stiff with depth, brown slightly silty sandy gravelly clay with occasional pockets of silty sand
and silty clay. Bedrock was not encountered. Groundwater was observed within the glacial
deposits at varying depths.
5.12.209 Soil samples tested as part of the investigation encountered petroleum hydrocarbons and
chlorinated solvents (up to 470mg/kg diesel range organics and 8.2mg/kg trichloroethene) in the
glacial deposits.
5.12.210 Sirius did not discuss the potential source of these contaminants. The maximum
concentration of trichloroethene that was observed was in excess of the generic assessment
criteria used by Sirius Geotechnical & Environmental Ltd. This indicates that there could be
localised risks to human health from exposure to trichloroethene which may be relevant to
construction workers at the site. Screening of soil arisings was undertaken during the
investigation using a PID which showed volatile vapours were present in the made ground and
glacial deposits.
5.12.211 Groundwater samples obtained from two wells installed in the glacial deposits by Sirius were
tested for petroleum hydrocarbons, VOCs and SVOCs. The results did not show any
contaminants to be present above the lower detection limits. However these water samples
were not taken from locations where solvent odours were noted during the drilling works as the
wells installed in these areas were dry when monitored.
5.12.212 The desk study and site investigation reports for the Solutia site were obtained from the
Contaminated Land Officer at the Council in 2011.
Bridgewater Canal
5.12.213 The Bridgewater Canal was opened in 1776. Information was obtained which suggested the
Bridgewater Canal (at least in part) was lined with puddle clay. However, information
subsequently provided by The Manchester Ship Canal Company in May 2008 states that the
Bridgewater Canal was not lined (at least in the Project area).
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Historical Exploratory Hole Location Plan
5.12.214 Drawing No. MG_REP_EIA_009/017 shows the location of the historical exploratory holes
obtained from previous site investigations in Widnes.
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6. BASELINE
6.1 Introduction
6.1.1 This section provides a review of the findings obtained from the assessment of the ground and
groundwater conditions, the chemical testing, and the ground gas and volatile vapour
monitoring based on information from the site investigations undertaken for the Mersey
Gateway Project.
6.2 Results of the Geophsyical Surveys
6.2.1 The geophysical surveys were undertaken at an early stage and investigated two corridors
across the estuary. The „western corridor‟ extended between the Wigg Island Visitor Centre on
the southern (Runcorn) shore and Spike Island / Catalyst Trade Park on the northern (Widnes)
shore. The geophysical survey along this corridor indicated that the rockhead profile sloped to
the northwest from c. +5 m OD on the northern shore of the Manchester Ship Canal to the
centre of the estuary where it levelled out at c. -7 m OD beneath the estuary until the shore of
Spike Island where it then fell to c. -34 m OD at the northwestern limit of the section.
6.2.2 The surveys also considered the rockhead profile from the „Eastern Corridor‟ which extended
between the eastern end of the Wigg Island Landfill on the southern (Runcorn) shore and the
former ICI Muspratt Site on the north (Widnes) shore. Along this survey line the rockhead
profile was found to fall to the northwest from c. 10 m OD immediately north of the Manchester
Ship Canal, to an elevation of c. -10 m OD, 100-200 m northwest of the former Latchford Canal
on Wigg Island. From here rockhead elevations were between -10 m OD and -15 m OD until a
point 100 m south of the shore of Widnes Warth where they sloped downward to the northwest
to an apparent minimum of c. -37 m OD beneath the centre of Widnes Warth.
6.2.3 Marine high resolution sub-bottom profiling results indicated that in the southern channel of the
Mersey Estuary between the Western and Eastern Corridors, the rockhead was approximately -
4 m OD. The results from the boomer data supported the hypothesis that there is a thick mantle
of weathered sandstone at the southern end of the Eastern Corridor, which reduced in thickness
to the west. Approximately 1,100m west of the Western Corridor the bedrock head surface was
found to drop smoothly to below -10 m OD and did not rise again before the site of the existing
crossing. Bedrock was observed during the geophysical surveys at low tide on the northern
side of Runcorn Gap, this could be followed southward in the seismic section to approximately
the centre of the Gap, where it became undetectable in the boomer data at a depth of c. -7 m
OD.
6.2.4 The results obtained suggest the presence of a deeper trough in the bedrock on the southern
side of Runcorn Gap, infilled with recent sediments and orientated parallel to the present
direction of river flow. The final bedrock contour model indicated that rockhead elevation across
the estuary was typically approximately -10m OD, deepening to the northwest, where a feature
identified in published reports as a buried sub-glacial valley was encountered. The minimum
elevation of the bedrock head surface encountered in the survey area was -37 m OD, on the
Eastern Corridor, beneath Widnes Warth.
6.2.5 The geophysical survey report is located in Appendix C. This includes figures which show the
extent of the survey profiles.
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6.3 Unexploded Ordnance (UXO)
6.3.1 The information obtained from the British Army (33 Explosive Ordnance Disposal Regiment in
Salisbury) in 2002 did not contain any records of unexploded ordnance in the area between
Bowers Business Park in Widnes and Astmoor Industrial Estate in Runcorn (the project area
under investigation in 2002) so has not been included within this report.
6.3.2 The Desk Top Explosive Ordnance Threat Assessment prepared for the Mersey Gateway (in
Appendix D) considered the assessed risk during the land based intrusive works to be low. The
risks from UXO were considered to be elevated for intrusive works in the River Mersey and
marshland on the basis it was very unlikely that the entry holes of UXO which fell in these areas
would have been noticed or dealt with. The report also indicated that bomb craters had been
observed in both the river and on the marshes but was not able to provide the locations. The
report also considered there to be a medium risk from UXO during works in the River Mersey
and on the marshland.
6.3.3 Within the proposed alignment, records of bomb strikes on the former Central Laboratory at the
ICI Widnes Experimental Works in Widnes were obtained. These strikes comprised two 250kg
high explosive (HE) bombs dropped during a raid on Widnes on 9th/10
th August 1942.
6.3.4 The report also indicates that on 9th/10
th January 1941 several HE bombs were dropped in the
River Mersey and on Runcorn Marsh. Craters were noted in the river off Dukesfield (at
southern end of the existing bridges) but were washed away by the tide.
6.3.5 A tracing provided of the „Bomb Census Map‟ for Widnes shows that an unopened incendiary
bomb container was found embedded in Widnes Warth saltmarsh opposite the Pilkington
Sullivan works, to the east of the route alignment. The contents had ignited. To the east, the
report references records of 50 incendiary bombs having fallen within former ICI Pilkington
Sullivan works on either side of the LMS railway line (existing Freight Line).
6.3.6 The report provides reference to records and anecdotal evidence that the road and rail bridges
across the Runcorn Gap were not targeted or bombed although they were identified on
Luftwaffe reconnaissance photographs. The report also states that „it was suggested by a local
historian that the German military intentionally avoided destroying the bridges as they would
have been more useful intact in the event of invasion‟.
6.3.7 Based on recommendations from the Desk Top Threat Assessment in 2006 for the River
Mersey, surveying for UXO was undertaken during the Phase 5 site investigation within the
estuary using a down-hole magnetometer as cable percussion boreholes were progressed. No
buried metallic objects were noted during this magnetometer survey.
6.3.8 A detailed UXO risk assessment was prepared by BAE Systems Environmental in accordance
with guidance in CIRIA C681 (2009) for the moderate risk areas identified in the BACTEC Desk
Top Threat Assessment for the construction phase of the scheme.
6.3.9 The results of this assessment identified a moderate probability of encountering German air
dropped UXO and a low to moderate probability of encountering UXO of an anti-aircraft origin
during the construction works in this part of the project area. However, if UXO was found, the
likelihood of initiating the device and causing an explosion was considered substantially lower.
Mitigation measures comprise ordnance awareness briefings for pile cap and cofferdam
excavations in Area D. No special measures were recommended for German air dropped UXO
during piling or drilling as the operator would not be able to see the soil being disturbed. The
UXO risk assessment is located in Appendix R.
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ICI Randle Island
6.3.10 The BACTEC report indicates that a chemical weapons production plant was located at Wigg
Island, Randle, approximately 400m east of the proposed approach viaduct.
6.3.11 BACTEC state that the plant was opened by ICI in the mid 1930s and was designed for the
production of phosgene and various types of mustard gas. In 1937 approval was given for the
construction of four „charging‟ buildings for the head filling of artillery and aerial bombs. Also at
this time, 100 semi-underground five ton pots were constructed holding 10,000lbs of
gunpowder. This report notes that fused weapons were stored in trenches elsewhere at Wigg
Island. The location of these trenches was unknown, but BACTEC state they are likely to have
been within the boundary of the ICI works and, therefore, would not pose a threat to the planned
intrusive works.
6.3.12 BACTEC indicate that in 1938 the government issued a requirement for remote storage facilities
as Randle was seen as easy to locate from the air and vulnerable to attack. In 1939 work
started on the Valley Works storage facility at Rhydymwyn in North Wales. BACTEC did not
find any records to suggest the facility at Randle Island was ever targeted or bombed.
6.3.13 Further information on the former Randle Island facility was obtained as part of the Proof of
Evidence of Contamination, Soils and Groundwater prepared for the Mersey Gateway Public
Inquiry in 2009. This involved research at the Public Records Office and the findings did not
show the former chemical weapons plant extended into the Project area. Extracts of information
obtained have been included in Appendix T.
6.4 Radiological Contamination
6.4.1 The documentary review by Radman Associates in Appendix S indicates that work with
radioactive materials did not occur at the site prior to 1940 when initial research began into the
processing of uranium hexafluoride and uranium metal. After 1954 no records exist for the site
to indicate further significant research or production involving radioactive materials.
6.4.2 No documentary evidence was obtained to suggest that radioactive waste was buried at the
site. It was considered that any residual contamination is likely to be the result of leaks and
spillages or dust generated during processing of the uranium metal.
6.4.3 None of the historical information obtained on the use of radioactive materials at the site
indicates that radiological contamination is likely to be present. In addition, previous surveys did
not identify any significant ground level radiological contamination or the need for special
protective measures to restrict exposure to individuals.
6.4.4 The most detailed surveys, which included analysis for radiological contamination, were
undertaken at Bowers Brook. These surveys identified radiological contamination in the
sediments. Radman Associates consider that any work within the drains or Bowers Brook
should expect to encounter contaminated sediments. Sources of information reviewed have
been referenced in the Radman Associates report.
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6.5 Ground Conditions Identified from Gifford Investigations
Ground Conditions Summary
6.5.1 The geological sequence observed from the ground investigation is in general agreement with
the information from published sources and previous investigations. Extensive areas of man-
made deposits (made ground) were encountered in built up areas and in localised areas on the
saltmarshes. The drift deposits encountered comprised alluvial materials associated with the
estuary, the saltmarshes and surface water courses together with extensive deposits of glacial
till. The glacial till was predominately cohesive with interbedded glacial sand and gravel
deposits, which was in turn underlain predominantly by sandstone bedrock, although mudstone
bedrock was encountered at some locations in Runcorn.
6.5.2 The distribution of strata encountered during the ground investigations along the proposed route
of the construction works is summarised in Tables 6.1 to 6.3:
6.6 Widnes (North of the St Helens Canal)
Table 6.1 – Geological Sequence from the Ground Investigations in Widnes
Material Depth
Encountered
(m bgl)
Level
Encountered
(m AOD)
Base of Statum
(m AOD)
Thickness
(m)
Made Ground 0.00 17.9 – 6.23 9.16 – -0.6 0.70 – 11.0
Drift: Alluvium 0.70 – 8.30 7.5 – 1.9 5.96 – -2.8 0.2 – 9.6
Drift: Glacial
Deposits
0.90 – 11.8 9.2 – -2.8 4.7 – -43.1* 0.30 – 46.9*
Solid: Sandstone 38.0 -30.4 -35.6* 5.2*
* Full thickness or base not proven
6.7 St Helens Canal to Manchester Ship Canal (including Mersey Estuary and Saltmarshes)
Table 6.2 – Geological Sequence from the Ground Investigations between St Helens Canal and
Manchester Ship Canal
Material Depth
Encountered
(m bgl)
Level
Encountered
(m AOD)
Base of Statum
(m AOD)
Thickness
(m)
Made Ground
(where present)**
0.00 6.2 – 13.7 11.5 – 5.3 0.4 – 8.3
Drift: Alluvium 0.00 – 8.3 1.50 – 6.0 -0.7 – -8.4 3.0 – 11.0
Drift: Glacial
Deposits**
0.4 – 13.3 11.53 – -7.8 5.03 – -32.7 1.3 – 29.9
Solid: Sandstone 6.9 – 39.6 5.03 – -32.7 0.83 – -50.32 0.2 – 31.4*
*Full thickness or base not proven
**Not encountered in the Estuary
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6.8 Runcorn (South of the Manchester Ship Canal)
Table 6.3 – Geological Sequence from the Ground Investigations in Runcorn
Material Depth
Encountered
(m bgl)
Level
Encountered
(m AOD)
Base of Stratum
(m AOD)
Thickness
(m)
Made Ground 0.0 83.8 – 12.0 83.1 – 10.5 0.2 – 5.8
Drift: Glacial
Deposits
0.0 – 12.0 71.3 – 2.4 66.3 – -5.9 1.30– 16.5
Solid: Sandstone 5.7 – 18.0 49.9 – -5.9 47.6 – -27.9* 0.8 – 22.0*
Solid: Mudstone 0.2 – 10.5 83.11 – 18.3 82.61 – 16.2* 0.50 – 15.5*
* Full thickness or base not proven
6.9 Geological Sections
6.9.1 Geological sections have been produced both parallel to and perpendicular to the proposed
route for the Updated Reference Design based on the ground conditions encountered during
the investigations. Where there is relevant existing geological information, such as those from
previous investigations, this was also incorporated (see Drawing Nos. MG_REP_EIA_009/018
to MG_REP_EIA_009/030). The geological sections are as follows:
Table 6.4 – Geological cross sections from the intrusive ground investigation
Section Details of Information Drawing Number
Section A-A St. Michaels Golf Course to Ditton Roundabout Northern Route MG_REP_EIA_009/018
Section B-B St. Michaels Golf Course to Ditton Roundabout Southern Route MG_REP_EIA_009/019
Section C-C Ditton Roundabout to Victoria Interchange MG_REP_EIA_009/020
Section C2-C2 Anglo Blackwell Site to Gussion Site MG_REP_EIA_009/021
Section D-D Victoria Interchange to St Helens Canal MG_REP_EIA_009/022
Section D2-D2 Catalyst Trade Park North to South MG_REP_EIA_009/023
Section D3-D3 Catalyst Trade Park Southern Boundary Line MG_REP_EIA_009/024
Section E-E St Helens Canal to Widnes Warf MG_REP_EIA_009/025
Section F-F Mersey Estuary MG_REP_EIA_009/026
Section G-G Runcorn Saltmarsh to Manchester Ship Canal MG_REP_EIA_009/027
Section H-H Manchester Ship Canal to Bridgewater Junction MG_REP_EIA_009/028
Section J-J Remote Junctions Central Expressway MG_REP_EIA_009/029
Sections K-K & L-L Remote Junctions Westpoint Expressway and M56 Junction 12 MG_REP_EIA_009/030
6.9.2 Where horizons are shown between exploratory hole positions on the geological sections these
are based on interpolation. The geological section within the estuary and saltmarshes also
includes geophysical data plotted from the geophysical digital data. For full details reference
should be made to the borehole logs included in the Contractor‟s Factual Reports, within
Appendix E to J
6.9.3 Conceptual ground models for the Project in Widnes and northern Runcorn are shown Drawing
Nos. MG_REP_EIA_009/031 and MG_REP_EIA_009/032 respectively.
6.9.4 The ground conditions from investigations in Area I and Spike Island in Area D have not been
included on the cross sections as these would not be located within the area for the proposed
constructions works.
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6.10 Made Ground
6.10.1 Made ground was encountered in every exploratory hole, with the exception of those formed on
the saltmarshes, within the estuary and a number of the exploratory holes undertaken between
the Bridgewater Junction and M56 Junction 12. This is consistent with what is known of the
history of the saltmarshes which have remained relatively undeveloped with the exception of
localised areas such as Wigg Island Landfill in Area D and tipping at the proposed northern
abutment on Widnes Warth in Area D.
6.10.2 The made ground was highly variable and no pattern has been established that relates a
particular type of made ground with specific areas. It was common to encounter several
successive horizons of granular and cohesive made ground in any one exploratory hole, but
often impossible to locate the same material in adjacent boreholes. The depth and levels of
made ground encountered during the investigations are summarised in Tables 6.1 to 6.3 above.
6.10.3 „Galligu‟ was noted to be present within the made ground at the majority of the locations from
the St Helens Canal to St Michaels Golf Course and Speke Road in Widnes (Area A to C).
6.10.4 As noted above, the made ground was variable and comprised the following:
a. Very loose to medium dense black slightly clayey sandy gravel;
b. Very soft grey brown and orange brown sandy gravely clay;
c. Very soft and soft black slightly sandy gravely clay;
d. Blue white and black slightly sandy slightly gravely clay;
e. Stiff dark grey and black mottled blue grey slightly sandy gravely clay;
f. Soft light grey and white slightly gravely silt;
g. White and grey gravely medium sand;
h. Multicoloured slightly silty very sandy gravel;
i. Soft red brown and grey fine to coarse gravel;
j. Soft to stiff dark brown and black mottled grey and white sandy slightly gravely clay;
k. Soft to firm orange brown and grey sandy slightly gravely clay/silt;
l. Very loose dark brown yellow and grey clayey sand and gravel;
m. Very dense dark grey brown and black cobbles;
n. Very soft to soft grey slightly sandy slightly gravely silt.
6.10.5 The following constituents were encountered in the made ground:
a. Brick
b. Clinker
c. Concrete
d. Ash
e. Cinder
f. Asphalt
g. Slag
h. Paper
i. Sandstone
j. Metal
k. Limestone
l. Glass
m. Coal
n. Leather
o. Vegetation
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p. Pottery
q. Plastic
r. Slate
s. Timber/Wood
t. Rope
6.10.6 Several exploratory hole records noted odours of chemicals, hydrogen sulphide, organic and
hydrocarbons within certain horizons. Green, blue, white and black staining was also noted
within the made ground throughout the investigation within Widnes (Area to C). Further detail is
provided in Section 6.14.
6.10.7 Evidence of possible phosphorous was encountered within the made ground from BH67 on St
Michaels Golf Course in Area A. This material started to smoulder/smoke once it began to dry
at the ground surface.
6.10.8 From historic data, the raised area of made ground around TP20 & TP21 on Widnes Warth was
believed to be „galligu‟ waste arising from one or more of the former chemical works that were
present north of the St Helens Canal. The raised area of made ground around BH1004 and
WS6 in the northwest corner of Widnes Warth was historically occupied by a works building with
an associated area of waste material (BH40) identified at the location of the proposed northern
abutment.
6.10.9 Made ground, including alkali waste was identified in the Wigg Island Landfill within BH18A and
BH32 at between 7.2m and 8.3mbgl respectively.
6.10.10 BH70, drilled during Phase 6 on St Michaels Golf Course in Area A recorded made ground to
11m bgl, the base of which was not proved. A review of the borehole log for BH70 indicates
that material from 9m to 11m bgl could be glacial till rather than made ground. The material
from 9m to 11m bgl comprised soft to firm slightly sandy slightly gravely clay, although the
gravels were described as sandstone, ash and coal.
6.10.11 The average thickness of made ground on the north side of the Estuary is approximately 4m
and to the south it is approximately 2m, where it is present.
Buried Foundations
6.10.12 Evidence from historical OS maps and exploratory hole records indicates that many structures
have occupied parts of the Project area, particularly in Widnes in Area A to C.
6.10.13 Although in some places there was no evidence of structures at ground level, thirty one
boreholes indicated the presence of buried foundations or encountered significant obstructions
during drilling within the made ground.
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6.11 Drift Geology: Alluvium
Alluvial material associated with the River Mersey was located within the saltmarsh areas in
Area D, and as recent materials (Runcorn Sands) within the Mersey Estuary. Alluvium was also
encountered in twenty six of the exploratory holes carried out to the north of St Helens Canal
extending northwards to the golf course in Area A to C. The extent of alluvial material
encountered during this investigation is in broad agreement with that shown on the BGS drift
map.
6.11.1 The alluvial deposits encountered during the investigation comprised the following:
a. Soft to firm slightly sandy clay;
b. Very loose to dense silty fine and medium sand;
c. Very loose to dense slightly sandy silt;
d. Medium dense to very dense sand and/or gravel; and occasional
e. Soft clayey peat.
6.11.2 All of the exploratory holes undertaken in the estuary and on the saltmarshes encountered
alluvial deposits. This indicates that on the north shore the thickness of alluvium increases
southwards from the St Helens Canal towards the estuary. Similar conditions were obtained
from Astmoor saltmarsh in Runcorn, where the thickness of alluvium also increased towards the
estuary. The base of the alluvium within the estuary was proved at between 7m and 11m bgl in
all five boreholes drilled during the Phase 5 site investigation. The alluvium in the estuary was
directly underlain by bedrock.
6.11.3 The greatest thickness of alluvium (13.3m) was encountered in BH37, which is at the mid point
of the saltmarsh on Widnes Warth. The base of the alluvium here was recorded at –7.8m AOD.
This was the lowest level at which the base of the alluvium was recorded.
6.11.4 Evidence of possible contamination was noted within the alluvium from exploratory holes
located on and adjacent to the Project area, in particular at the Catalyst Trade Park in Area C
(solvent, hydrocarbon, hydrogen sulphide and ammonia odours), St Michaels Golf Course
(hydrogen sulphide and chemical odours) and beneath the Wigg Island Landfill in Area D
(ammonia odours).
6.12 Drift Geology: Glacial Deposits
6.12.1 Glacial deposits were encountered across the majority of the study area. North of the St.
Helens Canal and south of the Manchester Ship Canal, where the alluvium was absent, the
glacial materials were found immediately underlying the made ground. Closer to the river
estuary, the glacial material was encountered underlying the alluvial materials. The glacial
deposits typically comprised the following:
a. Firm and stiff clay with varying amounts of granular constituents;
b. Medium dense to very dense silt; and
c. Medium dense to very dense sand and/or gravel.
6.12.2 Areas where glacial materials were noted to be absent in the Project area or only present
intermittently were as follows:
a. Wigg Island (bedrock at relatively high elevation and directly underlying alluvium); and
b. Runcorn Sands – across the Estuary (alluvium directly onto bedrock).
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6.12.3 The boreholes undertaken on the Widnes saltmarshes in Area D indicate that the glacial
deposits increase in thickness from the edge of the saltmarsh northwards to the St Helens
Canal, and more extensively beyond into Widnes. Boreholes drilled on the saltmarsh (BH35 to
BH37 and BH40) encountered rock at 16m, 21m, 31m and 40m bgl respectively, the depth
increasing northward. The base of the glacial till was not encountered at a depth of 53m bgl in
BH53 on the Ditton Roundabout in Area B1. Historical boreholes located in the vicinity of
Catalyst Trade Park in Area C proved the glacial till to depths of between 40m and 48m bgl.
6.12.4 South of the Manchester Ship Canal, the glacial deposits initially increase in thickness before
thinning out with increasing bedrock elevation towards the Daresbury Expressway, which
appears to be located on shallow bedrock.
6.12.5 Evidence of possible contamination (as sulphur or hydrogen sulphide odours and black staining)
was noted within near surface glacial clay underlying made ground considered to include
galligu, in particular the area between Gussion Transport (Area B2) and St Michaels Golf
Course (Area A) in Widnes.
6.13 Bedrock
6.13.1 The near surface bedrock underlying the proposed route typically comprised very weak to
moderately weak red sandstone with evidence of weathering encountered at the interface
between the drift deposits and solid strata. The weathered rock was generally encountered
within the top 3m of bedrock, however, it was encountered to a maximum thickness of 15.9m
within BHRC30 to the south of the Manchester Ship Canal in Runcorn.
6.13.2 Mudstone was encountered underlying the glacial deposits to the south of the estuary at Lodge
Lane Junction in Area G and possible mudstone was identified at the M56 Junction 12 in Area
H.
6.13.3 The bedrock encountered during the investigation comprised the following:
a. Very weak to moderately weak thinly to thickly laminated fine and medium grained red
sandstone;
b. Weak to moderately weak, locally very weak, thinly laminated red brown interbedded
mudstone and sandstone;
c. Very weak to weak red brown fine to coarse grained sandstone;
d. Weak to moderately weak fine grained red brown sandstone;
e. Weak to moderately weak, thinly laminated red brown locally grey green mudstone;
f. Very weak to weak red brown locally grey green thinly interlaminated mudstone; and
siltstone.
g. Moderately strong thinly laminated red brown siltstone.
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6.14 Area Specific Ground Conditions
Introduction
6.14.1 For the purpose of assessing the ground conditions for the proposed route alignment, the area
has been sub-divided into specific areas which are related to the different structures that are
anticipated along the route. This section outlines the specific ground conditions and soil
parameters for the various strata encountered underlying the route within these areas.
Area A to B1 – St Michaels Golf Course Speke Road to Ditton Junction
6.14.2 This area was investigated during the Phase 4 and Phase 6 site investigations. St Michaels
Golf Course has been included as it forms part of Area A and could be used as a construction
compound during the construction works.
6.14.3 Made Ground was present from ground level to depths of between 3.3m and 11m bgl (+9.16m
to +2.4m AOD), with an average thickness of 6.2m. The full thickness was not proved at 11m
bgl in BH70. Surface materials comprised grass and topsoil over clay (understood to be
capping to the landfill) to between 0.4mbgl to 1.40m bgl. This clay capping layer was not
encountered in BH75, WS26 and WS27 (WS26 and WS27 have been deleted as they are no
longer within the Project area).
6.14.4 The majority of made ground underlying St Michael‟s Golf Course in Area A was described as
chemical waste, comprising soft to firm light blue grey and black mottled white sandy clay/silt
(possible galligu) or black mottled red clayey sand and/or gravel. The gravel was typically
sandstone, brick, coal, timber, ash, clinker, slag, concrete and glass, with organic material
comprising roots and rootlets. The ground conditions confirm the information on the site history;
the area was used as a tipping area for chemical waste prior to the golf course development.
6.14.5 Where the made ground was not identified as possible chemical waste, this material comprised
very soft to firm (occasionally stiff) green brown and grey sandy gravelly clay or loose grey
brown slightly sandy gravel. Gravel was described as comprising sandstone, coal and brick.
Very soft to soft grey slightly sandy slightly gravelly silt which was possibly Pulverised Fuel Ash
(PFA) was occasionally encountered within the main body of the made ground.
6.14.6 Alluvial deposits from 0.4m to 2.5m thick were encountered directly underlying the made ground
within six exploratory holes in this area. The alluvium comprised grey and black slightly sandy
slightly gravelly silt with occasional organic matter and medium dense grey brown silty sand.
6.14.7 In exploratory holes BH63, BH62, and BH76 (located alongside Speke Road and Ditton
Junction) the glacial deposits were encountered as grey black slightly sandy slightly gravelly
clay with a strong sulphur or hydrogen sulphide odour. The discolouration of the glacial
deposits directly underlying the made ground is considered to be due to the effects of staining
and leaching from the overlying chemical waste/galligu.
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Area B2 and I1 – Ditton Junction to Freight Line
6.14.8 This area was investigated during Phase 6 site investigation. The ground conditions comprised
made ground overlying alluvial and glacial deposits.
6.14.9 Made ground was encountered in all exploratory holes from ground level to between 1.6m and
4.9m bgl (+6.2m AOD and +2.8m AOD), with an average thickness of 3.2m.
6.14.10 The made ground was highly variable comprising the following:
a. loose to medium dense dark grey mottled black and brown very clayey very gravelly
sand;
b. very soft to soft white grey slightly gravelly silt (possible galligu);
c. very loose light grey silty sandy gravel (possible galligu);
d. soft to firm dark grey and black slightly gravelly clay (possible galligu);
e. blue white and black slightly sandy slightly gravelly clay (possible chemical waste);
f. red brown slightly clayey slightly gravelly medium; and
g. coarse sand or soft brown and black very sandy slightly gravelly clay.
6.14.11 The gravel content comprised sandstone, ash, brick, slag, concrete, slate and clinker.
6.14.12 Cohesive alluvial material was encountered underlying the made ground in a number of
exploratory holes (WS16A, WS22 and BH49) up to 2.6m thickness. This material comprised
grey mottled black slightly sandy slightly gravelly slightly organic clay and clayey sand. In BH49
alluvium comprising organic clay with occasional plant fibres and plastic pseudofibrous peat was
encountered between 2.5m and 4.5m bgl. The glacial deposits comprised interbedded firm, stiff
and very stiff slightly sandy slightly gravelly clay and medium dense to dense slightly silty
gravelly sand. The gravel constituents were described as mudstone, quartz and sandstone,
with occasional cobbles of sandstone. The base of the glacial deposits was not encountered at
a maximum depth of 26.2m bgl in BH54E. Archive boreholes show the base of the glacial
deposits was encountered at 41.2m bgl (approximately -33m AOD) within the Gussion
Transport site.
6.14.13 In eight exploratory holes located within the Gussion Transport site, the near surface glacial clay
was observed to be stained from the overlying made ground/chemical waste materials. This
was encountered as firm and stiff grey black slightly sandy slightly gravelly clay with strong
sulphur or hydrogen sulphide odour noted at between 0.2m and 3m thickness.
Area C – Freight Line to St Helens Canal
6.14.14 This area was investigated during the Phase 1, Phase 4a and Phase 6 site investigations. A
layer of made ground was encountered across the site directly from ground level to a level of
between 0.7m bgl to 5.7m bgl (+7.5m AOD and +1.9m AOD), with an average thickness of
3.16m.
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6.14.15 The majority of the made ground was essentially granular in nature (mainly encountered as a
fine to coarse gravel). The made ground material was variable and contained the following
constituents:
a. Very soft black slightly gravelly clay/silt;
b. Very loose to medium dense red brown and light grey to black mottled cream slightly silty
locally slightly clayey gravelly fine to coarse sand;
c. Very soft to soft brown slightly sandy slightly gravelly clay;
d. Very loose to medium dense yellow brown and black clayey sand and gravel (possible
chemical waste);
e. Very dense dark grey brown and black cobbles (possible galligu);
f. Soft to firm red brown and grey sandy slightly gravelly ashy clay;
g. Loose to medium dense red to dark brown and light grey to black slightly clayey sandy
silty ashy gravel; and
h. Brown and black ashy sand and gravel.
6.14.16 The gravel content within the made ground was described as sandstone, ash, brick, concrete,
concrete, limestone, wood, slate, clinker and metal with occasional cobbles.
6.14.17 Alluvium was generally encountered directly beneath the made ground, with glacial deposits
directly underlying the alluvial material. This is consistent with the BGS drift map (Ref. 32).
Material interpreted as alluvium was encountered in boreholes to depths of between 2.6m and
9.55m bgl (-0.22m AOD and -2.8m AOD) with an average thickness of 6.7m. This material
comprised very soft to firm grey brown slightly sandy clay with frequent organic content, which
was typically underlain by loose to medium dense slightly silty fine sand or loose to medium
dense grey mottled black slightly sandy silt. There were instances where granular material and
laminated clay were encountered at greater depths in Area C. However, from a review of the
descriptions and an assessment of the levels at which these materials were present, these have
been interpreted as glacial deposits (see paragraph 6.3.18 below).
6.14.18 Alluvium was also encountered in the western part of Area C underlying the made ground in
BH48, BH95, and BH96 and BH148 at between 0.6m 1.5m and 1.7m thickness.
6.14.19 The glacial deposits were encountered to levels of between +3.472.2m AOD and -21.8m AOD
(the full thickness not being proved). The base of the glacial deposits was encountered in BH43
in the north eastern corner of Area C at 48.9m bgl (-39.44m AOD). The glacial deposits
consisted of firm to very stiff (occasionally soft) red brown slightly sandy slightly gravelly clay
with interbedded medium to dense brown slightly silty or clayey slightly gravelly fine and
medium sand. Gravel constituents were described as angular to subangular fine and medium of
sandstone and coal. Some of the descriptions for these materials include laminated clays,
these have been interpreted as glacial deposits based on a review of the levels at which these
materials were encountered.
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Area D – Saltmarshes and Estuary
Widnes Warth Saltmarsh (chainage 2250 to 2900m)
6.14.20 The ground conditions comprise recent estuarine alluvium associated with the River Mersey.
The alluvium (comprising clays overlying sands) rests upon glacial deposits, which is in turn
underlain at depth by sandstone. Localised made ground was encountered in the north western
part of Widnes Warth.
6.14.21 The made ground is not representative of the surrounding natural strata, but indicates the likely
remnants of historic land use in a limited area adjacent to the St Helens Canal, where the
saltmarshes have been raised locally. The made ground was encountered to +5.3m AOD in
BH40.
6.14.22 The recent alluvium was proved in all the boreholes undertaken on the saltmarshes and was
encountered in boreholes to depths of between 8.1m and 13.3m bgl (-2.8m AOD and -7.8m
AOD), with an average thickness of 10.9m. The alluvial material comprised very soft to firm
grey brown slightly sandy organic clay underlain by loose to medium dense grey brown slightly
silty fine and medium sand.
6.14.23 Directly beneath the recent alluvium glacial deposits were encountered comprising firm to very
stiff brown thinly laminated slightly gravelly sandy clay with interbedded loose to medium dense
brown slightly gravelly silty medium and coarse sand and proved to level of between 3.7m and
29.9m bgl (-9.3m AOD and -32.7m AOD) generally increasing from south to north, away from
the estuary.
6.14.24 Bedrock was encountered in three boreholes directly underlying the glacial deposits and
comprised weak red thinly to thickly laminated fine and medium grained sandstone, proved to a
maximum level of between -16m AOD and -39.1m AOD. A 4.9m thick layer of weathered
sandstone was encountered in BH35 near the edge of the saltmarshes. The base of the
sandstone was not proved.
Runcorn Sands, Mersey Estuary
6.14.25 The ground conditions comprised recent estuarine alluvium associated with the River Mersey.
The alluvium (comprising silty slightly gravelly sand) was found to rest directly on the Sandstone
(bedrock was proved during the Phase 5 investigation within the route alignment). The
exploratory holes within the Estuary cover a wider area than other parts of the Project area due
to the potential mobility of the sediments.
6.14.26 Recent alluvium was recovered in all the boreholes undertaken in the estuary and was
encountered to levels of between -4.4m AOD and -8.4m AOD, with an average thickness of
9.3m. The alluvial material comprised very loose to dense dark grey slightly silty slightly gravelly
fine and medium sand. The gravel content was described as subangular and subrounded fine
and medium of sandstone with occasional shell fragments and organic fragments of wood, coal
and silt within the upper sand. Very loose dark grey and black sandy slightly gravelly silt was
encountered from ground level to 3m bgl within BH58. Rare pockets, up to 25 mm in size, of
black organic silt and layers of soft and very stiff red brown slightly sandy slightly gravelly clay
(possible glacial deposits) were also encountered within the main body of alluvial sand.
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6.14.27 Bedrock was encountered in all five boreholes undertaken within the estuary during the Phase 5
site investigation, directly underlying the alluvium. The bedrock was initially encountered as
highly and completely weathered material comprising weakly cemented very dense red brown
locally silty fine and medium sand. The weathered bedrock graded into competent bedrock
which comprised very weak to weak, occasionally moderately weak, red brown medium to
thickly bedded fine to coarse grained sandstone. Fracturing was predominately sub-horizontal
tight to open, rough and generally clean with occasional clay and sand infill. The depth to the
sandstone increased towards the northern channel within the estuary.
Astmoor Saltmarsh and Wigg Island
6.14.28 The ground conditions comprised made ground (where present) overlying recent alluvium,
which was underlain by glacial deposits. Bedrock was found to directly underlie the glacial
deposits at relatively shallow depths.
6.14.29 The made ground material was associated with the raised ground at the Wigg Island Landfill,
and was encountered to levels of +6.4m AOD and +5.3m AOD, with a thickness of between
0.5m and 8.3m.
6.14.30 The alluvial material was encountered in all the boreholes undertaken on the saltmarshes
(except BH20 and BH31) to depths of between 6.1m and 8.8m bgl (-0.7m AOD and -2.96m
AOD), with an average thickness of 7.6m. The alluvial material comprised very soft to soft grey
brown slightly sandy organic clay underlain by loose to medium dense grey brown slightly silty
fine and medium sand.
6.14.31 Glacial deposits were encountered in BH33 and BH34 as a stiff to very stiff brown locally
laminated slightly gravelly sandy clay to depths of between 8.6m and 9.5m bgl (-2.9m AOD and
-3.7m AOD), and a thickness of 1.3m to 1.6m. Glacial deposits were not present in BH15,
BH17 or BH32. Within BH20 and BH31, located in the south of Wigg Island (near to the
Manchester Ship Canal), glacial deposits were encountered directly underlying the made
ground to a level of +5.0m AOD and +3.2m AOD, with an average thickness of 7 metres. The
glacial deposits were encountered as stiff brown sandy slightly gravelly clay. Dense red clayey
fine sand was encountered at the base of the glacial deposits from +3.2m to +1.0m AOD within
BH20.
6.14.32 Bedrock was encountered in all boreholes, directly underlying the alluvium or glacial deposits
and was initially described as very weak red brown sandstone, recovered as red brown medium
and coarse sand. The sandstone was encountered as very weak to moderately weak thinly to
thickly laminated red sandstone at depth. The sandstone was proved between +0.8m AOD to
maximum of -27.2m AOD (BH34). In each of the boreholes the sandstone was initially
recovered as sand with a thickness of between 3.3m to 11.5m, indicating the top of the bedrock
is highly to completely weathered.
Area E to F – Astmoor Industrial Estate and Bridgewater Junction
6.14.33 This area was investigated during the Phase 1 and Phase 6 site investigations. The ground
conditions encountered comprised made ground overlying glacial deposits, which in turn was
underlain by sandstone bedrock.
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6.14.34 A layer of made ground was encountered from ground level to a level of between 0.4m to 5m
bgl (+35m AOD to +10.5m AOD), with an average thickness of 1.6m. The made ground material
comprised soft, firm and stiff red and orange brown sandy slightly gravelly clay, loose grey
brown slightly sandy clayey gravel, dense grey brown slightly sandy gravelly cobbles, loose red
silty fine and medium sand or dark brown sandy gravelly silt. Gravel content comprised
sandstone, coal, concrete, shale, mudstone, rare brick and occasional organic matter.
6.14.35 Directly underlying the made ground, were glacial deposits. The base of the glacial deposits
was between 2.3m and 16.5m bgl (+32.7m AOD and -5.9m AOD). The glacial deposits
comprised stiff and very stiff (occasionally firm) brown slightly sandy slightly gravelly clay
underlain by dense and very dense red clayey slightly gravelly sand with occasional bands of
stiff brown very sandy clay. The gravel content was described as sub-angular to sub-rounded
fine to coarse of sandstone and coal and occasional mudstone and limestone. A layer of thinly
laminated light brown silt was encountered within the glacial deposits in BH116.
6.14.36 The bedrock was encountered in all of the boreholes undertaken within the Astmoor area
(except BH27 and BH28) and comprised very weak to weak sandstone, which extended to -
27.9m AOD in BHRC30. A very weak red brown mudstone overlying a moderately strong thinly
laminated red brown siltstone was encountered in BH29 from +32.7m AOD to +29m AOD.
6.14.37 The upper surface of the bedrock was found to be highly weathered and recorded in the
boreholes as very dense orange brown slightly silty/clayey slightly gravelly fine and medium
sand. The intact bedrock was encountered as very weak to weak (locally moderately weak) red
brown, grey and green thinly laminated fine and medium grained sandstone.
Area G1 – Lodge Lane Junction
6.14.38 This area was investigated during the Phase 6 site investigation. The ground conditions
comprised glacial deposits overlying interbedded sandstone and mudstone. Made ground was
encountered in BH126 located close to the bridge abutment on the verge of the A5126 (possible
abutment backfill material).
6.14.39 Made ground was also encountered in BH124 and BH126 from ground level to 0.5m and 2m bgl
respectively, comprising road construction to 0.6m bgl and grey slightly gravelly silt. The gravel
was found to be fine and medium ash, brick and limestone.
6.14.40 Glacial deposits were encountered across this area from ground level to a depth of between
2.05m to 11.5m bgl (+62.8m AOD and +54.1m AOD). The glacial deposits comprised firm, stiff
and very stiff orange brown slightly sandy, slightly gravelly clay. The gravel comprised sub-
angular to sub-rounded fine to coarse sandstone, occasional mudstone and limestone. A 1.1m
thick layer of medium dense orange brown clayey slightly gravelly sand was encountered in
BH122 at 1.9m bgl.
6.14.41 Bedrock was encountered at the base of each of the six boreholes undertaken at the Lodge
Lane Junction and proved to a maximum depth of 26m bgl (+40.3m AOD) in BHRC123. The
bedrock was initially recovered as very stiff red brown slightly sandy gravelly clay; the gravel
was described as fine to coarse and comprising of sandstone and mudstone.
6.14.42 Where bedrock was recovered, the strata comprised very weak to moderately weak red brown
fine grained sandstone with frequent laminae of red brown mudstone or very weak to weak
thinly laminated grey green and purple brown mudstone/siltstone with very closely to medium
spaced subhorizontal discontinuities.
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Area G2 – Weston Link Junction
6.14.43 The ground conditions comprised made ground overlying glacial deposits, which in turn was
underlain by weathered sandstone.
6.14.44 Made ground was encountered in each of the boreholes from ground level to a depth of
between 1.7m and 2.3m bgl (+56.7m AOD and +51.7m AOD), with an average thickness of
2.4m. The made ground material was fairly consistent and comprised soft, firm and stiff brown
and black sandy gravelly clay or red brown and black clayey very gravelly sand. The gravel was
described as sandstone and mudstone with occasional cobbles of concrete.
6.14.45 Directly underlying the made ground were glacial deposits to a depth of between 4.55m and
10m bgl (+51.9m AOD to +45.8m AOD), although the base was not proven at 10m bgl in BH127
and BH128. The glacial deposits comprised firm to stiff (becoming very stiff at depth) red brown
slightly sandy slightly gravelly clay.
6.14.46 Weathered bedrock was encountered in three of the five boreholes undertaken within this area
directly underlying the glacial deposits. The rock was recovered as very dense red brown
slightly sandy gravel with occasional cobbles of sandstone.
Area H – M56, Junction 12
6.14.47 This area was investigated during the Phase 6 site investigation. The ground conditions
encountered within this area comprised made ground overlying glacial deposits, which in turn is
underlain by weathered mudstone.
6.14.48 Made ground was encountered in each of the boreholes from ground level to a depth of
between 0.3m and 3.7m bgl (+30.9mAOD and +21m AOD), with an average thickness of 1.8
metres. The made ground material comprised firm to stiff red dark brown and grey slightly sandy
slightly gravelly clay or very dense red brown clayey gravelly sand. The gravel sized
constituents were described as mudstone, coal, concrete, brick and clinker. Sand, gravel and
clay fill was encountered in BH134 and BH135A.
6.14.49 Directly underlying the made ground were glacial deposits to depths of between 7.9m and
10.5m bgl (+21.2m AOD to +16.4m AOD), with an average thickness of 7.8m. The glacial
deposits comprised interbedded firm to stiff (occasionally soft, becoming very stiff at depth) red
brown slightly sandy slightly gravelly clay and medium dense (occasionally loose) orange brown
clayey slightly gravelly sand. Gravel is subangular to sub-rounded fine to coarse of mixed
lithologies including sandstone and mudstone.
6.14.50 Material identified as possible mudstone bedrock was identified at 9.5m and 7.9m bgl in BH134
and BH135 respectively.
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6.15 Visual and Olfactory Evidence of Soil Contamination
6.15.1 Visual and olfactory evidence of possible contamination was noted from the following
exploratory hole logs located on or adjacent to the Project area:
Table 6.5 – Evidence of Possible Contamination Noted on Exploratory Hole Logs from the
Phase 1 Investigation
Exploratory
Hole
Depth (m
bgl)
Unit Description from Exploratory Hole Log
Widnes
BH07 0.0 – 1.5
8.5 – 10.5
Made ground
Alluvium
Hydrogen sulphide odour
Organic odour
BH09 11.2
17.0 – 17.6
Alluvium Hydrogen sulphide odour
Slight hydrocarbon odour
BH12 6.8 – 9.35
14.1 – 15 +
Alluvium
Glacial sand
Slight organic odour
Slight odour
BH13 1.65 – 2.6 Alluvium Slight organic odour
BH14 0.65 – 2.4
2.4 – 3.0
10.0 – 10.2
Alluvium Slight organic odour
Organic odour
Slight organic odour
TP10 3.0 – 3.5 + Made ground Hydrogen sulphide odour
TP11 1.4 – 2.5 Glacial clay Organic/hydrocarbon odour
TP13 2.0 – 2.5 + Made ground Hydrogen sulphide odour
TP15 0.9 – 2.1 Made ground Tar fragments and tar plugs
TP17 0.8 – 0.9
1.2 – 2.2
2.2 – 2.8
Made ground Diesel odour
Hydrogen sulphide odour
Slight hydrocarbon odour
TP20 1.2 – 2.2
2.4 – 3.0 +
Made ground Strong organic odour
TP1002 2.8 – 2.9 Made ground Diesel hydrocarbon contamination
Runcorn
BH18A 0.2 – 1.75 Made ground Strong sulphurous odour
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Table 6.6 - Evidence of Possible Contamination Noted on Exploratory Hole Logs from the
Phase 4 Investigation
Exploratory
Hole
Depth (m
bgl)
Unit Description from Exploratory Hole Log
Widnes
BH40 1.6 – 2.1 Alluvium Faint organic odour
BH41 3.8 – 5.6
5.6 – 6.2
6.5 – 10.7
Made ground
Alluvium
Alluvium
Moderate hydrocarbon/organic odour
Slight organic odour
Organic odour
BH49 0.3 – 2.5 Made ground Slight organic odour
BH52 4.0 – 6.0 Made ground Very strong sulphurous odour
BH53 0.2 – 6.1
6.4 – 8.5
Made ground
Glacial clay
Strong sulphurous odour
WS1 1.9 – 2.0 Made ground Slight soapy odour
WS2 1.35 – 2.0 Made ground Strong ammonia odour
WS3 0.75 - 0.9 Made ground Slight ammonia odour
WS4 0.5 – 1.0 Alluvium Slight organic odour
WS6 3.55 – 6.2 Alluvium Slight sulphurous odour
WS7 4.0 – 4.3
4.3 – 5.5
Alluvium Sulphurous and slight organic odour
Sulphurous odour
Runcorn
BH32 0.8 – 8.3
8.3 – 9.2
Made ground
Alluvium
Chemical odour
Strong chemical odour (ammonia)
Table 6.7 – Evidence of Possible Contamination Noted on Exploratory Hole Logs from the
Phase 4A Investigation
Exploratory
Hole
Depth (m
bgl)
Unit Description from Exploratory Hole Log
Widnes
BH42 3.3 – 4.2
4.2 – 6.0
Made ground
Alluvium
Locally strong organic odour
Strong organic odour
BH56 6.5 – 9.5
9.5 – 9.9
Alluvium Strong „solvent‟ odour
Very strong solvent odour
WS10A 3.0 – 3.85
3.85 – 7.0
Made ground
Alluvium
Slight hydrocarbon odour
Slight organic odour
WS11 4.8 – 5.0 + Alluvium Moderate solvent odour
WS11A 4.5 – 7.65 Alluvium Strong solvent odour
WS12 3.1 – 5.0
5.0 – 6.5
Alluvium Strong solvent odour
Moderate solvent odour
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Table 6.8 – Evidence of Possible Contamination Noted on Exploratory Hole Logs from the
Phase 6 Investigation (continued overleaf)
Exploratory
Hole
Depth (m
bgl)
Unit Description from Exploratory Hole Log
Widnes
WS26 1.0 – 1.2
3.4 – 3.6
Made ground
Alluvium
Slight hydrocarbon odour
Moderate hydrogen sulphide odour
WS27 4.5 – 5.9+ Alluvium/glacial
clay
Strong hydrogen sulphide odour
BH73 2.6 – 4.0 Made ground Slight odour
BH63 1.3 – 3.0 Made ground Plastic odour
BH63 3.0 – 10.0 Made ground/
Glacial clay
Sulphur odour, becoming very strong sulphur
and hydrogen sulphide odour
BH62 2.8 – 6.1 Made ground/
alluvium
Slight to moderate hydrogen sulphide and
sulphur odour
BH75 2.2 – 2.65 Made ground Possible asbestos lagging
BH76 1.1 – 1.8
5.3 – 6.8
Made ground
Glacial clay?
Slight solvent odour
Strong hydrogen sulphide odour
BH61 0.7 – 7.5 Made ground Slight odour and possible odour of sulphur
BH77 3.8 – 6.2 Made ground/
Glacial clay
Strong hydrogen sulphide odour
BH78 5.0 – 8.5 Made ground/
Glacial clay
Strong and slight odour
BH80 0.4 – 6.0 Made ground/
Glacial clay
Slight to strong hydrogen sulphide odour
BH51 0.5 – 4.9 Made ground Very strong hydrocarbon odour
BH54D 3.0 – 3.4 Made ground Black liquor staining
BH54E 1.3 – 2.7
4.0 – 5.6
Made ground
Glacial clay
Sulphur odour
Strong sulphur odour
BH58 0.3 – 1.0
1.0 – 3.0
4.5 – 6.0
Made ground
Made ground
Glacial clay
Sulphur and diesel odours
Sulphur odour
Strong sulphur odour
BH60 3.0 – 3.45 Made ground Strong odour
WS16A 2.8 – 3.55
3.55 – 4.4
Possible glacial
clay
Strong hydrogen sulphide odour
Slight odour
WS17 0.7 – 3.0 Made ground Strong odour
WS18 1.5 – 1.85
1.85 – 2.55
Made ground
Glacial clay
Moderate hydrocarbon & sulphur odour
Moderate to strong sulphur odour
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Table 6.8 (continued) – Evidence of Possible Contamination Noted on Exploratory Hole Logs
from the Phase 6 Investigation
Exploratory
Hole
Depth (m
bgl)
Unit Description from Exploratory Hole Log
WS22 2.0 – 2.8
3.2 – 3.5
Made ground
Alluvium
Slight chemical odour
Strong sulphur odour
WS23 1.6 – 1.8 Glacial clay Slight hydrocarbon odour
WS24 3.2 – 4.0 Glacial clay Moderate hydrogen sulphide odour
WS24 1.2 – 4.0 + Made ground /
Glacial clay
Moderate to strong hydrogen sulphide odour
BH65C 2.0 – 9.8 Made ground/
alluvium
Slight to moderate solvent odour
BH101 1.1 Made ground Strong organic odour
BH103 2.5 – 5.4
6.6 – 8.0
Made ground
Alluvium
Strong hydrocarbon odour
Slight odour
BH104 3.0 – 10.0 Alluvium Organic odour
BH108 3.0 – 5.5 Alluvium Slight solvent odour
WS29 1.9 – 1.95
2.8 – 3.1
3.1 – 4.0
4.7 – 7.0 +
Made ground
Made ground
Alluvium
Alluvium
High viscosity paint like substance
Strong hydrocarbon odour
Slight chemical odour
Strong organic odour
WS31 3.1 – 4.6 Alluvium Moderate organic odour
WS35 3.5 – 3.8 Alluvium Strong organic odour
WS38 2.5 – 3.4
3.4 – 3.8
3.8 – 6.2
Made ground
Made ground
Alluvium
Ammonia odour
Strong ammonia odour
Strong ammonia odour
WS40 6.8 – 7.0 + Alluvium Strong organic odour
WS41 3.6 – 6.6
6.6 – 7.0 +
Alluvium Slight organic odour
Strong organic odour
WS42 2.5 – 5.5 Made ground/
Alluvium
Strong hydrocarbon odour
WS43 3.2 – 3.6 Alluvium Moderate hydrogen sulphide odour
WS46A 1.8 – 2.0
3.5 – 3.8
Made ground
Strong ammonia odour
Strong tar odour
BH66B 4.1 – 4.9
4.9 – 6.0
6.0 – 11.5
Made ground
Alluvium
Alluvium
Moderately strong sulphurous odour
Moderately strong odour
Slight odour
BH71 4.2 – 5.2
5.2 – 5.9
5.9 – 6.1
6.1 – 10.3
10.3 -11.3
Made ground
Alluvium
Strong chemical odour
Oily sheen and strong chemical odour
Strong chemical odour
Mild chemical odour
Slight organic odour
Runcorn
BH84 0.5 Glacial Clay Slight oily sheen and slight hydrocarbon
odour
BH114 1.60 – 1.70 Made Ground Possible asbestos
BH125 2.00 - 2.50 Glacial Clay Possible asbestos
BHRC140 4.30 – 5.40 Made Ground Strong tarmac odour (tarmac noted in
sample)
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6.16 Radiological Screening
6.16.1 Readings (as counts per second) exceeding twice background were encountered from the
radiological screening in made ground at two locations during the Phase 4A and Phase 6
investigations at Cataylst Trade Park; in the made ground in WS10 (Phase 4A) and in grey ashy
material located immediately beneath a limestone gravelled area approximately 10m northwest
of BH105 (Phase 6). The area near BH105 was identified whilst determining the background
levels of radiation prior to commencing the screening of soil arisings. Elevated „counts‟ were not
encountered in BH105 itself.
6.16.2 The exploratory hole log for WS10 records that readings of 2.5 background level were recorded
in the hand dug inspection pit in arisings up to 1m bgl. The arisings between 0.6m and 1.0m bgl
were described as very sandy fine to coarse gravels of brick with very frequent similar cobbles.
Groundwater Conditions
6.16.3 This section is based on the information obtained on the groundwater strikes, soil permeability,
evidence of possible groundwater contamination during field work, groundwater flow direction
and interactions with surface water within the Mersey Gateway Project area.
6.17 Field Evidence of Groundwater Strikes
6.17.1 Groundwater strikes were encountered during drilling in the made ground, drift deposits and
bedrock in the following exploratory holes:
Table 6.9 – Groundwater Strikes within the Alluvium
BH07 BH09 BH1003 BH10B
BH12 BH13 BH14 BH34
BH38 BH39 BH40 BH55
BH64 BH102 BH103 BH104
BH108 WS30 WS36 BH151
Table 6.10 – Groundwater Strikes within the Glacial Deposits
BH145 BH01* BH27 BH28
BH31 BH43 BH48 BH53
BH54E BH63 BH67A BH68
BH78 BH82 BH113 BH120
BH122 BH132 BH04 BH1005
BH12 BH18A BH22 BH24
BH38 BH40 BH41 BH43
BH48 BH49 BH52 BH53
BH42 BH44 BH45 BH46
BH47 BHRC137 BH54E BH65C
BH66B BH71 BH77 BH80
BH84 BH95 BH99 BH100A
BH101 BH102 BH104 BH105A
BH107 BH113 BH134 BH139
BH147 * Exploratory holes located outside of the project area
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Table 6.11 - Groundwater Strikes within the Made Ground
BH09 BH1001 BH52 BH53
BH54E BH63 BH67A BH72
BH88 BH93 BH99 BH101
WS17 BH10B BH40 BH41
BH48 BH49 BH50 BH53
BH42 BH45 WS12 WS14
BH51 BH61 BH65C BH66B
BH67 BH69 BH70 BH76
BH79 BH86 BH87B BH95
BH97 BH98 BH100A BH102
BH105A BH108 BH143 WS24
WS26* WS27* WS28 WS33
WS36 WS37B WS39C WS39B
WS40 WS42 WS43 WS46A
BH78 BH147 BH148 BH149
BH150 WS52 * Exploratory holes located outside of the project area
Table 6.12 - Groundwater Strikes within the Bedrock
BH01* BHRC118
* Exploratory holes located outside of the project area
6.17.2 Groundwater strikes were noted in the made ground during drilling in 19 exploratory holes.
There were limited groundwater strikes within the glacial clay deposits. The majority of
recorded water strikes were encountered within the granular horizons in the glacial till and
granular alluvial deposits. Therefore, in terms of shallow groundwater, the route is considered
to be underlain by water tables in both the made ground and granular drift deposits.
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 167 Report No. MG_REP_EIA_009
November 2011 Rev B
6.18 Field Evidence of Groundwater Contamination
Round 1 to 10 Groundwater Monitoring
6.18.1 Visual and olfactory evidence of possible groundwater contamination was noted at the following
locations during groundwater monitoring, these are shown in Table 6.13:
Table 6.13 - Field Observations of Possible Groundwater Contamination from Rounds 1 to 10 of
Groundwater Monitoring
Exploratory
Hole
Unit Description
Widnes
BH7 Alluvium (Sand) Black fluid noted at base of well during Round 2 only, but
was not identified during Round 3. Damage to the well
prevented further monitoring.
BH9 Glacial Sand 0.01m of LNAPL detected during Round 6 only but not
during any other round.
BH10b Alluvium (Sand) 0.02m LNAPL detected during Round 6 only but not during
any other round.
BH13 Alluvium (Sand) 0.25m LNAPL detected during Round 2 only but not during
any other round.
BH14 Sandstone 0.4m LNAPL detected during Round 2 only but not during
any other round.
BH41 Alluvium (Sand) Hydrocarbon odours noted from purged groundwater
during Rounds 7 & 8.
BH1001 Made Ground 0.02m LNAPL detected during Round 6 only but not during
any other round.
Runcorn
BH17 Alluvium (Sand) 0.32m LNAPL detected during Round 2 only but not during
any other round.
6.18.2 The observations of LNAPL recorded at BH13 and BH14 during Round 2 are likely to be
erroneous as these wells are located on Widnes Warth saltmarsh in Area D and no evidence of
free product was noted during other rounds. The monitoring wells installed in BH7, BH9,
BH10b, and BH1001 are located on the former ICI Muspratt and Thermphos sites. The
exploratory holes on Muspratt site have been considered as these are upgradient of Widnes
Warth saltmarsh in Area D.
6.18.3 BH17 is located on Astmoor Saltmarsh in Area D although it is close to the Wigg Island Landfill.
The assessment for LNAPL was undertaken using an interface meter, LNAPL was not detected
in this well during any other monitoring rounds.
6.18.4 LNAPL was only identified in each of the monitoring wells outlined in Table 6.13 on one
occasion and not during any other rounds of monitoring. On this basis, these results are not
considered to be representative and it is unlikely that LNAPL is present within these wells.
Field Observations of Groundwater Contamination during Phase 6 Site Investigation
6.18.5 Visual and olfactory evidence of possible groundwater contamination was reported at the
following locations during groundwater monitoring undertaken during the Phase 6 site
investigation (during which additional wells were installed to further delineate the occurrence of
free-phase product and contamination of soils and groundwater). An interface meter was used
to assess the possible presence of free product, results are reported in Table 6.14:
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 168 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 6.14 – Field Observations of Possible Groundwater Contamination from Monitoring for
the Phase 6 Investigation in 2007 (continued overleaf)
Exploratory
Hole
Unit Description
Widnes
BH51 Glacial sand 0.84m free product (LNAPL), pale green colour,
strong sulphur odour.
BH53A Made ground Strong sulphur odour.
BH54E Glacial sand Pale green colour, strong sulphur odour, 0.05m free
product (LNAPL).
BH58 Made Ground 0.09m free product (LNAPL). Sulpher and diesel
odours.
BH59 Made ground Slight sulphur odour. 0.05m free product (LNAPL).
BH60 Made ground Strong sulphur odour. 0.06m free product (LNAPL).
BH61 Made Ground 0.02m free product (LNAPL). Slight odour. Possible
odour of sulphur.
BH62 Made ground/
Alluvium
Very strong sulphur odour.
BH63 Glacial clay Very strong sulphur odour. 0.05m free product
(LNAPL).
BH64 Glacial sand Slight sulphur odour.
BH67A Made Ground 0.04m free product (LNAPL). No PID, visual or
olfactory evidence.
BH69 Made ground 0.01m free product (LNAPL).
BH70 Made ground 0.04m free product (LNAPL).
BH72 Made Ground 0.04m free product (LNAPL). No PID, visual or
olfactory evidence.
BH73 Made Ground 0.05m free product (LNAPL). Slight odour noted (no
description). No PID or visual evidence.
BH74 Made ground Sulphur odour.
BH76 Made Ground 0.04m free product (LNAPL). Slight solvent odour.
No PID or visual evidence.
BH78 Made ground Sulphur odour. 0.01m free product (LNAPL).
BH82 Glacial clay Slight sulphur odour. 0.07m free product (LNAPL).
BH93 Made ground Free product, sulphur odour.
BH97A Made ground Black water. 0.05m free product (LNAPL).
BH99 Glacial Sand 0.05m free product (LNAPL). No PID or olfactory
evidence.
BH103 Alluvium 0.05m free product (LNAPL).
BH106 Glacial Sand 0.05m free product (LNAPL).
BH107 Alluvium 0.04m free product (LNAPL).
BH108 Alluvium Slight solvent odour.
BH119 Glacial Sand 1.21m free product (LNAPL). No PID, visual or
olfactory evidence.
WS16A Possible glacial
clay/made ground
0.44m free product (LNAPL), blackish green colour,
sulphur odour.
WS17 Made ground 0.36m free product (LNAPL), slight petrochemical
odour, strong „sick/rotten apple odour‟, warm gas
tap
WS18 Made Ground Moderate hydrocarbon odour and sulphur odour
noted. 0.42m free product (LNAPL). No PID
evidence.
WS20 Made ground Dark green, sulphur odour. 0.04m free product
(LNAPL).
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 169 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 6.14 (continued) - Field Observations of Possible Groundwater Contamination from
Monitoring for the Phase 6 Investigation in 2007
Exploratory
Hole
Unit Description
Widnes
WS22 Alluvium Slight chemical odour. Strong sulphur odour. 0.01m
free product (LNAPL).
WS23 Made ground/ Glacial
clay
Slight sulphur odour. 0.06m free product (LNAPL).
WS24 Made ground Slight sulphur odour. 0.14m free product (LNAPL).
WS25 Made ground Slight sulphur odour. 0.05m free product (LNAPL).
WS26 Made ground Free product and strong sulphur odour. 0.04m free
product (LNAPL).
WS27 Made ground Free product, slight sulphur odour.
WS28 Made ground Grey water with sulphur odour. 0.05m free product
(LNAPL).
WS29 Made ground 0.06m free product (LNAPL).
WS30 Alluvium Strong solvent odour. 0.01m free product (LNAPL).
WS31 Alluvium Strong solvent odour. 0.05m free product (LNAPL).
WS32 Alluvium 0.05m of free product (LNAPL).
WS33 Glacial clay 0.04m free product (LNAPL).
WS36 Glacial clay 0.01m free product (LNAPL). No PID, visual or
olfactory evidence.
WS37B Made Ground 0.05m free product (LNAPL). No PID, visual or
olfactory evidence.
WS38 Glacial Sand Strong ammonia odour. 0.05m free product
(LNAPL).
WS40 Made Ground 0.04m free product (LNAPL).
WS43 Made Ground Moderate hydrogen sulphide odour. 0.05m free
product (LNAPL).
WS44 Made ground 0.01m free product (LNAPL).
WS46A Made Ground Strong tar odour. 0.05m free product (LNAPL).
Runcorn
BH84
(piezometer)
Possible weathered
sandstone
0.01m free product (LNAPL). Slight oily sheen and
slight hydrocarbon odour noted in made ground.
BHRC123 Sandstone 0.01m free product (LNAPL). No PID, visual or
olfactory evidence.
BHRC124 Sandstone 0.01m free product (LNAPL). No PID, visual or
olfactory evidence.
6.18.6 The results outlined in Table 6.14 indicated that floating free product was more extensive within
the Project area than the previous phases of investigation or monitoring has suggested.
Therefore, in order to confirm the Phase 6 investigation results, additional groundwater
monitoring was undertaken by Gifford during November 2007 and January 2008 using an
interface meter and recovering water samples in dedicated bailers. The results of this additional
monitoring are listed in Table 6.15, and with the exception of the following, evidence for free
phase contamination was not identified:
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Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 170 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 6.15 – Field Observations of Possible Groundwater Contamination from Monitoring
during November 2007 and January 2008
Exploratory
Hole
Unit Description
Widnes
BH51 Glacial sand No evidence of DNAPL using IM. Sheen (possible
evidence of LNAPL) seen on surface of water.
BH54E Glacial sand Unable to access.
BH58 Made Ground 0.002m of LNAPL detected using IM, 0.004m
observed in bailer.
BH60 Made ground Monitoring well damaged. Unable to monitor.
BH63 Glacial clay No evidence of LNAPL or DNAPL, but water did
have a greenish tinge and an odour of sulphide.
BH76 Made Ground No evidence of LNAPL or DNAPL, although a
dense layer of orange „spongey‟ precipitate noted.
BH78 Made ground No evidence of LNAPL or DNAPL, although
groundwater had a grey colour and a sulphide
odour was noted.
WS17 Made Ground Evidence of LNAPL
WS20 Made Gound Evidence of LNAPL
WS33 Glacial clay No evidence of LNAPL or DNAPL, although a slight
solvent smell was noted.
WS36 Glacial clay No evidence of LNAPL or DNAPL, although a
solvent smell was noted.
WS37B Made Ground Monitoring well damaged. Unable to monitor.
WS38 Glacial Sand No evidence of LNAPL or DNAPL, although
groundwater had a dark brown colour and a solvent
odour.
WS40 Made Ground No evidence of LNAPL or DNAPL, although a
solvent smell was noted.
Runcorn
BH84
(piezometer)
Possible weathered
sandstone
Unable to check using IM or bailer as installed as a
piezometer.
BH119 Glacial Sand 0.001m LNAPL detected using IM but no evidence
observed in bailer.
IM = Interface Meter
6.18.7 The results obtained from the additional monitoring by Gifford in November 2007 and January
2008 indicates that LNAPL was only present in BH51, BH58, WS17 and WS20 in the Project
area and it was not as widespread as had been reported during the Phase 6 site investigation.
The location of these monitoring wells is shown in Drawing Number MG_REP_EIA_009/074.
These monitoring wells are all located within the Gussion Transport site in Area B2. However, a
number of the monitoring wells were not accessible and the presence of LNAPL could not be
confirmed at these locations.
6.18.8 No physical evidence of DNAPL was recovered from any of the monitoring wells.
6.18.9 Visual and olfactory evidence of possible groundwater contamination was reported at the
following location during groundwater monitoring undertaken as part of the Phase 7 site
investigation.
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 171 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 6.46 – Field Observations of Possible Groundwater Contamination from Monitoring for the
Phase 7 Investigation in 2010
Exploratory
Hole
Unit Description
BH151 Alluvium Solvent odour 2.2m to 5.6m
Strong solvent odour 5.6m to 9.8m
6.18.1 Field evidence of possible groundwater contamination was reported at the following locations
during the Round 13 groundwater monitoring.
Table 6.47 – Field Observations of Possible Groundwater Contamination from Monitoring during
Round 13 in August 2010
Exploratory
Hole
Unit Description
Widnes
BH55 Alluvium Water brown-orange colour
BH58 Made Ground Black hydrocarbon present
BH108 Alluvium Sulphur odour
HBCBH1 Glacial sand Water orange colour (no odour)
WS11A Alluvium Strong decaying odour
6.18.1 Field evidence of possible groundwater contamination was reported at the following locations
during the Round 14 groundwater monitoring.
Table 6.48 – Field Observations of Possible Groundwater Contamination from Monitoring during
Round 14 in October 2011
Exploratory
Hole
Unit Description
Widnes
BH52 Made Ground Strong chemical odour
BH150 Alluvium Strong chemical odour
6.19 Groundwater Levels
6.19.1 The principal controls upon groundwater levels within the Mersey Estuary area are considered
to be as follows:
a. Geological strata
b. Groundwater abstraction by pumping
c. Tidal influences
d. Infiltration and surface drainage
6.19.2 The geological units present, and the anticipated hydrogeological properties of these horizons,
are discussed in Section 5.6. However, in the study area surveys have shown that both the tide
and the legacy of groundwater abstraction (both historic and current) affect the groundwater
flow regime.
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 172 Report No. MG_REP_EIA_009
November 2011 Rev B
6.19.3 Groundwater level monitoring data shows a clear trend of rising groundwater levels in the
Sherwood Sandstone aquifer in the Widnes area, although to on the south side of the estuary
no significant change is apparent. This trend is shown in Figure 6.1. The restriction of the
increase in height of the water table to the north of the estuary only and similar rate of change of
groundwater levels in this area provides evidence that groundwater is reacting to an influence
interpreted as recovering from drawdown induced by historical pumping activities. Additional
information obtained for the bedrock since the Orders ES has not altered this assessment and
has been included in Figure 6.1 and 6.2 below.
Figure 6.1 Variation in Groundwater Levels over Time for the Sherwood Sandstone in Widnes
(Updated)
Figure 6.2 Variation in Groundwater Levels over Time for the Sherwood Sandstone in Runcorn
(Updated)
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
5.00
01
/09
/20
02
14
/01
/20
04
28
/05
/20
05
10
/10
/20
06
22
/02
/20
08
06
/07
/20
09
18
/11
/20
10
Gro
undw
ate
r E
levation (
mA
OD
)
Date
Sandstone North of Mersey
BH01
BH1004 BH1005 BH14
BH35
-4.00
-2.00
0.00
2.00
4.00
6.00
8.00
05
/09
/20
02
18
/01
/20
04
01
/06
/20
05
14
/10
/20
06
26
/02
/20
08
10
/07
/20
09
22
/11
/20
10
Gro
undw
ate
r E
levation (
mA
OD
)
Date
Sandstone South of Mersey
BH15
BH22
BH24
BH25
BH31
BH32
BH34
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Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 173 Report No. MG_REP_EIA_009
November 2011 Rev B
6.19.4 Similar trends of rising groundwater levels were not observed in monitoring wells installed into
the shallow groundwater horizons. This is show in Figures 6.3 to 6.5.
Figure 6.3 – Variation in Groundwater Level over Time for the Glacial Deposits
(solid lines relate to monitoring wells located north of the Estuary and broken lines to the
south of the Estuary)
Figure 6.4 – Variation in Groundwater Level over Time for Estuarine the Alluvium
(solid lines relate to monitoring wells located north of the Estuary and broken lines to the
south of the Estuary) (Updated)
GLACIAL DEPOSITS
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
20.00
01/0
9/2
002
31/1
0/2
002
30/1
2/2
002
28/0
2/2
003
29/0
4/2
003
28/0
6/2
003
27/0
8/2
003
26/1
0/2
003
25/1
2/2
003
23/0
2/2
004
23/0
4/2
004
22/0
6/2
004
21/0
8/2
004
20/1
0/2
004
19/1
2/2
004
17/0
2/2
005
18/0
4/2
005
17/0
6/2
005
16/0
8/2
005
15/1
0/2
005
14/1
2/2
005
12/0
2/2
006
13/0
4/2
006
12/0
6/2
006
11/0
8/2
006
10/1
0/2
006
09/1
2/2
006
07/0
2/2
007
08/0
4/2
007
07/0
6/2
007
06/0
8/2
007
Date
Gro
un
dw
ate
r E
lev
ati
on
mA
OD
BH09
BH1009
BH17
BH27
BH28
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
01
/09
/20
02
14
/01
/20
04
28
/05
/20
05
10
/10
/20
06
22
/02
/20
08
06
/07
/20
09
18
/11
/20
10
Gro
undw
ate
r E
levation (
mA
OD
)
Date
ESTUARINE ALLUVIUM
BH07
BH1003
BH10B
BH12
BH13
WS2
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Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 174 Report No. MG_REP_EIA_009
November 2011 Rev B
Figure 6.5 – Variation in Groundwater Level over Time for the Made Ground
(solid lines relate to monitoring wells located north of the Estuary and broken lines to the
south of the Estuary)
6.19.5 The results obtained from the monitoring wells where the datalogger was installed (on and close
to the saltmarshes in Widnes and Runcorn) indicate that in the majority of wells, groundwater
levels in the Sherwood Sandstone and superficial drift horizons were found to fluctuate with the
tide. This indicates groundwater in these horizons is in hydraulic continuity with the estuary.
6.19.6 No such fluctuations were observed in wells installed into the glacial deposits. This indicates
that tidal influence does not affect all geological units and separate groundwater bodies may be
present in the shallow deposits and the bedrock (at least in the areas reviewed).
6.19.7 The information obtained also indicates that tidal influence varies with increasing distance from
the estuary; this is shown in Figure 6.6. At BH35, which is located on Widnes Warth in Area D
7m from the Mersey Estuary, the tidal influence is less than would be expected from the
Sherwood Sandstone, particular when considering the other results obtained. This variation
could have arisen from local variations in permeability. The datalogger monitoring indicates that
tidal influence was negligible to the north of Widnes Warth in Area C.
MADE GROUND
0.00
2.00
4.00
6.00
8.00
10.00
12.003
1/0
8/2
00
2
21
/11
/20
02
12
/02
/20
03
05
/05
/20
03
27
/07
/20
03
17
/10
/20
03
08
/01
/20
04
30
/03
/20
04
20
/06
/20
04
11
/09
/20
04
02
/12
/20
04
23
/02
/20
05
16
/05
/20
05
06
/08
/20
05
28
/10
/20
05
18
/01
/20
06
11
/04
/20
06
02
/07
/20
06
23
/09
/20
06
14
/12
/20
06
06
/03
/20
07
28
/05
/20
07
18
/08
/20
07
Date
Gro
un
dw
ate
r E
lev
ati
on
mA
OD
BH02A
BH06
BH1001
BH52
WS15
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Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 175 Report No. MG_REP_EIA_009
November 2011 Rev B
Figure 6.6 – Tidal Influence with Distance from the Estuary in Widnes
6.19.8 During development of the monitoring wells, groundwater was encountered at all locations
except BH18A and BH29 which were noted to be dry.
6.19.9 Where groundwater was encountered during the monitoring visits, it ranged from 0.4m bgl (in
WS21 at the Catalyst Trade Park) to 10.4m bgl (in BH32 on the Wigg Island Landfill), with an
average depth to groundwater of 4m bgl. BH18A and BH29 were noted as being dry during all
monitoring visits.
6.19.10 The groundwater levels obtained from BH65C and BH106, which were both installed into the
upper glacial sand layer in Area C, are different to the levels for the alluvium. This indicates that
in this area at least, these horizons are unlikely to be directly connected.
6.19.11 Groundwater head levels are higher within the shallow horizons than the major aquifer in the
Sherwood Sandstone. Therefore, it is anticipated that groundwater would flow from the
shallower groundwater horizons towards the deeper aquifer if a pathway were to be present.
However, it is possible that this trend would change in the future as water levels within the
bedrock continue to rise, particularly in Widnes.
Review of Groundwater Levels by Area
6.19.12 A review of the groundwater levels encountered during monitoring visits by Project area is
outlined below.
Groundwater Level Change Associated with Tide Range v.
Distance from Estuary
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 50 100 150 200 250 300 350 400 450 500
Distance from Mersey Estuary Mean High Water Mark(m)
Gro
un
dw
ate
r le
ve
l ti
da
l ra
nte
at
ma
xim
um
hig
h t
ide
illu
str
ate
d b
y r
esu
lts
fro
m s
ele
cte
d m
on
ito
rin
g p
oin
ts
Estuarine Alluvium
Sherwood Sandstone
BH35
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Contamination of Soils, Sediments and Groundwater
Technical Annex
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November 2011 Rev B
Areas A & B1 – Groundwater
6.19.13 Monitoring wells were installed into the made ground, alluvium and shallow glacial deposits in
this area. Water levels monitored during Round 10 and during the Phase 6 site investigation
were found to be between 6.39m and 11.17m AOD within made ground, between 7.71m and
8.57m AOD in alluvium, and between 6.27m and 9.40m AOD within the glacial deposits. During
Round 11 to 13, water levels were found to be between 6.67m and 8.26m AOD within made
ground, between 7.82m and 8.62m AOD in alluvium, and between 7.82m and 10.15m AOD
within the glacial deposits.
Areas B2 & I1 – Groundwater
6.19.14 Monitoring wells were installed into the made ground, alluvium (WS22 only) and shallow glacial
deposits in this area. Water levels monitored during the Phase 6 site investigation were found
to be between 6.08m and 7.11m AOD within made ground, at 6.42m AOD in alluvium (WS22),
and between 2.91m and 6.17m AOD within the glacial deposits. During Round 11 to 13, water
levels were found to be between 6.07m and 7.30m AOD within made ground, between 3.00m
and 3.07m AOD in alluvium (BH51), and between 3.04m and 6.41m AOD within the glacial
deposits.
Area C – Groundwater
6.19.15 Monitoring wells were installed into the made ground, alluvium and shallow glacial deposits in
this area. Water levels monitored during Round 10 and during the Phase 6 site investigation
were found between 5.18m and 6.89m AOD within made ground, between 3.85 and 6.27m
AOD in alluvium, between 2.50m and 6.93m AOD within the glacial deposits, and at 1.70m AOD
in the sandstone bedrock at BH43 in the north-eastern corner of Area C. During Round 11 to
13, water levels were found to be between 5.10m and 6.85m AOD within made ground,
between 4.01m and 6.45m AOD in alluvium, and between 2.55m and 6.88m AOD within the
glacial deposits.
Area D – Groundwater
6.19.16 Monitoring wells in this area were installed into the alluvium, glacial sand and bedrock on the
saltmarshes. Four monitoring wells were installed at the north eastern end of the Wigg Island
Landfill. Two of these wells were installed in boreholes commenced from the top of the landfill,
one of these wells was installed into the made ground and the other into bedrock. The
remaining two wells were placed in boreholes commenced from the lower slope of the landfill,
and these were installed into the alluvium. Water levels monitored during Round 10 were found
to be between 1.75m and 4.74m AOD in alluvium, 3.08m AOD within the glacial deposits, and
between 1.73m and 3.67m AOD in the sandstone bedrock.
6.19.17 The monitoring well installed into the made ground in the Wigg Island Landfill has been dry
during every monitoring and sampling round, although other investigations have encountered
groundwater within this material in the landfill. Only BH32 and BH55 in Area D were monitored
during Round 11 to 13. BH32 is installed into the sandstone aquifer and groundwater levels
were found to be similar to previous monitoring rounds (between 3.60m and 3.89m AOD).
BH55 is installed into the alluvium on the Widnes side of the estuary, and water levels were
found to vary between 4.66m and 5.06m AOD during Round 11 to 13.
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Contamination of Soils, Sediments and Groundwater
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Areas E & F – Groundwater
6.19.18 Monitoring wells were installed into the glacial deposits and sandstone bedrock. Water levels
monitored during Round 10 and during the Phase 6 site investigation were found at 21.24m
AOD within made ground at BH116, at 25.00m AOD in alluvium at BH120, at 23.50m AOD
within the glacial deposits at BH119, and between 3.24m and 6.75m AOD in the sandstone
bedrock. Three monitoring wells in Area F were monitored during Round 11 and 12, these were
BH116, BH119 and BH120 in the made ground, glacial deposits and alluvium respectively.
Water levels were found to be between 21.72m and 22.00m AOD at BH116 in the made
ground, between 24.98m and 25.29m AOD at BH120 in the alluvium, and between 23.44m and
23.98m AOD at BH119 in the glacial deposits.
Area G – Groundwater
6.19.19 Monitoring wells were installed into the made ground, glacial deposits and sandstone bedrock.
Water levels monitored during the Phase 6 site investigation were found to be 55.60m AOD
within the glacial deposits at BH122, and between 53.27m and 56.16m AOD in the sandstone
bedrock. The wells installed in made ground and three of the wells installed in glacial deposits
were found to be dry.
Area H – Groundwater
6.19.20 Monitoring wells were installed into the glacial deposits in this area. These wells were found to
be dry during monitoring works undertaken as part of the Phase 6 site investigation.
6.20 Groundwater Flow Direction
6.20.1 Determination of groundwater flow direction within the Sherwood Sandstone aquifer and shallow
drift aquifer is complicated by the influences of geologically controlled pathways (e.g. fault zones
and connectivity between permeable lithological units), recovery from historic groundwater
pumping, current groundwater abstraction and the tidal regime.
6.20.2 Groundwater level monitoring undertaken as part of the site works has been used to interpret
groundwater flow directions within the Mersey Gateway Project area. The monitoring results
are included in Appendix N. In order to correct for tidal effects, data was averaged from the
most recent annual period of monitoring.
6.20.3 In order to assess the flow directions, the following conditions were used:
a. A mean average of groundwater level was used in the derivation of predicted
groundwater flow direction
b. Data was averaged from a recent one year time period between December 2005 and
December 2006
6.20.4 The averaged groundwater levels are shown on Drawing Nos. MG_REP_EIA_009/033 to
MG_REP_EIA_009/034. These drawings also show the groundwater flow direction idetified in
the alluvium and bedrock.
6.20.5 It is understood from meetings held with the Environment Agency that their information indicates
groundwater flow in the bedrock beneath Widnes to be in an approximate southerly direction, at
least north of the buried glacial channel. However, investigations for the Mersey Gateway
Project show a clear north-westerly groundwater flow direction within the Sherwood Sandstone
in both Runcorn (north of the Manchester Ship Canal) and Widnes.
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6.20.6 Groundwater flow in the superficial deposits is different on both sides of the estuary. A clear
trend of groundwater flow towards the estuary has been identified in the alluvium. The indicated
groundwater flow directions show components of the local and deeper regional groundwater
flow systems.
6.20.7 The results from groundwater monitoring undertaken after the Orders ES does not indicate
there are any significant changes to the groundwater flow directions identified.
6.21 Groundwater–Surface Water Interactions
6.21.1 Groundwater has the potential to be in hydraulic continuity with a number of surface water
bodies; principally, the Mersey Estuary, Manchester Ship Canal, Bowers Brook and Stewards
Brook (although this is outside of the Project area and is understood to have been lined in the
Project area). It is also possible that groundwater could be in hydraulic continuity with water in
the St Helens Canal and the Latchford Canal Spur, although it is possible the St Helens Canal
is lined as its construction post-dates the introduction of lined canals. Available information
indicates that whilst the Bridgewater Canal may not be lined, the base is likely to be situated in
glacial clay in the Project area reducing the potential for hydraulic continuity with groundwater.
6.21.2 As previously discussed, evidence for the continuity of groundwater with the estuarine surface
waters in both the shallow aquifer and sandstone aquifers is provided by the tidal influence of
the groundwater levels in both. Further evidence is apparent from the conductivity values of the
groundwater resulting from increased salinity closer to the estuary and higher concentrations of
sodium and chloride closer to the estuary as shown in Figure 6.7:
Figure 6.7 – Concentrations of Conductivity, Sodium and Chloride in the Sherwood Sandstone
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6.21.3 The Mersey Estuary is likely to be both a gaining and loosing river channel system at its
margins, due to the tidal cycle. At higher tides, surface water levels in the estuary exceed
groundwater elevations and also flood the saltmarshes.
6.21.4 Electrical conductivity values for groundwater indicate there has been mixing with estuarine
surface waters due to the trend for higher values in close proximity to the estuary.
6.21.5 The Manchester Ship Canal is not known to have been lined. The Manchester Ship Canal is cut
through glacial deposits into the Sherwood Sandstone creating potential hydraulic continuity
between them. On the assumption that the depth of the Manchester Ship Canal is lower than
the groundwater table and surface water levels are higher than groundwater, the surface water
in the canal has the potential to recharge groundwater.
6.21.6 As noted in Section 5, there are records of drains beneath the Catalyst Trade Park (Area C) that
link to Bowers Brook. The information obtained indicates the base of Bowers Brook is likely to
have been constructed on the cohesive alluvium. To the south of the Catalyst Trade Park
Bowers Brook is located in a brick lined culvert. Interactions between shallow groundwater and
surface water are likely. Sampling by Gifford at the outfall to Bowers Brook on Spike Island in
2007 encountered chlorinated solvents. Additional information is provided in the Surface Water
Quality Chapter of the Environmental Statement.
6.21.7 Stewards Brook flows in a southerly direction through St Michaels Golf Course but it is located
outside of the Project Area, to the west of Area A. There is eEvidence had been obtained that
this watercourse is was being impacted by the contamination originating from the northern part
of the golf course (the area to the north of the Project area which is the subject of a Part IIA
determination) which resulted in remediation works being undertaken on that the northern part
of the golf course. However, information from the Council notes that the brook in adjacent to the
Project area is lined to prevent contaminants from migrating into the watercourse.
6.21.8 Further information on issues relating to surface water is provided in Chaper 8 (Surface Water
Quality) of the Environmental Statement.
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6.22 Soil Permeability Testing
6.22.1 The results of the falling head permeability testing undertaken by Soil Mechanics during the
Phase 6 site investigation in 2007 are shown in Table 6.16 below:
Table 6.16– Results of the Falling Head Permeability Testing
Exploratory
Hole
Location Ground Conditions Results (m/s)
Area A
BH61 Ditton Roundabout/
Speke Road slip road
Made Ground: slightly gravely SILT 6.7x10-6
BH62 Speke Road Sandy gravely SILT (Alluvium) 1.2x10-5
BH67 Golf Course - Unable to fill
borehole (40
gallons
added)
BH67A Golf Course Made Ground: slightly sandy slightly gravely CLAY 4.9x10-6
BH75 Golf Course Made Ground: slightly sandy slightly gravely SILT
Made Ground: slightly clayey gravely SAND
2.3x10-5
Area B1
BH76 Ditton Roundabout/
Speke Road slip road
Made Ground: ashy slightly clayey to clayey very
gravely medium SAND
Made Ground: clayey very sandy GRAVEL
2.0x10-4
BH77 Ditton Roundabout Made Ground: very clayey very gravely SAND 1.6x10-4
BH80 Ditton Roundabout Made Ground: Galligu 1.8x10-4
Area B2
BH54F Gussion Made Ground: grey brown galligu 1.2x10-7
BH58 Gussion Made Ground: sandy slightly gravely CLAY
Slightly gravely CLAY (Glacial Clay) at base
5.1x10-7
BH59 Anglo Blackwells Made Ground: sandy ashy GRAVEL
Slightly sandy CLAY (Glacial Clay) at base
3.2x10-7
BH82 S. Evans Scrapyard - Unable to fill
borehole (750
litres added)
Area C
BH95 Fallon Brothers Scrapyard Made Ground: slightly silty very sandy GRAVEL 2.8x10-5
BH97A West of Victoria Road Made Ground: Ash and stone fill
Made Ground: slightly sandy slightly gravely CLAY
at base
3.6x10-5
BH66B Thermphos Made Ground: slightly sandy gravely CLAY
Made Ground: sandy GRAVEL at base
1.0x10-5
BH65C Catalyst Trade Park Slightly clayey to clayey gravely fine and medium
SAND (Alluvium)
9.2x10-7
BH65C Catalyst Trade Park Slightly clayey fine and medium SAND (Glacial
Sand)
1.0x10-6
BH101 Catalyst Trade Park Made Ground: ashy sandy gravely CLAY 1.7x10-4
BH102 Catalyst Trade Park Made Ground: slightly silty very sandy GRAVEL 2.4x10-4
BH103 Catalyst Trade Park Made Ground: sandy ashy GRAVEL 1.1x10-5
BH104 Catalyst Trade Park Made Ground: SAND and GRAVEL with large
cobbles
1.3x10-5
BH105A Catalyst Trade Park Made Ground: slightly clayey very sandy GRAVEL 1.4x10-3
BH105A Catalyst Trade Park Made Ground: slightly clayey very sandy GRAVEL
Made Ground: slightly sandy slightly gravely CLAY
1.4x10-5
BH106 Catalyst Trade Park Made Ground: slightly silty very sandy GRAVEL
Made Ground: slightly silty very gravely SAND
Sandy gravely CLAY (Glacial Clay) at base
8.6x10-6
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6.23 Assessment of Soil Analytical Results
6.23.1 The results of the chemical testing undertaken on soil samples are included in Appendix LP.
The results are discussed below in terms of where contaminants exceed the selected
assessment criteria, the location of exceedances are shown on Drawing Nos.
MG_REP_EIA_009/035 to MG_REP_EIA_009/049.
6.23.2 For the purposes of assessing the soil, leachate and groundwater results, concentrations which
were reported below the lower analytical detection limit were set at the analytical detection limit.
This approach is considered to be conservative, particularly where analytical detection is close
to or exceeds the assessment criteria or where significant number of results are below detection
(i.e. results may appear as false positives).
6.23.3 The results of the soil testing have been considered under the headings of made ground and
drift deposits for the Areas outlined below.
6.24 Zoning for Assessing Soil Testing Results
6.24.1 To assess the results of the soil testing the Project area has been divided into a series of areas
based on the potentially contaminating land uses identified in Section 5. These areas are
outlined in Drawing No. MG_REP_EIA_009/003. A summary of the land uses in each area is
provided below. However, the ground conditions encountered, and in particular made ground,
have been shown to be highly variable in nature and this includes within individual areas.
Area A & B1 – St Michaels Golf Course and Ditton Junction
6.24.2 The southern part of this golf course was historically a landfill site for chemical waste which
included Galligu. The Ditton Road Roundabout area has been included within this Area as this
has also been identified as an area of fill. In addition to the made ground, near surface glacial
deposits have also been identified as having been impacted by contaminants in these areas
from the site investigations.
Area B2 and I1 – Gussion Transport and Anglo Blackwells
6.24.3 The Area incorporates Gussion Transport Services, Widnes Tanker Services and former Anglo
Blackwells site which, although current land uses may differ, have historically been used for
industries including Alloy Works, Foundries and Chemical Works. Shallow ground conditions
comprised made ground (including galligu) over glacial clay. This zone includes the northern
part of Area I.
Western and Northern part of Area C and Northern part of Area I2 - Railway Land
6.24.4 Historical OS maps show extensive areas used by railways in Widnes, with the area north of
Hutchinson Road and south of the existing heavy good rail line having many railway lines
crossing it. Also the area north east of Catalyst Trade Park and beneath the existing A557
Expressway were historically used as railway sidings.
Area C - Catalyst Trade Park (CTP) and Thermphos
6.24.5 The area incorporates the exploratory holes on and adjacent to the Catalyst Trade Park and
Thermphos. Historical plans and maps show these areas to have been occupied by chemical
works including alkali works and similar ground conditions have been identified from the site
investigations.
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Area I2 – De-Linking
6.24.6 This area comprises existing road embankments for A533 Queensway and the A557 Widnes
Eastern Bypass parts of which it is proposed would be removed as part of the works.
Information obtained indicates the A533 Queensway road was constructed in the 1960s as part
of the works for the Silver Jubilee Bridge and the A557 Expressway was constructed in the
1990s.
Area D Saltmarshes and Mersey Estuary
6.24.7 The information obtained indicates the estuary and majority of the saltmarshes have not been
developed. Similar ground conditions were identified on Widnes Warth and Astmoor Saltmarsh.
6.24.8 This area includes made ground associated with the Wigg Island Landfill and former Wigg East
Works, although this data was considered separately to the saltmarsh data.
Area E to F - Astmoor Industrial Estate to Bridgewater Junction
6.24.9 Historical OS maps indicate the majority of this area was developed during the 1960s. The area
comprises an industrial estate with a wide variety of land uses and the existing junction to the
A533 Bridgwater Expressway.
Area G1 to G2 - Central Expressway (Weston Link Junction to M56 Junction 12)
6.24.10 This area includes Weston Point Expressway, Southern Expressway Junction and Central
Expressway. Historical maps show these areas to have been occupied by highways.
6.25 Information on Soils for CLEA Model
6.25.1 The assessment criteria for made ground has been used on the basis that made ground has
been encountered within all of the exploratory holes in Widnes land based areas, within the
Astmoor Industrial Estate and remote junctions in Runcorn. The made ground has been shown
to be highly variable and this material can vary within individual exploratory holes. The made
ground comprised variable quantities of clay, silt, sand and also gravels. Due to the variability
of this material, the parameters for a typical sandy soil from SR3 CLEA Briefing Note 2 have
been used to derive the assessment criteria for the made ground as this is likely to be provide a
degree of conservatism particularly where finer grained soils are also present.
6.25.2 The assessment criteria have been based on the default parameters from SR3 CLEA Briefing
Note 2 (20049) for a commercial/industrial land use and for sandy soil adjusting the total organic
carbon (TOC) and pH for site specific derived values. The numerical mean values for TOC and
pH in the made ground obtained from chemical testing are as follows. The average TOC and
pH derived for each area were used for deriving the assessment criteria. The average TOC and
pH derived for all of the made ground samples for Runcorn and Widnes have also been
included below for comparison:
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Table 6.17 – Mean Soil TOC and pH in Made Ground across Project Area
Area Mean Soil TOC Mean Soil pH
Runcorn
Overall Mean for Runcorn 2.64 8.07
Area E 2.47 8.02
Area F to H - Expressways 3.14 8.24
Widnes
Overall Mean for Widnes 8.51 8.75
Area A and B1 5.37 9.34
Area I and C - Existing and
former Railway Land 8.17 8.10
Area B2 15.93 8.77
Area C 8.14 8.25
Note: Where fraction of organic (Foc) has been tested this has
been converted to TOC by multiplying the Foc result by 100
6.25.3 The range of mean pH values obtained for made ground is 8.02 to 9.34 and the range of TOC is
2.47% to 15.93%. The soil pH of 8 and TOC of 5.37% has been used for the made ground in
Widnes, and a soil pH of 8 and TOC of 2.47% for the made ground in Runcorn. The use of the
lowest average TOC for made ground in Widnes is conservative when assessing acceptable
concentrations for organic contaminants in soils.
6.25.4 The mean TOC and pH for the glacial clay and alluvium in Runcorn and Widnes (not including
the saltmarshes and estuary) were as follows:
Table 6.18 – Mean Soil TOC and pH in Drift Deposits across the Project Area
Area Mean Soil TOC Mean Soil pH
Runcorn
Glacial Clay 0.82 8.21
Widnes
Glacial Clay 1.05 8.5
Alluvium 5.18 7.8
Note: Where fraction of organic (Foc) has been tested this has been
converted to TOC by multiplying the Foc result by 100
6.25.5 The mean TOC and pH results for alluvium in Widnes are similar to those derived for the made
ground. The mean TOC results obtained for glacial clay are lower than those obtained for the
made ground. The soil type can affect the assessment criteria derived by the CLEA UK model.
The approach adopted for deriving GAC for a commercial/industrial land use using granular
soils is likely to be conservative where finer grained soils are present.
6.25.6 The mean TOC and pH for the shallow alluvium encountered on Widnes Warth and Astmoor
Saltmarsh in Area D and the granular alluvium beneath the saltmarshes and within the estuary
is as follows:
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Table 6.19 – Mean Soil TOC and pH in Alluvium from Warth, Astmoor Saltmarshes and the
Mersey Estuary
Area Mean Soil TOC Mean Soil pH
Cohesive Alluvium - Runcorn
Area D – Astmoor
Saltmarsh
3.53 7.77
Cohesive Alluvium - Widnes
Area D – Widnes Warth 2.45 7.5
Granular Alluvium - Saltmarshes and Estuary
Area D 0.46 7.93
Note: Where fraction of organic (Foc) has been tested this has been
converted to TOC by multiplying the Foc result by 100
6.25.7 For assessing the possible risks to construction workers in the saltmarsh areas, the mean TOC
and pH for the shallow cohesive alluvium derived for Widnes Warth has been used, these are
more conservative than the higher mean values derived for Astmoor Saltmarsh. The default
values for a clay soil in the CLEA UK model have been used to derive the assessment criteria
for human health from contaminants in the shallow cohesive alluvium. The assessment criteria
for granular alluvium are based on the mean TOC and pH from the saltmarshes and estuary,
and the default values for a sandy soil in the CLEA UK model.
6.26 Assessment of Soil Test Results for a Commercial/Industrial Land Use
6.26.1 This section lists the parameters which exceed the GAC for a commercial/industrial land use
within the Project area. Separate GAC have been derived for Widnes and Runcorn. GAC for a
commercial/industrial land use were not derived for the saltmarshes, estuary and Wigg Island)
as the approach viaducts and bridge will be raised on piers in these areas. The following tables
show the number of samples and the percentage of the samples tested that exceed the GAC.
6.26.2 The GAC for commercial/industrial land use are located in Appendix MQ. Drawing Numbers
MG_REP_EIA_009/035 to MG_REP_EIA_009/049 show the distribution of soil contaminants
across the project area. The following section has been updated to reflect changes in the
assessment criteria derived from revisions to the CLEA model and input data.
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Made Ground
Widnes
Table 6.20 – Summary of Exceedances of Commercial / Industrial GAC Values within Made
Ground in Widnes (continued overleaf) (Updated)
Parameter Range of
concentrations
No. samples exceeding
GAC
Location of
exceedances (m bgl)
Arsenic (mg/kg) 1 – 7,700
Mean 248 247
11 (6.9%) 12 (5.9%) Area A Golf Course
BH74 at 5.0m
Area B2 & I1
WS22 at 1.0-1.2m
Area C (CTP/Thermphos)
WS11A at 0.4m
WS11A at 1.3m
WS12 at 2.0m
BH41 at 3.0m
BH41 at 4.0m
TP1003 at 0.8m
BH103 at 1.0m
BH103 at 2.0m
WS29 at 1.0-1.1m
BH101 at 1.0m
BH65C at 3.0m
BH66B at 2.5m
Nickel 1.90 – 1,600
Mean 53.48
2 (0.98%) Area A & B1
BH73 at 2.0m
Area B2 & I1
BH51 at 3.5m
Cadmium 0.3 - 350 1 (0.49%) Area A
BH74 at 3.5m
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Table 6.20 (continued) – Summary of Exceedances of Commercial / Industrial GAC Values
within Made Ground in Widnes (continued overleaf) (Updated)
Parameter Range of
concentrations
No. samples exceeding
GAC
Location of
exceedances (m bgl)
Lead (mg/kg) <2 – 22,000
Mean 873 893
43 (21.1%) Area A & B1
BH70 at 0.5m
BH73 at 2.0m
BH74 at 3.5 & 5.0m
BH93 at 0.5m
BH76 at 0.25m
BH76 at 2.0m
BH77 at 4.0m
Area B2 & I1
BH49 at 1.0m
WS02 at 1.8-2.0m
WS18 at 1.0-1.5m
WS23 at 0.2-0.5m
Area C
BH48 ay 0.4m
BH43 at 1.0m
WS15 at 0.0m–1.2m
WS11A at 0.4m
BH46 at 1.1m
WS12 at 2.0m
BH56 at 0.2m
BH57 at 0.4m
WS10A at 0.4m
BH41 at 1.0m
BH41 at 4.0m
BH1003 at 0.2m & 1.0m
TP1002 at 0.6m
TP1003 at 0.8m & 1.15m
TP1004 at 2.8m
WS46A at 0.8m-1.0m
BH102 at 2.0m
BH104 at 1.0m
BH103 at 1.0m
BH103 at 2.0m
WS47 at 0.5-0.9m
WS29 at 1.0m-1.1m
BH65C at 3.0m
BH1001 at 0.2m
BH101 at 1.0m
BH66B at 2.5m
BH97A at 0.5m
BH42 at 1.0m
BH71 at 1.0m
Total Sulphate (mg/kg) <100 – 350,000
Mean 45,299
109 (68%) All Areas
Water Sol Sulphate (g/l) 0.013 - 40
Mean 1.38 43
144 (63%) 145 (59%) All Areas
EC16-21 aromatic
(mg/kg)
<0.1 – 14,000
Mean 131
1 (0.7%) Area B2 (Gussion)
WS17 at 0.7-1.0m
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Table 6.20 (continued) – Summary of Exceedances of Commercial / Industrial GAC Values
within Made Ground in Widnes (Updated)
Parameter Range of
concentrations
No. samples exceeding
GAC
Location of
exceedances (m bgl)
EC21-35 aromatic
(mg/kg)
<0.1 – 11,000
Mean 197
1 (0.7%) Area B2 (Gussion)
WS17 at 0.7-1.0m
Hexachlorobutadiene
(mg/kg)
<0.001 – 24.7
Mean 0.395
1 (0.9%) Area C (CTP)
WS11A at 0.4m
Hexachloroethane
(mg/kg)
<0.1 – 341
Mean 6.3 5.6
1 (1.4%) 2 (1.7%) Area C (CTP)
WS11A at 0.4m
BH56 at 0.2m
Benzo(a)pyrene (mg/kg) <0.012 – 38
Mean 1.1 1.0
2 (1%) Area C
BH65C at 3.0m
BH71 at 4.5m
Cis-1,2,dichloroethene
(mg/kg)
<0.001 – 17
Mean 0.181
1 (1%) Area C
WS42 at 3.7-4.0m
Vinyl Chloride (mg/kg) <0.001 – 1.8
Mean 0.026
1 (1%) Area C
WS42 at 3.7-4.0m
Asbestos - 6 Area A (Golf Course)
BH75 at 2.0m & 3.0m
(chrysotile (white)
asbestos)
Area I2
BH85 at 6.0m
(amosite (brown)
asbestos)
Area C
BH46 at 2.0m
BH1003 at 1.0m
WS12 at 0.5m
(all chrysotile (white)
asbestos)
6.26.3 The lower analytical detection limit for EC7-8 aromatic hydrocarbons (<200mg/kg) for the
sample of made ground from 0.7m-1.0m bgl at WS17 in Area B2 was above the GAC for a
commercial / industrial land use (147mg/kg). However, the result has not been included as it
was below detection. These contaminants do not exceed the revised assessment criteria.
6.26.4 In addition to the samples listed in Table 6.20, exceedances were also obtained from Area I for
lead (five samples), benzo(a)pyrene (2 samples), dibenzo(ah)anthracene (1 sample) and
benzo(a)anthracene (1 sample).
6.26.5 Non-asbestos fibres were identified in samples tested in Area A at St Michaels Golf Course in
BH93 at 3.0m bgl. Fibres were noted on the exploratory hole log for BH74 at 5.0m but
laboratory test results indicate that no fibres were actually present.
6.26.6 Widespread elevated concentrations of total sulphate and water soluble sulphate have been
obtained from samples of made ground tested between Area A on St Michael‟s Golf Course and
Area C at Catalyst Trade Park/Thermphos.
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6.26.7 No target values have been obtained for ammonium (as NH4) or ammoniacal nitrogen (as N).
Concentrations of ammoniacal nitrogen (when expessed as N) in the made ground ranged from
<0.08 to 270mg/kg with a mean value of 29.4mg/kg. The highest concentration of 270mg/kg
was obtained from BH103 at 1.0m bgl in Area C. Drawing No. MG_REP_EIA_009/040 shows
the distribution of ammoniacal nitrogen (as N) within the made ground.
6.26.8 Sulphide concentrations ranged from below analytical detection to 18,000mg/kg. The lower
detection limit during testing varied between 0.5 and 50mg/kg. Some of the testing undertaken
by Fugro-Robertson Ltd as part of the Phase 4 investigation had an upper detection limit of
700mg/kg. Five samples from BH52 and BH53 in Area B1 were recorded at this upper
detection limit.
6.26.9 Soil pH ranged from 4.25 to 12.66 with an average of 8.754. The highest soil pH value was
obtained from BH61 at 3.0m bgl (Area B1) and the lowest soil pH value was obtained from
BH82 at 2.0m bgl (Area B2). Drawing No. MG_REP_EIA_009/037 shows the distribution of soil
pH within the made ground.
Runcorn
Table 6.21 – Summary of Exceedances of Commercial / Industrial GAC Values Within Made
Ground in Runcorn
Parameter Range of
concentrations
No. samples exceeding
GAC
Location of
exceedances (m bgl)
Lead (mg/kg) 2 – 1,200
Mean 71
1 (2.4%) Area G2 (Weston Link
Junction)
BH127 at 2.0m
Water Sol Sulphate (g/l) 0.003 – 1.2
Mean 0.4
2 (4.4%) Area F
BH117 at 0.2m
Area G
BH126 at 1.0m
Asbestos - 3 Area F (Bridgewater
Junction)
BH114 at 1.6m & 2.0m
(chrysotile (white) &
crocodilite (blue)
asbestos)
Area G
BH125 at 2.0-2.45m
(chrysotile (white) and
crocodilite (blue)
asbestos)
6.26.10 Testing for ammoniacal nitrogen was undertaken on made ground from Wigg Island in Area D.
Concentrations of ammoniacal nitrogen (when expessed as N) in the made ground at Wigg
Island ranged from 0.78 to 499mg/kg with a mean value of 81.1mg/kg. The highest
concentration of 499mg/kg was obtained from WS3 at 0.8-0.9m bgl which was located at the
eastern end of Wigg Island. Drawing No. MG_REP_EIA_009/040 shows the distribution of
ammoniacal nitrogen (as N) within the made ground.
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6.26.11 Sulphide concentrations ranged from below analytical detection to 219mg/kg in Area E to H,
with the highest concentration obtained from BH25 in Area E. At Wigg Island in Area D,
sulphide concentrations ranged from below analytical detection to >700mg/kg. The maximum
result was obtained from WS03 during the Phase 4 investigation, although this sample was
tested by by Fugro-Robertson Ltd usingan upper detection limit of 700mg/kg.
6.26.12 Soil pH in Runcorn (including Wigg Island) ranged from 2.9 – 12.3 with an average of 8.07. The
highest (pH12.3) and lowest (pH2.9 and 4.1) soil pH values were obtained from the made
ground in BH18A at the Wigg Island Landfill. Drawing No. MG_REP_EIA_009/037 shows the
distribution of soil pH within the made ground in Runcorn.
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Drift Deposits: Alluvium
Widnes
Table 6.22 – Summary of Exceedances of Commercial / Industrial GAC Values Within Alluvium
in Widnes (continued overleaf) (Updated)
Parameter Range of
concentrations
No. samples exceeding
GAC
Location of
exceedances (m bgl)
Arsenic (mg/kg) 1 – 520
Mean 65
1 (2.4%) Area C (CTP)
BH65C at 6.0m
Barium (mg/kg) 8 – 44,000
Mean 1207 1089
1 (2.5%) Area A (Golf Course)
BH75 at 5.0m
Lead (mg/kg) 7 – 7,400
Mean 403 367
4 (9.3%) 3 (7.1%) Area A (Golf Course)
BH75 at 5.0m
Area |2 (Hutchinson
Road)
BH50 at 3.0m
Area C (CTP)
WS7 at 4.0m
BH65C at 6.0m
Total Sulphate (mg/kg) 253 – 74,000
Mean 8084
12 (40%) Area A (Golf Course)
BH75 at 5.0m
Area B2
WS16A at 1.6-2.0m
WS18 at 2.0-2.3m
Area C (CTP)
BH65C at 6.0m
BH108 at 3.0m
BH104 at 3.0m
BH71 at 5.5 & 6.9m
WS10A at 4.5m
WS12 at 6.0m
BH107 at 8.0m
BH96 at 9.0m
Water Sol Sulphate (g/l) <0.003 – 6.6
Mean 0.9 0.83
23 (47%) 24 (48%) Area A
BH62 at 5.0m
Area B2
WS16A at 1.9-2.0m
WS18 at 2.0-2.3m
Area C
Various Locations
Area I2
BH50 at 3.0m
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Table 6.22 (continued) – Summary of Exceedances of Commercial / Industrial GAC Values
Within Alluvium in Widnes (updated)
Parameter Range of
concentrations
No. samples exceeding
GAC
Location of
exceedances (m bgl)
Fluorene <0.05 – 150
Mean 3.69
1 (2.3%) Area A
BH71 at 5.5m
Hexachlorobutadiene
(mg/kg)
<0.001 – 97.5
Mean 1.822
1 (1.9%) Area C (CTP)
WS11A at 5.0m
Hexachlorethane <0.1 – 158
Mean 6.9
1 (4.1%) Area C
WS11A at 5.0m
Trichloroethene (mg/kg) <0.001 – 52.9
Mean 1.7
1 (1.9%) Area C
BH56 at 4.5m
Vinyl Chloride (mg/kg) <0.001 – 0.43
Mean 0.021
1 (1.9%) Area C
WS12 at 6.0m
6.26.1 In addition to the exceedances outlined in Table 6.22, exceedances were also obtained from
Area I for lead and water soluble sulphate in BH50 at 3.0m
6.26.2 The lower method detection limit for benzo(a)pyrene and dibenzo(a,h)anthracene (<50mg/kg)
for the sample of alluvium from 5.5m bgl at BH71 in Area C was above the GAC for a
commercial / industrial land use. However, the results have not been included as they were
below detection.
6.26.3 Concentrations of ammoniacal nitrogen (when expessed as N) in the alluvium in Widnes ranged
from 3.73 to 490mg/kg with a mean of 62.5mg/kg. The highest concentration of 490mg/kg was
obtained from BH108 at 3.0m bgl in Area C.
6.26.4 Sulphide concentrations ranged from 0.6 to 12,000mg/kg. The maximum result was obtained
from BH75 at St Michaels Golf Course (Area A). Some of the testing undertaken by Fugro-
Robertson Ltd as part of the Phase 4 investigation had an upper detection limit of 700mg/kg,
one sample from WS07 in Area C was recorded at this upper detection limit.
6.26.5 Soil pH ranged from 4.1 – 12.37 with an average of 7.79. The highest soil pH value was
obtained from WS16A at 1.9m to 2.0m bgl (Area B2) and the lowest soil pH value was obtained
from TP1003 at 3.4m bgl (Area C).
Runcorn
6.26.6 There were no exceedances of the assessment criteria for a commercial / industrial land use for
alluvial deposits in Runcorn.
6.26.7 No testing for ammoniacal nitrogen was undertaken on alluvium in Runcorn. However, at Wigg
Island, concentrations of 284mg/kg and 90mg/kg at 9.3m bgl were obtained for ammonium
(when expressed as N) in BH32 at 8.5m bgl and 9.3m bgl respectively. A concentration of
182mg/kg for ammonium (as N) was obtained from WS04 at 1.6-1.8m bgl, with 317mg/kg at
1.4-1.6m bgl and 128mg/kg at 2.4-2.6m bgl from WS3 in the shallow alluvium beneath the
eastern end of the Wigg Island Landfill.
6.26.8 Elevated concentrations of water soluble sulphate were obtained from 5 samples of alluvium
located beneath the made ground at the Wigg Island Landfill.
6.26.9 Sulphide testing at Wigg Island encountered concentrations ranging from 11 to 740mg/kg, with the highest concentration obtained from WS03.
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Drift Deposits: Glacial
Widnes
Table 6.23 – Summary of Exceedances of Commercial / Industrial GAC Values within Glacial
Deposits in Widnes (Updated)
Parameter Range of
concentrations
No. samples exceeding
GAC
Location of
exceedances (m bgl)
Total Sulphate (mg/kg) 512 – 19,000
Mean 5,013
5 (42%) Area B1 (Ditton Junction)
BH77 at 5.0m
BH76 at 6.0m
Area B2 (Gussion)
BH51 at 5.0m
BH54E at 4.0m
BH58 at 5.0m
Water Sol Sulphate (g/l) 0.033 – 7.6
Mean 0.71 0.69
19 (41 38%) Area B1 (Ditton Junction)
BH53 at 7.0m
BH77 at 5.0 & 6.0m
BH76 at 6.0m
BH52 at 6.0m
BH78 at 7.0m
Area B2 (Gussion)
BH51 at 5.0 & 15.0m
BH58 at 5.0m
BH54 at 5.0m
Area C (CTP)
BH102 at 4.0 & 14.0m
BH101 at 10.0m
BH105A at 12.0m
BH104 at 9.0m
BH95 at 10.0m
BH96 at 14.0m
BH103 at 13.0m
Area I2
BH91 at 7.0m
6.26.10 Concentrations of ammoniacal nitrogen (when expessed as N) in the glacial deposits in Widnes
ranged from 14.3 to 88mg/kg with a mean of 27.4mg/kg. The highest concentration of 88mg/kg
was obtained from BH97A at 4.0m bgl in Area C.
6.26.11 Sulphide concentrations ranged from 8 to 4,100mg/kg. The maximum result was obtained from
BH77 at Area B1.
6.26.12 Soil pH ranged from 7.16 – 11.81 with an average of 8.478. The highest soil pH value was
obtained from BH54E at 4.0m bgl (Area B2).
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Runcorn
6.26.13 There were no recorded exceedances of the assessment criteria in the glacial deposits in
Runcorn, with the exception of water soluble sulphate from BH30 in Area E.
6.26.14 Ammonium (as N) was only detected at one location, BH31 at 0.5m bgl, where a concentration
of 0.78mg/kg was obtained from the glacial deposits.
6.26.15 Sulphide concentrations ranged from 0.6 to 1.9mg/kg in glacial deposits in Runcorn, although at
Wigg Island a result of 15mg/kg was obtained from BH31.
6.26.16 Soil pH ranged from 7.4 – 8.8 with an average of 8.2.
Volatile Organic Compounds – Free Product Assessment
6.26.17 The highest concentrations of VOCs in soils were obtained from the Catalsyt Trade Park in Area
C. An assessment has been undertaken using EA R&D 133 (2003) to determine whether free
product is likely to be present in the made ground and alluvium from soil samples obtained on
and adjacent to the Catalyst Trade Park based on the chemical testing results for chlorinated
solvents. This assessment is based on the following equation obtained from EA R&D 133
(2003):
awbd
b
iT
i HPKP
CC '
where: a. Ci
T is the concentration of an organic substance at or above that which may be present
in a non-aqueous phase (mg/kg),
b. Ci is the effective solubility of the substance in groundwater (mg/l),
c. Pb is the dry soil bulk density (kg/l),
d. Kd is the soil-water partition coefficient (l/kg),
e. θw is the water-filled porosity (dimensionless),
f. H‟ is the unitless Henry‟s law constant (dimensionless), and
g. θa is the air-filled porosity.
6.26.18 The soil-water partition coefficient (Kd) for organic compounds can be approximated using the
following equation:
ococd FKK
where: a. Koc is the organic carbon-water partition coefficient (l/kg),
b. Foc is the fraction organic carbon present in the soil (dimensionless).
6.26.19 The assessment was undertaken for chlorinated solvents exceeding 1mg/kg using published
values of Koc, H‟ and Ci (the sources of this information are outlined in Appendix MQ) and
estimated values for Pb, θa and θw.
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6.26.20 The bulk density (Pb) was based on 1.8kg/l for the made ground and alluvium. The estimates
for air and water filled porosity were based upon values obtained from CLEA Briefing Note 2
(2004). An air filled porosity (θa) of 15% was used for the made ground and 0% for alluvium (on
the basis the alluvium would be saturated). A water-filled porosity (θw) of 31% was used for the
made ground, and 46% and 0.51% for alluvium (to consider both sand and a loam/clay soil).
The organic carbon (Foc) was based on the mean values obtained from the chemical testing (8%
for made ground and 5% for alluvium).
6.26.21 The CiT values derived for each compound were compared to the maximum observed
concentrations for each soil type. None of the results obtained indicated that free product was
likely to be present in the samples tested.
6.26.22 A review of the input parameters indicates the CiT values were most sensitive to variations in
fraction of organic carbon (Foc). However, when the minimum observed values of Foc for made
ground and the mean value for cohesive alluvium from Widnes Warth (2.47%) are used, the
calculated CiT values for each chlorinated solvent remained greater than the maximum observed
concentrations, i.e. free product was still unlikely to be present in the soil samples tested.
6.26.23 On this basis it was considered that no free product was present in the soil samples that were
analysed.
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6.27 Statistical Assessment of Soil Contamination Data
6.27.1 Table 6.24 below summarises the contaminant distribution for the made ground in the each
areas where exceedances of the GACs for a commercial/industrial land use were identified.
The statistical assessment has been updated to reflect changes in the exceedances of the
assessment criteria.
Table 6.24 – Summary of Statistics for Contaminants in Made Ground Upper 2m of Soil that
Exceed GACs for Commercial / Industrial Land Use (Updated)
Contaminant
Number of
Samples
Assessed
Minimum
Value
Maximum
Value
Mean
Value
Standard
Deviation
WIDNES
Area A & B1 – St. Michaels Golf Course & Ditton Road Roundabout
Lead (mg/kg) 30 36 9 15,000 806
1033
2,717
3647
Cadmium 61 0.3 350 13 47
Nickel (mg/kg) 30 7.7 1,600 82 287
Area B2 & I1 - Gussion Transport, Anglo Blackwells & Railway Land
Arsenic (mg/kg) 27 36 <3 1,100 149
151 228 203
Lead (mg/kg) 27 36 <2 1,000 300
268 325 298
EC16-21 Aromatic Hydrocarbons (mg/kg) 27 <0.1 14,000 527 2,693
EC21-35 Aromatic Hydrocarbons (mg/kg) 27 <0.1 11,000 453 2,110
Area C - Catalyst Trade Park
Arsenic (mg/kg) 88 107 <1 7,700 306
378 936 1079
Lead (mg/kg) 88 107 6 12,182 913
1024
1,727
2597
Hexachlorobutadiene (μg/kg) 66 <1 24,665 626 3,148
Benzo(a)pyrene (μg/kg) 104 <50 38,000 1382 5218
Hexachloroethane (μg/kg) 42 51 <100 341,157 10,747
9041
53,191
48316
Vinyl chloride (μg/kg) 77 <1 1,800 31 204
RUNCORN
Area G2 – Weston Link Junction
Lead (mg/kg) 10 11 7 1,200 142
135 372 353
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6.27.2 The Chebyshev 95% UCL values have been calculated for the contaminants in Table 6.24 and
are shown below in Table 6.25.
Table 6.25 – Comparison of UCL0.95 Values to the GACs for Commercial / Industrial Land Use
(Updated)
Contaminant GAC Maximum
Concentration
Chebyshev
UCL0.95
Does UCL0.95
Exceed
GAC?
Are Outliers
Likely To Be
Present?
WIDNES
Area A & B1 – St. Michaels Golf Course & Ditton Road Roundabout
Lead (mg/kg) 750 15,000 2,968 3,068 Yes Yes
Cadmium 230 350 34 No Yes
Nickel (mg/kg) 1,590 1,600 311 No Yes
Area B2 & I1 - Gussion Transport, Anglo Blackwells & Railway Land
Arsenic (mg/kg) 500 1,100 340 300 No Yes
Lead (mg/kg) 750 1,000 572 484 No No
EC16-21 Aromatic Hydrocarbons
(mg/kg) 9,470 14,000 2,786 No Yes
EC21-35 Aromatic Hydrocarbons
(mg/kg) 9,470 11,000 2,223 No Yes
Area C - Catalyst Trade Park
Arsenic (mg/kg)
500 635 7,700 741 833 Yes Yes
Lead (mg/kg) 750 12,182 1,715 2,119 Yes Yes
Hexachlorobutadiene (μg/kg) 14,500 24,665 2,315 No Yes
Benzo(a)pyrene (μg/kg) 14,500 38,000 3,613 No Yes
Hexachloroethane (μg/kg) 231,000
97,500 341,157
46,523
38,532 No Yes
Vinyl chloride 105 1,800 132 Yes Yes
RUNCORN
Area G2 – Weston Link Junction
Lead (mg/kg) 750 1,200 655 600 No Yes
Note: Statistical outliers were not removed from the data for the above contaminants.
Review of Statistical Assessment Results
6.27.3 The 95% UCL values derived for lead at St. Michaels Golf Course (Area A) and the Catalyst
Trade Park (Area C) in Widnes, exceeded the GAC value of 750mg/kg. In addition, the 95%
UCL value for arsenic and vinyl chloride at the Catalyst Trade Park (Area C) in Widnes exceeds
the GAC.
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6.27.4 In addition, possible statistical outliers indicating other contaminant populations in soils were
identified at the following locations:
a. St. Michaels Golf Course & Ditton Road Roundabout (Area A & B1) - lead and nickel
cadmium.
b. Gussion Transport / Anglo Blackwells / Railway Land (Area B2 & I1) - arsenic, EC16-21
and EC21-35 aromatic hydrocarbons.
c. Catalyst Trade Park (Area C) – arsenic, lead, hexachlorobutadiene benzo(a)pyrene,
vinyl chloride and hexachloroethane.
d. Weston Link Junction (Area G2) - lead.
6.28 Assessment of Soil Test Results for Construction Workers
6.28.1 The results of the chemical testing for made ground have been compared against the
assessment criteria derived for construction workers from excavations for pile caps using the
CLEA UK model. Separate assessment criteria have been derived for exposure by construction
workers to made ground in Widnes and Runcorn, the shallow cohesive alluvium on the
saltmarshes and the granular alluvium on the saltmarshes and estuary. Groundworkers are
considered to be the principal human health receptor to contaminants during the construction
works, although it is possble that other receptors such as visitors or trespassers could also be
exposed during the construction works. The assessment criteria for cohesive and granular
alluvium from the CLEA UK model for construction workers (female) are located in Appendix
MQ. Exceedances of the assessment criteria are detailed in the following sections.
Construction Workers - Widnes
6.28.2 Contaminants in made ground exceeding the assessment criteria for construction workers in
Widnes comprised the following:
a. Metals/metalloids; arsenic and barium in Areas A to C at the Golf Course and Ditton
Junction, Gussion Transport/Anglo Blackwells, Railway Land, and Catalyst Trade
Park/Thermphos. Copper was found to exceed the assessment criteria in one sample
of made ground at the Golf Course. Chromium was found to exceed the assessment
criteria in two samples, one from Area B2 at the former Anglo Blackwell site and one
from Area C Catalyst Trade Park. Vanadium was found to exceed the assessment
criteria in one sample from Area B2 at Gussion Transport. Mercury was found to
exceed the assessment criteria in one sample from WS12 in Area C. Nickel exceeded
the assessment criteria in two samples of made ground, one in Area A and one in Area
C.
b. Widespread exceedances for lead were obtained from made ground in Area A at the
Golf Course and Ditton Junction, Area B2 in Gussion Transport/Anglo Blackwells, Area
C & I in the railway land, and Area C in Catalyst Trade Park/Thermphos.
c. Locally elevated Petroleum Hydrocarbons; GRO and EPH, aliphatic and aromatic
hydrocarbons in Area B2 at Gussion Transport/Anglo Blackwells, Area C & I at the
Railway Land and Area C in Catalyst Trade Park/Thermphos and Area A at the Golf
Course.
d. BTEX; elevated benzene concentrations were found in one sample from Area B2 at
Gussion Transport and four samples from Area C in Catalyst Trade Park. The majority
of samples tested did not exceed the detection limit. However, the analytical detection
limit exceeded the assessment criteria for a construction worker. The assessment
criteria derived for toluene was exceeded in one sample from Area B2 and one from
Area C.
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e. The assessment criteria for chloroform, 1,1,1-trichloroethane, carbon tetrachloride, 1,1-
dichloroethane, 1,2-dichloroethane, 1,1,1,2-tetrachloroethane, 1,1,2,2-
tetrachloroethane, trichloroethene, 1,1,2-trichloroethane, 1,1-dichloroethene, cis-1,2-
dichloroethene, vinyl chloride, 1,2,3-trichloropropane, trans-1,2-dichloroethene,
tetrachlorothene, propylbenzene, 4-isopropyltoluene, dichloromethane, carbon
disulphide, 1,2,4-trichlorobenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene and
hexachlorobutadiene were exceeded in Area C at the Catalyst Trade Park.
f. The assessment criteria for chloroform, carbon disulphide and 4-isopropyltoluene were
exceeded in Area B1 (Ditton Road Roundabout) along with carbon disulphide, 4-
isopropyltoluene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene in Area A (St.
Michaels Golf Course).
g. The assessment criteria for carbon disulphide, dichloromethane, propylbenzene,
isopropylbenzene, 4-isopropyltoluene 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene
and sec-butylbenzene were exceeded in Area B2 (Gussion Transport).
h. Locally elevated concentrations of benzo(a)pyrene in individual samples from Area A,
B1, B2 and C. Naphthalene was found to exceed the derived assessment criteria in
thirty one samples from Area A, B and C.
6.28.3 A comparison of the results for Area I2 to the assessment criteria derived for construction
workers indicates that locally elevated concentrations of arsenic and lead, along with EC10-12
and EC12-16 aliphatic and aromatic hydrocarbons, naphthalene, benzo(a)pyrene, benzene,
toluene, isopropylbenzene and 4-isopropyltoluene. A number of chlorinated solvents were
obtained from made ground near the base of the embankments. These comprised carbon
disulphide (BH89, BH96, BH98), and trichloroethene (BH96 and BH98) and styrene, 1,2-
dichloroethane, tetrachloroethane and cis and trans 1,2-dichloroethene (BH98).
6.28.4 A number of the lower analytical detection limits for TPHs and VOCs were above the derived
assessment criteria. For example, the detection limit for TPH using RBAP exceeds the
assessment criteria derived for the EC5-16 aliphatic and EC6-35 aromatic fractions.
6.28.5 An assessment of the exceedances for VOCs compared to the assessment criteria for
construction workers encountered at the Catalyst Trade Park in Area C has been undertaken
using the mean TOC for made ground derived for this site of 8.14%. The results indicate that
concentrations of these contaminants would still exceed the assessment criteria.
6.28.6 As part of the sensitivity analysis, further assessment of the VOC exceedances at Catalyst
Trade Park was undertaken by adjusting the depth of contamination in the CLEA UK model from
0.0m to 0.1m bgl. None of the VOC results exceed the assessment criteria derived for
contaminants present at 0.1m bgl as the assessment criteria derived are up to 5 orders of
magnitude higher that the GACs derived for contaminants present at the ground surface.
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Construction Workers - Runcorn
6.28.7 The contaminants in made ground exceeding the assessment criteria derived for construction
workers were only obtained from localised areas only in Runcorn. These were as follows:
a. Metals/metalloids; arsenic (two samples from Area G), total chromium (one sample from
Area F and one from Area H), vanadium assessment criteria for a female construction
worker (BH133 at 0.50m bgl).
b. Elevated concentrations of lead were encountered in nine samples of made ground
(Area E, F, G and H) and one sample from the glacial deposits (Area F).
c. Locally elevated concentrations of petroleum hydrocarbons above the lower analytical
detection limit were identified in Area E, F, G and H.
d. One elevated concentration of benzene and toluene was obtained from glacial deposits
in Area G (BH126).
e. One exceedance was obtained for MTBE in Area G (BH130).
f. PAHs; locally elevated concentrations of benzo(a)pyrene in individual samples from
Area F (made ground) and Area G (glacial deposits). The lower analytical detection
limit of 50µg/kg for naphthalene was higher than the assessment criteria for all samples
tested. The lower analytical detection limit was exceeded on 12 occasions.
Construction Workers - Saltmarshes
6.28.8 A review of the parameters tested in the sediments from the saltmarshes in Area D (i.e.
between St Helen‟s Canal and Manchester Ship Canal) has been undertaken as this area would
be accessed for the construction of pile caps and piles for the approach road piers.
Assessment criteria have been derived for construction workers on saltmarshes using the
default values for a clay soil from the CLEA UK model and the mean pH and TOC values from
the shallow alluvium derived for Widnes Warth. This is likely to be more conservative (in
particular for organic contaminants) than using the slightly higher values derived for Astmoor
Saltmarsh. Assessment criteria have also been derived for granular alluvium in the estuary and
underlying the cohesive alluvium on the saltmarshes using the mean pH and TOC values for
these soils.
6.28.9 Elevated concentrations of the following contaminants in excess of the assessment criteria were
obtained from the saltmarshes:
a. Arsenic from BH12 to BH14, BH35 to BH40, BH55, BH1005, WS01 to WS03, WS06,
TP20 and TP21 in Area D on Widnes Warth and Spike Island, BH15, BH17, BH33,
BH34 and BH1007 on Astmoor Saltmarsh, and BH31, BH32 and WS04 from Wigg
Island.
b. Lead from BH12 to BH14, BH35 to BH40, BH55, BH1004, BH1005, WS01 to WS03,
WS06, TP20 and TP21 in Area D on Widnes Warth and Spike Island, BH15, BH17,
BH33, BH34 and BH1007 on Astmoor Saltmarsh, and BH18A, BH31, BH32 and WS04
from Wigg Island.
c. Barium from BH12, BH35, BH37, BH38, BH39, BH55, BH1005, TP20, TP21 and WS02
in Area D on Widnes Warth and Spike Island, and BH15 from Astmoor Saltmarsh.
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6.28.10 The detection limits for benzene and a number of SVOC parameters were above their
respective assessment criteria. However, the majority of results obtained for these
contaminants were below the analytical detection limit, with the exception of benzene, 4-
methylphenol, 1,2-dichlorobenzene and dibenzofuran. Benzene was obtained above the lower
detection limit from BH55 at Spike Island and BH32 at Wigg Island. 4-methyl phenol was
obtained from BH40 on Widnes Warth and BH32 at Wigg Island. 1,2-dichlorobenzene was
obtained above the lower detection limit from BH55 at Spike Island. Dibenzofuran was obtained
above the lower detection limit from BH40 on Widnes Warth and BH55 on Spike Island.
Concentrations above the lower detection limit for dibutyl phthalate and bis(2-
ethylhexyl)phthalate were also obtained, although assessment criteria have not been derived for
these contaminants.
6.28.11 The lower limit of detection for the majority of PAHs was greater than the assessment criteria.
However, concentrations of PAHs (including naphthalene and benzo(a)pyrene) above the
detection limit were obtained from the saltmarshes and Wigg Island,.
6.28.12 Concentrations of chloroform and trichloroethene above the assessment criteria were obtained
from BH55 at Spike Island.
6.28.13 Concentrations of arsenic and lead from the alluvial sediments in BH18A and BH32 underlying
Wigg Island Landfill in Area D exceeded the assessment criteria.
6.28.14 One result for arsenic (SS27A at 3.0m bgl) and one for lead (SS28A at 3.0m bgl) exceeded the
assessment criteria derived for granular alluvium in the Estuary in Area D. These two
exploratory holes were located over 500m to the east of the proposed route alignment in the
Estuary.
6.28.15 Concentrations of lead and arsenic from made ground encountered in Area D in Runcorn and
Widnes exceeded the assessment criteria.
Construction Workers - Acute risks
Free & Complex Cyanides
6.28.16 The concentrations of cyanides obtained from the soil chemical testing are shown in Table 6.26:
Table 6.26 – Summary of Cyanide Concentrations in the Project Area
Parameter Range of concentrations for
Widnes and Runcorn (mg/kg)
Total Cyanide 1 to 1,660
Free Cyanide 1 to 3
Complex Cyanide 1 – 17
6.28.17 None of the made ground samples tested in Widnes or Runcorn exceed the acute assessment
criteria derived for free or complex cyanides.
6.28.18 No nationally accepted assessment criteria are currently available to protect construction
workers from total cyanides in soils. Therefore, a comparison of the results for total cyanide
against the assessment criteria for free cyanide has been undertaken, although this is likely to
be conservative.
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6.28.19 The highest result for total cyanide within the project area was 1660mg/kg from BH18A at
0.2m bgl. BH18A is located on the Wigg Island Landfill in Area D Runcorn and close to one of
proposed approach viaduct piers. The result obtained from BH18A at 0.2m bgl for total
cyanide does not exceed the acute assessment criteria derived for free cyanide in soil. It is
understood that excavated material from the former gas works at Bowers Business Park was
deposited into the Wigg Island Landfill and this could be a source of cyanide at this location.
Hydrogen Cyanide
6.28.20 An acute soil assessment criteria has been been derived for hydrogen cyanide gas of
0.12mg/kg for made ground (based on a sandy soil) in Widnes and 0.027mg/kg 0.04mg/kg for
Wigg Island Landfill in Runcorn. This is based on the contaminant source being present at the
ground surface and using the information outlined in the table above Appendix Q which has
been updated with information on soil type and receptors in the Environment Agency‟s SR3
report (2009).
6.28.21 The acute assessment criteria derived for hydrogen cyanide are below the lower analytical
detection limit of <1mg/kg for free cyanide.
6.28.22 As a sensitivity analysis, the depth to contamination was increased to 0.01m bgl. In this case,
none of the results for free cyanide would exceed the acute inhalation assessment criteria for
contaminants in Widnes of 30mg/kg 51mg/kg and 7.9mg/kg 17mg/kg for the Wigg Island Landfill
in Runcorn. However, exceedance of this assessment criteria would be obtained for total
cyanide, from made ground in Area C (seven six samples) and one sample in Area I, and at the
Wigg Island Landfill in Area D (nine six samples). One sample of alluvium in Area C and two at
Wigg Island in Area D would also exceed the assessment criteria.
Arsenic
6.28.23 An acute ingestion assessment criteria for arsenic of 1,000mg/kg 1160mg/kg has been derived
for construction workers. Eight Seven samples of made ground exceeded the acute
assessment criteria for arsenic in Area C in Widnes (WS11A (two samples), WS12, WS29 and
BH65C, and BH103 at Catalyst Trade Park, and BH41 and BH66B at Thermphos). One sample
of made ground also exceeds in Area I in Widnes from BH86.
6.28.24 None of the samples tested exceed the acute assessment criteria of 1000mg/kg 1160mg/kg for
arsenic in Runcorn.
6.28.25 The acute assessment criteria for arsenic was also exceeded in five four samples of made
ground from TP20 and TP21, and two one sample of alluvium in BH39 and BH40 in Area D on
Widnes Warth saltmarsh.
6.29 Phytotoxic Metals
6.29.1 The assessment criteria for potentially phytotoxic metals (namely copper, nickel, zinc) is based
on the soil pH as outlined in MAFF (1998) The Soil Code (Code of Good Agricultural Practice for
the Protection of Soil). The assessment only covers the Project area outside of the saltmarshes
and estuary as these are areas where soft landscaping may be introduced. The saltmarshes is
covered in the Terrestrial and Avian Ecology chapter of the Environmental Statement. As a
mean soil pH of 8 has been derived from the chemical testing, the results have been compared
against the assessment criteria for pH>7.
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Copper
6.29.2 The phytotoxic assessment criteria (PAC) for copper is 200m/kg based on a soil pH>7. In
Widnes there were 74 75 exceedances across the made ground in all areas outside the
saltmarshes (St Michaels Golf Course in Area A to Thermphos in Area C).
6.29.3 In Runcorn only one exceedance of the PAC for copper was encountered from the made
ground, this was from Area G2 Weston Link Junction in BH127 at 2.0m bgl.
Nickel
6.29.4 The PAC for nickel is 110m/kg based on a soil pH>7. In Widnes there were 28 13 exceedances
from the made ground in all areas outside of the saltmarshes (Area A St Michaels Golf Course
to Area C Thermphos).
6.29.5 In Runcorn, no exceedances of the PAC were obtained.
Zinc
6.29.6 The PAC for zinc is 300m/kg based on a soil pH>7. In Widnes there were 95 112 exceedances
from the made ground in all areas outside of the saltmarshes (St Michaels Golf Course in Area
A to Thermphos in Area C).
6.29.7 In Runcorn one exceedance was obtained from the made ground, again this was from BH127 at 2.0m bgl at Weston Link Junction in Area G2.
6.30 Concrete in Aggressive Ground Conditions
6.30.1 The results of pH and sulphate testing of soil samples are summarised in below in Table 6.27
with Design Sulphate (DS) Class for the materials determined in accordance with BRE Special
Digest 1 (2005).
6.30.2 Characteristic Values have been calculated based on the number of samples for each soil type
in accordance with BRE Special Digest 1 to determine the Design Sulphate classification and
Aggressive Chemical Environment for Concrete classification.
Table 6.27 – Summary of Sulphate Testing Results for Runcorn and Widnes
Material pH Total Sulphate
SO4 (%)
2:1 water/soil
extract
SO4 (mg/l)
Peak
DS
Class
Made Ground 2.9 – 12.66 <0.01 – 35 3 – 40,000 DS-5
Drift: Alluvial Deposits 4.1 – 12.37 0.03 – 7.4 <3 – 8,000 DS-5
Drift: Glacial Deposits 7.16 – 11.81 0.03 – 1.9 4 – 7,600 DS-5
Estuarine Deposits (within
inter-tidal area of estuary)
7.3 – 8.8 0.02 – 0.10 32 – 1,300 DS-2
Esturine Deposits
(Saltmarshes)
3.0 – 9.3 0.04 – 0.33 30 – 8,000 DS-5
Bedrock 8.3 – 8.9 - 10 – 110 DS-1
6.30.3 Drawing Number MG_REP_EIA_009/038 shows the exceedance of the DS-1 level for water
soluble sulphate in soil.
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6.31 Buried Water Supply Pipes
6.31.1 An assessment of the chemical testing results against the threshold values outlined in WRAS
(2002) for the installation of buried water supply pipes to proposed office buildings in Widnes
indicates exceedances for arsenic, lead, antimony, chromium, selenium, mercury, PAHs,
petroleum hydrocarbons, sulphate, sulphides, pH from all areas (St Michaels Golf Course in
Area A to Thermphos in Area C).
6.31.2 An assessment was not undertaken for buried plastic water supply pipes in Runcorn on the
basis that no buildings such as toll plazas or offices are proposed for this area.
6.31.3 In addition to the contaminants outlined above but not listed within the WRAS guidance,
elevated concentrations of VOCs have been encountered in soils on, and adjacent to the
Catalyst Trade Park. It is possible these contaminants could affect the integrity of buried plastic
services and lead to tainting of drinking water.
6.31.4 An assessment was not undertaken for buried plastic water supply pipes in Runcorn on the
basis that no buildings such as toll plazas or offices are proposed for this area. This text has
been deleted to reflect changes to the guidance for buried water pipes which has been
discussed below.
6.31.5 An assessment of the chemical testing results against the threshold values outlined in United
Utilities (2011) for the installation or diversion of buried water supply pipes indicates
exceedances of the threshold values for polyethylene pipe (PE) for the following:
a. Area A & B1: petroleum hydrocarbons
b. Area B2: petroleum hydrocarbons, VOCs, SVOCs and BTEX
c. Area C: petroleum hydrocarbons, VOCs, SVOCs, BTEX, phenol, cresols and
chlorinated phenols
d. Area I: petroleum hydrocarbons, VOCs and BTEX
6.31.6 The assessment for buried plastic water supply pipes in Runcorn showed only localised
exceedances for petroleum hydrocarbons and/or SVOCs in Area E, F and G.
6.32 Assessment of Sediments Test Results from the Saltmarshes and Estuary
6.32.1 The results of the chemical testing from the saltmarshes and estuary have been used to assess
the possible impact of mobilising contaminated sediments on ecology in the Estuary.
6.32.2 The „Guidelines for managing water quality impacts within UK European marine sites‟ have
been used to make an assessment of the risk from toxic substances in sediments to organisms
within the estuary. The results of the chemical testing for sediments have been compared to
threshold Interim Sediment Quality Guidelines (ISQGs) and Probable Effect Levels (PELs).
The results are shown in Drawing Nos. MG_REP_EIA_009/050 to MG_REP_EIA_009/055.
Area D - Intertidal Zone
6.32.3 Metals were tested in samples at depths ranging from 0.0m to 9.0mbgl. Widespread elevated
concentrations of metals in excess of their respective ISQG values were encountered in the
intertidal zone. The exception was chromium where only one sample (BH64 at 5.5m bgl)
exceeded the ISQG value. The results indicate widespread elevated concentrations of metals
and metalloids.
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6.32.4 Only localised exceedances of the respective PELs were obtained for metals; arsenic (2
samples), lead (1 sample), mercury (5 samples) and zinc (10 samples). The maximum
exceedance of the PEL for arsenic (41.6mg/kg) was 115mg/kg from SS27A at 3.0m bgl which is
located approximately 500m east of the route alignment.
6.32.5 Testing for BTEX and MTBE were carried out as part of the GRO testing during Phase 5 in all
exploratory holes and on samples obtained from 0.0m to 6.5m bgl. Only toluene in BH58 at
2.5m bgl (0.003mg/kg) was encountered above the lower analytical detection limit. No ISQG
values have been published for BTEX or MTBE.
6.32.6 Samples were tested for Diesel Range Organics (DRO) at seven locations in the estuary during
the Phase 5 site investigation. The peak concentration was 557mg/kg obtained from BH58 at
2.5m bgl. No ISQG values have been published for DRO. Samples tested from BH58 at 1.0m
bgl, BH59 at 1.0-1.5m bgl, BH61 at 2.0-2.5m bgl, BH64 at 1.5m bgl and BH67 2.0m bgl were
also present at concentrations greater than 100mg/kg. Information provided by the laboratory
indicates the DRO was likely to be due to „humic acids (natural organic matter), lube oil or
PAHs.
6.32.7 The chemical testing does not indicate widespread impact by DRO or BTEX compounds in
sediments.
6.32.8 VOCs were tested during Phase 5 investigation at all five borehole locations at depths between
0.25m and 3.25mbgl. Carbon tetrachloride (at BH58 at 2.5m bgl), chlorobenzene (at BH55 at
2.0-2.5m bgl and BH58 at 2.5m bgl), 1,3-dichlorobenzene (at BH55 at 2.0-2.5m bgl), 1,4-
dichlorobenzene (at BH55 at 1.0-1.5m bgl and 2.0-2.5m bgl, BH58 at 2.5m bgl and at BH64 at
3.0m bgl) and 2-chlorotoluene (at BH58 at 2.5m bgl) were encountered above the lower
analytical limit of detection. The highest concentration detected was 0.042mg/kg of
chlorobenzene from BH58 at 2.5m bgl. Carbon tetrachloride was also encountered in this
sample at a concentration of 0.003mg/kg, along with 2-chlorotoluene at a concentration of
0.02mg/kg and 1,4-dichlorobenzene at a concentration of 0.019mg/kg.
6.32.9 VOCs were detected at a limited number of locations and only at depth, i.e. not within the
shallow mobile zone. It is likely that VOCs within the zone of mobile sediments would have
readily volatilised during successive sediment erosion and depositional processes.
6.32.10 PAHs were tested at 14 locations in this area. The lower limit of detection for PAHs in samples
tested during the Phase 3 investigation was higher than the PEL/ISQG values. The results
obtained from Phase 5 investigations encountered exceedances of ISQG values at all borehole
locations and across the full depth range tested between 0.25m and 7.25mbgl.
6.32.11 Phenols were tested at depths between 0.25m and 3.25m bgl during the Phase 3 and 5
investigations, all results were below the lower detection limit. However, the lower detection
limit used by Fugro-Robertson in Phase 3 exceeded the ISQG and PEL values.
6.32.12 Pesticides were tested in 16 samples obtained between 0.0m and 6.0m bgl. None of the results
were above the lower analytical detection limit.
6.32.13 Total cyanides were tested in 16 samples obtained between 0.20m and 4.25m bgl.
Concentrations above the <1mg/kg limit of detection were only encountered in SS27A and
SS28A at 3m bgl only during the Phase 3 site investigation. In both cases the results were
2mg/kg.
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6.32.14 Ammonia (as NH4) was tested at four locations during the Phase 3 site investigation. Samples
were obtained from depths between 0.2m and 4.0m bgl. Whilst all of the samples tested were
observed to have concentrations of ammonia (as NH4) above the detection limit, none of the
concentrations exceeded 1mg/kg. All of the concentrations of ammonia (as NH4) were below
10mg/kg during Phase 5.
6.32.15 PCBs were tested in 21 samples during the Phase 3 investigation, but no none were
encountered above the lower detection limit of 0.3mg/kg. PCBs were also tested in 16 samples
during the Phase 5 investigation. The highest result (0.146mg/kg) for the sample tested in
BH61 (at 3.0-3.45m bgl) exceeds the ISQG for total PCBs of 0.0215mg/kg and the ISQG for
PCBs as Arochlor 1254 of 0.0633mg/kg. The PELs for total PCBs and PCBs as Arochlor 1254
were not exceeded.
Area D - Saltmarshes
6.32.16 Metals/metalloids have been tested at depths ranging from 0.04m to 11.55m bgl on Widnes
Warth and 0.04m to 9.3m bgl at the Astmoor Saltmarsh during the Phase 2 and 4 site
investigations. The highest concentrations were encountered in the upper 2m of saltmarsh
sediments (not including made ground), however, concentrations decreased with depth.
Exceedances of the respective ISQG values for arsenic, cadmium, chromium, copper, lead,
mercury and zinc were obtained associated with the shallow cohesive alluvial sediments at all
exploratory hole locations. Exceedances of the respective PELs were obtained for all metals in
cohesive sediments on the saltmarshes.
6.32.17 The highest concentrations for DRO (tested as DRO by Fugro-Robertson Laboratories as part
of the Phase 4 site investigation and as EPH (DRO) C10 – C40 by ALcontrol Geochem
Laboratory as part of the Phase 4 A site investigation) were obtained from made ground in
BH55 and BH40 (Widnes Warth) at concentrations of 1,127mg/kg and 667mg/kg respectively,
and at WS3 (Wigg Island Landfill) at a concentration of 436mg/kg. In the alluvium, the
maximum DRO concentration was 230mg/kg at BH33 at 0.25m bgl on Astmoor Saltmarsh. No
ISQG values have been published for DRO.
6.32.18 Testing for BTEX and MTBE was carried out as part of the GRO and VOC testing in samples
obtained from 0.2 to 9.3m bgl. BTEX compounds were encountered in made ground from
Widnes Warth at BH40 and BH55 and at the Wigg Island Landfill from BH18A and BH32. The
maximum observed concentration was 13μg/kg of toluene at BH55 (0.2m bgl). In the underlying
alluvial deposits, BTEX compounds were only obtained from BH40 at 1.75m bgl where xylene
(as sum of m, p & o-xylene) recorded at 41μg/kg. MTBE was not obtained from the saltmarshes
in Area D. No ISQG values have been published for BTEX compounds or MTBE.
6.32.19 None of the results for PRO were above the lower analytical detection limit. No ISQGs or PELs
have been published for petroleum hydrocarbons (PRO/GRO or DRO).
6.32.20 SVOCs (excluding PAHs) were encountered within the upper 0.2m of sediment at BH12 and
BH14, where concentrations of bis(2eththylhexl)phthalate of 7 g/kg were obtained. There are
no ISQGs or PELs for phthalates.
6.32.21 PAHs were tested in samples from the majority of exploratory holes but were generally not
encountered above the lower limit of detection from testing undertaken by Fugro-Roberston
Laboratories during the Phase 2 and 4 investigations. However, the lower limits of detection
were above the PEL/ISQG values. Concentrations of PAHs above the lower detection limit
were obtained from made ground at 0.2m bgl in BH31 (Wigg Island), where a maximum
concentration of 15mg/kg for fluoranthene was recorded.
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6.32.22 PAH testing undertaken as part of the SVOC suite of tests during the Phase 1, 2 and 4 site
investigations also encountered concentrations of PAHs above the lower limit of detection at
several locations. The maximum concentration observed on the northern saltmarshes was
57mg/kg of phenanthene at BH40 (0.25m bgl) in made ground. The maximum concentration at
Wigg Island was 15mg/kg of fluoranthene in BH31 (0.2m bgl) from the made ground. The
maximum concentration at Astmoor Saltmarsehes was 2mg/kg of fluoranthene and
benzo(b)fluoanthene at BH17 (0.5m bgl) in the alluvium. All of the observed concentrations
exceed the ISQG/PEL values.
6.32.23 Additional PAH testing using lower detection limits was undertaken during the Phase 6
investigation on six shallow sediment samples (labelled as HDP33 to 38) obtained from
between 0.05m and 0.20m in hand dug pits on the saltmarshes. HDP33 to 38 were located
within 5m of BH33 to BH38 respectively. Concentrations of all PAHs exceeded the ISQG
values for all compounds (where published). The respective PEL values were exceeded by the
majority of PAHs on Astmoor Saltmarsh and four PAHs (acenaphthylene, phenanthrene,
benzo(a)pyrene, dibenzo(a,h)anthracene) on Widnes Warth.
6.32.24 Phenols were encountered above the lower analytical limit of detection in three of the samples
analysed from this area; 1mg/kg of 4-methylphenol was obtained from BH32 at 8.5m bgl in the
alluvium at Wigg Island and BH40 at 1.75m in the alluvium in Widnes. No ISQG values have
been published for phenolic compounds.
6.32.25 The VOCs tested during Phase 4 investigation (excluding BTEX and MTBE) were below the
lower analytical detection limit in all samples tested with the exception of BH55 on Spike Island,
where chloroform, trichloroethene and tetrachloroethene were obtained from the made ground
(with a maximum concentration of 22μg/kg of chloroform at 0.6m bgl) and trichloroethene and
tetrachloroethene were obtained from the alluvium (with a maximum concentration of 8μg/kg of
tetrachloroethene at 5.6m bgl). There are no ISQG values published for these VOC
compounds.
6.32.26 Organochlorine and organophosporous pesticides were tested at 17 locations on Widnes Warth
and four locations at Astmoor Saltmarsh. The lower limits of detection for these pesticides were
all above the ISQG and PEL values. Concentrations of organochlorine pesticides above the
lower limit of detection (specifically DDT and lindane) were observed at WS03 at 0.2m bgl on
Widnes Warth. No pesticides were detected above the lower analytical detection limit on
Astmoor Saltmarsh.
6.32.27 No target values have been obtained for ammonium (as NH4) or ammoniacal nitrogen (as N).
The highest concentrations of ammonia (when expressed as N) in the made ground were
obtained from the Wigg Island Landfill with the highest concentration of 498.7mg/kg obtained
from WS03 at 0.8m to 0.9m bgl). The highest concentration from the made ground at Widnes
Warth was 14.2mg/kg from BH55 at 0.6m bgl. Within the alluvium, the highest concentrations
were obtained beneath the Wigg Island Landfill where 317.42mg/kg of ammonium was recorded
from WS03 at 1.4m to 1.6m bgl.
6.32.28 Total PCBs were tested in samples of cohesive alluvium from 4 locations on Astmoor Saltmarsh
and 18 locations on Widnes Warth. The highest concentration was 0.3mg/kg from BH36 at
0.25m bgl, this exceeds the ISQG for total PCBs of 0.0215mg/kg and the PEL for total PCBs of
0.189mg/kg. Eight of the results for total PCBs from Widnes Warth exceed the ISQG, all of
these were obtained from 0.25m bgl or shallower.
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Distribution of Contaminants on Saltmarshes and Estuary
Area D - Intertidal Zone
6.32.29 Potential contaminants of concern identified within the intertidal zone were heavy
metal/metalloids and PAH compounds.
6.32.30 No specific trend in sediment grain size with depth has been identified within the intertidal zone
alluvial deposits, this could be attributable to channel switching geomorphological processes
and cross-bedding of sediments. Therefore, it is likely that contaminant concentrations would
be poorly correlated with depth.
6.32.31 The relationship between metals and PAHs with TOC within the sediment was assessed using
regression (R2) values as a measure for the degree of correlation within a data series. Low R
2
values were obtained for the majority of metal/metalloid contaminants when compared to TOC
which indicates the degree of correlation between metals/metalloids and TOC is poor.
However, the data does show an overall increase in contaminant concentrations with TOC and
although these data correlations are poor, the data trends for metals/metalloids do appear
consistent.
6.32.32 With the exception of one data point, a good relationship (R2) between TOC and PAH
compounds was identified from the Phase 5 investigation chemical testing data.
6.32.33 The general trend indicates that metals/metalloids and PAHs tend to concentrate within
cohesive sediments and those with higher TOC, although no specific relationship with depth
was identified.
Area D - Saltmarshes
6.32.34 Potential contaminants of concern in this area comprise metals/metalloids, PAHs, ammonium
and pesticides.
6.32.35 The alluvial sediments identified within the upper 1.9m to 2.7m on the saltmarshes are cohesive
and in some cases have a high organic content. The concentrations of contaminants were
significantly higher in the shallow cohesive alluvial sediments than the underlying coarser
alluvium where there were no exceedances of the PEL values.
Statistical Assessment of Sediment Concentrations in the Estuary from Scouring
6.32.36 Data for the intertidal zone was divided into mobile (above 0.7m AOD) and scoured depth zones
(sediments above -1.3m AOD). In order to assess the potential impact from deeper scouring
than has been predicted at present, two additional 2m depth zones were created, these were for
sediments above -3.3m AOD and sediments above -5.3m AOD. The data from the Phase 5
investigation was used for the PAH assessment due to the lower analytical detection limits.
6.32.37 It is assumed that scoured sediments would mix with those already in the mobile zone, this is
shown in Figure 6.9 below. Statistical tests were undertaken on data from mobile sediments
and for all sediments from surface down to the base of each of the scoured horizons. A total of
four datasets were created representing the mobile zone for each of the scenarios shown in
Figure 6.8 below.
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Figure 6.8 – Conceptualisation of Scouring and Sediment Mixing.
6.32.38 The 95th percentile of contaminant concentrations for each dataset was calculated using the
mean value test from CLR7 (2002) and compared to that for the zone of mobile sediments. The
results of the statistical tests are shown in Figures 6.9 and 6.10 below for metals and PAHs
respectively.
Figure 6.9 - Comparison of 95th
Percentile Metal Concentrations to ISQG & PEL
1 4
Zone of Mobile Sediments
0.7mAOD
Anticipated Scour Zone
-1.3mAOD
Possible Additional Scour
-3.3mAOD
Possible Additional Scour
-5.3mAOD
2 3
Scour
Hole
Comparison of 95th Percentile Metal Concentrations Derived for Various Levels
0.10
1.00
10.00
100.00
1000.00
Hg As Cr Cu Zn Cd Pb
Contaminant
Co
nc
en
tra
tio
n (
mg
/kg
)
Above0.7mAOD
Above -1.3mAOD
Above -3.3mAOD
Above -5.3mAOD
PEL
value
ISQG
value
KEY
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Figure 6.10 - Comparison of 95th
Percentile PAH Concentrations to ISQG & PEL
6.32.39 The 95th percentiles derived for metals and PAH in the intertidal zone already exceed the ISQG
values, with the exception of chromium and copper. A number of PAHs also exceed PEL
values.
6.32.40 The results from this assessment indicate a possible slight increase in the concentration of
arsenic with scouring, although this increase would be very small. Although the chemical
testing results for arsenic in the mobile estuary sediments already exceed the ISQG, they would
not exceed the PEL.
6.32.41 The assessment for acenaphthylene, chrysene, benzo(a)pyrene and dibenzo(a,h)anthracene
indicates that a very slight increase in concentration could be obtained from scouring down to -
1.3m AOD. However, the assessment indicates that scouring to greater depths could result in a
reduction for these PAHs concentrations within the mobile zone.
6.32.42 The results of the statistical assessment indicate that scouring of deeper sediments and mixing
with sediments in the mobile zone would produce very little change in metal contaminant
concentrations, and for PAHs a general trend of decreasing concentrations is likely to be
obtained from successive scouring.
6.32.43 Even if contaminants were associated with particular horizons in the area of scouring, their
liberation from scouring would be a one-off occurrence. However, the results indicate that
scouring would not produce any additional exceedances of ISQG or PEL values within the near-
surface mobile sediment zone in the Project area.
Comparison of 95th Percentile PAH Concentrations Derived for Various Levels
0.01
0.10
1.00
Nap
htha
lene
Ace
naph
thylen
e
Ace
naph
then
e
Fluor
ene
Ben
zo(a
)ant
hrac
ene
Chr
ysen
e
Phe
nant
hren
e
Ant
hrac
ene
Fluor
anth
ene
Pyr
ene
Ben
zo(a
)pyr
ene
Diben
z(a,
h)an
thra
cene
Contaminant
Co
nc
en
tra
tio
n (
mg
/kg
)Above0.7mAOD
Above -1.3mAOD
Above -3.3mAOD
Above -5.3mAOD
PEL
value
ISQG
value
KEY
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6.33 Assessment of Soil Leachate Test Results
6.33.1 Soil leachate testing was undertaken on soil samples obtained during Phase 1, 2, 4, 4a and 6
site investigations. Samples were selected for leachate testing on the basis of possible
contamination identified during the site works or from areas previously identified from soil
testing. This section has been updated to reflect changes in a number of the assessment
criteria. The following results were obtained.
6.33.2 The soil leachate testing results have been compared against the currnet assessment criteria.
Metals
6.33.3 Elevated concentrations of metals in excess of the water quality thresholds were obtained in
localised areas in Widnes and on Wigg Island from the leachate testing. Elevated
concentrations of arsenic, copper, and mercury were also encountered in samples tested from
Runcorn to the south of the Manchester Ship Canal. A review of the results for metals in
leachate is shown in Table 6.28 and 6.29 below:
Table 6.28 – Distribution of Metals in Leachate
Parameter Chromium Lead Arsenic Vanadium Zinc Cadmium Copper
EQS (μg/l) 15 32 25 7.7 25 100 40 2.5 0.2 5
DWS (μg/l) 50 10 10 N/A N/A 5 2000
Range of
Exceedances*
(μg/l)
18-720 19-6900
6600 12-3100 120
42-
140000 2.7-24000 6-320
Range of Depths
of Exceedances
*(m bgl)
0.2-1.0 0.2-6.0 0.2-9.8 0.85 0.2-7.0 0.9-6.0 0.2-9.8
Strata at
Exceedances*
MG, ALL,
PEAT
MG,
ALL,
PEAT
MG,TS,
ALL,
PEAT
MG MG MG MG, ALL,
PEAT
Areas where
Exceeded* A, C, D
A, B1, C,
D All B2
A, B1, B2,
C, D, I
A, B1, C,
B2, I
A, B1, B2, C,
D, E, F, G2, I
Location of Peak
Result
WS2 0.2m
1.7-1.95m
bgl
Area D
BH32
6m bgl
Area D
WS2
1.83m
1.7-1.95m
bgl
Area D
WS17
0.85m bgl
Area B2
BH7
3 3m bgl
Area A
BH7
3 3m bgl
Area A
BH64
0.2 bgl
Area A
Strata of Peak
Result MG MG MG MG MG MG MG
Notes Only one
exceedance
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Table 6.29 – Distribution of Metals in Leachate (Updated)
Parameter Aluminium Antimony Iron Manganese Nickel Selenium Mercury
EQS (μg/l) N/A N/A N/A N/A 20 N/A 0.3 0.05
DWS (μg/l) 200 5 200 50 20 10 1
Range of
Exceedances*
(μg/l)
1200-7400
50 (one
value only)
None
None None 21-1000 11-45 0.8-10.05.1
Range of
Depths of
Exceedances
*(m bgl)
0.25-1.0 0.2 N/A N/A N/A 0.3-6.0 0.2-9.8 0.25-3.0
Strata at
Exceedances* ALL, PEAT MG N/A N/A N/A MG ALL, MG
MG, ALL,
PEAT
Areas where
Exceeded* D D N/A N/A N/A
A, B2, C,
I
B1, B2, C,
D, I B2, C, D, H
Location of
Peak Result
BH36
1mbgl
Area D
WS2
0.2mbgl
Area D N/A
N/A N/A BH73
3.0mbgl
Area A
BH56
9.8mbgl
Area C
BH132
1mbgl
Area H
BH34
0.25m bgl
Area D
Strata of Peak
Result ALL MG N/A N/A N/A MG ALL MG ALL
Notes
Testing at 7
6 locations
on
saltmarshes
One test
undertaken
One test
undertaken
One test
undertaken
Ground Conditions – MG=Made Ground, ALL=Alluvium, PEAT=Peat, TS=Top Soil
* - Exceedance refers to the lowest of EQS or DWS
pH & Sulphate
6.33.4 Nineteen Thirteen leachate samples recorded pH values in excess of the upper target value of
pH 8.5 9. The highest pH value of 12.6 was obtained from made ground in Area C in BH52 at
1.0m bgl. Alkaline pH above 8.5 9 was encountered in Runcorn from WS2 WS1 and BH32 at
the Wigg Island Landfill (in Area D) in the from made ground in BH132 at M56 Junction 12 (Area
H).
6.33.5 Four Seven leachate samples recorded pH values in excess of the lower than the target value
of 6 pH 6. The lowest value of pH 4.3 was recorded from made ground in Area D in BH40 at
1.0m 0.75m bgl on Widnes Warth.
6.33.6 The DWS for sulphate is 250mg/l. The highest concentrations of sulphate in soil leachate were
1600mg/l from BH71 (4.5m bgl) and BH73 (3.0m) at St Michaels Golf Course in Area A.
Results exceeding 250mg/l were obtained from the made ground in Widnes, in Area A, B1, B2,
C and the existing road embankments in Area I.
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Hydrocarbons
6.33.7 Leachable ethylbenzene was detected at 27 16μg/l in BH132 at 1m bgl in Area H M56 Junction
12. No water quality standards have been obtained for ethylbenzene. Due to the leachate
preparation process, it is likely that the volatile nature of these compounds would result in a
lower concentration being recorded during testing.
6.33.8 Where encountered, TPH was present in leachate in the heavier range of EC12-C35 fraction or
as diesel range (EPH) within the Catalyst Trade Park in Area C and in BH132 at 1.0m bgl at
M56 Junction 12 in Area H. Leachable TPH was recorded above the lower detection limit in
three locations, BH71 in Area C on the Thermphos site, BH91 beneath the road embankment in
Area I and BH132 in Area H at M56 Junction 12 in Runcorn.
6.33.9 Leachable GRO was detected in made ground from BH98 at 9m bgl immediately north of
Catalyst Trade Park in Area C (99µg/l) and at BH132 at 1.0m bgl in Area H M56 Junction 12,
Runcorn (22µg/l). Leachable MTBE was also detected in this sample.
6.33.10 BH132 was located close to the eastbound slip road off the M56 at Junction 12 and such results
could have resulted from a fuel spill. However, no visual or olfactory evidence of hydrocarbons
were noted on the exploratory hole log for BH132.
6.33.11 Volatile organic compounds (other than BTEX compounds which were included as part of
TPHCWG testing) were not scheduled for leachate testing as it was considered the results
would not be representative due to volatilisation during the leachate preparation by the
laboratory.
SVOCs
6.33.12 The highest PAH results in leachate were obtained from Widnes. However, the only locations at
which any PAH compounds were found at concentrations exceeding 5 1.2µg/l (saltwater EQS
for naphthalene) were as folllows:
a. Range of PAHs in made ground from BH71 at Thermphos in Area C and BH54D at
Gussion Transport in Area B2.
b. Napthalene in the made ground from BH54D at Gussion Transport in Area B2 and
cohesive alluvium in two samples of alluvium from BH36 on Widnes Warth in Area D.
c. Made ground in BH32 and WS2 from the Wigg Island Landfill in Area D in Runcorn.
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6.33.13 In BH71 and BH54D, the PAHs exceeding 5 1.2μg/l comprised acenaphthene, acenaphthylene,
anthracene, fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene. At all other
locations, PAHs did not exceed 5 1.2µg/l. A summary of the individual PAH exceedances is
provided below in Table 6.30:
Table 6.30 – PAHs detected above 5 1.2µg/l
Exploratry hole BH32 BH36 BH36 BH54D BH71 BH71 WS2
Depth (m bgl) 1.00 0.25 1.00 3.00 4.50 5.50 1.83
Strata MG ALL ALL MG MG ALL MG
Area D D D B2 C C D
PAH (μg/l)
Acenaphthene <1 4.0 2.0 <1 65.0 700.0 2.0
Acenaphthylene <1 2.0 <1 <1 0.8 7.8 <1
Anthracene <1 <1 <1 <1 12.0 14.0 <1
Fluoranthene <1 <1 <1 <1 10.0 18.0 <1
Fluorene <1 3.0 <1 2.0 52.0 300.0 2.0
Naphthalene 32.0 62.0 6.0 21.0 0.6 8.3 26.0
Phenanthrene <1 4.0 3.0 2.0 65.0 300.0 3.0
Pyrene <1 <1 2.0 <1 5.4 7.7 <1
Ground Conditions – MG=Made Ground, ALL=Alluvium
Concentrations above 5 1.2µg/l shown in bold, other values shown in grey
6.33.14 In addition, exceedance of the EQS for benzo(a)pyrene was also obtained from made ground at
BH86 (6m bgl) in Area I, alluvium at BH71 (5.5m bgl) in Area A and made ground at BH133
(0.5m bgl) in Area H. Exceedances of the EQS for other PAHs have also been obtained in
localised areas from Area A, B2, C, D, and I.
6.33.15 Other SVOCs were detected in leachate from made ground in BH71 in Area A. These SVOCs
comprised 2-methylnaphthalene, carbazole, dibenzofuran and bis(2-ethylhexyl)phthalate, and
are summarised in Table 6.31:
Table 6.31 – SVOCs in Soil Leachate Samples
Exploratry hole BH32 BH35 BH35 BH36 BH36 BH54D BH71 BH71 WS2 WS21
Depth (m bgl) 6 0.25 1 0.25 1 3 4.5 5.5 1.7 - 1.95 0.5
Strata MG PEAT ALL ALL ALL MG MG ALL MG MG
Area D D D D D B2 C C D D
PAHs (μg/l)
2Methynaphthalene <1 <1 <1 5 2 21 <5 <10 3 <1
Bis(2ethylhexyl)phthalate 81 <5 <5 <5 <5 <1 <5 <10 <5 <1
Carbazole - - - - - <1 77 40 - <1
Dibenzofuran <1 1 1 2 <1 <1 87 230 1 <1
Ground Conditions – MG=Made Ground, ALL=Alluvium
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6.34 Assessment of Groundwater Test Results
6.34.1 The results of the groundwater chemical analysis are included in Appendix LP. Where
necessary, the following text has been updated to reflect changes in the assessment criteria
and additional information obtained (Round 11 to 14 and Phase 7). A review of the results is
outlined below.
Temporal Variations in Groundwater Chemistry
6.34.2 An assessment has been undertaken to demonstrate the variation in inorganic contaminant
concentrations over time in groundwater. The information has been obtained from three
monitoring wells (BH1001, BH1003 and BH1004) in Widnes as these wells have been amongst
the most frequently sampled and were installed into different horizons. The results for arsenic,
boron and barium have been used to demonstrate these variations as they were encountered at
high enough concentrations at these locations to demonstrate possible trends. The assessment
is based upon the groundwater testing data obtained from all rounds of investigation for these
three monitoring wells from which a wider range of inorganic compounds were also detected.
6.34.3 Samples from these monitoring wells have been tested on eight 11 occasions (excluding rounds
for which „total‟ rather than „dissolved‟ metals were tested by the laboratory). The response
zones for these wells are located in the following horizons; BH1001 in made ground, BH1003 in
the alluvium, and BH1004 in the Sherwood Sandstone aquifer. The results are shown below in
Figure 6.11:
Figure 6.11 – Variation in Metal Concentrations Over Time for Different Groundwater Horizons
(Updated)
6.34.4 Although inorganic concentrations have varied to some degree over time, no significant or
consistent trend of either increasing or decreasing concentrations has been identified in the
results. The degree of variability is greatest in the made ground and alluvium, although the
more soluble species (such as boron) show a lesser degree of variation. Regardless of horizon,
the inorganic determinands show a similar overall consistent pattern in their concentrations.
6.34.5 Variable results have been obtained for organic contaminants in groundwater where
encountered. Some contamiants have shown no consistent trend, whilst others have been fairly
consistent. This is illustrated by the results for BH1003 in Area C immediately south of Catalyst
Trade Park which are shown in Figure 6.12:
0.0001
0.0010
0.0100
0.1000
1.0000
10.0000
Co
nce
ntr
atio
n (
mg/
l)
BH1001 (Made Ground)
As_mg/l Ba_mg/l B_mg/l
0.0001
0.0010
0.0100
0.1000
1.0000
10.0000
Co
nce
ntr
atio
n (
mg/
l)
BH1003 (Alluvium)
As_mg/l Ba_mg/l B_mg/l
0.0001
0.0010
0.0100
0.1000
1.0000
10.0000
Co
nce
ntr
atio
n (
mg/
l)
BH1004 (Bedrock)
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Figure 6.12 – Variation in Chlorinated Hydrocarbon Concentrations over Time (Updated)
6.34.6 The variation in the results for BH1003 shown in Figure 6.12 does not appear to be related to
the change in laboratories from Fugro-Robertson to Alcontrol. The method of groundwater
purging and sampling has remained the same between Round 2 and Round 10 13 (the period
of time shown in Figure 6.12 above).
Results of Groundwater Testing
6.34.7 The results of the chemical testing from the groundwater samples obtained (with the exception
of those metal concentrations obtained by the „total‟ analysis method) have been compared to
the EQS and DWS. The EQS and DWS values are shown in Appendix MQ. The results are
summarised in the following sections. The tables and information presented in the following
sections are based upon data obtained during Rounds 1 to 10 14 and during the Phase 4, 4A,
and 6 and 7 site investigations. As many locations have been sampled on more than one
occasion, only the maximum values identified at each location have been used. Furthermore,
where the maximum value is less than the detection limit and the detection limit exceeds the
EQS or DWS, the data has not been included as an exceedance within the statistics shown.
6.34.8 The groundwater testing results have been compared against the current assessment criteria.
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Metals – Arsenic, Iron, Vanadium and Zinc
6.34.9 Elevated concentrations of iron, arsenic, vanadium and zinc exceeding the respective EQS and
DWS values were obtained from the Widnes side of the estuary from all aquifer units. Locally
elevated concentrations were obtained in Runcorn for each of these metals, although arsenic
concentrations did exceed the DWS across the Project area. Table 6.32 below summarises the
occurrences of these determinands in the Project area:
Table 6.32 – Elevated Arsenic, Iron, Vanadium and Zinc Concentrations in Groundwater
(Updated)
Arsenic Iron Vanadium Zinc
EQS (mg/l) 0.025 1 0.1 0.04
DWS (mg/l) 0.01 0.2 N/A 5
Maximum
Concentration (mg/l)
9.9 340 0.37 470
Location of
Maximum
WS41
Alluvium
Area C
WS17
Made Ground
Area B2
WS17
Made Ground
Area B2
BH73
Made Ground
Area A
% Sample above
threshold in Project
Area
EQS
DWS
55% 42%
68% 57%
27% 38.5%
38% 25%
1%
-
28% 25.5%
4% 3%
Locations where
EQS exceeded (%
of samples
exceeding EQS in
brackets)
Widnes Areas A B1
B2 C D I1 (89%
97%)
Runcorn Area D
(11% 3%)
Widnes Areas A B1
B2 C D (81% 91%)
Runcorn Area D F
(19% 9%)
Widnes Area B1 B2
(100%)
Widnes Areas A, B1
B2 C D I2 (90%
97%)
Runcorn Areas D G
(10% 3%)
Locations where
DWS exceeded (%
of samples
exceeding DWS in
brackets)
Widnes Areas A B1
B2 C D I1 (85%
95%)
Runcorn Areas D E
F (15% 5%)
Widnes Areas A B1
B2 C D (87% 88%)
Runcorn Areas D F
(13% 12%)
- Widnes Areas A B1
C (100%)
Strata where
threshold exceeded
Glacial
Alluvium
Made Ground
Sandstone
Glacial
Alluvium
Made Ground
Sandstone
Made Ground
Glacial
Alluvium
Made Ground
Sandstone
6.34.10 The distribution of these metals is shown in Drawing Numbers MG_REP_EIA_009/056 to
MG_REP_EIA_009/059.
6.34.11 Locally elevated concentrations of arsenic, iron and zinc were obtained during Round 14 from
made ground and alluvium in Area C, D and I, although the results did not exceed the highest
values outlined in Table 6.32 above. Significantly elevated concentrations of arsenic (>1mg/l)
were obtained from alluvium at Catalyst Trade Park (Area C) and Spike Island (Area D) during
Round 14. The results from Round 14 are not considered to have a significant effect on the
information shown in Table 6.32.
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Metals – Antimony, Copper, Cadmium, Mercury
6.34.12 The results obtained for antimony, copper and cadmium show widespread exceedance of the
EQS values, and not just areas identified as previously having industrial uses or areas of waste
deposition. These elevated concentrations were encountered in horizons including the made
ground, alluvium and Sherwood Sandstone, their distribution is shown in Drawing Numbers
MG_REP_EIA_009/060 to MG_REP_EIA_009/063 and summarised in Table 6.33 below.
Table 6.33 – Elevated Antimony, Copper, Cadmium and Mercury Concentrations in
Groundwater (Updated)
Antimony Copper Cadmium Mercury
EQS (mg/l) N/A 0.005 0.0025 0.0002 0.0003 0.00005
DWS (mg/l) 0.005 2 0.005 0.001
Maximum
Concentration (mg/l)
0.89 3.78 0.53 5.4 0.0015
Location of Highest BH52 BH53A
Made Ground
Area B1
BH73 BH53A
Made Ground
Area A B1
BH74
Made Ground
Area A
WS28
Made Ground
Area I1
% Above EQS in
Project Area
N/A 44% 54.5% 24% 95% 18% 68%
% Above DWS in
Project Area
20% 29% 0.25% 23% 30% 1% 2%
Locations where
EQS exceeded
(% of samples in
brackets)
- Widnes Areas A B1
B2 C D I1 (70%
87%)
Runcorn Areas D E
F G (30% 13%)
Widnes Areas A
B1 B2 C D I1 I2
(65% 87%)
Runcorn Areas D E
F G (35% 13%)
Widnes Areas A B1
B2 C D I1 (55% 69%)
Runcorn Areas D E F
(45% 31%)
Locations where
DWS exceeded
(% of samples in
brackets)
Widnes Areas B1
B2 C D (91% 97%)
Runcorn Area E
(9% 3%)
None Widnes Area
B1 (100%)
Widnes Areas A
B1 C D I1 I2 (64%
78%)
Runcorn Areas D E
F (36% 12%)
Widnes Area I1 B2
(100%)
-
Strata where
threshold exceeded
Made Ground
Alluvium
Glacial
Sandstone
Made Ground
Alluvium
Glacial
Sandstone
Made Ground
Alluvium
Glacial
Sandstone
Made Ground
Alluvium
Glacial
Sandstone
6.34.13 The analytical detection for mercury used during earlier rounds of groundwater testing by Fugro-
Robertson Laboratories (Rounds 1 to 3) was 1μg/l which is the same as the DWS and greater
than the EQS. Only three of the results obtained by Fugro-Robertson Laboratories exceeded
the DWS. The results obtained from the chemical testing by Alcontrol using a lower detection
limit indicates exceedances of the DWS and EQS for mercury in the Project area.
6.34.14 The highest concentration of antimony outlined in Table 6.33 was obtained from BH53A during
Round 13. Groundwater samples have been obtained from BH53A on four occasions, however,
antimony was only tested at this location during Round 13.
6.34.15 The results for cadmium in groundwater from the Round 4 chemical testing were all recorded as
0.01mg/l by the laboratory. Although not shown in the results, this appears to have been the
lower analytical detection limit for cadmium.
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6.34.16 Locally elevated concentrations of antimony, cadmium and copper were obtained during Round
14 from made ground and alluvium in Area C, D and I. The results for cadmium (7μg/l) from
made ground in WS52 (Area I) is higher than the peak value outlined in Table 6.33 above. The
result for cadmium from the bedrock in BH43 (1.1μg/l) which is located towards the north of
Area C is slightly above the EQS. However, the results for cadmium during previous rounds of
testing at BH43 have been below the detection limit and the results from Round 14 do not
appear to be representative. Overall, the results from Round 14 are not considered to have a
significant effect on the information shown in Table 6.33.
Metals – Chromium, Lead, Aluminium, Nickel and Selenium
6.34.17 Chromium concentrations exceeding the EQS value of 0.015 0.032mg/l were obtained from the
alluvium in BH57 (Area C), and BH57 WS3 (Area D) and BH146 (Area I) and, the made ground
in WS17 (Area B2) and sandstone bedrock in BH24 (Area E) BH93 (Area A), BH76 (Area B1)
and BH53A (Area B1). The results from BH146, BH53A and BH55 None of the results for
chromium exceeded the DWS.
6.34.18 Concentrations of lead in excess of threshold values are summarised in Table 6.34 below:
Table 6.34 – Concentrations of lead exceeding threshold values (Updated)
Area Geology Peak Lead (mg/l) Threshold Exceedances
BH73 Area A Made Ground 0.93 EQS & DWS
BH74 Area A Made Ground 1.1 EQS & DWS
BH75 Area A Alluvium 0.097 EQS
BH76 Area B1 Made Ground 0.41 EQS & DWS
WS07 Area C Made Ground 4.0 EQS & DWS
WS10A Area C Made Ground 0.061 EQS & DWS
WS43 Area C Made Ground 0.82 EQS & DWS
WS29 Area C Made Ground 0.013 EQS & DWS
WS46A Area C Made Ground 0.01 EQS
WS38 Area C Alluvium 0.0079 EQS
BH107 Area C Alluvium 0.0095 EQS
WS02 Area D Alluvium 4.0 EQS & DWS
WS03 Area D Alluvium 0.05 EQS & DWS
BH50 Area I Made Ground 0.02 EQS & DWS
EQS = 0.0072mg/l, DWS = 0.01mg/l
6.34.19 Concentrations of aluminium in groundwater were below the DWS (0.2mg/l) with the exception
of 0.78mg/l from BH52 and 6.83mg/l from BH59 (made ground in Area B2), 0.33mg/l from BH12
(alluvium in Area D), 0.31mg/l from WS14 (made ground in Area C), 0.26mg/l from BH25
(sandstone in Area E), and 0.22mg/l from BH40 (sandstone in Area D).
6.34.20 Nickel concentrations exceed the DWS (0.052mg/l) and EQS (0.032mg/l) in Area A, B1, B2, C
and D and I in Widnes and at Astmoor Saltmarsh in Area D in made ground, alluvium and
glacial deposits. The highest recorded concentrations (above 0.1mg/l) occur within Areas A,
B1, B2 and C, with the highest from the made ground in BH74 (0.88mg/l) at St. Michaels Golf
Course (Area A).
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6.34.21 Elevated concentrations of selenium exceeding the DWS of 0.01mg/l have been obtained from
all groundwater horizons in Widnes and Runcorn. The highest concentration of 0.6 2.59mg/l
was obtained from the made ground in WS25 BH60 at Anglo Blackwells (Area B2).
6.34.22 The distribution of elevated lead and nickel in groundwater is shown in Drawing Nos.
MG_REP_EIA_009/065 and MG_REP_EIA_009/066 respectively.
6.34.23 Locally elevated concentrations of chromium, nickel and selenium were obtained during Round
14 from made ground and alluvium in Area C, D and I although the results did not exceed the
highest values from the samples discussed above.
pH
6.34.24 A plan showing the pH values in groundwater across the study area is shown in Drawing
Number MG_REP_EIA_009/067. The plan shows that in the majority of locations, pH is within
the range of 6-8.5 6.9 and does not exceed the EQS.
6.34.25 Isolated occurrences of low pH (acidic) groundwaters have been encountered in BH75 within
the alluvium in Area A, BH59 and WS17 within the made ground in Area B2 at Gussion
Transport and W29 in Area C in Widnes.
6.34.26 High pH (alkaline) conditions have been identified in Widnes and localised areas of made
ground identified in Area D on Widnes Warth and Astmoor Saltmarsh (Wigg Island Landfill).
The higher pH values are likely to be attributed to the former alkali industry and deposition of
alkali waste. The highest pH of 12.93 was obtained from made ground at WS28 in Area I.
Alkaline pH has also been obtained from the alluvium in Widnes (Areas A, C and D) with the
highest pH of 12.8 from BH62 (Area A).
6.34.27 Acidic pH values outside of the DWS range occur at BH108 and BH41 in alluvium at Catalyst
Trade Park (Area C), BH59 and WS17 within the made ground in Area B2 at Gussion Transport
in Widnes, and at BH34 in sandstone on Astmoor Saltmarsh in Area DBH75 in alluvium from St
Michaels Golf Course (Area A), BH59 and WS17 in made ground from Area B2 and WS29 in
made ground from Catalyst Trade Park (Area C). The lowest pH value of 5.82 4.83 was
obtained from WS17 WS29 in Area C.
6.34.28 The results obtained from pH testing do not indicate there to be any consistent rising or falling
trends in the data.
Chloride
6.34.29 To assess the effects of saline surface waters on groundwater, chloride concentrations have
been normalised against sodium to remove the effect of seawater. This has been undertaken to
assess whether chloride could be related to sources other than seawater.
6.34.30 Drawing No. MG_REP_EIA_009/068 shows chloride levels at more than 40% from the seawater
standard. This value was derived from an inspection of the chemical testing data as it enabled
anomalies and areas of potential chloride contamination to be identified (i.e. those unlikely to be
related to seawater).
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Sulphate
6.34.31 The EQS and DWS value for sulphate in groundwater is 250mg/l. The highest sulphate
concentration was 8,691mg/l from WS02 at the Wigg Island Landfill in Area D (alluvium).
Elevated The highest values were obtained in Widnes (Areas A to D and I) and Area D in
Runcorn and areas of waste deposition in Runcorn (Wigg Island Landfill in Area D). One locally
elevated result was obtained from sandstone in Area G. No distinct relationship between
concentrations of sulphate and the geological horizon were observed, and a high degree of
variability was recorded. Sulphate values are elevated across the Project area.
Cyanide
6.34.32 Total cyanide concentrations exceeded the DWS of 0.05mg/l at several locations in Areas B1,
B2, C and D. The maximum concentrations of total cyanide were obtained from alluvium in
WS02 and WS03 (in Area D beneath the Wigg Island Landfill). In Widnes, the highest
concentration was obtained from made ground in WS10A (Area C).
6.34.33 A limited amount of testing was undertaken for free cyanide for the Orders ES. Free cyanide
was detected at a concentration greater than the DWS at BH12 (alluvium at Widnes Warth Area
D) at a concentration of 0.07mg/l.
Ammonia
6.34.34 Concentrations of ammonia in groundwater were reported as ammonia (as NH3,) ammonium
(as NH4) and ammoniacal nitrogen (as N) by laboratories. The results for each of the reporting
methods were converted to ammonia (as N) for comparison. The EQS for ammonia (as N) is
0.021mg/l.
6.34.35 The concentrations encountered are shown in Drawing Number MG_REP_EIA_009/069.
Elevated concentrations of ammonia are found across the project area, and were not confined
to any part of the site. Groundwater in all response zones, both in Runcorn and Widnes, was
affected.
6.34.36 Overall concentrations were higher on the Widnes side of the estuary, and the highest
concentrations of ammonia were identified in Area C at Catalyst Trade Park. The highest
recorded concentration was 588.4mg/l obtained from the glacial clay at BH47 in Area C.
BTEX and Petroleum Hydrocarbons
6.34.37 The DWS for benzene and EQSs for benzene, toluene and xylene (BTX) for estuarine waters
are shown in Table 6.35. No published EQS or DWS are available for ethylbenzene.
6.34.38 The lower analytical limit for benzene was greater than the DWS during Rounds 2 to 7 and 14,
and Phase 4 and 7, and equal to the DWS during Rounds 8 to 10 and Phase 4A and Phase 6.
6.34.39 BTX concentrations exceeding threshold values were obtained in the area of Unit 6 at Catalyst
Trade Park (Area C), WS17 (in Area B2 at Gussion Transport) and Spike Island.
6.34.40 The highest concentrations of BTEX compounds were obtained from WS17 (Gussion
Transport). The presence of a Light Non Aqueous Phase Liquid (LNAPL) of 0.36m thickness
was identified on the surface of the groundwater in WS17 by Soil Mechanics during the Phase 6
site investigation. Subsequent monitoring by Gifford in November 2007 encountered 0.22m
thickness of free product in WS17.
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6.34.41 The location of elevated concentrations of BTX is shown on Drawing Numbers
MG_REP_EIA_009/070 to MG_REP_EIA_009/072.
6.34.42 Table 6.35 below shows the location and concentrations of elevated BTEX and MTBE:
Table 6.35 –BTEX & MTBE Concentrations in Groundwater Exceeding the Relevant Threshold
Values (Updated)
Concentrations ( g/l)
Benzene Toluene Ethyl
benzene
m,p-
xylene
o-
xylene
MTBE
Well Response
Zone
Area EQS 30.00 8.00 40.00 n/a 30.00 30.00 n/a
DWS 1.00 n/a n/a n/a n/a n/a
WS17 Made
Ground
B2 250 2200 50 190 100 95
BH107 Alluvium C 240 1900 <10 25 <10 <10
WS30 Alluvium C 11 120 <1 4 <1 <1
WS11A Alluvium C <100 392 <100 <100 <100 <100
BH106 Glacial
Sands
C 19 53 <1 <1 <1 <1
BH108 Alluvium C 9 180 11 25 17 <1
BH103 Alluvium C 4.82 <1 87.5 8 15 <1
BH42 Alluvium C 3 2 <1 <1 <1 <1
BH65C Glacial
Sand
C 38.1 123 <1 17.3 <1 <1
WS29 Made
Ground
C 2.66 17.1 <1 <1 <1 <1
WS38 Alluvium C 1.6 7 <1 <1 <1 <1
WS41 Alluvium C 20 510 <1 <1 22 <1
BH66B Glacial
Sands
C 1.55 1.4 <2.5 <2.5 <1.7 <1.6
BH149 Alluvium D 77.2 43.5 <2.5 <2.5 <1.7 <1.6
BH150 Alluvium D 122 335 <2.5 <2.5 <1.7 <1.6
BH151 Alluvium D 248 335 <2.5 <2.5 <1.7 <1.6
HBCBH01 Glacial
Sands
D 41 8 <1 <2 <1 <1
HBCBH02 Alluvium D 71 10 <1 <2 <1 <1
HBCBH03 Alluvium D 2.05 3 <1 <2 <1 <1
n/a – not available.
6.34.43 Elevated concentrations of benzene, toluene and xylenes were also obtained during Round 14
from Catalyst Trade Park (Area C) and Spike Island (Area D) from locations identified in Table
6.35.
6.34.44 Elevated hydrocarbons were detected in groundwater to the north of the Mersey Estuary, and
south of the estuary at Astmoor Saltmarsh and Astmoor Industrial Estate. The highest
concentrations were as follows:
a. Total Aliphatics EC5-35: 1300mg/l in WS17 at Gussion Transport B2 (Made Ground)
b. Total Aromatics EC6-35: 590mg/l in WS17 at Gussion Transport Area B2 (Made
Ground) 961mg/l in WS42 at Catalyst Trade Park in Area C (Made Ground)
c. Total EC5-35: 1890mgl in WS17 at Gussion Transport B2 (Made Ground)
d. Diesel Range Organics (DRO) 2.8mg/l at WS10A on Catalyst Trade Park Area C (Made
Ground)
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e. Petrol Range Organics (PRO) 0.46mg/l at BH40 on Widnes Warth (Sandstone) Area D
f. Gasoline Range Organics (GRO C4-C10) 16.5mg/l at WS11A on Catalyst Trade Park
Area C (Alluvium)
g. Gasoline Range Organics (GRO C10-C12) 0.84mg/l at WS11A on Catalyst Trade Park
C (Alluvium)
6.34.45 PRO was detected in BH40 at Widnes Warth (Area D) during the initial round of groundwater
sampling on this well as part of the Phase 4 investigation in February 2005. In total, five rounds
of samples have been obtained from this monitoring well and the latest two rounds (February
and May 2007) were undertaken using speciated TPHCWG testing which did not encounter any
concentrations above the lower instrument detection. The result for PRO from the Phase 4 site
investigation is not considered to be representative.
6.34.46 To date only one round of samples have been obtained from the wells installed during the
Phase 6 investigation (including WS17, BH107, WS30, BH106, WS41 and BH108). The later
rounds of groundwater testing did not include DRO, PRO, GRO (c4-12) or mineral oil as
analytical testing was undertaken using TPHCWG to obtain more information on petroleum
hydrocarbon fractions where present.
6.34.47 The Surface Water DWS (DW1) for hydrocarbons (dissolved or emulsified) is 50 g/l. Drawing
Number MG_REP_EIA_009/073 show the locations where the total c5-35 aliphatic and aromatic
hydrocarbons from the TPHCWG testing undertaken during Round 9 and 10 to 14 and the
Phase 6 and 7 site investigations exceeded 50 g/l. Exceedances of the assessment criteria for
TPH were obtained from the following areas:
a. Area A - St Michaels Golf Course (BH67A, BH69, BH72, BH75 and BH93) and Speke
Road (BH63)
b. Area B2 & I1 - Made ground in Gussion Transport (BH58, WS17, WS20 and WS22) and
glacial sand (BH51) in Gussion Transport
c. Area C - Catalyst Trade Park (made ground, alluvium and upper glacial sand)
d. Area D - Widnes Warth saltmarsh alluvium (BH13 and BH55 – both during Round 10
only) and Spike Island.
6.34.48 Although not exceeding the DWS for hydrocarbons, concentrations of total c5-35 from the
TPHCWG testing were above the lower analytical detection limit of 10 g/l in groundwater from
BH35, BH1004, BH1005 (bedrock), BH38, BH39, WS05B and WS06 (alluvium) on Widnes
Warth during the Round 10 testing. None of these results were above the lower detection limit
during Round 9 testing.
6.34.49 Total aliphatic or aromatic hydrocarbons at concentrations greater than 50 g/l were obtained
from the following locations for banded ranges of hydrocarbons:
a. Areas identified from monitoring data and high contaminant concentrations as having
possible LNAPL free product during the Phase 6 investigation
b. Petrol range aliphatics hydrocarbons in BH55 Catalyst Trade Park (in Area C) and on
Spike Island in Widnes (220 g/l)
6.34.50 The areas where elevated BTEX was noted in groundwater were also coincident with elevated
concentrations of aliphatic and aromatic hydrocarbons. The majority of these hydrocarbons
were within the petrol range at Catalyst Trade Park (Area C), and the petrol, diesel and heavy
oils range in the made ground from WS17 at Gussion Transport (Area B2) and Spike Island
(Area D). No other significantly elevated concentrations of BTEX were obtained from the other
monitoring wells at the Gussion Transport site.
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6.34.51 As discussed in Section 6.17, LNAPL was identified in WS17 (along with WS20, BH51 and
BH54) at Gussion Transport site in Area B2 during monitoring in November 2007 by Gifford. A
sample of product from WS17 was recovered during monitoring works in November 2007. This
sample was scheduled for analysis to determine the composition of the free product, the
following information was obtained by the laboratory. The laboratory assessment is included in
Appendix L:
a. The Chemical Oil Fingerprint was described as „an unknown pattern of discrete peaks‟
with „two clusters of discrete peaks between C6-10 and C17-C26‟
b. The LNAPL was composed predominantly of fatty acids and fatty acid methyl esters
(FAME), with forty compounds being identified in total from this sample.
c. VOC and SVOC analysis found trace levels of chlorinated solvents, volatile fatty acids,
BTX compounds and MTBE.
6.34.52 Further assessment was undertaken by Jones Environmental Forensics Ltd. to determine the
likely source of this LNAPL. The assessment is also included in Appendix L. The review found
that the sample results for WS17 indicated an LNAPL of long chain fatty acids, a dissolved
phase of C3 to C6 volatile FAME compounds, a dissolved phase of trace unleaded petrol and a
dissolved phase of chlorinated solvents. Furthermore, the following was identified:
a. The main LNAPL was a vegetable oil consisting of mainly C12-C22 fatty acids, and that
the most likely predominant fatty acid was octadecanoic fatty acid ester.
b. These FAME compounds are classed as vegetable oils and are found in food
manufacture, pharmaceuticals, and in biodiesel.
c. There was no evidence of diesel in the LNAPL layer, indicating that the LNAPL was not
a biodiesel.
d. The LNAPL is more likely to be a mixture of FAME compounds produced by or for an
industrial process, such as within the food manufacture or pharmaceutical industries.
e. The dissolved phase concentrations of BTX, MTBE and chlorinated solvents are likely
to be unrelated to the presence of LNAPL within the sample.
6.34.53 Additional samples of groundwater were obtained from BH51, BH58 and WS20 at the Gussion
Transport site in Area B2, where LNAPL or potential LNAPL had been identified. These
samples were submitted for chemical testing to confirm the source of the potential LNAPL and
to determine if they were related to the LNAPL identified at WS17. The results can be
summarised as follows:
a. BH51 - Sheen of LNAPL identified on surface of shallow water sample. Insufficient
LNAPL for Whole Oil Analysis. Water phase contained arsenic (6.5mg/l), dissolved
sulphate (1500mg/l), TPH (0.7mg/l, aliphatic C6-C8, Gasoline Range), some PAH
compounds, trace phenols and a range of BTEX and benzene based SVOC and VOC
compounds.
b. BH58 - 4mm of LNAPL observed, but insufficient sample for Whole Oil Analysis. Water
phase contained arsenic (1mg/l), sulphate (1300mg/l), TPH (4.2mg/l), PAHs (11μg/l
total), trace phenols, and trace BTEX and benzene based VOC compounds.
c. WS20 - Fine particles of potential LNAPL in suspension. Insufficient sample for whole
oil analysis. Water phase contained sulphate (990mg/l) and a high pH (12.56 pH units).
No TPH, VOCs or SVOCs were observed, indicating that the fine particles may not have
been an LNAPL.
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6.34.54 Drawing No. MG_REP_EIA_009/074 shows the location of LNAPL in groundwater.
6.34.55 No published EQS or UK DWS have been obtained for methyl tertiary butyl ether (MTBE). In
each of the wells where BTX compounds were identified at concentrations in excess of the
EQS, MTBE was also present at concentrations of 5µg/l or more. In addition to the samples
identified in Table 6.35 above, MTBE was also encountered from the TPHCWG testing above
the lower analytical detection limit in the made ground from WS33 and BH97A, and glacial sand
in BH65C up to 160 g/l (WS33). MTBE was present at concentrations of 5µg/l or more from the
glacial deposits in BH82 (Area B2), and made ground in WS33 (Area C) and WS17 (Area B2)
up to 160µg/l (WS33).
6.34.56 Samples tested from Phase 6 investigations were analysed for MTBE by both GC-FID
(TPHCWG) and GC-MS (VOC) laboratory methods. Testing using GC-MS is considered to
provide more accurate data on MTBE. Whilst testing for TPHCWG using GC-FID indicated the
presence of MTBE, MTBE was not identified from the testing by GC-MS and on this basis
MTBE is not considered to be present.
6.34.57 The presence of BTEX compounds within monitoring wells installed into upper glacial sand layer
in Area C (BH106 and BH65C) indicates the possibility of vertical migration through the glacial
clay or link between the alluvium and glacial sand. However, it is likely these compounds
migrated as part of a multi-component free phase mixture which included denser solvents (see
discussion of VOCs below).
Volatile Organic Compounds (VOCs)
6.34.58 A total of 27 volatile organic compounds were included in the VOC suite for groundwater
samples. This includes a range of halogenated hydrocarbons, benzene compounds and carbon
disulphide.
6.34.59 Carbon disulphide was detected in monitoring wells installed into the alluvium on and adjacent
to Catalyst Trade Park in Area C at WS11A, WS30 and WS41, BH42 (Round 14), BH57, BH107
at concentrations up to 3,400μg/l. Carbon disulphide was also detected in the made ground
from WS18 (Round 13) and WS29 (Round 13) up to 1.85 μg/l and upper glacial sand layer in
BH106 at concentrations up to 37µg/l 102 μg/l (Round 14). Carbon disulphide was obtained
from glacial sand in BH66B at Thermphos (23,000 μg/l during Round 13), and east of Area C at
BH10B (at the former ICI Muspratt site) at concentrations up to 6,531μg/l. Carbon disulphide
was also present in alluvium from BH149 to BH151 on Spike Island (Area D) and in made
ground from BH58 (Area B2) during Round 14.
6.34.60 Drawing No. MG_REP_EIA_009/075 shows the locations at which carbon disulphide was
detected in groundwater.
6.34.61 DWS are available for 1,2-dichloroethane, tetrachlorethene (plus trichlorethene),
tetrachloromethane (carbon tetrachloride), trihalomethanes and vinyl chloride. The
trihalomethanes in the DWS comprise chloroform, bromoform, dibromochloromethane,
bromodichloromethane.
6.34.62 Concentrations of these contaminants detected in excess of the DWS occur in groundwater at
St Michaels Golf Course in Area A, Gussion Transport in Area B2, Catalyst Trade Park in Area
C in made ground, alluvium and glacial deposits and Spike Island. Elevated concentrations of
VOCs above the DWS were not identified in Runcorn.
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6.34.63 Concentrations in excess of DWS were not identified in any of the wells installed into the
sandstone in Widnes. VOCs have been noted during five of the 10 sampling rounds at BH1004
(Rounds 3, 6, 7, 8 and 14) with a peak concentration of 29.3µg/l for 1,1,2-trichloroethane (no
DWS) obtained during Round 14. Solvents were encountered in BH1005 during Round 8 up to
22µg/l (trichloroethene and cis-1,2-dichloroethene). This monitoring well was installed into the
sandstone bedrock on Widnes Warth. The concentrations of solvents in BH1005 were below
analytical detection during all other rounds of testing. This indicates the results from Round 8
for BH1005 are unlikely not considered to be representative. VOCs have not been detetected in
BH43.
6.34.64 The lower analytical detection limit (1µg/l) for vinyl chloride exceeds the DWS of 0.5µg/l.
Concentrations of vinyl chloride above the lower analytical detection limit have been obtained
from 16 20 wells at the Catalyst Trade Park in Area C in the made ground, alluvium and glacial
sand, and Area D (including Spike Island) in the alluvium, glacial deposits and sandstone. The
highest concentration of vinyl chloride (814µg/l) was encountered from the made ground in
WS12 during the Phase 4A investigation (although significantly lower concentrations were
obtained during Round 9 and 10 testing at 15µg/l and <1µg/l respectively). The highest
concentration of vinyl chloride (1180µg/l) was encountered from the alluvium in BH55 during
Round 14 (with an overall increasing trend in concentrations noted from this location since it
was first sampled during Phase 4A). The concentration of vinyl chloride identified in the
sandstone in BH1005 (Area D) was 3μg/l during Round 8 and 5.2μg/l from BH1004 during
Round 14. The results from other rounds at these locations were below detection.
6.34.65 The locations where chlorinated solvents exceed the DWS are shown in Drawing Numbers
MG_REP_EIA_009/076 to MG_REP_EIA_009/080.
6.34.66 A range of halogenated hydrocarbons were included in the suite of VOC testing including
brominated, chlorinated and fluorinated compounds. EQS have been published for the
following chlorinated solvent compounds:
a. 1,1,1-Trichloroethane
b. 1,1,2-Trichloroethane
c. 1,2-Dichloroethane
d. 2-Chlorophenol
e. 4-Chloro 3 Methylphenol
f. Carbon Tetrachloride
g. Chloroform
h. Hexachlorobutadiene
i. Tetrachloroethene (PCE)
j. Trichlorobenzene
k. Trichloroethene (TCE)
6.34.67 The compounds listed above have been used as indicators for contamination by solvents
(including brominated and fluorinated) on the basis these compounds were the most
widespread and were encountered at the highest concentrations.
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6.34.68 The laboratory limits of detection (1µg/l) for hexachlorobutadiene and trichlorobenzene were
higher than the EQS values of 0.1µg/l and 0.4µg/l respectively. Trichlorobenzene was not
detected above the lower analytical detection limit. Hexachlorobutadiene was detected above
the lower analytical detection limit in made ground in BH42B, WS10A and WS12 (up to 46µg/l),
and in the alluvium in WS11A (up to 40,000µg/l) and BH56 (up to 32µg/l). These wells were all
located at the Catalyst Trade Park in Area C. Hexachlorobutadiene was also detected in glacial
sand from BH66B at Thermphos during Round 13 (at 3.7µg/l). It should be noted that
hexachlorobutadiene was included on the VOC and SVOC suite of analysis and the results from
both tests have been considered. However, where results above the lower detection limit were
obtained for the same sample from both tests, then the VOC results have been reported as it is
understood from the laboratory these are likely to be more representative.
6.34.69 The highest concentrations of solvents were obtained from the alluvium in WS11A at the
Catalyst Trade Park (in Area C) during Round 9, these were carbon tetrachloride (260mg/l) and
tetrachloroethene (240mg/l). The highest concentrations of 1,1,2,2-tetrachloroethane (240mg/l)
and 1,1,1,2-tetrachloroethane (120mg/l) were obtained from the alluvium in BH107 at Catalyst
Trade Park during the Phase 6 investigation. BH107 also recorded the highest concentration of
trichlorethene (86135 mg/l during Round 14) and 1,1,2-trichloroethane (33mg/l) in Area C,
although the overall highest concentration of 1,1,2-trichloroethane (52.9mg/l) was obtained from
alluvium in BH151 on Spike Island during Phase 7. The lower dectection limit for VOCs in
WS11A during Phase 4a and Round 9 and 10 was 100µg/l.
6.34.70 Other halogenated solvents have been detected in excess of the EQS from Area C in
groundwater samples obtained from the made ground, alluvium and the upper glacial sand.
The location of monitoring wells where samples exceeded the EQS is shown in Drawing
Numbers MG_REP_EIA_009/081 to MG_REP_EIA_009/088.
6.34.71 Elevated concentrations of solvents above the EQS values have also been obtained from Area
A at St Michaels Golf Course in monitoring wells installed into the made ground (BH67A, BH69,
BH72 and BH93) and alluvium (BH75), and in Areas B2 & I1 at Gussion Transport in the made
ground (BH58, BH60, WS16A, WS17, WS20 and WS22). The highest concentration from
Areas A & B1 was 0.88mg/l of 1,1,2,2-tetrachloroethane from BH93. In Area B2 & I1, the
highest concentration was 0.92mg/l of 1,1,2,2-tetrachloroethane from WS22.
6.34.72 Cis-1,2-dichloroethene is one of the compounds that can be produced from the reductive
dechlorination of trichloroethene by anaerobic biodegradation. No EQS or DWS has been
obtained for cis-1,2-dichloroethene. The highest concentration of cis-1,2-dichloroethene
(14.5mg/l) was obtained from BH42 which was installed into the alluvium at the Catalyst Trade
Park. Cis-1,2-dichloroethene has been encountered in made ground, alluvium and glacial sand
above the lower analytical detection limit in 27 30 monitoring wells installed on and adjacent to
the Catalyst Trade Park in Area C and 6 monitoring wells at Spike Island. Cis-1,2-
dichloroethene has also been obtained in the bedrock from BH1004 (3µg/l during Round 3) and
BH1005 (22µg/l during Round 8) on single occasions.
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VOC - Free Product Assessment
6.34.73 High concentrations of chlorinated solvents from chemical testing could indicate the presence of
free product as a dense non-aqueous phase liquid (DNAPL). EA R&D 133 (2003) indicates that
a potential DNAPL source may be present upstream of a monitoring well if sample
concentrations exceed 1% of the effective solubility of the component of interest. This
assessment has been updated with effective solubilities obtained from SR7 (2009), LQM/CIEH
(2009) and CLAIRE/AGS/CIEH (2009) and results from additional rounds of groundwater testing
undertaken following the Order ES in 2008.
6.34.74 The presence of free phase DNAPL was assessed using the methodology outlined in EA
R&D133 (2003) for all groundwater monitoring wells at which a DNAPL component was
detected above 0.5mg/l. The chemical testing results are provided in Appendix L.
6.34.75 EA R&D133 (2003) indicates that effective solubility for a component in a multicomponent
system can be calculated using Raoult‟s law, this is as follows:
iii SmC
Ci is the effective solubility of the component i
Mi is the mole fraction of the component in the NAPL
Si is the single component solubility of the component
6.34.76 Following the approach outlined above and by using the 1% rule above, the following equation
has been used to assess the possible presence of free product upstream of a monitoring well:
Free Product Present if 01.0i
obs
i
S
C
Ciobs
is the concentration observed in the monitoring well
6.34.77 The assessment using EA R&D133 (2003) indicates that free phase DNAPL could be present
upstream of WS11A, WS30, WS31, WS41, BH56, and BH107 and BH108 (alluvium), WS10A
and WS12 (made ground) and BH106 and BH65C (upper glacial sand) all of which were located
on or immediately adjacent to the Catalyst Trade Park in Widnes (Area C). The assessment
shows DNAPL could be present in the alluvium upstream of BH149, BH150 and BH151 and
also in BH2 (installed by the Council in 2008) on Spike Island to the south of St Helens Canal.
The results also show DNAPL could be present in glacial sand near to BH66B on Thermphos
(Area C). These are shown on Drawing No. MG_REP_EIA_009/089.
6.34.78 This assessment did not indicate that free phase DNAPL was likely to be present in the samples
tested from other parts of the project area.
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6.34.79 Additional water samples were obtained in November 2007 from the base of the monitoing wells
installed at Area C Catalyst Trade Park where the possible free phase DNAPL had been
identified from the chemical testing and EA R&D133 (2003). These monitoring wells were as
follows:
a. BH56
b. BH106
c. WS10a
d. WS11A
e. WS30
f. WS40
6.34.80 It was not possible to obtain samples at that time from WS12 as this well was covered by a lorry
and WS41, BH107 and BH108 could not be located during the monitoring visit. The
methodology used to obtain these samples is described in Section 4.29 and the subsequent
method of analysis is described in Section 4.34.15.
6.34.81 Groundwater samples were also collected from BH149, BH150 and BH151 on Spike Island on
7th March 2011 for laboratory DNAPL testing.
6.34.82 The laboratory testing indicates that although chlorinated solvents were present in these
samples, non-aqueous phase liquid (i.e. free phase DNAPL) was not detected. The
concentrations of chlorinated solvents from this chemical testing did not exceed the results
obtained from previous testing. However, EA R&D 133 (2003) does indicate that in most types
of porous media, site investigation activities such as well purging will not draw residual DNAPL
into monitoring wells.
6.34.83 The results also indicated the possible presence of a plasticiser compound (octahydro-dimethyl-
(methylethyl)-phenanthrenecarboxylic acid) within the sample obtained from WS10A at a
concentration of 159μg/l.
6.34.84 The testing indicated the possible presence of BTEX compounds / petrol residues within the
sample obtained from BH106 which was installed into the glacial sands. It is likely these
compounds migrated as part of a multi-component free phase mixture with denser solvents.
6.34.85 The possible presence of glycol (diglyme) was also identified within the sample obtained from
WS40 at a concentration of 22μg/l.
6.34.86 To date wells have not been installed into the deeper glacial sand layer or Sherwood Sandstone
aquifer beneath the Catalyst Trade Park to avoid possibility of introducing pathways for further
contaminant migration to depth. However, there is the potential for these contaminants to have
migrated deeper under gravity through the glacial deposits either via fissures, the
internconnection of more permeable lenses or due to pathways formed by existing foundations.
Polycyclic Aromatic Hydrocarbons
6.34.87 Of the 16 USEPA PAHs, an EQS value has only been derived only for naphthalene.
6.34.88 Naphthalene is the most soluble of the PAHs tested for, and as such has been used as a
surrogate marker for PAH contamination.
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6.34.89 The highest concentration of naphthalene (220 g/l) within the project area was obtained from
BH108 installed into the alluvium in Area C on Catalyst Trade Park. The EQS for naphthalene
has reduced from 5 g/l to 1.2 g/l since the Orders ES. Elevated concentrations of naphthalene
above the EQS (and above lower detection limit) were obtained from BH49 and BH51 (glacial
deposits) and BH58 (made ground) in Area B2 at Gussion Transport, and at 12 locations from
the made ground, alluvium and glacial deposits (alluvium) in Area C on Catalyst Trade Park at
10 g/l and 7.3 g/l respectively. Elevated concentrations of naphthalene were also obtained in
Area D from Wigg Island in WS02 and WS03 (alluvium) and BH37 on Widnes Warth
(sandstone) along with BH123 in Area G (sandstone).
6.34.90 In addition to napthalene, Eelevated concentrations of individual PAH compounds above the
EQS of 1.2 g/l were detected in groundwater from the monitoring wells shown in Table 6.36
listed below. This has resulted in a greater number of results for PAHs being above the EQS of
1.2 g/l. These locations are discussed below and shown in Drawing No.
MG_REP_EIA_009/090.
a. Area A: BH93 (made ground)
b. Area B2: BH58 (made ground), BH49 and BH51 (glacial sand)
c. Area C: WS29, WS43, WS44 (made ground), WS11A, WS32, WS41, BH41, BH103,
BH107 (alluvium), BH65C, BH66B, BH71 (glacial sand)
d. Area D: BH37 (sandstone), BH150 (alluvium),
e. Area I: WS52, WS53 and WS54 (made ground) and BH146 (alluvium)
Table 6.36 – PAHs in Excess of 5 g/l (Table Removed as superseded by Section 6.34.87 above)
Exploratory
Hole
Area Response Zone PAHs Detected above
5 g/l
Comments
WS2 D Alluvium Naphthalene (6 g/l) Determined from Phase 4 SI
WS3 D Alluvium Naphthalene (7 g/l) Determined from Phase 4 SI
BH37 D Sandstone Naphthalene (6 g/l) Determined from Round 8
BH103 C Alluvium Acenaphthene (9.1 g/l) Determined from Phase 6 SI
BH108 C Alluvium Naphthalene (220 g/l) Determined from Phase 6 SI
BH10B East of Area
C at the
former ICI
Muspratt site
Made Ground Phenanthrene (6 g/l)
Fluoranthene (6 g/l)
Determined from Round 2.
Not within Project area
BH10B East of Area
C at the
former ICI
Muspratt site
Made Ground Phenanthrene (16 g/l)
Fluoranthene (14 g/l)
Pyrene (10 g/l)
Benz(a)anthracene (7 g/l)
Chrysene (7 g/l)
Benzo(b)fluoranthene
(6 g/l)
Determined from Round 3.
Not within Project area
WS41 C Alluvium Naphthalene (7.3 g/l) Determined from Phase 6 SI
BH49 B2 Glacial Sand Pyrene (6 g/l) Determined from Phase 4 SI
BH51 B2 Glacial Sand Naphthalene (10 g/l)
Acenaphthene (8.4 g/l)
Determined from Phase 6 SI
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6.34.91 No other individual PAH compounds were detected at concentrations above 5 1.2 g/l in
groundwaters from made ground, alluvial and glacial horizons at the locations within the Area
B2 or C.
6.34.92 In addition, exceedance of the EQS for were also obtained for benzo(a)pyrene and other PAHs
(fluoranthene, sum of benzo(b)fluoranthene and benzo(k)fluoranthene, and sum of
benzo(ghi)perylene and indeno(1,2,3-cd)pyrene) from made ground, alluvium, glacial deposits
and sandstone in Area A, B1, B2, C, D, F and I.
6.34.93 DWS are defined for benzo(a)pyrene and total PAHs (sum of benzo(b)fluoranthene,
benzo(k)fluoranthene, benzo(ghi)perylene and indeno(1,2,3-cd)pyrene). Comparison to the
DWS for benzo(a)pyrene and total PAH has been made for samples where the laboratory
detection limit was less than the DWS of 0.01 g/l and 0.1 g/l respectively or where these
compounds were reported above the lower detection limit.
6.34.94 Exceedances of the DWS for benzo(a)pyrene were obtained from Areas A & B1, B2, C and D in
groundwater from the made ground, alluvial and glacial deposits, and in sandstone at BH31.
Exceedances were also obtained from glacial deposits in Area F during Round 11 and 12
(BH116, BH119 and BH120) and sandstone in Area G during Round 11 (BH121 and BH123)
The highest concentration of 0.088 7.9 g/l was obtained from BH75 in alluvium from Area A
during Round 12 BH13 (Round 10) in alluvium at Widnes Warth (Area D), although 4μg/l was
obtained from BH10B to the east of Area C at the Former ICI Muspratt site.
6.34.95 Exceedances of the DWS for total PAHs were obtained from the following locations:
a. Area A and B1: made ground and alluvium (at concentrations up to 23μg/l in alluvium
from BH75 during Round 12)
b. Area B2: made ground and glacial deposits (at concentrations up to 8.26μg/l in made
ground from BH58)
c. Area C: made ground, alluvium and glacial deposits (at concentrations up to 24.4μg/l in
made ground from WS43)
d. Area D: alluvium and sandstone (at concentrations up to 1μg/l in sandstone from
BH1004 on Widnes Warth). Exceedance was also obtained from alluvium in BH150
and HBCBH02 at Spike Island
e. Area I: made ground, alluvium and glacial deposits (at concentrations up to 106μg/l in
made ground/alluvium in WS53 during Round 14)
6.34.96 Exceedances of the DWS for total PAHs were also obtained from glacial deposits from BH116
(Round 12) and BH119 (Round 11 and 12) in Area F. However, exceedances were not noted at
these locations during Phase 6 or Round 13 testing
6.34.97 made ground in Area C at WS14, WS15 and WS43 (at concentrations up to 0.194μg/l), and in
Area D (Widnes) from the alluvium (where 0.26μg/l was obtained from BH13) and the
sandstone (where 1μg/l was obtained from BH1004). Concentrations of total PAHs that exceed
the DWS were also obtained from the former ICI Muspratt site to the east of Area C (up to
12 g/l.
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Semi Volatile Organic Compounds (SVOCs)
6.34.98 Of the parameters included in the SVOCs suite for groundwater, only 14 17 SVOCs compounds
were detected above laboratory detection limits. The only SVOCs encountered for which EQS
values have been published are shown below in Table 6.37 together with the highest
concentration in each case:
Table 6.37 – Maximum SVOC concentrations detected (Updated)
Exploratory
Hole
Area Response Zone Determinand EQS
( g/l)
Max
Value
( g/l)
WS16AWS11A
B2C Glacial Sand and
ClayAlluvium
Phenol 307.7 130 1280
BH58 B2 Made Ground 2-Chlorophenol - 4
WS16A B2 Glacial Sand and
Clay
2-Methylphenol - 62 81
WS16AWS11A B2C Glacial Sand and
Clay Alluvium
4-Methylphenol - 85 7170
BH58 B2 Made Ground 2,4-Dichlorophenol 20 16 28
BH37 D Sandstone Bis(2-chloroethyl)ether - 4
WS17BH45
BH66B
B2C Made Ground
Glacial Sand
Bis(2-ethylhexyl)
phthalate
- 170(1000)
223
WS5B D Alluvium Di-n-butyl phthalate - 7
(BH25)
BH1003
E
C
(Sandstone)
Alluvium
Di-n-octyl phthalate - (199)
83
WS11A C Alluvium Hexachloroethane - 16755
BH53 B1 Made Ground Isophorone - 2
BH56 C Alluvium Nitrobenzene - 52
BH51 B2 Glacial Sand Dibenzofuran - 18
WS16A B2 Glacial Deposits 2,4-Dimethylphenol - 25
WS18 B2 Made Ground 4-Chloro 3-Methyl
Phenol
- 1.95
BH58 B2 Made Ground 2,4,6-Trichlorophenol - 2
BH71
BH103
C Glacial Sand
Alluvium
Carbazole - 3
Note: Values in brackets are considered to represent cross contamination
6.34.99 Overall, concentrations were much lower within the sandstone bedrock than the overlying
shallow groundwater horizons. The single elevated occurrence of phthalate obtained from
BH25 (in Area E at Astmoor Industrial Estate) is not considered to be representative, particularly
given that this borehole has been sampled on nine occasions, eight of which showed no
concentrations of phthalates exceeding the lower analytical detection limit.
6.34.100 Elevated concentrations of phenol above the EQS were obtained from made ground,
alluvium and glacial deposits in Area A to C. Exceedances were also obtained from alluvium at
Spike Island and Wigg Island in Area D. The highest concentration of 2,4-dichlorophenol did
not in made ground at BH58 exceeds the EQS of 20 g/l. Concentrations of 2-chlorophenol
above the limit of detection were as only observed at one location, BH58 in Area B2 (2μg/l
4μg/l), and in alluvium from BH150 and BH151 on Spike Island (1.59 and 1.79 μg/l
respectively). Concentrations of 4-chloro-3-methylphenol and butylbenzylphthalate, were
obtained above the lower analytical laboratory limit, although an EQS has not been published
for these contaminants.
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Pesticides
6.34.101 A range of organochlorine and organophosphorous pesticides were tested in groundwater on
and adjacent to Catalyst Trade Park in Area C. Of these, lindane (alpha, beta and gamma (also
known as lindane) hexachlorocyclohexanes (HCH), chlordane, heptachlor and
hexachlorobenzene were detected above the lower laboratory detection limits. These
compounds are all organochlorine pesticides.
6.34.102 Heptachlor and chlordane were detected at concentrations exceeding the DWS at BH56 in
groundwater from the alluvium (Area C), with a maximum of 1.9 610 g/l and 4.5 3400 g/l (t-
Chlordane) recorded respectively during Round 12. Results for these compounds from other
rounds of testing were significantly lower. Heptachlor and chlordane were also detected at
concentrations exceeding the DWS at BH107 from the alluvium (Area C), with a maximum of
1.93 g/l and2.6 g/l (t-Chlordane) recorded respectively during Round 14.
6.34.103 Gamma HCH (lindane) concentrations exceed the DWS at WS33 (made ground), BH107
(alluvium) and BH56 (alluvium) within the Catalyst Trade Park in Area C. The highest
concentration of 770 g/l was obtained from BH56 during Round 12, although results from other
rounds were lower. Alpha-HCH was present above the DWS for individual pesticides in WS30
(alluvium), WS33 (made ground), BH107 (alluvium) and BH56 (alluvium) in Area C, beta-HCH
was also present in BH107 and BH56. Organochlorine pesticides were also observed above the
DWS in alluvium from BH149 on Spike Island.
6.34.104 The only pesticide encountered with an EQS value is hexachlorobenzene (0.031 g/l). This
compound was detected in samples obtained from made ground and alluvium at the Catalyst
Trade Park in Area C.
6.34.105 The highest individual concentration of pesticides was hexachlorobenzene was at 28 g/l
from WS13 in Area C which was installed into the base made ground and underlying glacial till.
Hexachlorobenzene was not encountered above the lower analytical detection limit in
groundwater samples from the Sherwood Sandstone.
6.34.106 The concentration of „total‟ pesticides ranged from 0.04 g/l to 70 7790 g/l, based on the
sum of the organochlorine pesticides above the lower analytical detection. The DWS for total
pesticides is 0.5 g/l. The highest concentration was obtained from made ground in Area C at
WS13 during Round 9 alluvium in BH56 in Area C during Round 12, although the results were
below detection from this well during Round 10 the results from other rounds of testing at this
location ranged from below detection to 7.85 g/l. In addition to WS13BH56, the DWS was
exceeded in alluvium from WS38 WS30 and BH107 and made ground in WS29 and WS33 in
Area C.
6.34.107 Drawing No. MG_REP_EIA_009/091 shows the distribution of total pesticides in
groundwater (where compounds were identified above the lower analytical detection).
Herbicides
6.34.108 Acid herbicides were tested in groundwater samples obtained during the Phase 6 site
investigation and Round 10 to 13 groundwater sampling in the made ground, alluvium and
glacial deposits.
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6.34.109 Acid herbicides were detected above laboratory detection limits in samples from Area C
when tested during Phase 6 and Round 10 to 14. The locations where acid herbicides have
been encountered are in WS29, WS46A and WS33 installed within the made ground, and
WS30, BH107, BH1003, BH42, BH55, and BH56 and BH57 installed within the alluvium. All of
these monitoring wells are located on or adjacent to at the Catalyst Trade Park with the
exception of BH55 which is located on Spike Island in Widnes to the south of Area C and the St
Helens Canal. The highest concentration of herbicides was 16 g/l of loxynil from alluvium in
BH55 during Round 10.
6.34.110 There are no DWS for herbicides. EQS values have been produced for benzatone, 2,4-D,
mecoprop and pentachlorophenol. The EQS for pentachlorophenol (0.4 g/l) was only
exceeded at BH56 in Area C during Round 10, 12 and 13, where with a peak concentration of
pentachlorophenol was encountered at 4.6 g/l encountered during Round 10 which exceeds
the EQS of 2 g/l.
6.35 ‘Spring’ on Astmoor Saltmarsh
6.35.1 A sample of water was obtained in February 2005 from a spring identified on the southern bank
of a drainage channel on Astmoor Saltmarsh, just north of the Wigg Island Landfill in Runcorn
(and 20m west of the route alignment). Soft white precipitate was noted around the spring. The
results of the testing indicate that lead (30 g/l) slightly exceeded the EQS (25 g/l) and the pH of
11.1 exceeded the upper EQS of pH 8.5. No EQS has been published for The results for
ammonia (as NH4), although the result of 10.2mg/l exceeds the DWS of 0.5mg/l and EQS of
0.021µg/l. No EQS has been published forThe result for total cyanide, again the result of
0.28mg/l exceeds the DWS of 0.05mg/l and EQS of 0.001µg/l.
6.36 Detailed Quantitative Risk Assessment - Controlled Waters
6.36.1 A Detailed Quantitative Risk Assessment (DQRA) for controlled waters has also been
undertaken for contaminants in groundwater at Gussion Transport (Area B2) and Catalyst Trade
Park (Area C) where free product has been identified.
6.36.2 The DQRA established that contaminants arising from LNAPL at Gussion Transport did not
represent a risk to surface water at Marsh Brook 350m to the southwest from off-site migration.
In Area C, the contaminants arising from DNAPL in made ground and alluvium at Catalyst Trade
Park were not considered to represent a risk to the River Mersey. However, a risk was
identified from contaminants in the made ground at Catalyst Trade Park to Bowers Brook
6.36.3 The outputs from the DQRA have been agreed with the EA and this has informed the
requirements for advanced works remediation. The DQRA has been included in Appendix V.
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6.37 Gas Monitoring
6.37.1 Gas monitoring visits were undertaken on the following dates to assess the concentrations of
methane, carbon dioxide, oxygen and hydrogen sulphide, the results of each monitoring visit
are included in Appendix OT:
a. 13 to 14 January 2003
b. 20 to 21 February 2003
c. 26 February 2003 (limited to Route 3, north of St Helens Canal)
d. 3 to 7 March 2003
e. 24 to 25 July 2003
f. 12 to 20 January 2004
g. 23 November 2004
h. 13 to 20 December 2004
i. 22 August, 14 and 19 October 2005
j. 6 to 9 December 2005
k. 8 to 13 February 2006
l. 5 to 7 July 2006
m. 1 to 3 November 2006
n. 23 to 26 January 2007
o. 17 to 27 October 2008
p. 26 to 29 April 2010
6.37.2 Based on the number of rounds of gas monitoring undertaken and removal of tolls booths and
offices, further rounds of gas monitoring were not considered to be required.
6.37.3 All of the monitoring wells were also assessed for the presence of volatile organic vapours using
a photo-ionisation detector (PID) on the following dates:
q. March 2003
r. January 2007
s. October 2008
6.37.4 Monitoring for volatile vapours using a PID was also undertaken during the checking of wells for
free product in January 2008.
Results of Gifford Ground Gas Monitoring
Widnes Urban Areas
Table 6.38 – Summary of ground gas monitoring results in Widnes Urban Areas between
January 2003 and January 2007
Strata Methane
(%)
Carbon
Dioxide (%)
Oxygen (%) Hydrogen
Sulphide
(ppm)
Carbon
Monoxide
(ppm)
Flow Rate
(l/hr)
Made
Ground
0.0 - 0.3 0.0 – 3.1 6.6 – 21.9 0.0 – 3.0 0.0 – 5.0 -3.0 – 1.4
Alluvium 0.0 – 0.4 0.0 – 3.8 13.0 – 21.9 0.0 – 4.0 0.0 - 55 -8.4 – 3.0
Glacial
Deposits
0.0 – 0.1 0.0 – 4.1 3.2 – 21.2 0.0 – 3.0 0.0 – 22 -13.4 – 4.7
Bedrock 0.0 – 0.4 0.0 – 2.1 19.4 – 21.2 0.0 – 3.0 0.0 – 8.0 -0.1 – 1.1
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6.37.1 Subsequent rounds of ground gas monitoring in Widnes have encountered the following results
which exceed the values outlined in Table 6.38:
a. BH51 (Area B2) - 0.7% methane and 4.6% carbon dioxide from the glacial deposits in
October 2008
b. BH59 (Area B2) - 4.1% carbon dioxide from the made ground in October 2008
c. WS26 (adjacent to Area A) – 6.7% carbon dioxide from the made ground in October
2008
Saltmarshes
Table 6.39 – Summary of ground gas monitoring results in Saltmarshes between January 2003
and January 2007
Strata Methane
(%)
Carbon
Dioxide (%)
Oxygen (%) Hydrogen
Sulphide
(ppm)
Carbon
Monoxide
(ppm)
Flow Rate
(l/hr)
Made
Ground *
0.0 - 0.2 0.0 – 0.4 13.4 – 21.8 0.0 – 0.0 0.0 – 6.0 0.0 – 1.0
Alluvium 0.0 – 0.2 0.0 – 9.9 0.5 – 21.9 0.0 – 3.0 0.0 – 7.0 -6.0 – 1.2
Bedrock 0.0 – 0.9 0.0 – 9.6 1.1 – 21.9 0.0 – 3.0 0.0 – 8.0 -12.0 – 1.7
* Based on results for exploratory holes BH18A only
Runcorn Urban Areas
Table 6.40 – Summary of ground gas monitoring results in Runcorn Urban Areas between
January 2003 and January 2007
Strata Methane
(%)
Carbon
Dioxide (%)
Oxygen (%) Hydrogen
Sulphide
(ppm)
Carbon
Monoxide
(ppm)
Flow Rate
(l/hr)
Glacial
Deposits
0.0 – 0.2 0.0 – 0.6 16.8 – 21.1 0.0 – 3.0 0.0 – 3.0 -0.2 – 1.3
Bedrock 0.0 – 0.2 0.0 – 5.8 2.4 – 21.6 0.0 – 3.0 0.0 – 14 -0.6 – 7.6
6.37.2 Ground gas monitoring was undertaken by Soil Mechanics on 46 monitoring wells installed
during the Phase 6 site investigation between 15th May and 13
th June 2007, the results are as
follows:
Widnes Urban Areas
Table 6.41 – Summary of ground gas monitoring results in Widnes Urban Areas between May
and June 2007
Strata Methane
(%)
Carbon
Dioxide (%)
Oxygen (%) Hydrogen
Sulphide
(ppm)
Carbon
Monoxide
(ppm)
Flow Rate
(l/hr)
Made
Ground
0.0 - 1.8 0.0 – 12.0 0.8 – 21.5 0.0 – 5.4 NR -0.7 – 1.0
Alluvium 0.0 0.0 – 3.9 17.4 – 21.7 0.0 – 1.0 NR -0.8 - 0.0
Glacial
Deposits
0.0 – 0.0 0.0 – 0.6 17.8 – 21.5 0.0 NR 0.0
NR = not recorded
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Runcorn Urban Areas
Table 6.42 – Summary of ground gas monitoring results in Runcorn Urban Areas
between May and June 2007
Strata Methane
(%)
Carbon
Dioxide (%)
Oxygen (%) Hydrogen
Sulphide
(ppm)
Carbon
Monoxide
(ppm)
Flow Rate
(l/hr)
Made
Ground
0.0 0.2 – 3.3 18.1 – 20.7 0.0 NR 0.0
Glacial
Deposits
0.0– 10.5 0.0 – 24.0 1.5 – 21.4 0.0 NR -2.3 – 0.4
Bedrock 0.0 0.0 – 0.2 20.5 – 21.5 0.0 NR 0.0 – 0.2
6.37.3 The highest concentrations for methane (10.5%) and carbon dioxide (24%) were obtained from
BH131A which was installed into glacial till in Runcorn. Subsequent monitoring of BH131A was
undertaken by Gifford on 20th November 2007 and during October 2010. During monitoring in
2007, cCarbon dioxide was present up to 12.9% after 160 seconds and had reduced to 1.1% at
5 minutes. No methane was encountered above the lower instrument detection limit and the
borehole flow rate was -0.3litres/hour. Oxygen reached a low of 4% rising to 19.3% after 5
minutes and the atmospheric pressure was 989mb. Monitoring in 2010 at BH131A encountered
carbon dioxide up to 11.1% (reducing to 0.1% after 5 minutes), methane was below detection
and oxygen was 10.1% rising to 20.2% after 5 minutes. No sources for ground gas in BH131A
were identified from the historical information reviewed or the ground conditions encountered.
However, for the purpose of assessing the gas concentrations, all of the results from BH131A
have been considered.
6.37.4 Ground gas monitoring was undertaken by AEG on monitoring wells installed during the Phase
7 site investigation on 16th November 2010, the results are as follows:
Widnes Urban Areas
Table 6.49 – Summary of ground gas monitoring results in Widnes Urban Areas during Phase 7
Strata Methane
(%)
Carbon
Dioxide (%)
Oxygen (%) Hydrogen
Sulphide
(ppm)
Carbon
Monoxide
(ppm)
Flow Rate
(l/hr)
Made
Ground
<0.1 0.2 – 0.8 19.2 – 19.5 <1.0 2 - 5 0.0 – 0.1
Alluvium <0.1 <0.1 - 0.1 19.5 – 19.7 <1.0 3 - 8 -1.1 – 0.0
Glacial
Deposits
<0.1 0.4 19.5 <1.0 5 -4.1
NR = not recorded
Widnes - Spike Island
Table 6.50 – Summary of ground gas monitoring results in Spike Island during Phase 7
Strata Methane
(%)
Carbon
Dioxide (%)
Oxygen (%) Hydrogen
Sulphide
(ppm)
Carbon
Monoxide
(ppm)
Flow Rate
(l/hr)
Alluvium <0.1 – 0.3 <0.1 - 0.9 18.8 – 20.2 <1.0 4 - 13 -7.4 – 0.1
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Review of the Ground Gas Results
Assessing Risks to Buildings
6.37.5 A review of the methane and carbon dioxide results has been undertaken using the approach
outlined in CIRIA C665 (2007) Assessing Risks Posed by Hazardous Ground Gases to
Buildings for the proposed construction of toll plazas and offices at St Michael‟s Golf Course
(Area A), Gussion Transport/Anglo Blackwells (Area B2) and in the northern/eastern part of
Catalyst Trade Park (Area C).
6.37.6 It should be noted that to date only one round of ground gas monitoring has been undertaken
on monitoring wells installed during the Phase 6 site investigation. The majority of monitoring
installations on/adjacent to Gussion Transport/Anglo Blackwells (Area B2) and St Michaels Golf
Course in Area A were installed during the Phase 6 investigation. Table 5.5 in CIRIA C665
(2007) indicates that for a low sensitivity development (commercial) the typical frequency of
monitoring is likely to be between 4 and 12 rounds over a period of between four and twelve
months (depending on the generation potential of the source).
Table 6.43 – Gas Screening Values Derived Using CIRIA C665
Parameter Peak Gas
Concentration
(% v/v)
Peak Borehole
Flow Rate
(litres/hour)
Gas Screening
Value
(litres/hour)
Comments
Methane Area A
0.0*
Area B2
1.8
Area C
0.3
Area A
20**
Area B2
20**
Area C
4.72
Area A
0.0
Area B2
0.36
Area C
0.014
CS1
CS2
CS1
Carbon
Dioxide
Area A
2.3
Area B2
12
Area C
3.1
Area A
20**
Area B2
20
Area C
4.72
Area A
0.46
Area B2
2.4
Area C
0.15
CS2
CS2
CS2
Notes: The results for monitoring wells installed during the Phase 6 site investigation are based on only
one round of ground gas monitoring by Soil Mechanics. In particular this affects the assessment of the
results from Area A (Golf Course) and Area B2(Gussion Transport/Anglo Blackwells).
*The level of CH4 was recorded as 0. The detection limits of the gas analyser is 0%-100% with accuracy
of 0.2% at 5%, 1% at 30% and 3% at 100%.
**The flow rate was recorded as „off the scale‟. The maximum detection limit of the analyser used by Soil
Mechanics is 20L/hr, therefore, this value was used although this may not be sufficiently conservative.
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6.37.7 Using the concentrations and gas screening values identified above, Characteristic Situations
(CS) in accordance with guidance from CIRIA C665 (2007) have been identified.
6.37.8 For the proposed toll booths in Area C towards the north of Catalyst Trade Park and Area A at
St Michaels Golf Course the information obtained to date indicates CS1 for methane and CS2
for carbon dioxide. For the proposed toll booths in Area B2 in the area of Gussion Transport
Services and Anglo Blackwells, CS2 has been derived for methane and carbon dioxide.
6.37.9 For the proposed toll booths Area B2 at Gussion Transport/Anglo Blackwells, WS17 is the only
borehole to exceed the 1% methane and 5% carbon dioxide workplace exposure limits (WEL).
However, the flow in this borehole was recorded as 0.0 L/hr. BSI 8485:2007 (Draft for
Consultation) notes that if the flow is not recorded, the lowest limit of the analyser is to be used.
In this case the limit is 0.1L/hr from which a GSV of 0.0018L/hr for methane and 0.012 L/hr
carbon dioxide would be obtained, both of which are within CS1 (<0.07 L/hr). However, the
peak carbon dioxide results exceeds typical concentration of 5% for CS1 outlined in Table 8.5 of
CIRIA C659 (2006), therefore, this has been increased to CS2. This text has been deleted as
toll booths and offices are no longer proposed.
Construction Workers
6.37.10 A comparison of the ground gas results against the workplace exposure limits (WEL) shows the
following exceedances (the long term (8 hour) exposure limits been used on the basis it is
possible workers would be in excavations for extended periods and these limits are more
conservative for this assessment than the short term (15 minute) exposure limit:
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Table 6.44 – Ground Gas Concentrations Exceeding WEL
Parameter Long Term
WEL Other Criteria
No. of monitoring
points exceeding Location
Methane - 5% v/v (LEL) None
Carbon Dioxide 0.5 % v/v - Widnes
Made Ground: 8
17
Alluvium: 9
Glacial: 4 5
Runcorn
Bedrock: 3
Glacial: 1 3
Saltmarshes
Alluvium: 7 9
Bedrock: 4
BH10A, BH1001, BH42B,
WS07, WS12, WS14,
WS15, WS21, BH58,
BH59, WS10A, WS18,
WS29, WS33, WS42,
WS44, WS46A
BH7, BH1003, BH10B,
BH41, BH56, BH57,
WS02, WS03, WS08,
WS31
BH9, BH44, BH46,
WS09, BH51
BH24, BH25, BH29
BH20, BH116, BH131A
BH12, BH13, BH17,
BH33, BH36, BH38,
WS05B, WS02, WS03
BH14, BH15, BH31,
BH34, BH37, BH40,
BH1004, BH1005
Hydrogen
Sulphide
5 ppm - 1 (none exceed
short term WEL of
10ppm)
BH18A (Runcorn)
Carbon Monoxide 30 ppm - 2 (none exceed
the short term
WEL of 200ppm)
WS11A
BH42
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6.37.11 A comparison of the results obtained by Soil Mechanics during the Phase 6 site investigation
against the workplace exposure limits (WEL) shows the following exceedances:
Table 6.45 – Ground Gas Concentrations from the Phase 6 Site Investigation Exceeding WEL
Parameter Long Term
WEL Other Criteria
No. of monitoring
points exceeding Location
Methane - 5% v/v (LEL) Glacial: 1 BH131A (Runcorn)
Carbon Dioxide 0.5 % v/v - Widnes
Made Ground: 9
Made Ground/
Alluvium: 1
Alluvium: 2
Glacial/Made
Ground: 1
Runcorn
Glacial: 2
Glacial/Made
Ground: 1
Made Ground: 1
WS16A, WS17, WS23,
WS33, WS28, BH76,
WS42, WS46A, WS26
WS41,
WS31, BH107
WS23
BH131A, BH136
BH116
BH127
Parameter Long Term
WEL Other Criteria
No. of monitoring
points exceeding Location
Hydrogen
Sulphide
5 ppm - None
Volatile Organic Compounds
6.37.12 A survey of the monitoring wells was undertaken by Gifford on 14th March 2003 using a photo-
ionisation detector (PID) on monitoring wells installed during the Phase 1 and 2 site
investigation. The concentrations encountered ranged from 0.0 to 3.3 parts per million (ppm),
the highest value was encountered in BH1007, which was located at the western end of the
Wigg Island Landfill, to the west of the proposed route alignment and installed into the bedrock.
The results are included in Appendix OT.
6.37.13 PID monitoring was undertaken during the ground gas monitoring visit in January 2007 on
monitoring wells installed during the Phase 1 to 4A site investigations. The concentrations
encountered ranged from <0.1ppm to 85.5ppm, with the highest value encountered in WS11A
at the Catalyst Trade Park which was installed into the alluvium. Concentrations of 50ppm and
71ppm were also recorded at the Catalyst Trade Park in BH56 and BH42 respectively, these
monitoring wells were also installed into the alluvium.
6.37.14 PID monitoring was also undertaken during ground gas monitoring in October 2008 on 15no.
wells; two of which were installed at Anglo Blackwells and Gussion Transport (Area B2) and
13no. at Catalyst Trade Park (Area C). The concentrations in Area B2 were 0.3ppm (WS24)
and 11.4ppm (BH58). The concentrations in Area C ranged from 1.6ppm to 103.2ppm, with the
highest value encountered in WS11A which is installed in the alluvium.
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Phase 6 Investigation Soil Vapour Monitoring
6.37.15 Vapour monitoring on soil arisings in Widnes was undertaken during the Phase 6 site
investigation using a photo-ionisation detector (PID). A screening level of 2ppm has been used
to assess the results obtained, this level is based on the long term (8 hour time weighted
average) workplace exposure limit for carbon tetrachloride and chloroform (both encountered in
samples tested from Area C). The long term workplace exposure limit for carbon disulphide is
10ppm and hydrogen sulphide is 5ppm.
6.37.16 The results obtained from the Phase 6 investigation ranged from 0pmm to 3031ppm with the
highest reading obtained from BH66B at 11.7m bgl (from Area C in Thermphos). BH66B also
recorded the second highest result of 2644ppm at 12.0m bgl. A total of 159 of the 745 soil
samples assessed exceeded the 2ppm screening level.
6.37.17 Subsequent PID monitoring was undertaken in January 2008 prior checking monitoring wells
installed during the Phase 6 investigation for free product. The highest concentration of
110ppm was recorded in WS38 at Catalyst Trade Park, this well was installed into the alluvium.
Although much lower than WS38, readings greater than 2ppm were also obtained from seven
other wells at Catalyst Trade Park (from 2.7 to 17.6ppm), two at Gussion Transport (3.9 and
8.1ppm) and one at the former Anglo Blackwell site (2.4ppm). One slightly elevated reading
(4.2ppm) was obtained from BH119 at the Bridgwater Junction in Runcorn.
Phase 7 Investigation Soil Vapour Monitoring
6.37.18 The results obtained from soil arisings during the Phase 7 investigation were all below detection
at the reclamation yard off Hutchinson Street. The results from BH149 to BH151 on Spike
Island ranged from 20.4 to 1348ppm with all results exceeding the screening level. The highest
result was obtained from made ground at 0.2m bgl in BH151. The concentration of volatile
vapours from BH149 to BH151 reduced with depth.
6.37.19 Soil PID readings for Runcorn and Widnes are shown in Drawing No. MG_REP_EIA_009/092.
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7. RISK ASSESSMENT
7.1 Introduction
7.1.1 The assessment and significance of contamination has been based on the following model:
Source – Pathway – Receptor
7.1.2 For a risk to exist at least one plausible pollutant linkage between each component of the model
needs to be present. The aim of the assessment has been to identify, on a qualitative basis, the
extent to which linkages may be present and then to assess the level of risk.
7.1.3 This assessment has been based on the current site status and on the possibility that a linkage
might be introduced through development related to the Mersey Gateway Project in the future.
This reflects the Contaminated Land Regulations (2000) where establishing a significant
pollutant linkage is an important part of defining statutory „Contaminated Land‟.
7.1.4 Text and tables have been updated in the following sections where necessary to reflect
changes in the Updated Reference Designand baseline information obtained.
7.2 Conceptual Site Model
7.2.1 This risk assessment has been prepared on the basis of the following conceptual site model.
The conceptual site model is shown on Drawing Numbers MG_REP_EIA_009/093 to
MG_REP_EIA_009/096. The Project has been considered as separate areas and these are
shown on Drawing Nos. MG_REP_EIA_009/003.
Environmental Setting
Current Land Uses
a. In Widnes the current land uses within the Project area comprise highways, light
industrial buildings, a lorry trailer park, a metal alloy producing business, two
scrapyards, a railway line, a chemical works (Thermphos) and a public golf course
which is currently closed.
b. The public golf course is closed due to the presence of contamination; the northern part
of this site is currently subject to determination under Part IIA of the Environment Act
1990. Although the southern part of the golf course is within the Project area and is
available for use as a construction compound, it is not located within the footprint of the
proposed construction works.
c. The northern side of the River Mersey is flanked by saltmarsh known as the Widnes
Warth that is currently undeveloped open space covered by saltmarsh vegetation.
d. South of the river in Runcorn, the current land use comprises highways between the
M56 Junction 12 and Bridgewater Junction. To the north of the Bridgewater Junction
lies the Astmoor Industrial Estate and the Manchester Ship Canal. Beyond this lies
Wigg Island and Astmoor Saltmarsh. Wigg Island is a Community Park whilst Astmoor
Saltmarsh has the same land use as Widnes Warth.
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Historical Land Uses
a. In Widnes numerous historical land uses have been identified with the potential to
cause contamination. Chemical and other industrial land uses have been identified
between St Michaels Golf Course and the St Helens Canal (Areas A to C). There is
evidence for a very limited amount of past industrial development on the Widnes Warth
saltmarsh to the north of the Mersey and west of the route alignment in Area D.
b. In Runcorn several chemical works were also present on Wigg Island (Area D), adjacent
to the Manchester Ship Canal.
c. A former tannery was located in Area F, immediately north of the Bridgewater Canal.
There is also evidence of limited localised potentially contaminative land uses on the
Astmoor Industrial Estate in Runcorn, these all date from after the estate was developed
in the late 1960‟s.
d. Evidence for the widespread disposal of chemical and industrial wastes has been
identified between St Michaels Golf Course and St Helens Canal in Widnes (Areas A to
C). Similar evidence was noted for the Wigg Island Landfill on Astmoor Saltmarsh.
Chemcial wastes that have been disposed of include alkali waste, known locally as
galligu.
e. Historical information notes that the former ICI Experimental Works was located on the
site currently occupied by Catalyst Trade Park and to the north beneath the existing
A557 Expressway (Area C). A wide range of chemical compounds were historically
associated with this site, including volatile organic compounds. From the available
information it appears that the site was disposed of by ICI in the late 1990‟s.
Surface Water Courses
a. The largest surface water feature within the project area is the River Mersey, this
separates the towns of Runcorn and Widnes. The River Mersey is tidal in this area,
with extensive sandbanks exposed at low tide. The River Mersey is flanked to the north
and south by Widnes Warth and Astmoor Saltmarshes respectively.
b. In Widnes the route crosses Stewards Brook (Area A), the St Helens Canal (Area C)
and Bowers Brook (Areas C and D).
c. Stewards Brook is located to the west of Area A. Marsh Brook is located southwest of
Area B2 and west of Area I, although a buried culvert extends between Ditton Junction
in Area B1 and Marsh Brook.
d. In Runcorn the proposed route crosses the Bridgwater Canal (Area F), Manchester Ship
Canal (Area D), Latchford Canal (Area D) and Flood Brook (Area H).
e. The Bridgewater Canal may not have been lined but its base is likely to have been
constructed in glacial clay. It is possible that the St Helens Canal is lined, however, the
status of the Latchford Canal is not known.
f. Anecdotal information from the Contaminated Land Officer at the Council indicates that
to the south of the Speke Road, Stewards Brook has been lined to provide protection
against contaminants associated with the fill material on St Michaels Golf Course.
g. Bowers Brook is present to the south of Catalyst Trade Park (Area C). This watercourse
is partly in open channel and partly in a brick culvert, however, there is no evidence to
suggest that it is cut off from the adjacent areas of contaminated land. It flows parallel
to the St Helens Canal and discharges into the River Mersey at Spike Island.
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Hydrogeology
a. Parts of the proposed route alignment in Widnes (Areas A, C and D) are directly
underlain by a Secondary (undifferentiated) minor aquifer associated with alluvial drift
deposits. Wigg Island in Runcorn (Area D) is also shown as being directly underlain by
a Secondary (undifferentiated) minor aquifer. as is Secondary (undifferentiated) and
Secondary A aquifers are shown to be associated with the drift deposits in the area
around M56 Junction 12 (Area H).
b. No aquifer classification is provided for the glacial drift deposits between Area E and G
in Runcorn. A non-aquifer is present at shallow depth from the Central Expressway to
the Weston Link Junction (Areas G1 to G2).
c. The bedrock A major aquifer is present beneath Widnes and Runcorn (Areas A to F) is
shown as a Principal aquifer. The bedrock to the south of Area F in Runcorn (Area G to
H) is shown as Secondary B aquifer.
d. The Principal major aquifer is at depth beneath Widnes (Areas A to D) but it is near
surface to the west of Runcorn and beneath Astmoor Industrial Estate and Bridgewater
Junction (Areas E and F).
e. The Principal major aquifer is formed by the Sherwood Sandstone and the Secondary B
minor and non-aquifers relate to drift geology and mudstone bedrock respectively.
f. The Principal major aquifer underlies the Secondary minor aquifer though they are not
necessarily directly connected, particularly in Widnes (Areas A to D) where extensive
deposits of glacial till are present.
g. The area from St Michaels Golf Course to Catalyst Trade Park in Widnes (Areas A to C
is located in a Area 3 SPZ (total catchment), and the western most part of the scheme
at St Michaels Golf Course and Speke Road (Area A) are located in a Area 2 SPZ
(outer protection zone). However, it should be noted that this SPZ refers to the major
aquifer at depth.The project area is no longer located within an SPZ. The nearest SPZ
(total cathchment) is approximately 500m west of Area A and is associated with the
bedrock.
Groundwater Abstraction
a. There are public drinking water abstractions from the bedrock aquifer some 3km north
of the Project area. No industrial abstractions have been identified within the Project
area itself. Information obtained from the EA shows the presence of solvents in the
bedrock aquifer in parts of Runcorn and to a lesser extent Widnes (in wells south of St
Michaels Golf Course) although recent monitoring by the EA indicates concentrations
have reduced.
b. Historical plans for the former ICI Widnes Experimental Site at the Catalyst Trade Park
in Area C show a well was located in the north west of the Catalyst Trade Park adjacent
to the existing Unit 3 (currently beneath an area of hard cover). ICI records indicate this
well extended 207m into the sandstone bedrock and that the well was covered/capped
in 1960s, however, no records of how the well was capped have been located.
c. Historical information obtained on the former High Speed Steel Alloys (HSSA) site in
Area B2 indicates the water supply for this works was obtained from a 250 foot deep
borehole located within the centre of the site. The information obtained does not show
the location of the well historical OS maps indicate the centre of former HSSA site
(shown as Steel Alloy Works) would have been located towards the centre of the
existing Gussion Transport site.
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Ground Conditions from Investigations
Widnes
a. Ground conditions in Widnes comprise made ground over Glacial Till which in turn
overlies Sandstone Bedrock. Alluvium comprising silt/clay over granular deposits has
been identified in the southern parts of St Michaels Golf Course in Area A and Catalyst
Trade Park in Area C. This material was present between the made ground and the
Glacial till. The alluvium then extends south to the River Mersey across the
saltmarshes in Area D. The Glacial Till comprised clay with interbedded granular
horizons, in all locations where the till was encountered the upper surface was found to
be clay.
b. The made ground was encountered in all of the exploratory holes to the north of St
Helens Canal in Areas A to C. It was also present in localised areas on the northern
edges of the saltmarshes in Area D. The made ground overlies the cohesive alluvium
and includes material identified as galligu. Visual and olfactory evidence of
contamination was noted throughout the made ground as well as, more rarely, in the
alluvium and the upper layers of the glacial till.
c. An approximate east-west trending buried glacial channel has been identified in Widnes
beneath Ditton Junction (Area B1), north of the A557 Expressway (Area B2), the Rail
Freight Line and the former ICI Muspratt site (east of Area C). In this area the deepest
depth at which the rock was recorded was 49.5m bgl (-40.04m AOD) to the north of the
A557 Expressway and there is a significant thickness of glacial till.
d. Chemical waste, including galligu, was identified within the project area in Widnes
between the St Michaels Golf Course and St Helens Canal (Area A to C) and on the
northern edge of Widnes Warth (Area D).
Runcorn
a. Ground conditions in Runcorn comprise localised areas of made ground over Glacial Till
which in turn overlies Sandstone and Mudstone Bedrock. Alluvium comprising silt/clay
over granular deposits has been identified in Area D to the north of Manchester Ship
Canal extending north to the River Mersey. The Glacial Till comprised clay but only
rarely were interbedded granular horizons noted, in all locations where the till was
encountered the upper surface was found to be clay.
b. Made ground to the north of Manchester Ship Canal was identified in the Wigg Island
Landfill (landraise) and former Wigg East Works (Kemet Works) and on the north bank
of the canal itself. Ground conditions on the Wigg Island Landfill comprised made
ground over alluvium which in turn rested upon sandstone.
c. Glacial clay was locally absent beneath Wigg Island Landfill and Astmoor Saltmarsh
where the alluvium rested directly on the bedrock.
Mersey Estuary
a. Ground conditions within the Area D in the Mersey Estuary comprise granular alluvium
directly overlying Sandstone Bedrock.
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Groundwater
a. Shallow groundwater has been identified within the made ground, alluvium and glacial
deposits. No clear pattern of groundwater flow could be established in the made
ground.
b. Groundwater flow direction within the alluvium was found to be towards the Mersey
Estuary on both banks of the river.
c. The groundwater in the glacial deposits was within granular layers, in Widnes these
appear to be separated from the groundwater in the alluvium.
d. Groundwater has also been identified within the Sherwood Sandstone bedrock. In the
Project area groundwater flow in the bedrock was found to be to the north.
e. There is evidence of groundwater rebound in the bedrock beneath Widnes, though not
under Runcorn.
f. The base of St Helens Canal and the Bowers Brook culvert are considered to be
located on or within the cohesive alluvial deposits. St Helens Canal may be lined with
„puddled‟ clay. Bowers Brook is channelled through a brick lined culvert; historical
survey photographs show evidence of shallow groundwater seepage into Bowers
Brook. On this basis it is probable that there is connectivity between shallow
groundwater and surface water at the Brook. There is evidence of elevated
concentrations of contamination in the sediments in the Brook and in water discharged
from the Brook.
g. Manchester Ship Canal is unlined and is constructed into the bedrock; the water in the
canal is likely to be in hydraulic continuity with the underlying sandstone. The
Bridgewater Canal is also not thought to be lined although the presence of glacial clay
would reduce the potential for continuity with groundwater.
Contamination
Soil Contamination - Commercial/Industrial Land Use Assessment
7.2.2 The soil testing results were compared against recent guidance which has resulted in a number
of changes to the exceedances obtained.
a. Elevated concentrations of soil contamination exceeding the assessment criteria
derived for a commercial/industrial land use have been encountered within the made
ground, alluvium and upper glacial deposits in Widnes. These contaminants comprise
arsenic, lead, sulphates and locally elevated concentrations of petroleum hydrocarbons
(Area B2 Gussion Transport) and semi volatile and volatile organic compounds (Area C
Catalyst Trade Park). Asbestos was encountered at depths of between 2m and 3m bgl
within two boreholes (BH75 and BH83) in Area A on St Michaels Golf Course and three
exploratory holes in Area C on and adjacent to the Catalyst Trade Park.
b. Only localised exceedances of the assessment criteria derived for a
commercial/industrial land use were encountered in Runcorn, these were associated
with made ground and alluvium. These comprised lead (one two samples of made
ground from the Weston Link Junction) and water soluble sulphate (in made ground and
glacial depositsalluvium). Asbestos was encountered within the made ground in BH114
(1.6m and 2.0m bgl) in Area F at the Bridgewater Junction and BH125 (2.0-2.45m bgl)
in Area G1.
c. UCL0.95 upper confidence limits for the mean value were derived using Chebyshev‟s
Theorom for parameters exceeding the assessment criteria for a commercial/industrial
land use. The UCL0.95 values derived for lead exceeded the assessment criteria in
samples tested from the St Michaels Golf Course and Catalyst Trade Park (Areas A and
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C). The UCL0.95 values derived for arsenic at Gussion Transport (Area B2) and the
Catalyst Trade Park (Area C) also exceed the assessment criteria. The UCL0.95 values
derived for EC 16-35 aromatic hydrocarbons in Area B2, and for hexachlorobutadiene
and hexachloroethane vinyl chloride in Area C exceeded the assessment criteria
d. Potential outliers for contaminants were identified for lead and nickel cadmium at St
Michaels Golf Course (Area A), at Gussion Transport for arsenic and aromatic
hydrocarbons (Area B2), at Catalyst Trade Park for arsenic, lead, hexachlorobutadiene
and hexachloroethane and vinyl chloride (Area C) and at Weston Link Junction for lead
(Area G).
Soil Contamination - Construction Workers Land Use Assessment
a. Elevated concentrations of metals, hydrocarbons, SVOCs and VOCs have been
encountered within the made ground in Widnes exceeding the assessment criteria
derived for construction workers. The elevated SVOCs and VOCs were encountered in
Area C on and adjacent to the Catalyst Trade Park and localised areas in Area A and
B2. Concentrations of arsenic in soils have been identified which could represent an
acute risk to construction workers if ingested in Area C at Catalyst Trade Park,
Thermphos and in Area D on Widnes Warth.
b. Localised exceedances of the assessment criteria derived for construction workers in
the made ground were obtained in Runcorn comprising metals, petroleum hydrocarbons
and PAHs.
c. Exceedances of the assessment criteria for construction workers were obtained for
metals in the shallow cohesive alluvium on Widnes Warth and Astmoor Saltmarsh.
Soil Contamination - Phytotoxicity
a. Widespread elevated concentrations of potentially phytotoxic metals have been
encountered from the made ground in Widnes. Only one sample recorded elevated
potentially metals (copper and zinc) in Runcorn in Area G2 (BH127 at 2.0m bgl).
Soil Contamination - Marine Life from Sediments
a. Elevated concentrations of metals/metalloids have been encountered in the cohesive
alluvium on the saltmarshes when compared to the sediment quality guidelines.
Concentrations of PCBs and organochlorine pesticides also exceeded the sediment
quality guidelines in localised areas on Widnes Warth associated with the cohesive
alluvium.
b. Elevated concentrations of metals/metalloids and PAHs were encountered in sediments
within the estuary when compared to the sediment quality guidelines.
Soil Contamination - Buried Water Supply Pipes
7.2.3 The soil testing results were compared against recent guidance which has resulted in a number
of changes to the exceedances obtained.
a. Elevated concentrations of contaminants have been identified within shallow soils in
Widnes which could impact on buried plastic pipes and drinking water quality. Locally
elevated concentrations of contaminants were also encountered in Area E, F and G in
Runcorn.
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Other specific contaminants
a. Material identified as likely to be phosphorous was encountered in the made ground
from one exploratory hole (BH67) on the Golf Course in Area A.
Soil Leachate Testing
7.2.4 The soil leachate testing results were compared against recent guidance which has resulted in a
number of changes to the exceedances obtained.
a. Soil leachate testing encountered elevated concentrations of metals in made ground
and alluvium in Widnes and the saltmarshes, and in localised areas from made ground
in Runcorn.
b. Locally elevated concentrations of petroleum hydrocarbons were encountered within at
Catalyst Trade Park in Area C, elevated concentrations of PAHs were obtained from
Area C at Thermphos and Area B2 Area I at within an existing road embankment
Gussion Transport. Elevated TPH was encountered in one location from the made
ground at the M56 Junction 12 in Area H.
c. SVOC testing encountered locally elevated PAHs in the made ground and alluvium at St
Michaels Golf Course in Area A. Elevated naphthalene was encountered in one sample
of made ground from Gussion Transport in Area B2, one sample of cohesive alluvium
from Widnes Warth and the made ground from the Wigg Island Landfill in Area A, B2, C,
D, I and H.
d. Carbazole and dibenzofuran were encountered in the made ground and alluvium from
St Michaels Golf Course in Area A Thermphos in Area C. Bis(2-ethylhexyl)phthalate
was encountered the made ground from Wigg Island Landfill in Area D and 2-
methylnaphthalene from made ground and alluvium in Area D.
Groundwater Contamination
7.2.5 The groundwater testing results were compared against recent guidance which has resulted in a
number of changes to the exceedances obtained. Additional rounds of groundwater testing
have also been undertaken since the Orders ES in 2008.
a. Widespread elevated concentrations of metals/metalloids were recorded in Widnes
within shallow groundwater. The concentration of metals/metalloids in the bedrock was
low.
b. Elevated concentrations of petroleum hydrocarbons were identified at Catalyst Trade
Park (Area C), Spike Island (Area D) and at Gussion Transport (Area B2) together with
BTEX and floating free product (see below). Elevated concentrations of petroleum
hydrocarbons were also identified at St Michaels Golf Course (Area A),
c. Widespread elevated concentrations of ammonium were also encountered across the
project area.
d. Significantly elevated concentrations of a number of volatile organic compounds,
including chlorinated solvents such tetrachloroethene, trichloroethene and
tetrachloroethane, were identified in groundwater samples obtained from the made
ground, alluvium and the upper glacial sand on and adjacent to the Catalyst Trade Park
(Area C). Evidence for free phase DNAPL in groundwater has been obtained from
samples tested at the Catalyst Trade Park in made ground, alluvium and glacial sand, at
Thermphos (one location in glacial sand) and Spike Island in alluvium (see below).
e. Elevated concentrations of solvents were also encountered intermittently in shallow
groundwater samples obtained from the made ground and alluvium at Gussion
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Transport (Area B2) and St Michaels Golf Course (Area A). The recorded
concentrations were not indicative of free phase DNAPL and no samples of DNAPL
could be recovered from these monitoring wells.
f. No evidence was noted of migration of dissolved phase chlorinated solvents along the
proposed route beneath Widnes Warth saltmarsh. A limited number of wells were
installed in the alluvium down hydraulic-gradient of Catalyst Trade Park. These wells
showed rapid decreases in solvent concentrations.
g. There was evidence of breakdown products including cis-1,2-dichloroethene at Catalyst
Trade Park (Area C) and Spike Island (Area D) arising from the reductive dechlorination
of chlorinated compounds, which indicates that natural attenuation of these compounds
is likely to be taking place.
h. Concentrations of organochlorine pesticides in excess of the drinking water standards
were recorded in the alluvium and made ground in Area C and alluvium in Area D on
Spike Island.
i. Acid herbicides above the lower analytical detection limit were recorded in shallow
groundwater samples tested on and adjacent to the Catalyst Trade Park in Area C. Of
these, only pentachlorophenol exceeded the EQS in one borehole.
j. In Runcorn, locally elevated concentrations of metals/metalloids including arsenic were
obtained on from Areas D to G from the alluvium, glacial deposits and Sherwood
Sandstone.
k. No groundwater has been encountered in BH18A which was installed into the fill
material on top of the Wigg Island Landfill. However, information obtained from
historical investigations indicates that groundwater has been encountered elsewhere
within the Wigg Island Landfill. Elevated concentrations of ammonia and sulphate were
recorded in samples from monitoring wells installed into the made ground in the vicinity
of the proposed pier location on the eastern slope of this landfill.
l. There was evidence that the groundwater beneath Wigg Island Landfill has suffered
some impact with elevated concentrations of arsenic and ammonia having been
recorded. Elevated concentrations of arsenic have also been recorded in wells on the
saltmarshes downgradient of the Wigg Island Landfill.
m. A DQRA was undertaken for contaminants arising from the NAPL identified at Gussion
Transport (in Area B2) and Catalyst Trade Park (Area C). A risk was identified to
Bowers Brook in Area C from contaminants in the made ground. However, a risk was
not identified from the possible chlorinated solvent free product in the made ground and
alluvium at Catalyst Trade Park to the River Mersey or from LNAPL at Gussion
Transport to Marsh Brook.
Surface Water Interactions
a. There is evidence of chlorinated solvents in Bowers Brook at the outfall at Spike Island;
it is possible that there is some continuity between the contaminants at the Catalyst
Trade Park (Area C) and the brook. Historical records indicate that drains on Catalyst
Trade Park and surrounding sites discharged to Bowers Brook, solvents and radioactive
materials have been reported in the drains at Catalyst Trade Park.
b. Stewards Brook is understood to be lined where it crosses the site area through the
southern part of St Michaels Golf Course (to the west of Area A). On this basis it is
considered that contaminants from the Project area are unlikely to be migrating into this
water course under the proposed route.
c. The St Helens Canal is probably founded in the cohesive alluvium and dates from a
time when canals were frequently lined. On this basis it would form a barrier to
migration of contaminants at shallow depth to the south towards the River Mersey. To
date no historic records have been located to confirm whether the canal is lined.
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d. Evidence of a spring breaking out to a drainage channel north of the Wigg Island
Landfill in Area D was noted, this was approximately 20m west of the route alignment.
Elevated concentrations of ammonia, cyanide and an alkaline pH were recorded from
this spring.
Non Aqueous Phase Liquids
a. Light Non Aqueous Phase Liquids (LNAPL) was found during specific sampling in only
four exploratory holes, all located at the Gussian Transport site in Area B2. A review of
the free product testing from WS17 indicates the LNAPL comprised predominantly fatty
acids and fatty acid methyl esters. Two clusters of discrete peaks between C6-10 and
C17-C26 were also present and VOC and SVOC analysis found trace levels of
chlorinated solvents, volatile fatty acids, BTX compounds and MTBE.
b. The maximum thickness of LNAPL recorded at this site was 0.44m in WS17. The
LNAPL at this site was found to be floating on top of groundwater in the made ground.
The DQRA did not indicate that LNAPL was likely to represent a risk to surface water at
Marsh Brook.
c. VOC and SVOC analysis found trace levels of chlorinated solvents, volatile fatty acids,
BTEX compounds and MTBE.
d. On the basis of the dissolved concentrations in groundwater there was evidence of
potential Dense Phase Non Aqueous Phase Liquids (DNAPL) at Catalyst Trade Park
and Thermphos (Area C) and including wells at or close to the site boundary to the
south and west of the Project area on Spike Island (Area D).
e. There was evidence of DNAPL in two wells from the made ground, six from the granular
alluvium and two a single boreholes in the upper sand layer of the Glacial Till (which
suggests that the DNAPL has pentrated into the till). There was also evidence of
DNAPL in the alluvium on Spike Island and glacial sand at one location on Thermphos.
f. Elevated concentrations of volatile organic compounds were noted in soil samples
analysed from the made ground and the alluvium, though the concentrations were not
indicative of DNAPL.
g. Subsequent sampling specifically targetted at the wells containing potential DNAPL was
unable to recover any free product.
h. The DNAPLs were found to be constrained to the north of Catalyst Trade Park (Area C)
by a slope in the glacial till, interpreted as a buried bank of the Mersey, that trends from
north east to south west beneath Catalyst Trade Park.
i. Although the route crosses the area of potential DNAPL no evidence of DNAPL
extending out beneath the route under Widnes Warth saltmarsh to the east and south
east was recorded.
j. There was evidence of the potential DNAPL extending to the south western boundary of
Catalyst Trade Park and this is consistent with information from the Council which
indicates that chlorinated solvents are present beneath the Honeywell site to the south
west.
k. It is postulated that if DNAPL is present it may be DNAPL appears to be following the
former course of the River Mersey to the south west of Area C.
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Contamination in the Vicinity of Former Abstraction Wells
a. Metals/metalloids, petroleum hydrocarbons and PAHs were noted in soil samples tested
from the made ground in the exploratory holes located nearest to the area identified by
ICI of the former works well at Catalyst Trade Park (BH47 and WS14).
b. BH47 and WS14 were installed with monitoring wells into the made ground. A slightly
elevated concentration of arsenic was obtained in the groundwater sample tested from
WS14 during the Round 10 sampling when compared to the DWS (16μg/l compared to
DWS of 10μg/l).
c. Elevated concentrations of VOCs were not obtained from wells installed into the glacial
sand located towards the north and northwest of the Catalyst Trade Park suggesting
that solvents are unlikely to be migrating in this horizon towards the former works well at
present.
d. The top of the glacial clay in the area of the well at Catalyst Trade Park was present
beneath the made ground at shallow depth between 1.0m and 2.0m bgl.
e. Elevated concentrations of metals/metalloids were identified in soils at Gussion
Transport. VOCs and SVOCs at concentrations above the lower analytical detection
limit were also encountered in soils within this area. Elevated concentrations of
metals/metalloids, organic compounds (including SVOCs and petroleum hydrocarbons)
and LNAPL were identified in shallow groundwater at Gussion Transport.
Saline Intrusion & Tidal Influences
a. Groundwater within the drift deposits and bedrock adjacent to the estuary in Widnes
and Runcorn has been impacted by saline intrusion.
b. Groundwater in both the alluvium and bedrock beneath the salt marshes shows
evidence of tidal influence although this does not extend beyond the St Helens Canal in
the alluvium in Widnes.
Ground Gas
a. Concentrations of ground gas have been identified which indicate that protection
measures would be required for buildings such as toll plazas and offices. This text has
been removed as toll booths and offices are no longer proposed.
b. Elevated concentrations of carbon dioxide exceeding the short and long term workplace
exposure limits have been encountered from the made ground, alluvium (Widnes),
saltmarshes, glacial deposits and bedrock in Widnes and Runcorn.
c. Elevated concentrations of methane exceeding the lower explosive limit of 5% (v/v)
have been encountered in one exploratory hole (BH131A) in Runcorn, this was installed
into the glacial deposits during the Phase 6 investigation. Subsequent monitoring of
BH131A did not encounter methane above the lower instrument detection limit.
d. Elevated concentrations of carbon monoxide exceeding the long term workplace
exposure limit were only encountered in two monitoring wells installed into the alluvium
north of St Helens Canal (WS11A and BH42). Elevated concentrations of hydrogen
sulphide exceeding the long term workplace exposure limit have been encountered only
in BH18A on the Wigg Island landfill.
e. Elevated concentrations of volatile vapours have been encountered within the made
ground and drift deposits in Widnes, in particular on and adjacent to Area C Catalyst
Trade Park/Thermphos in Widnes.
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Unexploded Ordnance
a. A desk top threat assessment prepared by BACTEC noted that area of Widnes and
Runcorn in or close to the Project area were subject to aerial bombing.
b. The possible risks from UXO on the saltmarshes and within the estuary were assessed
to be moderate, and low within other parts of the scheme.
c. A detailed risk assessment was prepared by BAE Systems on the moderate risk areas
identified by BACTEC for the proposed construction works. The results of this
assessment identified a moderate probability of encountering German air dropped UXO
and a low to moderate probability of encountering UXO of an anti-aircraft origin during
the construction works in this part of the project area. However, if UXO was found, the
likelihood of initiating the device and causing an explosion was considered substantially
lower.
d. No ordnance was encountered during the investigation.
e. A former chemical weapons production facility has been identified at Randle Island in
Runcorn. The site appears to have been located approximately 380m east of the
proposed approach viaduct, at the location of the existing Randle Island Landfill. No
evidence has been obtained to indicate A more detailed assessment undertaken for the
Public Inquiry showed that this facility did not extend into the Project area.
Radioactive Contamination
a. Historical evidence indicates that material with low levels of radiation have been
encountered in localised areas in Area C at Catalyst Trade Park.
b. No documentary evidence has been obtained to suggest that radioactive waste was
buried at this site. Residual contamination is likely to be the result of leaks and
spillages or dust generated during processing of the uranium metal
c. Previous surveys did not identify any significant ground level radiological contamination
or the need for special protective measures to restrict exposure to individuals
d. Previous surveys at Bowers Brook identified radiological contamination in the
sediments.
e. Anecdotal evidence indicates that material with low levels of radiation from Area C could
have been incorporated into the A557 embankment during construction of the road.
f. Elevated levels of radiation were only encountered at two locations during the site
investigations. Slightly elevated levels of radiation, up to 2.5 times background
readings, were identified in one exporatory hole located towards the centre of the
Catalyst Trade Park in Area C, this was associated with shallow made ground.
Elevated readings were also recorded from ashy material immediately underlying a
gravelled area adjacent to BH105.
g. Screening of soil samples recovered from the full depth of the made ground did not
reveal any further evidence of radioactive material.
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Construction Proposals
The following construction proposals have been considered for the conceptual site model.
a. The conceptual model is based on ground improvement being required for
embankments on made ground and/or alluvium comprising vibro-concrete columns
founded on the glacial till with a load transfer platform. The vibro-concrete columns
would only have limited penetration into the underlying glacial clay (200mm to 300mm).
b. Foundations for larger structures will require piles where there are significant depths of
made ground or alluvium. Particular structures to be piled include the piers for the
bridge approach viaducts and the northern and southern abutments. The railway
bridge, the bridges at Ditton Junction and Victoria Road will also have piled foundations.
c. The piles for these structures will be founded on rock to the south of the estuary. To the
north the piles for the approach viaduct piers closest to the river will be founded on rock,
thereafter piles for all structures to the north will be founded in the higher level glacial
till.
d. The main towers in the estuary will be founded on either piles or barrettes that will
extend to the bedrock.
e. The structures at the Widnes Loops, located in Area C at Catalyst Trade Park, will be
box structures founded on VCC be piled, although these structures would not be located
within the area of DNAPL contamination. It is assumed the embankments in this area
would be founded on vibro-concrete column improved ground.
f. There will be a new retaining wall on the south-east side of the existing north
roundabout at M56 Junction 12. This would involve the installation of a line of
contiguous bored concrete piles over a length of 75m and 262m of inverted reinforced
concrete retaining wall.
g. It is assumed that where piles are used, these would comprise either CFA or Bored and
Cast in Place piles in accordance with EA (2001) guidance for piling and penetrative
ground improvement on land affected by contamination.
h. In addition to excavations for pile caps, replacement piling such as CFA or and Bored
and Cast in Place methods would produce arisings.
i. Where possible it is proposed to re-use excavated material. However, a significant
quantity of fill material will need to be imported.
j. A site strip would not be undertaken.
k. Excavations will be required for structures (pile caps) and services, otherwise only
limited areas of cutting will be required in Widnes. It is assumed that no extensive
excavations for site preparation will be required in other parts of Widnes. No topsoil
strip will be undertaken on St Michaels Golf Course in Area A.
l. Excavations for structures (pile caps) and services will be required in Runcorn. It is
assumed the proposed pier location on the Wigg Island Landfill will be piled, with
excavations for the pile cap. Excavations to the east of the Central Expressway (Area
G1) are proposed; material encountered in this area comprised glacial clay. Localised
excavations for re-grading around existing junctions in Runcorn may be required, again
it is anticipated that these will be in glacial till.
m. Post construction the site will comprise a road with landscaped embankments. Toll
plazas and office buildings will be located on embankment fill in Widnes. It is assumed
that a nominal thickness of topsoil (between 200mm to 300mm) would be introduced
over fill material in areas of landscaping.
n. The placing of embankments directly over soft material without ground improvement
could lead to the displacement of contaminated shallow groundwater off-site as the
underlying ground settles.
o. Toll booths would be accessed from overhead walkways.
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p. Attenuation/balancing ponds for run-off would be introduced close to Ditton Junction
(Area B1/B2), Widnes Loops (in Area C), Bridgewater Junction (Area F) and Lodge
Lane (Area G). It is assumed that all ponds would be lined. The pond in Area C would
be located above ground.
q. Although not located within the footprint of the proposed construction works ,some parts
of the project area would be used as construction compounds, for instance the southern
section of St Michaels Golf Course in Area A.
7.2.1 Where the Construction Methods Report indicates there are a number of options for the design,
in particular between the Freightline Railway Bridge and Victoria Road, Widnes Loops and also
over St Helens Canal in Area C, these have been considered within the risk assessment based
on the assumptions outlined above. It has been assumed that embankments or retained earth
structures would be located on improved ground comprising vibro-concrete columns with
viaducts and abutments requiring piled foundations comprising either CFA or bored and cast in
place piles. However, the use of embankments would provide greater coverage of existing soils
than viaducts.
7.3 Source
7.3.1 The following potential sources have been identified in the Mersey Gateway Project area:
a. Contaminants associated with made ground and drift deposits (including free product
and those materials with the potential to give rise to ground gas and vapours)
b. Contaminants in groundwater
c. Contaminants in surface waters (including drains).
7.3.2 The contaminants identified represent the existing conditions and this baseline will be present
even if the Project does not proceed. On the basis of a review of the information included in the
Orders ES combined with the additional sampling and analysis undertaken for the Further
Applications ES, it is considered that no new sources of contamination are present. The
information collected with regards to groundwater contamination indicates that concentrations
have not altered significantly since the Orders ES.
7.4 Receptors
7.4.1 Potential receptors for the Mersey Gateway Project have been assessed as follows:
a. Human Health during Construction Phase; construction workers, site visitors, local
residents, trespassers.
b. Human Health during Operational Phase; future site users (workers in toll booths or
offices), maintenance workers, landscaping contractors, road users.
c. Controlled waters (groundwater and surface water).
d. Buildings and buried services.
e. Flora in areas of soft landscaping.
f. Flora and fauna on the saltmarshes and within the estuary
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7.5 Pathways
7.5.1 Potential pathways for the Mersey Gateway Project for human health have been assessed as
follows:
a. Outdoor iIngestion, dermal contact or inhalation of contaminated dust, gas and/or
vapours by construction workers, site visitors, trespassers, local residents, future site
users, road users, service maintenance workers or landscaping contractors
b. Indoor ingestion, dermal contact or inhalation of dust, gas and/or vapours by future site
users or maintenance workers from migration into buildings or confined spaces.
c. Migration of contaminated waters into excavations or surface waters
d. Ingestion or dermal contact with water from contaminated water supply pipes.
Inhalation of volatile contaminants in water supplies from contaminated pipes is also
possible.
7.5.2 In addition to the pathways identified above for human health, the following pathways could also
be present:
a. Plant uptake in areas of soft landscaping.
b. Pollution of controlled waters by vertical migration due to downward leaching to
groundwater and / or horizontal migration of mobile contaminants.
c. Pollution of controlled waters by vertical migration along existing and proposed
foundations.
d. Migration of contaminated groundwater including from placement of embankments.
e. Pollution of surface waters through migration of contaminated groundwater
f. Damage to building materials or services through direct contact with contaminants or
through contaminant migration.
g. Direct contact by flora or fauna on the saltmarshes or within the estuary.
7.5.3 It is also likely that odours associated with contaminated material or ground gas and vapours
could arise from the proposed works in some areas, and in particular from excavations.
7.5.4 On the basis of the modifications incorporated in the Updated Reference Design it is considered
that the potential pathways and receptors remain appropriate. No new potential pathways or
receptors have been identified. The receptor workers in toll booths and offices will not be
present in the Project including the Proposals and there are changes to the Project area for
Area A. These changes are reflected in the risk and effect assessment Tables 7.4 to 7.9.
7.6 Assessment Criteria
7.6.1 The risk assessment is based on the guidance provided in CIRIA Report C552 – Contaminated
Land Risk Assessment – A Guide to Good Practice (2001). Scenarios have been assessed for
the Do-Nothing, Construction and Operational Stages. This is still considered to be an
appropriate approach for the Further Applications ES.
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7.6.2 The following descriptions on the classification of probability, consequence and risks are
provided in CIRIA C552:
Classification of Consequence
Table 7.1 – Classification of Consequence
CIRIA C552
Classification
Examples of Criteria Threshold
Severe
Short term (acute) risk to human health likely to result in „significant
harm‟ as defined in EPA, 1990 Part IIA. Short term risk of pollution of
sensitive water course. Catastrophic damage to buildings/property. A
short term risk to a particular eco-system or organism forming part of
such eco-system.
Medium
Chronic damage to human health („significant harm‟). Pollution of
sensitive water resources. A significant change in a particular eco-
system or organism forming part of such eco-system. Significant
damage to plants, buildings, structures and services.
Mild Pollution of non-sensitive water resources. Damage to sensitive
buildings, structures, services or the environment
Minor
Harm, although not necessarily significant which may result in financial
loss or expenditure to resolve. Easily repairable effects of damage to
buildings structures and services.
Classification of Probability
Table 7.2 – Classification of Probability
CIRIA C552
Classification
Examples of Criteria Threshold
High Likelihood
There is a pollutant linkage and an event that either appears very likely
in the short term and almost inevitable over the long term, or there is
evidence at the receptor of harm or pollution
Likely There is a pollutant linkage and all the elements are present and in the
right place, which means that it is probable that an event will occur
Low Likelihood
There is a pollutant linkage and circumstances are possible under which
an event could occur. However, it is by no means certain that even over
a longer period such an event would take place, and it is less likely in the
shorter term
Unlikely There is a pollution linkage but circumstances are such that it is
improbable that an event would occur even in the very long term
Comparison of Consequence against Probability
Table 7.3 – Comparison of Consequence against Probability
Consequence
Severe Medium Mild Minor
Pro
bab
ilit
y
High Likelihood Very high risk High risk Moderate risk Moderate/low
risk
Likely High risk Moderate* risk Moderate/low
risk Low risk
Low Likelihood Moderate risk Moderate/low
risk Low risk Very low risk
Unlikely Moderate/low
risk Low risk Very low risk Very low risk
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7.6.3 A description of the classified risks and likely action is outlined below:
Very High Risk
There is a high probability that severe harm could arise to the designated receptor from an
identified hazard or there is evidence that severe harm to a designated receptor is currently
happening. The risk, if realised is likely to result in substantial liability. Urgent investigation
(if not undertaken already) and remediation are likely to be required.
High Risk
Harm is likely to arise to a designated receptor from an identified hazard. Realisation of the
risk is likely to present a substantial liability. Urgent investigation (if not undertaken already)
is required and remedial works may be necessary in the short term and are likely over the
longer term.
Moderate Risk
It is possible that harm could arise to a designated receptor from an identified hazard.
However, it is either relatively unlikely that any such harm would be severe, or if any harm
were to occur, it is likely that the harm would be relatively mild. Investigation (if not already
undertaken) is normally required to clarify the risk and determine the potential liability. Some
remedial works may be required in the longer term.
Low Risk
It is possible that harm could arise to a designated receptor from an identified hazard but is
likely that this harm, if realised, would at worst normally be mild.
Very Low Risk
There is a low possibility that harm could arise to a receptor. In the event of such harm
being realised it is not likely to be severe
7.6.4 It is important to note that the Moderate* risk category is not contained in CIRIA C552.
However, it has been included on the basis of the definitions provided for a „likely probability‟
and „medium consequence‟. This probability would mean that it is probable that an event will
occur, i.e. a significant possibility. A „medium consequence‟ could involve chronic damage to
human health, pollution of sensitive water resources, a significant change in a particular eco-
system or organism forming part of such eco-system, significant damage to plants, buildings,
structures and services, i.e. „significant harm‟. Other moderate risks involve either a „low
probability‟ or a „mild consequence‟ and, therefore, have not been considered to represent a
„Significant Possibility of Significant Harm‟.
7.6.5 Based on the definitions provided in CIRIA C552, Moderate*, High and Very High risks are
considered to have the potential to meet the requirements outlined in Part IIA for „Significant
Harm‟ or a „Significant Possibility of Significant Harm‟.
7.6.6 The risk assessment considered whether a source-pathway-receptor linkage was likely to be
present. The degree of risk was then assessed through analysis of the consequence of the
effect and the probability of the effect based on guidance outlined in CIRIA C552. The risk
assessment assumes that no mitigation measures are introduced.
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Assessment of Risks
7.6.7 The likelihood of a pollutant linkage being present within the Mersey Gateway Project area and
the potential level of risk for each identified linkage is outlined in the following tables. Each
source – pathway – receptor linkage has been assigned a reference number, prefixed by either
„W‟ for Widnes or „R‟ for Runcorn.
7.6.8 These potential risks are based on the assumption that no additional mitigation measures are
introduced.
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Table 7.4 – Risk Assessment Do-Nothing (Widnes) (continued overleaf) (Updated)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Contaminants on
Site
Ingestion
Inhalation
Dermal Contact
Human Health
Site users, off-site
residents
W1 Low Medium Moderate/Low
Human Health
Construction or
service
maintenance
workers
W2 High Medium High
Contaminated water
supplies from buried
services
Human Health W3 Likely Medium Moderate*
Leaching and
vertical migration of
contaminants into
groundwater
including along
existing buried
foundations
Shallow
Groundwater W4 High Medium High
Groundwater in
Bedrock W5 Low Medium Moderate/Low
Vertical Migration of
contaminated
groundwater along
disused water wells
Groundwater in
Bedrock beneath
CTP
W6 Low Medium Moderate/Low
Groundwater in
Bedrock beneath
Gussion
W7 Likely Medium Moderate*
Vertical Migration of
Free Product along
disused water wells
Groundwater in
Bedrock beneath
CTP
W8 Low Medium Moderate/Low
Groundwater in
Bedrock beneath
Gussion
W9 Likely Medium Moderate*
Off-site migration of
contaminated
groundwater
Shallow
Groundwater W10 High Medium High
Groundwater in
Bedrock W11 Low Medium Moderate/Low
Off-site migration of
LNAPL
Shallow
Groundwater
adjacent to Gussion
W12 LikelyLow Medium Moderate*
Moderate/Low
Off-site migration of
DNAPL
Shallow
Groundwater
adjacent to CTP
W13 High Medium High
Transfer of
contaminants from
LNAPL to
groundwater
Shallow
groundwater
beneath Gussion
W14 High Medium High
Transfer of
contaminants from
DNAPL
groundwater
Shallow
groundwater
beneath CTP
W15 High Medium High
Migration of
contaminants along
buried drains or
services
Off-site shallow
groundwater or
surface water
W16 Likely Medium Moderate*
Migration of
contaminants
through
groundwater to
surface
watercourses
River Mersey W17 Low Medium Moderate/Low
Stewards Brook W18 Low Medium Moderate/Low
Bowers Brook W19 High Medium High
St Helens Canal W20 Unlikely Medium Low
Direct Contact
Integrity of buried
plastic services W21 Likely Mild Moderate/Low
Buried foundations W22 High Mild Moderate
Plant uptake Planting/soft
landscaping W23 Likely Mild Moderate/Low
Direct Contact
Flora and Fauna on
Saltmarshes or
Estuary
W24 Low Medium Moderate/Low
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Table 7.4 (continued) – Risk Assessment Do-Nothing Stage (Widnes) (Updated)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Gas and vapours from
made ground, free
product, and natural
soils
Migration of ground
gas into buildings
Human Health
Site users or site
visitors
W25 Likely Medium Moderate*
Migration of volatile
vapours into
buildings (localised
areas only)
Human Health
Site users or site
visitors
W26 Likely Medium Moderate*
Human Health
Adjacent site users W27 Low Medium Moderate/Low
Migration of ground
gas into
excavations Human Health
People entering
excavations
W28 Likely Severe High
Migration of volatile
vapours into
excavations
(localised areas
only)
W29 Likely Severe High
UXO Direct Contact –
Urban Areas Human Health W30 Unlikely Severe Moderate/Low
Direct Contact –
Salt Marshes Human Health W31 Unlikely Severe Moderate/Low
*1 - SPR – Source / Pathway / Receptor linkage number (W=Widnes, R=Runcorn), as shown in Drawing Numbers MG_REP_EIA_009/093 to
MG_REP_EIA_009/096.
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Table 7.5 – Risk Assessment Do-Nothing Stage (Runcorn) (continued overleaf)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Contaminants on
Site
Ingestion
Inhalation
Dermal Contact
Human Health
Residents/Visitors to
Wigg Island
R1 Low Medium Moderate/Low
Human Health
Residents/visitors,
workers outside Wigg
Island
R2 Unlikely Medium Low
Human Health
Construction or service
maintenance workers at
Wigg Island
R3 Likely Severe High
Human Health
Construction or service
maintenance workers
outside Wigg Island
R4 Low Medium Moderate/Low
Contaminated
water supplies from
buried services
Human Health R5 Low Medium Moderate/Low
Leaching and
vertical migration of
contaminants
between made
ground and shallow
groundwater
including along
existing buried
foundations
Shallow groundwater
beneath Wigg Island R6 Likely Medium Moderate*
Groundwater outside
Wigg Island R7 Low Medium Moderate/Low
Vertical migration of
contaminated
groundwater to
bedrock
Groundwater in Bedrock
outside Wigg Island R8 Low Medium Moderate/Low
Groundwater in Bedrock
beneath Wigg Island R9 Likely Medium Moderate*
Off-site migration of
contaminated
groundwater
Made Ground R10 Low Mild Low
Alluvium R11 Likely Medium Moderate*
Glacial Deposits R12 Low Mild Low
Bedrock at Wigg Island R13a Likely Medium Moderate*
Bedrock outside Wigg
Island R13b Low
Medium Moderate/Low
Migration of
contaminants along
buried drains or
services
Off-site groundwater or
surface water R14 Low Medium ModerateLow
Migration of
contaminants
through
groundwater to
surface
watercourses
River Mersey R15 Low Medium Moderate/Low
Latchford Canal R16 Low Medium Moderate/Low
Manchester Ship Canal R17 Low Medium Moderate/Low
Bridgewater Canal R18 Low Medium Moderate/Low
Direct Contact
Integrity of buried plastic
services R19 Likely Mild Moderate/Low
Buried Foundations
outside Wigg Island R20 Likely Mild Moderate/Low
Buried Foundations at
Wigg Island R21
Unlikely (none
encountered or
shown on
historical OS
maps)
Mild Low
Plant uptake Planting/soft
landscaping R22 Likely Mild Moderate/Low
Direct Contact Flora and Fauna on
Saltmarshes or Estuary R23 Low Medium Moderate/Low
Gas and vapours
from made ground
and natural soils
Migration of ground
gas into buildings Human Health (site
users or site visitors)
R24 Low Medium Moderate/Low
Migration of volatile
vapours into
buildings
R25 Unlikely Medium Low
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 262 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 7.5 (continued) – Risk Assessment Do-Nothing Stage (Runcorn)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Gas and vapours
from made ground
and natural soils
Migration of ground
gas into
excavations at
Wigg Island Human Health
People entering
excavations
R26 Likely Severe High
Migration of volatile
vapours into
excavations at
Wigg Island
R27 Likely Severe High
Migration of ground
gas into
excavations outside
Wigg Island Human Health
People entering
excavations
R28 Low Severe Moderate
Migration of volatile
vapours into
excavations outside
Wigg Island
R29 Unlikely Severe Moderate/Low
UXO Direct Contact –
Urban Areas Human Health R30 Unlikely Severe Moderate/Low
Direct Contact –
Salt Marshes Human Health R31 Unlikely Severe Moderate/Low
*1 - SPR – Source / Pathway / Receptor linkage number (W=Widnes, R=Runcorn), as shown in Drawing Numbers MG_REP_EIA_009/093 to
MG_REP_EIA_009/096.
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 263 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 7.6 – Risk Assessment Construction Stage (Widnes) (continued overleaf) (Updated)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Contaminants on
Site
Ingestion
Inhalation
Dermal Contact
Human Health
Construction/ground
workers
W32 High Severe Very High
Human Health
Site visitors, trespassers W33 Likely Severe High
Human Health
Local residents W34 Likely Medium Moderate*
Contaminated water
supplies from new
buried services
Human Health W35 No Pathway
Leaching and
vertical migration of
contaminants
between
groundwater
horizons
Shallow Groundwater W36 High Medium High
Bedrock W37 Low Medium Moderate/Low
Vertical Migration of
contaminated
groundwater along
disused water wells
Groundwater in Bedrock
beneath CTP W38 Low Medium Moderate/Low
Groundwater in Bedrock
beneath Gussion W39 Likely Medium Moderate*
Vertical Migration of
Free Product along
disused water wells
Groundwater in Bedrock
beneath CTP W40 Low Medium Moderate/Low
Groundwater in Bedrock
beneath Gussion W41 Likely Medium Moderate*
Vertical migration of
contaminants due to
installation of piled
foundations
Shallow Groundwater W42 Unlikely Medium Low
Groundwater in Bedrock
outside CTP W43 Unlikely Medium Low
Groundwater in Bedrock
beneath CTP W44 Low Medium Moderate/Low
Vertical migration of
contaminants in
areas where existing
foundations are
removed
Shallow Groundwater W45 High Medium High
Vertical migration
between horizons
during installation of
vibro-concrete
columns
Shallow Groundwater W46 Low Medium Moderate/Low
Shallow Groundwater
beneath CTP (DNAPL) W47 Low Medium Moderate/Low
Off-site migration of
contaminated
groundwater
Shallow Groundwater W48 High Medium High
Bedrock W49 Low Medium Moderate/Low
Off-site migration of
LNAPL
Shallow Groundwater
adjacent to Gussion W50 LikelyLow Medium
Moderate*
Moderate/Low
Off-site migration of
DNAPL
Shallow Groundwater
adjacent to CTP W51 High Medium High
Transfer of
contaminants from
LNAPL to
groundwater
Shallow groundwater
beneath Gussion W52 High Medium High
Transfer of
contaminants from
DNAPL groundwater
Shallow groundwater
beneath CTP W53 High Medium High
Off-site migration of
contaminated
groundwater due to
placing embankment
(without ground
improvement)
Shallow Groundwater W54 Low Medium Moderate/Low
Bedrock W55 Unlikely Medium Low
Migration of
contaminants along
buried drains or
services
Off-site groundwater or
surface water W56 Likely Severe High
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Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 264 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 7.6 (continued) – Risk Assessment Construction Stage (Widnes) (Updated)
Source Pathway Receptor SPR No.*1 Probability Consequence Risk Classification
Contaminants on
Site
Migration of
contaminants
through
groundwater to
surface
watercourses
River Mersey W57 Low Medium Moderate/Low
Stewards Brook W58 HighLow SevereMedium Very High
Moderate/Low
Bowers Brook W59 High Severe Very High
St Helens Canal W60 Unlikely Medium Low
Migration of
contaminants
through surface
water run-off to
surface
watercourses
River Mersey W61 Likely Medium Moderate*
Stewards Brook W62 Likely Medium Moderate*
Bowers Brook W63 Likely Medium Moderate*
St Helens Canal W64 Likely Medium Moderate*
Direct Contact
Integrity of new buried
plastic services W65 No Pathway
New Foundations W66 High Mild Moderate
Plant uptake Planting/soft
landscaping W67 No Pathway
Direct Contact
Flora and Fauna on
Saltmarshes or
Estuary
W68 Low Medium Moderate/Low
Scour/Erosion
around Piers
releasing
contaminants
Saltmarsh or Estuary W69 Low Medium Moderate/Low
Gas and vapours
from made ground
and natural soils Migration of ground
gas into
excavations Human Health
People entering
excavations
W70 Likely Severe High
Migration of volatile
vapours into
excavations
W71 High Severe Very High
Migration of ground
gas to adjacent
areas outside
excavations
Human Health
(site users, site
visitors, local
residents, workers and
trespassers)
W72 Unlikely Medium Low
Migration of volatile
vapours to adjacent
areas outside
excavations
W73** Likely Medium Moderate*
Migration of gas or
vapours into
buildings off-site
Human Health W74 Low Medium Moderate
UXO
Direct Contact
ground works in
urban areas
Human Health W75 Unlikely Severe Moderate/Low
Direct Contact
ground works on
saltmarshes
Human Health W76 Low Severe Moderate
*1 - SPR – Source / Pathway / Receptor linkage number (W=Widnes, R=Runcorn), as shown in Drawing Numbers MG_REP_EIA_009/093 to
MG_REP_EIA_009/096.
** The Ennvironmental Statement shows this pollutant linkage as „moderate‟. The requirement for mitigation measures has been outlined in Table 8.1
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 265 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 7.7 – Risk Assessment Construction Stage (Runcorn) (continued overleaf)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Contaminants on
Site
Ingestion
Inhalation
Dermal Contact
Human Health Visitors to
Wigg Island R32 Low Medium Moderate/Low
Human Health
Residents/Visitors
outside Wigg Island
R33 Unlikely Medium Low
Human Health
Local Workers R34 Low Medium Moderate/Low
Human Health
Site visitors, trespassers
at Wigg Island
R35 Likely Severe High
Human Health
Site visitors, trespassers
outside Wigg Island
R36 Unlikely Medium Low
Human Health
Construction workers at
Wigg Island
R37 High Severe Very High
Human Health
Construction workers
outside Wigg Island
R38 Low Medium Moderate/Low
Contaminated water
supplies from new
buried services
Human Health R39 No Pathway
Leaching and vertical
migration of
contaminants between
made ground and
shallow groundwater
Groundwater outside
Wigg Island R40 Low Medium Moderate/Low
Groundwater beneath
Wigg Island R41 High Medium High
Vertical migration of
contaminants due to
installation of piled
foundations
Groundwater outside
Wigg Island R42 Low Medium Moderate/Low
Groundwater beneath
Wigg Island R43 Likely Medium Moderate*
Vertical migration in
areas where existing
foundations are
removed
Groundwater outside
Wigg Island R44 Low Medium Moderate/Low
Groundwater beneath
Wigg Island R45
Unlikely (none
encountered or
shown on historical
OS maps)
Medium Low
Vertical migration of
contaminated
groundwater to
bedrock
Groundwater in Bedrock
outside Wigg Island R46 Low Medium Moderate/Low
Groundwater in Bedrock
beneath Wigg Island R47 Likely Medium Moderate*
Off-site migration of
contaminated
groundwater
Shallow Groundwater
beneath Wigg Island R48 Likely Medium Moderate*
Shallow Groundwater
outside Wigg Island R49 Low Mild Low
Groundwater in Bedrock
beneath Wigg Island R50 Likely Medium Moderate*
Groundwater in Bedrock
outside Wigg Island R51 Low Medium Moderate/Low
Migration of
contaminants along
buried drains or
services
Off-site groundwater or
surface water R52 Low Medium Moderate/Low
Migration of
contaminants through
groundwater to
surface watercourses
River Mersey R53 Low Medium Moderate/Low
Canals R54 Low Medium Moderate/Low
Migration of
contaminants through
surface water run-off
to surface
watercourses
River Mersey R55 Likely Medium Moderate*
Canals R56 Likely Medium Moderate*
Direct Contact
Integrity of new buried
plastic services R57 No Pathway
New Foundations
outside Wigg Island R58 Low Medium Moderate/Low
New Foundations at
Wigg Island R59 High Mild Moderate
Plant uptake Planting/soft landscaping R60 No Pathway
Direct Contact Flora and Fauna on
Saltmarshes or Estuary R61 Low Medium Moderate/Low
Scour/Erosion around
Piers releasing
contaminants
Saltmarsh or Estuary R62 Low Medium Moderate/Low
*1 - SPR – Source / Pathway / Receptor linkage number (W=Widnes, R=Runcorn), as shown in Drawing Numbers MG_REP_EIA_009/093 to
MG_REP_EIA_009/096.
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 266 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 7.7 (continued) – Risk Assessment Construction Stage (Runcorn)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Gas and vapours
from made ground
and natural soils
Migration off-site of
ground gas into
buildings Human Health
Site users or visitors
R63 Low Medium Moderate/Low
Migration off-site of
volatile vapours into
buildings
R64 Unlikely Medium Low
Migration of ground
gas into excavations
at Wigg Island
Human Health
People entering
excavations
R65 Likely Severe High
Migration of volatile
vapours into
excavations at Wigg
Island
R66 High Severe Very High
Migration of ground
gas into excavations
outside Wigg Island
R67 Unlikely Severe Moderate/Low
Migration of volatile
vapours into
excavations outside
Wigg Island
R68 Unlikely Severe Moderate/Low
UXO
Direct Contact ground
works in urban areas
Human Health
R69 Unlikely Severe Moderate/Low
Direct Contact –
ground works on
saltmarsh or Estuary
R70 Low Severe Moderate
*1 - SPR – Source / Pathway / Receptor linkage number (W=Widnes, R=Runcorn), as shown in Drawing Numbers MG_REP_EIA_009/093 to
MG_REP_EIA_009/096.
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 267 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 7.8 – Risk Assessment Operational Stage (Widnes) (continued overleaf) (Updated)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Contaminants on
Site
Ingestion
Inhalation
Dermal Contact
Human Health
Site Users/Workers in
toll booths or offices
W77 Low Medium Moderate/Low
Human Health
Service Maintenance
Workers
W78 High Medium High
Human Health
Local Residents W79 Unlikely Medium Low
Human Health
Road Users W80 No Pathway
Contaminated water
supplies from new
buried services
Human Health W81 High Medium High
Leaching and
vertical migration of
contaminants
between
groundwater
horizons
Shallow Groundwater W82 High Medium High
Groundwater in
Bedrock W83 Low Medium Moderate/Low
Vertical Migration of
contaminated
groundwater along
disused water wells
Groundwater in
Bedrock beneath CTP W84 Low Medium Moderate/Low
Groundwater in
Bedrock beneath
Gussion
W85 Likely Medium Moderate*
Vertical Migration of
Free Product along
disused water wells
Groundwater in
Bedrock beneath CTP W86 Low Medium Moderate/Low
Groundwater in
Bedrock beneath
Gussion
W87 Likely Medium Moderate*
Vertical migration of
contaminants due to
piled foundations
Shallow Groundwater W88 Unlikely Medium Low
Groundwater in
bedrock outside CTP W89 Unlikely Medium Low
Groundwater in
bedrock beneath CTP W90 Low Medium Moderate/Low
Vertical migration of
contaminants in
areas where existing
foundations are
removed
Shallow Groundwater W91 High Medium High
Vertical migration
between horizons in
areas of vibro-
concrete columns
Shallow Groundwater W92 Unlikely Medium Low
Shallow Groundwater
beneath CTP
(DNAPL)
W93 Unlikely Medium Low
Off-site migration of
contaminated
groundwater
Shallow Groundwater W94 High Medium High
Bedrock W95 Low Medium Moderate/Low
Off-site migration of
LNAPL
Shallow Groundwater
adjacent to Gussion W96 LikelyLow Medium
Moderate*
Moderate/Low
Off-site migration of
DNAPL
Shallow Groundwater
adjacent to CTP W97 High Medium High
Transfer of
contaminants from
LNAPL to
groundwater
Shallow groundwater
beneath Gussion W98 High Medium High
Transfer of
contaminants from
DNAPL to
groundwater
Shallow groundwater
beneath CTP W99 High Medium High
Off-site migration of
contaminated
groundwater due to
placing embankment
Shallow Groundwater W100 Low Medium Moderate/Low
Bedrock W101 Unlikely Medium Low
Migration of
contaminants along
buried drains or
services
Off-site groundwater
or surface water W102 Likely Severe High
Migration of
contaminants
through groundwater
to surface
watercourses
River Mersey W103 Low Medium Moderate/Low
Stewards Brook W104 HighLow Medium HighModerate/Low
Bowers Brook W105 High Medium High
St Helens Canal W106 Unlikely Medium Low
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 268 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 7.8 (continued) – Risk Assessment Operational Stage (Widnes) (Updated)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Contaminants on
Site Direct Contact
Integrity of buried
plastic services W107 High Mild Moderate/Low
New Foundations W108 High Mild Moderate
Plant uptake
Planting/soft
landscaping with
nominal thickness of
topsoil
W109 Low Mild Low
Direct Contact
Flora and Fauna on
Saltmarshes or
Estuary
W110 Low Medium Moderate/Low
Scour/Erosion
around Piers
releasing
contaminants
Saltmarsh or Estuary W111 Low Medium Moderate/Low
Gas and vapours
from made
ground, free
product, and
natural soils
Migration of ground
gas Human Health site
users within offices or
toll booths
W112 LikelyUnlikely Medium Moderate*Low
Migration of volatile
vapours W113 LikelyUnlikely Medium Moderate*Low
Migration of volatile
vapours or ground
gas to adjacent
areas outside
excavations
Human Health
Site and Road users W114 No Pathway
Migration of volatile
vapours or ground
gas to adjacent sites
Human Health
Local residents W115 Unlikely Medium Low
Migration of ground
gas into excavations Human Health
People entering
excavations
W116 Likely Severe High
Migration of volatile
vapours into
excavations
W117 Likely Severe High
UXO
Direct Contact
Human Health
Site or road users W118 No Pathway
Human Health
Workers from
excavations
W119 Unlikely Severe Moderate/Low
*1 - SPR – Source / Pathway / Receptor linkage number (W=Widnes, R=Runcorn), as shown in Drawing Numbers MG_REP_EIA_009/093 to
MG_REP_EIA_009/096.
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Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 269 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 7.9 – Risk Assessment Operational Stage (Runcorn) (continued overleaf)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Contaminants on
Site
Ingestion
Inhalation
Dermal Contact
Human Health Site
Users/Workers R71 No Pathway (No toll booths or offices)
Human Health
Service Maintenance
Workers at Wigg
Island
R72 High Severe Very High
Human Health
Service Maintenance
Workers outside
Wigg Island
R73 Low Medium Moderate/Low
Human Health Local
Residents or
Workers
R74 Unlikely Medium Low
Human Health Road
User R75 No Pathway
Contaminated water
supplies from new
buried services
Human Health R76 Unlikely Medium Moderate/Low
Leaching and vertical
migration of
contaminants
between made
ground and shallow
groundwater
Shallow
Groundwater outside
Wigg Island
R77 Low Medium Moderate/Low
Shallow
Groundwater
beneath Wigg Island
R78 Likely Medium Moderate*
Vertical migration of
contaminants due to
piled foundations
Groundwater outside
Wigg Island R79 Unlikely Medium Low
Groundwater
beneath Wigg Island R80 Low Medium Moderate/Low
Vertical migration in
areas where existing
foundations are
removed
Groundwater R81
Unlikely (none
encountered or
shown on historical
OS maps)
Medium Low
Vertical migration of
contaminated
groundwater to
bedrock
Groundwater in
Bedrock outside
Wigg Island
R82 Low Medium Moderate/Low
Groundwater in
Bedrock beneath
Wigg Island
R83 Likely Medium Moderate*
Off-site migration of
contaminated
groundwater
Shallow
Groundwater
beneath Wigg Island
R84 Likely Medium Moderate*
Shallow
Groundwater outside
Wigg Island
R85 Low Mild Low
Groundwater in
bedrock beneath
Wigg Island
R86 Likely Medium Moderate*
Groundwater in
Bedrock outside
Wigg Island
R87 Low Medium Moderate/Low
Migration of
contaminants along
buried drains or
services
Off-site groundwater
or surface water R88 Low Medium Moderate/Low
Migration of
contaminants through
groundwater to
surface watercourses
River Mersey R89 Low Medium Moderate/Low
Canals R90 Low Medium Moderate/Low
Direct Contact
Integrity of buried
plastic services R91 Likely Mild Moderate/Low
Foundations outside
Wigg Island R92 Low Medium Moderate/Low
Foundations at Wigg
Island R93 High Mild Moderate
Plant uptake
Planting/soft
landscaping with
nominal topsoil
R94 Low Mild Low
Direct Contact
Flora and Fauna on
Saltmarshes or
Estuary
R95 Low Medium Moderate/Low
Scour/Erosion around
Piers releasing
contaminants
Saltmarsh or Estuary R96 Low Medium Moderate/Low
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 270 Report No. MG_REP_EIA_009
November 2011 Rev B
Table 7.9 (continued) – Risk Assessment Operational Stage (Runcorn)
Source Pathway Receptor SPR
No.*1
Probability Consequence Risk Classification
Gas and vapours
from made ground
and natural soils
Migration of ground
gas or volatile
vapours
Human Health
Local residents R97 Unlikely Medium Low
Migration of ground
gas or volatile
vapours
Human Health
Road users R98 No pathway
Migration of ground
gas into excavations
at Wigg Island
Human Health
People entering
excavations
R99 High Severe Very High
Migration of volatile
vapours into
excavations at Wigg
Island
R100 High Severe Very High
Migration of ground
gas into excavations
outside Wigg Island
R101 Unlikely Severe Moderate/Low
Migration of volatile
vapours into
excavations outside
Wigg Island
R102 Unlikely Severe Moderate/Low
UXO
Direct Contact
Human Health
Site or road users R103 No Pathway
Human Health
Workers from
excavations
R104 Unlikely Severe Moderate/Low
*1 - SPR – Source / Pathway / Receptor linkage number (W=Widnes, R=Runcorn), as shown in Drawing Numbers MG_REP_EIA_009/093 to
MG_REP_EIA_009/096.
The Mersey Gateway Project Gifford
Contamination of Soils, Sediments and Groundwater
Technical Annex
Page 271 Report No. MG_REP_EIA_009
November 2011 Rev B
8. MITIGATION AND ENHANCEMENT MEASURES
8.1 Introduction
8.1.1 The potential risks of the proposed scheme have been assessed without mitigation. This
section discusses measures to mitigate the identified risks, which means remediation and other
associated activities such as specific monitoring. It should be noted that further data is likely to
be needed to fully define the remediation strategy. In addition to this, the overall strategy will
need to be concluded before works commence and approved by the Local Authority and EA. On
the basis of the Project including the Proposals the effect assessment has not changed
materially and so the mitigation measures remain as defined in the Orders ES. Advance works
are underway for the DNAPL contamination identified in Area C and plans for this have been
incorporated into the mitigation measures where appropriate.
8.1.2 The mitigation measures are discussed as follows:
a. A Preliminary Remediation Options Appraisal undertaken for soil and groundwater
contamination;
b. Potential remediation measures to address significant risks identified in Section 7 above;
and
c. Areas where mitigation measures will need to be considered during the three stages of
the works for each of the following:
i. Detailed Design;
ii. Construction; and
iii. Operation.
8.1.3 A review of the Preliminary Remediation Options Appraisal is included in Section 8.2. This was
undertaken to identify possible mitigation measures for contaminants in soil and groundwater in
the Project Area.
8.1.4 An overview of the potential remedial measures to mitigate the significant risks identified in
Tables 7.4 to 7.9 are outlined below in Section 8.3.
8.1.5 Sections 8.4 to 8.6 provide an overview where mitigation measures will need to be considered
during the detailed design, construction and operation stages to address the risks identified in
Tables 7.4 to 7.9 in Section 7. The assessment of significant risks has been based on the
concept of a Significant Possibility of Significant Harm. There are still potential risks that whilst
not identified as significant would still need to be addressed as part of the works. Mitigation
measures have also been considered for these risks. A summary of the mitigation measures by
Project area is included in Section 8.7.
8.1.6 A discussion on the potential risks associated with contamination that could arise from the
Project is included in Section 8.8 along with a discussion on the existing risks that would
continue regardless of the whether the Project is undertaken in Section 8.9.
8.1.7 The requirement for implementing mitigation measures has been included within the
Construction and Operation Code of Practice for Environmental Management (COPE)
(B4027D/COPE/R01, April 2009) which forms part of the planning application.
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Technical Annex
Page 272 Report No. MG_REP_EIA_009
November 2011 Rev B
8.2 Preliminary Remediation Options Appraisal for Soil and Water Contamination
8.2.1 A Preliminary Remediation Options Appraisal has been carried out to establish viable
techniques that could be used for the remediation of soil and groundwater contamination
identified in the Project area. This has formed the basis for the remedial measures currently
being developed as part of the advance works. The Preliminary Remediation Options Appraisal
is located in Appendix Q. The ultimate choice of method would be the subject of approval prior
to the implementation of the relevant works.
8.2.2 Section 78A(7) of Part IIA of the Environmental Protection Act 1990 defines remediation as:
“(a) the doing of anything for the purpose of assessing the condition of -
(i) the contaminated land in question; or
(ii) any controlled waters affected by that land; or
(iii) any land adjoining or adjacent to that land;
(b) the doing of any works, the carrying out of any operations or the taking of any steps in
relation to any such land for the purpose –
(i) of preventing or minimising, or remedying or mitigating the effects of, by reason of
which the contaminated land is such land; or
(ii) of restoring the land or waters to their former state; or
(c) the making of subsequent inspections from time to time for the purpose of keeping under
review the condition of the land or waters”.
8.2.3 DEFRA Circular 01/2006 gives extensive guidance on contaminated land with respect to UK
legislation, including Part IIA of the Environmental Protection Act (1990), as updated by further
pieces of legislation. Chapter 3 of Annex 3 of the Circular gives specific guidance on the
remediation of contaminated land and describes in full the process of remediation and the
considerations that should be made in determining when remediation is required and to what
standard. This includes the implementation of phased remediation works, the reasonableness
of remediation (incorporating an appraisal of the likely seriousness of harm or of pollution to
controlled waters), and the practicability, durability and effectiveness of remediation together
with the need to consider adverse environmental impacts and probability of success.
8.2.4 Chapter 3 of EA CLR11 (2004) provides guidance on undertaking a detailed Remediation
Options Appraisal. This process requires that consideration is given to each individual or
combination of pollutant linkages that have been demonstrated through the undertaking of a
detailed risk assessment process, to present a risk to potential receptors. The detailed
remediation options appraisal is currently in preparation for the advance works remediation at
Catalyst Trade Park in Area C.
8.2.5 The Preliminary Remediation Options Appraisal examined remediation techniques currently
available in the UK to determine their potential applicability to the ground conditions and the
pollutant linkages that have been identified within the Project area.
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Technical Annex
Page 273 Report No. MG_REP_EIA_009
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8.2.6 The preliminary appraisal was undertaken by compiling a database of remediation technologies.
This database was compiled following an investigation of remediation techniques using the
following sources of information:
a. Halton Borough Council (previous remediation projects within study area);
b. Environment Agency;
c. Remediation contractors – as part of a consultation process;
d. Contaminated Land: Applications in Real Environments (CL:AIRE);
e. Publicly available case studies and technology information sources; and
f. Academic journals on the subject of contaminated land and remediation technologies.
8.2.7 The appraisal considered three broad types of remediation techniques, namely:
a. Engineering solutions, such as containment walls, landfilling and soil capping layers;
b. Ex-situ works, such as landfarming and groundwater treatment; and
c. In-situ works, such as bioremediation or permeable reactive barriers.
8.2.8 All of the techniques investigated were sub-divided into the following categories, as used in the
EA Remediation Position Statements (2006):
a. Civil Engineering Methods;
b. Biological Methods;
c. Chemical Methods;
d. Physical Methods;
e. Stabilisation & Solidification Methods; and
f. Thermal Methods.
8.2.9 Each treatment option was then assessed against the following criteria to aid comparison with
other remediation techniques:
a. Contaminant types and phase that can be treated;
b. Ground conditions in which the technique is capable of operating;
c. Treatment time;
d. Complexity;
e. Advantages and disadvantages of the technique; and
f. Relevance to the site specific issues identified within the project area.
8.2.10 The following sections detail the findings at each stage of the appraisal.
Consultation Process for Remedial Measures
8.2.11 Consultations was have been undertaken as part of the Preliminary Remediation Options
Appraisal in order to obtain an understanding of the likely requirements for remediation from the
regulators and details on techniques that have been applied within the Project area previously.
8.2.12 This consultation process involved the EA, the Council and a range of remediation contractors.
Each of these consultations is discussed in more detail below.
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Environment Agency
8.2.13 The EA was consulted through a series of progress meetings held to discuss the regulatory
requirements for the Mersey Gateway Project, which included remediation requirements. The
EA highlighted the following as being of importance in its view:
a. Remediation works would need to be determined through the risk assessment process
in direct consultation with the EA.
b. Whilst excavation of contaminated soils and subsequent disposal off-site may be
required at the site, the EA accepts that this technique, should it be applied wholesale to
the Project, would introduce severe sustainability and cost issues. Likewise, providing
containment around the entire perimeter of the site would also be costly and impractical.
Therefore, the EA will not be insisting that extensive source removal works are
undertaken.
c. The works should not increase any of the risks to groundwater or surface water that
currently exist within the project area. This requires that only those risks that may be
increased by construction works would require mitigation.
d. With regard to waste management, every effort should be undertaken to reduce the net
volume of waste being produced throughout the project. Furthermore, where materials
must be excavated, they should be re-used wherever possible providing that suitability
criteria are met and that regulatory requirements are adhered to.
e. The main contaminants of concern were considered to be the potential free phase
DNAPL identified on/adjacent to the Catalyst Trade Park. The EA has indicated they
normally require the removal of free product before piling.
f. Based on the findings of the DQRA, agreement has been obtained from the EA that
remediation would only be required for DNAPL in Area C as the LNAPL in Area B2 was
not identified as representing a risk to surface water.
g. Further consultation is being undertaken with the EA regarding the proposals for
DNAPL remediation as part of the advanced works.
Halton Borough Council
8.2.14 Consultations were held with the Concil to establish remediation works that have been
undertaken in the Borough and their relative success or failure together with remediation
techniques that have been trialled or discarded for various applications within the region. A
review of remediation works previously undertaken within the Borough is detailed below.
Information regarding other techniques not used (or not used extensively) in the Borough has
been incorporated directly within the Preliminary Remediation Options Appraisal.
8.2.15 Further consultation is being undertaken with the Council regarding the proposals for DNAPL
remediation as part of the advanced works.
Remediation Contractors (2007)
8.2.16 Responses were received in 2007 to a A process of consultation was undertaken with
remediation contractors to establish the range of techniques available in the UK market and the
applicability of specific methods to the Scheme.
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8.2.17 This process commenced with the creation of a database of remediation contractors operating
in the UK. From this list, 12 remediation contractors were selected for consultation based upon
the following factors.
a. Experience within the UK remediation sector and with various remediation technologies.
b. Range of remediation technologies provided by each contractor and to give a range of
techniques across all contractors.
c. Whether contractors provide and operate their own remediation systems or only
managed remediation projects and then sub-contracted remediation works.
8.2.18 These contractors were provided with information regarding ground conditions, contamination
and the proposed works. They were asked to provide information on specific remediation
techniques that might be suitable for use at the site. Responses were received back from nine
contractors. These are listed below in alphabetical order:
a. Biogenie Site Remediation Ltd.
b. Celtic Technologies Ltd.
c. Churngold Remediation Ltd.
d. Cognition Land & Water Ltd.
e. Envirotreat Ltd.
f. Land & Water Remediation Ltd.
g. QDS Environmental Ltd.
h. RAW Remediation Ltd.
i. VHE Construction Plc.
8.2.19 From these contractors the following remediation technologies were identified for the various
sites within the project area:
a. Soil Stabilisation / Solidification – 7 suggestions for use.
b. Ex-situ Bioremediation – 7 suggestions for use.
c. In-situ Bioremediation – 5 suggestions for use.
d. Chemical Oxidation – 4 suggestions for use.
e. Dual Phase Vacuum Extraction – 3 suggestions for use.
f. Soil Vapour Extraction – 2 suggestions for use.
g. Permeable Reactive Barriers – 1 suggestion for use.
h. Soil Washing – 1 suggestion for use.
i. Air Sparging – 1 suggestion for use.
j. Excavation & disposal – 1 suggestion for use.
8.2.20 These suggestions, along with comments made by the contractors as part of the consultation,
were considered when undertaking the Preliminary Remediation Options Appraisal.
Review of Information Obtained on Previous Remedial Works in Runcorn and Widnes
8.2.21 The following summarises information obtained on remediation works undertaken within the
Mersey Gateway Project area or on adjacent sites where similar ground conditions and/or
contaminants were present. Information regarding remediation works at these sites has been
obtained either directly from the Council or from publicly available data sources, including the
internet, CL:AIRE and the University of Greenwich Centre for Contaminated Land Remediation.
The use and effectiveness of these remediation techniques have been considered within the
Remediation Technique Assessment.
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St. Michaels Golf Course, Widnes
8.2.22 In the 1970‟s the northern part of the site was subject to remediation works which comprised re-
directing the route of Stewards Brook, re-profiling works, screening of the waste and capping
the site with a layer of soil to enable the site to be reclaimed for use as a golf course. The
southern part of the site was subsequently remediated in the 1980‟s using the same technique
of re-profiling and capping of the waste.
8.2.23 However, according to the Council and Jacobs UK Ltd (Remediation Options Appraisal
Document Reference: R01, April 2007), the northern part of the site was subsequently
determined as statutory „Contaminated Land‟ under the Contaminated Land (England)
Regulations 2006. Investigations by Atkins in 2005 and by AMEC in 2007 found the capping
layer was insufficient, with areas encountered where underlying waste materials were exposed
at the ground surface. Evidence of slope failure and extensive leaching of contaminants into
the diverted Stewards Brook was also noted.
8.2.24 It is understood that proposals are being considered by HBC for remedial works in the northern
part of the site. These measures are likely to be implemented prior to works commencing for
the Project. The remedial measures are expected to comprise re-capping and installation of a
Permeable Reactive Barrier (PRB). The Remediation Options Appraisal by Jacobs UK Ltd was
commissioned by Land & Water Remediation Ltd. and undertaken on behalf of HBC. The
detailed design for the Mersey Gateway will need to take account of these proposed remedial
measures. This text has been deleted as remediation works have been undertaken on the
northern section of St Michaels Golf Course to improve the water quality in Stewards Brook and
remove pathways from existing soil contaminants to site users. These works were completed
2010 and comprised recapping using site won material from the re-alignment of Stewards Brook
and imported material to form a 350mm sand cap and 150mm topsoil. The former route of
Stewards Brook is being used as a leachate collection facility with the periodic removal of
leachate off-site.
Former ICI Coal Stockyard / Hutchinson Street Development, Widnes
8.2.25 Ground remediation works were undertaken in 2003 to bring into use an area of land between
the A553 Queensway Road and the A557 Expressway previously used by ICI as a coal
stockyard, and where Galligu and chemical waste had previously been identified. A process
was initiated by the Council to engage with remediation contractors and environmental
regulators to attempt to find alternative solutions for the treatment of Galligu waste. This
commenced in 1999 and culminated in a series of field trials for a range of treatment techniques
including soil Stabilisation/Solidification and PRBs, this resulted in a stabilisation/solidification
technique being selected for use at the site.
8.2.26 The remediation works comprised an in-situ stabilisation/solidification technique using cement
and Powercem© (a proprietary additive provided by Powerbetter Ltd.) to form a 350mm deep
impermeable cap across the site to prevent surface water infiltration into the underlying soils.
An imported granular material, geotextile, sand & topsoil were then laid over the
stabilisation/solidification cap so that the site could be utilised for recreational activities.
Validation works demonstrated that the process had succeeded in reducing the permeability of
the treated soils whilst greatly reducing contaminant leachability and improving soil strength. It
is understood that validation works are on-going at the site as part of an assessment into the
long term behaviour of stabilisation/solidification treated soils.
Catalyst Trade Park, Widnes
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8.2.27 In preparation for the development of the Catalyst Trade Park following the previous use of the
land by ICI, extensive demolition works were undertaken, including storage tanks, infrastructure,
chemical plant and equipment, and the removal of low level radioactive material. The A557
Expressway was constructed over the northern part of the site and some radioactive material
was placed beneath the Victoria Road eastern abutment and covered by concrete (according to
anecdotal evidence obtained from the Council).
8.2.28 It is understood that, during construction of the existing Unit 6, remediation works were
undertaken to address historical contamination by chlorinated solvents. In addition, gas/vapour
protection measures were incorporated into the building foundations.
8.2.29 A report obtained from the Council and prepared by Halcrow Group Ltd (dated March 2004) for
the site owners (St. Modwen) notes that the remediation works comprised the installation of an
in-situ bioremediation system designed to inject nutrients into the subsurface under pressure.
This system was incorporated into the building construction design and was scheduled to
operate for 1 year between 2000 and 2001. Validation testing by Halcrow found that whilst
bioremediation had reduced concentrations of chlorinated solvents beneath the building, the
process was unable to sustain the contaminant concentration reduction. This may have been
due to the excessive mass of chlorinated solvents beneath the site or re-contamination from
adjacent areas.
Inter-modal Rail Depot, Widnes
8.2.30 The Inter-Modal Rail Depot is located west of the Queensway Road and outside the Project
area. However, as part of a planned extension to that site it was identified that ground
improvement works were required due to poor ground conditions due in part to the presence of
Galligu.
8.2.31 It is understood that a trial was undertaken at this site to determine the effectiveness of an
Activated Carbonation Technology (ACT) stabilisation/solidification for the treatment of Galligu.
Details of the trials undertaken using ACT were obtained directly from the University of
Greenwich‟s Centre for Contaminated Land Remediation.
8.2.32 The trial found that ACT stabilisation/solidification was able to reduce leachate concentrations of
metals to below the UK Drinking Water Standards and that the granular material produced
demonstrated much improved geotechnical properties. These properties conformed with to the
Highways Specification for granular engineering fill (Manual of Contract Documents for Highway
Works, Volume 1: Specification for Highway Works 1998 (as amended)).
Bowers Business Park, Widnes
8.2.33 Bowers Business Park is located in area where the former land use included an alkali works,
foundry and gas works. Bowers Business Park is located to the north of the Mersey Gateway
Project, to the north of Thermphos in Area C.
8.2.34 During redevelopment works in the 1980s, it is understood that contaminated material was
excavated from the Business Park site and removed off-site. This included waste pumped out
from the former gas holders. The excavations were then backfilled with imported materials and
capped off with clay and a layer of hardcore for construction.
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8.2.35 Information from the Council‟s Contaminated Land Officer indicates that information on
remediation for this site is limited but it is understood that all surface structures were removed
and a significant amount of the contaminated fill within the top “1m or so” was removed to
landfill (at least some of the gas works waste was removed to Wigg Island Landfill). Excavated
materials were replaced with „inert‟ fill. It is also understood that several large underground
structures were cleaned out, particularly the former gas holders. More recent investigation for a
proposed commercial development at this site indicates that some remedial measures do
appear to have been undertaken as given the site‟s history, little significant contamination was
encountered.
Former Vines Chemical Works Development, Widnes
8.2.36 Information obtained from the Unitary Development Plan Public Inquiry Contaminated Land
Topic Paper Issued on 12 December 2002 (Version 1.3) indicates the Greenoaks retail scheme
in Widnes is located on the former Vine Chemical Works. This works was abandoned leaving
behind large heaps of waste on a site that was adjacent to Widnes Town Centre. The main
products produced by the former Vines Chemical Works were pigments and fillers,
predominately zinc and barium based. Contamination levels for zinc and barium were high
enough for the economic recovery of the minerals to be considered. The site was cleared and
re-graded, then capped with 300mm of hardcore and 1000mm of pulverised fuel ash (PFA) from
Fiddlers Ferry Power Station. No consideration was given to pollution of controlled waters as
part of the redevelopment, although Bowers Brook culvert that runs adjacent to the site is
understood to have been engineered to cope with the aggressive nature of the water in the
brook (including pH values ranging from 2 to 12). The Council retained the environmental
liability for the site to ensure that it could be redeveloped. The site is now largely occupied by
Morrisons Supermarket. The current buildings are constructed on piled foundations.
Wigg Island, Runcorn
8.2.37 Information from the Council‟s Contaminated Land Officer indicates this area was historically the
site of an alkali works, sulphuric acid plant and metal refining/processing works. The former
Wigg Island Landfill was used as a tip for wastes from around the Borough particularly during
1970s and 1980s reclamation schemes. It was capped with various thicknesses of inert
material during the 1980s. Remediation works at the site comprised extensive capping of the
site (with clay and topsoil) to remove the potential for contact of contaminated soils by site
users, coupled with extensive site maintenance procedures to prevent future pathways from
occurring.
8.2.38 From 2000, the Council undertook a project to address leachate impacting the small section of
the former Latchford Canal. The canal spur was heavily contaminated by a highly acidic, metal
rich leachate. The canal was dredged and the silts disposed of at the adjacent Randle Island
landfill, with parts of the canal being lined with a low permeable material ('Andracite', which is
mainly calcium sulphate) and a large collection and treatment channel created. This was filled
with limestone and covered to raise the leachate pH and reduce the concentration of metals in
solution. This feeds into a reed bed/polishing basin before discharge into the open water
section of the canal. This water ultimately discharges to the River Mersey.
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Summary of Techniques
8.2.39 In summary the following techniques have previously been implemented in the Borough
adjacent to the site:
a. Excavation and removal of contaminants;
b. Soil stabilisation (with various proprietary additives);
c. In-situ bioremediation; and
d. Capping (of both contaminated land and of landfills).
8.2.40 Remedial works that are known to be currently under consideration for use in the Borough
adjacent to the Project area comprise:
a. Capping; and
b. Permeable Reactive Barriers.
Results of Preliminary Remediation Options Appraisal
8.2.41 Following the preliminary appraisal, each remediation technology was assigned a category
classification based upon potential for use, with Category A technologies having the greatest
potential for use, and Category C technologies having the least potential for use within the
Project area. As noted above, the preliminary remediation options appraisal is in the process of
being developed for the advance works remediation at Catalyst Trade Park/Thermphos in Area
C. However, the technologies outlined below could also be used by the Project Company
during the construction of the Project including the Proposals and so have been retained in this
report.
Category A Technologies
8.2.42 These techniques have a good potential for use based on the types of contaminants assessed
as present and their extent across the Project area, and upon the complexity, cost effectiveness
and reliability of the technique. Category A techniques comprise:
a. Soil Stabilisation/Solidification, either ex-situ or in-situ depending upon application /
presence of a relevant pollutant linkage;
b. Cement based techniques including with the addition of additives;
c. Activated Carbon Technology coupled with cement stabilisation;
d. Capping – through the use of soil stabilisation/solidification, clay or concrete;
e. Permeable Reactive Barriers (PRBs), in particular redox PRBs (to dechlorinate
chlorinated hydrocarbons) and biological based PRBs (to remove metals, phosphate and
nitrate from groundwater, and which, with additions, could also treat organic
contaminants);
f. Re-use on-site, for example, within road embankments;
g. Source Removal and Monitored Natural Attenuation (MNA);
h. Pre-hydrated High Density Bentonite – used as barrier walls, capping layers or landfill
liner;
i. Gravity separation – for the separation of oil/water/sediment phases from liquid waste
streams;
j. Enhanced bioremediation – using oxygen or hydrogen releasing compounds in areas of
organic contamination;
k. Pump & treat – using pumps to bring contaminated groundwater to the surface for
treatment and eventual disposal to sewer or ground;
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l. Solvent Extraction – use of solvents with product recovery systems and soil washing plant
to increase rate of desorption of residual product from soil to groundwater;
m. Dual Phase Vacuum Extraction – application of high vacuum to air/water interface to
abstract vapours, LNAPL and contaminated groundwater;
n. Soil Washing – using specialist plant to screen and wash contaminated soils. Can reduce
volumes of waste being removed from site, and produce suitable engineering fill
materials. Can be coupled with other technologies to improve performance depending
upon soil and contaminant types;
o. Use of piles (rotary bored cast in-situ piles or Vibro-concrete columns (VCC‟s);
p. Use of lightweight fill materials for embankments to minimise requirement for piled
foundations; and
q. Use of PVD/Wick drains and groundwater treatment systems to increase rate of
settlement beneath embankment and minimise requirement for piled foundations.
8.2.43 In addition to the above, the following techniques have been identified as having good potential
for use but over which the certainty of use may be limited by restrictions of use, either in terms
of practicality, effectiveness, reliability, treatable contaminants or availability in the UK. These
remediation techniques comprise:
a. Steel sheet pile walls with sealed clutches – to contain contaminants on-site and prevent
off-site migration. However, the EA have indicated they would prefer not to see extensive
cut-off structures;
b. Bored or excavated slurry walls;
c. Sorption based PRBs – increased costs due to the need for long term media
replacement; and
d. Hydraulic containment / flow path management – this has long term implications due to
the need for ongoing maintenance.
8.2.44 In addition to the above, the following techniques have been identified as having potential for
use, but only in limited areas for a limited range of contaminants:
a. Chemical Oxidation – either in-situ or ex-situ, primarily for the treatment of organic
contaminants;
b. Bioremediation of groundwater – either in-situ or ex-situ;
c. Bioremediation of soils - either in-situ or ex-situ;
d. Low Temperature Thermal Desorption - either in-situ or ex-situ;
e. Steam or Heated Air Injection;
f. Air sparging; and
g. Soil Vapour Extraction.
Category B Technologies
8.2.45 These are techniques that have been identified as having potential for use as a supplementary
technology or with a lesser degree of certainty or applicability. Category B comprises:
a. Precipitation based PRBs;
b. Ozone sparging;
c. Air stripping;
d. Ultra Violet Oxidation;
e. Magnetic separation;
f. Hydraulic Fracturing;
g. Electrokinetics; and
h. Use of granular trench to dewater embankments and adjacent ground.
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8.2.46 In addition to the above, the following techniques have potential for use in some areas but are
unlikely to be utilised due to practicability, complexity, effectiveness, reliability, availability and/or
range of treatable contaminants. These techniques comprise:
a. Cement & asphaltic emulsion based stabilisation/solidification;
b. Ion exchange; and
c. Electrochemical separation.
Category C Technologies
8.2.47 These are techniques that have been identified as having very little potential for use and are
unlikely to be utilised due to practicability, complexity, effectiveness, reliability, availability and/or
range of treatable contaminants. Category C techniques comprise:
a. High temperature Incineration;
b. Phytoremediation;
c. Excavation and disposal, due to the increase cost and lack of sustainability; and
d. Use of stone columns for embankments (in contaminated areas).
8.2.48 Any remediation contractors working at the site will need to hold a relevant Mobile Plant License
and Deployment Form. Furthermore, they will need to have a Method Statement and full Risk
Assessment agreed with the Council prior to initiating works in order to ensure that they have
the necessary health and safety procedures in place. These will need to include emergency
procedures in the event of chemical or product spills/releases, as well as measure to ensure site
security, safe emissions, and compliance with license and permits.
Remediation Contractors (2009)
8.2.49 A second remediation consultation exercise was undertaken by Gifford in September and
October 2009 which was intended to build upon the findings of the first consultation (outlined above in Section 8.2.15 to 8.2.19) and refine the estimated costs and programme for remediation.
8.2.50 The consulation was undertaken prior to the detailed quantitative risk assessment for controlled waters being undertaken in 2010 which did not indicate there was likely to be a risk to surface water from off-site migration of contaminants associated with the LNAPL in Area B2. Therefore, remediation of LNAPL was included as a requirement in the consultation process.
8.2.51 A report on the consultation was prepred by Gifford in September 2010, a summary of the findings has been provided below. This information is being incorporated into the detailed remediation options appraisal for the advanced works remediation.
8.2.52 Remediation contractors were provided with information regarding ground conditions, contamination and the proposed works and contaminants in the Project Area. Information was sent out to 60 consultees and a total of 22 responses were received.
8.2.53 The information received from Consultees indicates there is a wide range of techniques
available for the remediation of contaminated soil and groundwater within the Project Area.
8.2.54 A review of the responses received indicates that the most commonly proposed remediation techniques for the project are as follows:
a. LNAPL:
i. DPVE / MPE;
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ii. Pump and Treat;
iii. Steam Injection; and
iv. Skimming.
b. DNAPL:
i. DPVE / MPE;
ii. Pump and Treat;
iii. Steam Injection; and
iv. Surfactant / solvent flushing.
c. Galligu / Chemical Waste:
i. Stabilisation (in-situ and ex-situ); and
ii. Capping.
d. Soils contaminated with chlorinated solvents / residual DNAPL / residual LNAPL:
i. Chemox;
ii. Ex-situ bioremediation;
iii. Thermal Desorption; and
iv. Soil washing.
e. Groundwater:
i. DPVE / MPE;
ii. Pump and Treat;
iii. ISCO;
iv. HRC / ORC; and
v. Bioremediation.
f. Cross-Boundary Migration:
i. Permeable Reactive Barriers; and
ii. Barrier systems (slurry walls, sheet piles etc).
8.2.55 The consultation exercise did not identify any remediation techniques that had not previously been considered. The majority of the remediation techniques provided were identified during the Preliminary Remediation Options Appraisal above as Category A technologies, i.e. ones that had a good potential for use based on the types of contaminants that were present and their extent across the project area, and upon their complexity, cost effectiveness and reliability.
8.2.56 The information received on programme by Consultees for the remediation of groundwater,
DNAPL and LNAPL indicates that some techniques are capable of being used in relatively short timeframes (weeks to months), whereas others require much longer timeframes (months to years). However, the choice of remediation technique, and associated with this the likely cost, will be dependant on when a site becomes available for remediation.
8.2.57 The information from Consultees on remediation indicates that LNAPL remediation could take
between four and 18 months (although up to 60 months was quoted by one Consultee). For DNAPL recovery/treatment and groundwater remediation typical timescales provided were six to 24 months. Information received on the programme for soil remediation indicates this could be in the region of weeks to 6 months.
8.2.58 A number of Consultees proposed the use of a treatment centre either on or off-site for soil
remediation during the construction stage. This would remove the need for smaller treatment areas in different parts of the site. Such soil treatment centres would have to be managed by the Project Company during the construction works.
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8.3 Potential Remedial Measures
8.3.1 This section provides an overview of the potential remedial measures that can be utilised to
mitigate the significant risks identified in Tables 7.4 to 7.9 above. This overview also considers
the findings of the Preliminary Remediation Options Appraisal. A number of these mitigation
measures will need to be implemented as part of the advanced works remediation. Other
measures will be appropriate to both the advanced works remediation and wider construction
works.
Removal/treatment of contaminated soils, including Galligu and other chemical wastes
8.3.2 The Preliminary Remediation Options Appraisal indicates there are a wide range of methods
available to treat inorganic and organic contaminants identified in soils within the Project area.
8.3.3 For the treatment of Galligu and chemical wastes, soil stabilisation/solidification techniques
have been used extensively in the Borough as it has been widely accepted as one of the few a
remediation techniques capable of mitigating the risks posed by Galligu and other forms of
chemical waste, with the exception of excavation & off-site disposal. Off-site disposal of
contaminated material has declined over the last decade due to increased environmental
concerns over sustainability and significant increases in landfill costs.
8.3.4 Different variations of stabilisation/solidification using lime, cement, and various additives have
been trialled extensively by the Council. The region is subject to substantial research by
CL:AIRE as part of the PASSiFy programme, aimed at documenting the use of
stabilisation/solidification techniques and obtaining long term performance data so that the
efficacy of the various techniques can be verified.
8.3.5 The most significant potential disadvantage with stabilisation/solidification techniques is that the
contaminant mass is not actively treated. The process does result in a net decrease in
contaminant concentration but only because the net volume of soil is increased with the addition
of the cement and various additives. There are environmental impacts associated with
stabilisation/solidification, particularly due to the use of large volumes of cement and the
environmental effects associated with the extraction and manufacture of this material. There is
extensive EA guidance on the use of stabilisation/solidification and the re-use of
stabilised/solidified treated soils.
8.3.6 Other techniques that have the potential to be effective treatment techniques for Galligu and
chemical waste soils include high temperature incineration to re-use soil within embankments,
although this option carries extensive costs, has potential environmental impacts (in particular
high energy requirements and emissions to atmosphere) and requires extensive regulatory
liaison for approval.
8.3.7 Re-use of soil within embankments, including treated soils, is likely to require an appropriate
exemption from the Environmental Permitting Regulations 2007, in some cases possibly an
authorisation under the Environmental Permitting Regulations 2007 from the EA. Alternatively,
it should be possible to re-use material under the CL:AIRE Development Industry Code of
Practice (2011). Re-use of soils, assuming the risks were acceptable, would offset the need for
disposal off site and/or the importation of materials, and would be a potentially beneficial
environmental impact.
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8.3.8 Where it is proposed to remove material off-site then Section 10(1) of the Landfill (England and
Wales) Regulations 2002 (as amended) the Landfill Directive (implemented by the
Environmental Permitting (England and Wales) Regulations 2010) requires that the operator of
any landfill must ensure all waste is subject to prior treatment unless:
a. it is inert waste for which treatment is not technically feasible; or
b. it is waste other than inert waste and treatment would not reduce its quantity or the
hazards which it poses to human health or the environment.
8.3.9 Regulations 2 notes require that treatment comprises any physical, thermal, chemical or
biological activities that change the characteristics of the waste in order to reduce its volume or
hazardous nature, facilitate its handling or enhance recovery. Sorting of waste is considered to
be treatment.
8.3.10 To meet this definition, a treatment must fulfil three criteria:
a. It must be a physical, thermal, chemical or biological process (which can include
sorting).
b. It must change the characteristics of the waste.
c. It must do so in order to:
(a) reduce its volume, or
(b) reduce its hazardous nature, or
(c) facilitate its handling, or
(d) enhance its recovery.
Contaminated Groundwater
8.3.11 It has been agreed with the EA that specific mitigation of groundwater to prevent migration from
the Project area would not be required other than for DNAPL in Area C. However, groundwater
treatment could still be required as part of a broader strategy for remediation or for water
removed from excavations during the works.
8.3.12 The Preliminary Remediation Options Appraisal indicates there are a wide range of methods
available to treat inorganic and organic contaminants identified in groundwater within the Project
area. These range from groundwater containment systems using sheet piles or bentonite slurry
walls through groundwater control systems (such as PRBs and flow path management
techniques) in-situ dosing treatments (including enhanced bioremediation and chemical
oxidation) a wide range of ex-situ treatment techniques (that can be designed to address
specific contaminants and site conditions) to monitored natural attenuation.
8.3.13 Consideration will need to given to the possibility of migration of contaminated groundwater in
the Project area. This will apply in two cases. First, the possibility of contaminants migrating
out of the Project area and secondly that areas remediated as part of the Works could be
affected by sources of contamination outside the Project area.
8.3.14 Any mitigation measures that rely on containment will have to be considered in the context of
the wider groundwater flow regime to ensure that they do not interrupt groundwater flows or
cause contaminants to migrate to other areas, potentially not currently affected by
contamination.
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8.3.15 Treatment of contaminated groundwater can require long time periods and, if this is requested,
it will need to be taken into account in programming the works. It is possible that mitigation
measures for groundwater contamination will need to be built into the works so that they can
continue to operate after completion.
8.3.16 The environmental impacts of these techniques vary widely. Monitored natural attenuation has
a very low environmental impact as long as there are no adverse impacts from allowing
contamination to remain in place. Environmental impacts associated with other techniques
produce emissions and require energy use during disposal and/or destruction of recovered
contaminants and during installation and operation of treatment facilities or containment
measures. In particular, in this respect the destruction of certain contaminants present on site
may involve incineration. The use of cement and bentonite in barriers can have environmental
impacts related to the extraction and manufacture of these materials.
8.3.17 Water pumped from excavations for bridge piers and towers (such as on the salt marshes and
estuary) is also likely to require treatment prior to disposal. Treatment may comprise settlement
lagoons, but additional treatment may also be required (depending on contaminant
concentrations) before disposal. The disposal of treated water from the Project will also need to
consider the following:
a. Discharge to ground which could potentially mobilise shallow contaminants and increase
risk of contaminant migration beneath the site. Discharge consents would need to be
obtained from the EA. Furthermore, the treated groundwater is likely to have to comply
with the UK DWS and/or EQS values for coastal and estuarine waters;
b. Discharge to land drains which would ultimately discharge to the River Mersey, and so is
likely to have to comply with the EQS values for coastal and estuarine waters; and
c. Discharge to sewer which would require detailed consultation with the local water
authority to determine if their existing sewer system and treatment systems are capable
of accepting the proposed discharge rate and quality. The requirements of any discharge
consent agreed with the local water authority would need to be considered in the design
of the water treatment system.
LNAPL
8.3.18 Specific remediation of LNAPL to reduce the risk from off-site migration is not considered to be
required. However, LNAPL could still be encountered in excavations and would need to be
managed. In this case there are several remediation options available to deal with free product
in excavations including pump & treat, dual phase vacuum extraction, skimmer pumps, solvent
extraction and flow path management techniques for LNAPL that can then be coupled with
gravity separation and air stripping techniques to separate product from groundwater. A
number of techniques have been removed as remediation of LNAPL to prevent off-site migration
is not required.
8.3.19 It will be necessary to combine the treatment of free phase contamination with any other
remediation measures that are proposed for groundwater.
8.3.20 Environmental impacts associated with the above techniques for mitigation of LNAPLs would
arise from emissions and energy use in the manufacture, installation and operation of the
facilities and potential emissions associated with the destruction of contaminants, especially if
incineration is required.
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8.3.21 The use of any of the techniques listed above will not guarantee that all of the free product will
be recovered. It is generally accepted that complete LNAPL removal is not possible, and that
product recovery operations must be combined with extensive monitoring to look for any
potential rebound of product beneath the site.
DNAPL
8.3.22 The requirement for remediation of DNAPL has been identified at Catalyst Trade Park in Area C
and this is currently being developed as part of the advanced works. Options for the
remediation of DNAPL are likely to comprise source removal or recovery as far as is reasonably
or practically possible, to include:
a. Removal / remediation of DNAPL tanks and/or shallow made ground soils saturated with
DNAPL; and
b. Removal/recovery of DNAPL from beneath the site (made ground, granular alluvium and
glacial sand) using techniques such as flow path management, low flow pneumatic
pumps, solvent extraction, hot water injection or pump and treat. For low permeability
soils, techniques such as hydraulic fracturing can be coupled with any of the above
techniques to mobilise product.
c. Groundwater remediation to reduce concentrations of dissolved phase chlorinated
solvents (discussed in paragraphs 8.3.11 to 8.3.16).
8.3.23 The advanced works is focussing on source removal using the best practicable technique over a
fixed time period with the objective of betterment. This has been agreed with the EA.
Groundwater remediation has not been proposed other than where this would be required for
DNAPL treatment.
8.3.24 The use of any of the techniques listed above will not guarantee that all of the product within the
soil will be recovered. Using currently available techniques, it is generally accepted that
complete DNAPL removal is not possible, and that product recovery operations must be
combined with extensive monitoring to look for potential rebound of product beneath the site.
Source reduction is the principal driver behind the approach for the advanced works
remediation.
8.3.25 Dissolved phase chlorinated solvents are treatable using a range of techniques that are based
upon reduction of the chlorinated compounds into lower weight chlorinated compounds and,
eventually, to water and carbon dioxide. Techniques that can be utilised to stimulate this active
dechlorination process include enhanced bioremediation using oxygen and/or hydrogen
releasing compounds or other forms of nutrient, through chemical oxidation methods or, as used
in the waste water treatment industry, ultraviolet oxidation. However, groundwater remediation
works alone may have a limited impact if a source of the product remains.
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8.3.26 An alternative would be to utilise monitored natural attenuation (exploiting the fact that
contaminants change in nature and/or reduce in concentration naturally over time) with a record
of progress maintained in case intervention is needed. An extensive period of monitoring is
likely to be required to demonstrate whether attenuation is already occurring, although this may
prove to be an effective solution in the long term. Consideration would need to be given to
residual risks to human health and to groundwater/surface water during attenuation. Monitored
Natural Attenuation would need to be coupled with an Emergency Action Plan detailing specific
remediation works that could be undertaken in the event that monitoring suggests that natural
attenuation is not effective, or that potential receptors are at risk. This Emergency Action Plan
would need to detail how the measures would be implemented if the area of concern extended
beneath the area of the Works. This might require that measures are built into the scheme to
allow for emergency actions to be implemented should the need arise. An extended period of
monitoring would have to be included in the overall project programme. If this approach is
adopted then the form of works would require approval in this specific respect to ensure that
emergency measures were possible. Monitored Natural Attenuation is unlikely to form part of
the immediate remedial works though it may form part of a longer term management strategy.
8.3.27 It will be necessary to combine the treatment of free phase contamination with any other
remediation measures that are proposed for groundwater. Given that complete remediation of
DNAPL product is unlikely to be possible consideration would need to be given to any residual
effect arising from dissolved phase contamination of groundwater following remediation. This
could be achieved through a programme of monitored natural attenuation of the residual effect
or through containment combined with treatment such as PRBs.
8.3.28 Environmental impacts associated with the above techniques for mitigation of DNAPLs would
arise from emissions and energy use in the manufacture, installation and operation of the
facilities and potential emissions associated with the destruction of contaminants, especially if
incineration is required. Environmental impacts associated with monitored natural attenuation
would generally be less than more intensive techniques, assuming there are no adverse
impacts from allowing the contaminants to remain in place whilst attenuation occurs.
8.4 Detailed Design Stage
8.4.1 So as to accommodate appropriate design responses to contamination the final design of the
Project must accommodate mitigation. Also mitigation measures themselves will require
detailed design prior to implementation of relevant parts of the Project. There are also issues
that need to be considered in the detailed design which would have implications for
contamination, such as drainage issues. These are discussed below. On the basis of the
review of information obtained since the Orders ES in 2008, these mitigation measures remain
appropriate and no new measures are considered necessary.
Construction Environmental Management Plan
8.4.2 A Construction Environmental Management Plan (CEMP) provides the management framework
needed for the planning and implementation of construction activities in accordance with
environmental commitments identified within the Environmental Statement (ES) and any
requirements of planning conditions. The purpose of the CEMP is to reduce the risk of adverse
impact of construction on sensitive environmental resources and to minimise disturbance to
local residents. The CEMP is discussed in greater detail in Chapter 23 of the ES.
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8.4.3 The CEMP describes the checking, monitoring and audit processes that would be implemented
to ensure works are being undertaken in accordance with these requirements, together with
measures to ensure that appropriate corrective actions or mitigation measures are taken. A
CEMP will need to be prepared once a Concessionaire has been appointed and the detailed
design has been completed.
8.4.4 The CEMP forms part of the overall Project Management and as such, activities described
would be integrated with other Quality, Sustainability and Health and Safety management
processes.
8.4.5 The CEMP would be developed from the Construction and Operation code of Practice for
Environmental management (COPE). The purpose of the COPE is to define the measures
required to mitigate and monitor the construction and operation of the Project including the
Proposals contained in the Project including the Proposals so as to protect the environment.
8.4.6 As part of this Further Application ES and to protect the environment a COPE has been
developed to outline the measures required to mitigate and monitor the construction and
operation of the Project. Furthermore the COPE outlines the provision for auditing, reporting
and action to be taken to rectify breaches to the COPE during construction and operation
phases.
8.4.7 The COPE will be developed by the Project Company into a Construction Environmental
Management Plan (CEMP).
Minimisation of Intrusive Works
8.4.8 Where possible, design of structures in areas known to contain contamination should minimise
the amount of material that has to be excavated and minimise the volume of waste that is
produced. Examples include:
a. Consideration of piling techniques (following EA guidance (2001)) and balancing the need
to minimise the potential to create pathways with reducing the volume of arisings;
b. Avoiding the use of deep trench footings; and
c. The use of supported excavations rather than battered excavations.
8.4.9 This will have benefits in that it will minimise:
a. The risk of personal injuries to site workers and trespassers at the site;
b. The risk of exposure of site workers and trespassers to contaminated soil and
groundwater at the site;
c. The potential for ground gas or volatile vapours to:
i. Accumulate (in the case of carbon dioxide) at the base of excavations;
ii. Increase potential for a fire or explosion (in the case of methane and volatile
vapours); and
iii. Escape to atmosphere.
d. The risk of introducing new pathways for vertical contaminant migration;
e. The risk of migration of contaminants to surface watercourses via surface run-off;
f. The volume of potential waste being produced at the site; and
g. The volume of contaminated soils requiring treatment.
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8.4.10 Limiting the extent of excavations is likely to reduce environmental impacts through reducing the
need for disposal and/or treatment of contaminated soils and liquids, assuming that the impacts
arising from leaving contaminants in place are mitigated. It is unlikely that the environmental
impacts from mitigating these risks will outweigh those from wholesale excavation and removal
of contaminated soils from beneath the Project area.
Design of Measures to Incorporate and Protect Surface Water Features from Contamination
8.4.11 The design of the structures and associated embankments will need to consider the presence of
surface water features such as Stewards Brook, Bowers Brook, St. Helens Canal and the
Mersey Estuary. Measures will need to be incorporated to protect these features from
contamination during construction works and during the operational stage. This is discussed in
Section 8 (Surface Water Quality) of the ES.
Design of Measures to Prevent Vertical Migration of Contaminants
8.4.12 Where contamination coincides with poor ground conditions in geotechnical terms it may be
necessary to carry structural loads carried to more competent strata at depth. This may involve
piling or other forms of ground improvement that could form pathways for vertical and (to a
lesser degree) lateral migration. Where piling or other forms of ground improvement is required,
consideration must be given to EA guidance (2001) on pollution prevention on land affected by
contamination. It is likely that the piling strategy would need to be approved by the EA.
8.4.13 The most likely foundation solution is based on auger or bored piles with vibro-concrete
columns for ground improvement and has considered the requirement to reduce the potential for
introducing preferential pathways. Ground improvement and piling is likely to be needed for
various parts of the scheme and these will need to be designed to take account of
contamination where it is present. The assessment for the orders ES was based on auger or
bored piles with vibro-concrete columns for ground improvement and that has been used for the
assessment for the Further Applications ES. These methods are techniques which are
acknowledged in EA guidance (Ref. 40) as presenting low risks of introducing preferential
pathways. If alternative foundation solutions are proposed it will be necessary to design
mitigation measures to prevent such migration occurring. A wide range of potential solutions to
this issue are available, and the exact technique to be used will be dependent on the type of pile
to be used and the techniques available at the time of construction. Techniques include:
a. The use of temporary or permanent sleeving of the piles through contaminated ground;
and
b. Avoidance of ground improvement techniques such as stone columns which introduce
high permeability pathways.
8.4.14 It will also be necessary to seal existing monitoring wells that are not required for long term
monitoring to prevent the risk of vertical migration of contaminants. The exact number and
location of the wells to be sealed would depend on the remediation measures that are adopted.
8.4.15 Measures will be required to deal with potential contaminant migration along piles and leachate
generation potential for the approach viaduct pier at the Wigg Island Landfill.
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8.4.16 Specific mitigation measures at the Wigg Island Landfill (Area D) would include the use of
specialist piles (the form and technique for which would require approval from the EA) to
minimise the potential for contaminant migration along the piles to occur. Alternatively, it would
be possible to excavate the landfill beneath the footprint of the pier, and have the piles/pile caps
founded within natural soils only. This would remove any risk of vertical migration of landfill
leachate along the piles. The waste material from the landfill could either be sent off-site for
disposal or re-interred as part of the subsequent landfill re-instatement works. This would be
subject to EA approval, and an authorisation or possibly an exemption from the Environmental
Permitting Regulations is likely to be required.
8.4.17 At Wigg Island, the need to remove material around the pier that is located in the former landfill
will have a greater environmental impact than installing piles through the landfill, assuming that
the risk of contaminant migration is mitigated.
Design Measures for Contaminants Remaining Beneath Sections of the Route to be Covered
8.4.18 Where the proposals involve covering contaminated ground, for instance with an embankment,
this would be a suitable means of remediation in its own right for certain pathways and it would
also reduce infiltration of water into the ground.
8.4.19 The design would need to consider the nature of the contaminants in the ground beneath the
embankment given that the structure will be present for the long term. In these areas it may be
necessary to consider removing or containing contaminants that may represent a long term risk.
This is particularly the case where significant depths of embankment materials are present.
8.4.20 Depending on the mitigation options eventually adopted, it is possible that remedial measures
would need to be incorporated within the works to allow long term remediation to be undertaken
in some areas. These works would likely relate to the remediation of LNAPL or DNAPL, as
discussed in paragraphs 8.3.1721 to 8.3.26.
8.4.21 Where existing embankments are to be removed (such as in Area I2 as part of the de-linking
works), there is a risk of exposure of soils (in underlying made ground and natural soils) that
could contain contaminants from previous land uses. In these areas, measures should be
considered to prevent exposure of these soils to site workers, visitors, local residents or
trespassers until development of these sites takes place. Specific measures could include the
retention of some embankment material to form a cap and prevent exposure of the original
made ground, or the import / construction of a new capping layer. The overall risks associated
with these areas would need to be considered as part of any future development works.
Design of Specific Remediation Measures
8.4.22 Remediation measures for specific contamination issues, as detailed in Section 8.3, would need
to be designed in detail to suit the specific conditions at the site. Remediation techniques are
available and are discussed in more detail within the Preliminary Remediation Options Appraisal
(Section 8.2). The specific contamination issues are as follows:
a. Soil remediation;
b. Groundwater remediation;
c. LNAPL remediation (in excavations); and
d. DNAPL remediation.
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Recontamination of Treated Areas
8.4.23 Detailed design measures for remediation may need to take into account contamination outside
the Project area, which could potentially re-contaminate treated areas. A means to prevent
recontamination, such as a containment system with or without treatment sections, could be
required in such circumstances. However, the EA have agreed that this would not be
practicable and they would prefer not to see extensive cut-off walls/barriers and on this basis it
is consider unlikely that such measures would be used. These measures are also discussed in
the Preliminary Remediation Options Appraisal in Section 8.2.
Migration of Contaminants Outside of the Project Area
8.4.24 A further factor that will need to be taken into account in the detailed design stage is the
possibility that residual contaminants remaining within/beneath land occupied by the works
could migrate outside the Project area. This might also drive the need for remediation and/or
containment works. However, other than DNAPL in Area C, the EA have agreed that
remediation of groundwater to prevent migration off-site would not be required for the Project
area. However, this effectively means that contamination would remain in the Project area.
Design of Protection Measures for Buried Services
8.4.25 Where buried drinking water supply pipes need to be diverted as part of are to be incorporated
in the design, consideration of the location of contamination should be made. Contaminated
areas should be avoided where possible but, if necessary, buried plastic drinking water supply
pipes in such areas will require some form of mitigation from aggressive contaminants.
8.4.26 There may also be risks to construction and maintenance workers where buried services are
located in contaminated soils. Buried services include (but should not be limited to) electrical
services, gas pipes, drains and sewers, and covers both existing and proposed services. It may
be necessary to divert buried services to avoid contaminated soils, or to mitigate any potential
risks by installing services above ground or within protected service ducts.
Drainage Design
8.4.27 It will be necessary to avoid infiltration drains in areas of contamination as these could mobilise
contaminants. Further detail on the proposed drainage strategy is included in Appendix 8.2 of
Chapter 8 Surface Water Quality in the ES.
8.5 Construction Stage
8.5.1 There will be a need to control risks arising from the site operations and implement the design
measures set out above. These include:
a. Measures to manage the mitigation of contaminants and/or recontamination of treated
areas;
b. Measures to prevent vertical migration of contaminants;
c. Measures for contaminants remaining beneath sections of the route to be covered; and
d. Measures to prevent migration of contaminants from embankment or structural loading
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8.5.2 It will also be necessary to implement specific remediation measures as discussed in Section
8.2. These include specific consideration of the following contamination issues at the site:
a. Soil contamination;
b. Groundwater contamination;
c. LNAPL remediation (in excavations); and
d. DNAPL.
8.5.3 There will be a requirement to undertake monitoring and validation works for specific
remediation works that are required at the site. The remediation works, with monitoring,
validation and action plans would all need to be approved by the Local Authority and EA prior to
undertaking the works. Specific remediation techniques are discussed in the Preliminary
Remediation Options Appraisal in Section 8.2, and further discussions on the use of these
techniques within the Project area is included in Section 8.3.
8.5.4 Mitigation measures have been considered for the construction stage and these are discussed
below. The final extent and combination of mitiation measures to be deployed will be subject to
approval by the regulators. These mitigation measures would also apply to the advanced
works. Each mitigation measure has been assigned a suffix letter for reference in the summary
table included in Table 8.1 within Section 8.7.
Soil Remediation Works (A)
8.5.5 In overall terms the construction of the bridge and associated access roads will break the
pathway between site users and soil contamination.
8.5.6 Soil remediation works may be required to mitigate the risks to groundwater from contaminants
within the soil. They may also be required to treat waste soils prior to removal from the site or
prior to re-use.
Groundwater Remediation Works (B)
8.5.7 Groundwater remediation works may be required to mitigate the risks to controlled waters
(groundwater beneath the project area, off-site groundwater, or surface water) from
contaminated soils (including chemical wastes), LNAPL and DNAPL.
LNAPL Remediation Works (C)
8.5.8 The DQRA indicates that specific remediation works would not would be required to remediate
LNAPL in Areas B2 and I1 to mitigate the risks to groundwater and site (and adjacent site)
users. However, LNAPL encountered during excavations will still need to be managed.
DNAPL Remediation Works (D)
8.5.9 Specific remediation works would be required to remediate DNAPL in Area C to mitigate the
risks to groundwater, surface water and site (and adjacent site) users. These are being
developed as part of the advanced works.
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Minimisation of Intrusive Works (E)
8.5.10 The detailed design mitigation measures to minimise the extent of excavations at the site
outlined in paragraph 8.4.5 to 8.4.7 should be implemented to minimise the risks to construction
workers/visitors/trespassers, local residents, groundwater and surface water from contaminated
soil, groundwater and/or ground gas.
Measures to Mitigate Exposure to Contaminated Soils (F)
8.5.11 Where exposure of receptors such as workers and trespassers or local residents and workers to
contaminated soils could arise, it would be possible to break this pathway by introduction of
barrier layers. As noted above, the placement of a road would act as a barrier layer. Capping
layers may be required in areas of landscaping.
8.5.12 Where contaminated material is excavated and stockpiled, it will be necessary to ensure there is
no possibility of migration of contamination from stockpiled material. In addition to the mitigation
measures for dusts and vapours/odours such as damping down or sheeting, lining of stockpiled
areas could also be required. In the most extreme cases it is possible that work will need to be
carried out in temporary structures.
8.5.13 There will be environmental impacts associated with the extraction, transport and placement of
fill materials for barrier layers. These have been taken into account as part of the EIA process
for the Project as a whole.
Measures to Prevent Vertical Migration of Contaminants (G)
8.5.14 It will be necessary to consider the use of mitigation measures to prevent the vertical migration
of contaminants. These are summarised as follows:
a. Vertical migration along foundations:
i. Selection of appropriate foundation solutions;
ii. Consideration of pile types;
iii. The use of temporary or permanent sleeving of the piles through
contaminated ground; and
iv. Avoidance of ground improvement techniques such as stone columns which
introduce high permeability pathways.
b. Vertical migration during removal of buried foundations in Areas B2 and C:
i. Backfill the resulting excavations using appropriate methods to ensure that
pathways to deeper layers are not created.
c. Vertical migration at Wigg Island (Area D):
i. Use of specialist piles for piers approved by the EA; and
ii. Removal of landfill material prior to construction of pier.
d. Vertical migration along historic abstraction wells in Areas B2 and C.
i. These wells should be located and grouted before construction works
commence.
e. Vertical migration along existing monitoring wells in all areas.
i. It will be necessary to remove and grout these wells during the construction
phase where they are not required for long term monitoring.
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Dust Suppression (H)
8.5.15 Dust generated from areas of contaminated soils during dry weather is a potential means for
migration of contaminants to both site workers, residents and workers in the locality. Dust
suppression measures would be necessary during the works such as the damping down or
sheeting of exposed of soils. Monitoring of dust will be required during the works. In some
cases it is possible that work would need to be carried out in temporary structures/tents.
Control of Odours & Vapours (I)
8.5.16 Odours are primarily unpleasant. However, there is also the possibility at this site that volatile
organic compounds could give rise to vapours with the potential to cause harm. Unmitigated,
this could affect site workers and, potentially, nearby residents or workers.
8.5.17 In addition to minimising excavations, odour controls may still be needed in some areas. Such
measures can include covering sources or use of sprays to act as barriers, odour
counteractants or modifiers. In terms of vapours with the potential to cause harm, dilution
should usually be sufficient to mitigate this impact. However, specific measures may be
required in some areas. Monitoring of vapours and odours during the works will be required. In
some cases it is possible that work will need to be carried out in temporary structures/tents.
Buried Plastic Pipes (J)
8.5.18 Protection measures for buried plastic water supply pipes at the site would comprise the use of
upgraded pipe material, such as to steel, specialist plastic pipes, use of clay backfill to trenches,
and/or the installation of service ducts or tunnels to minimise any contact with contaminated
soils. The latter would also prevent maintenance workers from coming into contact with
contaminated soils.
Gas/Vapour Protection (K)
8.5.19 Gas protection measures would comprise the use of properly installed gas resistant membranes
and the incorporation of passive or active ventilation measures in new buildings. For protection
against the ingress of volatile vapours, organic vapour resistant membranes installed within
foundations would be required.
8.5.20 The need for mitigation measures could be offset if remediation works were able to reduce the
concentrations of, or remove, contaminants from the site that produce ground gas, and in
particular, volatile vapours. Given the small extent of protection measures that are likely to be
required this benefit may not be substantial enough to outweigh the additional remediation work
needed. This text has been deleted as toll booths and offices are no longer proposed.
8.5.21 In order to comply with health and safety requirements during construction it will be necessary
to ensure that monitoring is undertaken prior to entering confined spaces, this may include
some excavations.
Aggressive Ground Conditions (L)
8.5.22 Due to the potential for encountering aggressive ground conditions, it will be necessary to
ensure that where buried concrete foundations are introduced these take into account the
appropriate design sulphate class.
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Landscaping (M)
8.5.23 Due to the potential for encountering phytotoxic contaminants within the existing soil or
embankment fill, it may be necessary to introduce additional sub-soil and topsoil into
landscaping areas particularly where trees are proposed, and particularly in areas where
contaminants wold be exposed at or near surface. This would also help to ensure the potential
for accidental contact by residents, trespassers or workers undertaking maintenance works,
such as grass cutting, is minimised. The updated Reference Design involves smaller extent of
construction works which could require greater areas of landscaping. The options being
considered for structures would also impact on the area of landscaping required as an
embankment would result in greater coverage of existing soils than a viaduct.
8.5.24 Under the current scheme proposals at St. Michaels Golf Course in Area A, where no
landscaping is required outside of the footprint of the road and embankment. Where the site is
used as a construction compound there would be a need to re-instate to the current condition.
The existing clay cap, which separates site users from the underlying chemical waste, will
require improvement/re-instatement due to its limited thickness in some areas. Such measures
would need to be designed appropriately.
Site Hygiene and Personal Protective Equipment (N)
8.5.25 Due to potentially high risks to construction workers from contamination in some parts of the
Project, where risks to site workers cannot be fully controlled through changes in design,
physical or management mitigation measures, personal protective equipment will be required on
site. Good site hygiene, together with the provision of washing facilities, is also an important
part of controlling the risks to site workers in terms of preventing ingestion of contaminated
materials.
Site Health & Safety File (O)
8.5.26 The site Health and Safety File would be the means to ensure that all site users are aware of
the risks present at the site, and the safety management procedures that are in place. The file
should also contain all of the relevant risk assessments and method statements for all forms of
work required at the site. Following completion, this file would then be made available for
maintenance workers to minimise their risk of exposure.
Protocols to Deal with Unexpected Contamination (P)
8.5.27 It will be necessary to have in place protocols to deal with unexpected areas of contamination.
Site Security (Q)
8.5.28 Due to the potential for exposing soil and water contaminants during construction works, or the
accumulation of ground gas in excavations and confined spaces during construction works,
working areas will need to be secured against potential trespassers.
Accidental Spillages / Releases (R)
8.5.29 In the event of an accidental chemical or fuel spill/release within the saltmarsh and estuary
during construction works, response measures will be required to recover spilt products and
remove contaminated sediments as quickly and efficiently as possible, whilst taking due care
and consideration of the sensitive ecology of the salt marshes and estuary.
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Protection or Removal of Drains (S)
8.5.30 During construction works it may be necessary to undertake the following works to surface
water drains due to the potential for discharge into surface water courses.
a. Protect drains from site run-off water, which may be contaminated from contaminated
soils at the site;
b. Remove or divert drains to enable the construction works to take place;
c. Grout drains to prevent current or future migration of contaminated silts, sludges,
groundwater or site surface water run-off;
d. Remove potentially contaminated silts and sludges from the base of drains to prevent
their migration (these silts and sludges would be regarded as waste); and
e. Replace drains to provide greater protection from shallow contaminated soils.
Protection of Surface Water Features (T)
8.5.31 Measures will need to be undertaken to prevent surface water run-off on and adjacent to the
Project area from excavations and other working areas from entering surface water courses
such as the River Mersey or and also Stewards Brook if St Michaels Golf Course (Area A) were
to be used as a construction compound. This requirement is discussed in Chapter 8 Surface
Water Quality. Measures may include:
a. Surface drain protection;
b. Bunds where construction works are required immediately adjacent to water features;
c. Wheel washing facilities;
d. Siting of stockpiles away from water courses;
e. Sheeting of soil stockpiles;
f. Control of water levels in excavations; and
g. Secure storage of contaminated water removed from excavations prior to its treatment,
discharge or off-site removal.
h. Lining of surface water attenuation features in areas of contamination.
Radioactive Contaminated Land (U)
8.5.32 The concrete encapsulated radioactive contamination understood to be beneath the A557 in
Widnes would be removed where necessary. However, wherever possible it is proposed that
this remains in place. If the intention was to remove radioactive contamination from the site,
further investigation would be required to delineate the area of concern. No additional
investigation is proposed if there is no intent to disturb material. However, it may be prudent to
undertake monitoring works to protect site workers when undertaking excavations in the vicinity
of the A557 embankment if any radioactive contamination is present.
8.5.33 Radioactive contamination has also been identified from investigations in shallow soils and
drains at the Catalyst Trade Park. Mitigation measures would primarily consist of on-site
monitoring during any required excavation works at Catalyst Trade Park, and for local drains
beneath the site to be removed, grouted or sealed to prevent radioactive contamination from
migrating from the site. If significant volumes of radioactive contaminated soil are identified
during shallow excavations at the site, such as for pile caps or contamination source removal
works, these soils would need to be disposed of a suitably licensed facility.
8.5.34 The text above has been superseded following a review of existing information by Radman
Associates in 2011 (Appendix 14.11) to inform the advanced works remediation which has been
summarised below.
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8.5.35 Evidence of radiological contaminants has been identified from previous investigations in
shallow soils in localised areas and drains on and adjacent to Catalyst Trade Park. No
evidence for radiological waste burial has been obtained. None of the exposure levels identified
from the existing ground level radiological surveys indicate the need for special protective
measures to restrict exposure to individuals. However, a non-intrusive site walkover survey
should be undertaken to identify gross contamination in existing near surface material with
surface sampling if elevated instrument levels are obtained
8.5.36 Monitoring should also be undertaken during any excavation works at Catalyst Trade Park.
However, if radioactive contaminated soil were to be identified during shallow excavations at the
site, such as for pile caps or contamination source removal works, these soils may need to be
disposed of to a suitably licensed facility
8.5.37 Sediment within the drains or Bowers Brook may be contaminated and samples should be
tested for radiological contaminants. Local drains beneath the site may need to be removed,
grouted or sealed to prevent radioactive contamination from migrating from the site
8.5.38 No specific information has been obtained at this stage to indicate that radioactive material is
present beneath the A557, although recent anecdotal evidence indicates that radioactive
material could be present in the embankment. Therefore, as a precautionary measure, the
requirement for screening using hand held monitors during re-working of the existing road
embankment should be implemented.
Unexploded Ordnance (V)
8.5.39 The assessment undertaken has identified a risk that German Air Dropped unexploded
ordnance may be encountered within shallow sediments at bridge pier and tower locations,
particularly in the estuary and on the saltmarshes. Personnel involved in significant intrusive
works (such as pile caps, northern abutment or cofferdams in the estuary) should be provided
with ordnance awareness briefing prior to work commencing. This would need to inform staff on
identifying UXO, the associated risks, working procedures and contingency measures.
Monitoring will may also be required during excavations for these piers and towers. If UXO is
encountered then work will need to be stopped until the object has been removed and made
safe by suitably qualified specialist personnel.
8.5.40 BAE Systems did not consider ordnance awareness briefings to be effective for personnel
involved in piling or drilling because the operator would not be able to see the soil being
disturbed. Therefore, no special protection measures were considered necessary by BAE
Systems to migate the risk of encountering German air-dropped UXO during these activities.
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8.6 Operation Stage
Site Users
8.6.1 Given that users will be separated from any areas of contamination by the road construction and
through either being on an embankment or the bridge it is considered that no pathway would be
present to this receptor during the operation stage. Accordingly, the Project itself will provide
mitigation for this potential receptor.
Site Staff
8.6.2 Ground gas and/or vapour protection measures would be necessary to mitigate possible risks to
site staff in toll booths or offices from contaminants in fill material or existing underlying ground.
These measures are described in paragraphs 8.5.19 to 8.5.21 above. This text has been
deleted as toll booths and offices are no longer proposed as part of the construction works.
Maintenance Workers
8.6.3 Maintenance workers who need to excavate ground during the operation phase in areas of
contamination may be exposed to risk. Mitigation for such workers would comprise protocols to
ensure the use of gas monitors, personal protective equipment and escape equipment common
to all maintenance work to specific requirements that may be covered in the design.
8.6.4 Information on ground conditions and construction methods should be retained within the site
health and safety file.
Local Residents and Workers
8.6.5 Risks to residents and workers are assessed to be low during the operation phase and there
may even be a net benefit due to remedial works undertaken as part of the bridge construction
works and because the physical works will form a barrier to contamination in many areas.
Monitoring
8.6.6 Monitoring during the operation phase will be required to ensure the effectiveness of any
mitigation measures. Monitoring of the effectiveness of mitigation measures to prevent
migration of contamination within groundwater may also be needed.
8.6.7 Long term monitoring may be required to demonstrate that the bridge, embankments and
associated structures have not had an adverse effect on groundwater migration and
contamination beneath the site. This could require regular monitoring of contaminant
concentrations in shallow and deeper groundwater bodies over a prolonged period of time.
8.6.8 In particular, there may be a requirement to undertake long term monitoring wherever long term
remediation systems or certain types of remediation (such as stabilisation) are implemented.
Maintenance
8.6.9 Any maintenance works will need to consider the above factors. Specifically, any long term soil
and / or groundwater remediation systems installed at the site will require well defined, regular
maintenance visits to ensure that the efficiency of the system is maximised at all times and to
ensure that licences or consents (such as sewer discharge consents) are being complied with.
Furthermore, any filtration media will require replacement at appropriate intervals.
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Action Plans
8.6.10 Action plans will be required should monitoring indicate that post-construction remediation or
mitigation measures are not performing as anticipated.
Validation
8.6.11 Validation will be required during any long term monitoring and to conclude the remedial works.
Such validation monitoring may extend beyond the construction works into the operational
stage. Any Validation Report should be updated and submitted to the regulators for approval as
appropriate. Once agreed, the report should be kept with the site Health & Safety file.
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8.7 Summary of Mitigation Measures by Area
8.7.1 The mitigation measures identified above are shown in Table 8.1 along with the relevant risks
identified in Tables 7.4 to 7.9: Table 8.1 has been updated to remove pollutant linkages that are
no longer relevant due to revisions to the proposed construction works.
Table 8.1 – Summary of Specific Contaminants of Concern, Effects and Viable
Remediation Measures (continued overleaf) (Updated)
Area SPR No. *1
Nature of
Contaminants
Potential
Mitigation
Measures
Area A – Speke Road/
St. Michaels Golf
Course
Area B1 - Ditton
Junction
W36, W45, W48, W56, W58, W82, W91,
W94, W102, W104, [W4, W10, W16]
Contaminated
Groundwater
A, B, E, F,
G, J, L, N,
O, P, Q, R,
S
As above, plus W32, W33, W34, W78, W81,
[W2, W3]
Contaminated
Soils*2
A, E, F, H, J,
L, M, N, O,
P, Q
W70, W112, W116, [W28] Ground Gas
and/or Vapours
E, I, K, N, P,
O, Q, R
W62 Surface Water B, E, R, S, T
Area B2 & I1 -
Gussion/former Anglo
Blackwell site
W36, W39, W41, W45, W48, W50, W52,
W56, W82, W85, W87, W91, W94, W96,
W98, W102, [W4, W7, W9, W10, W12, W14,
W16]
Contaminated
Groundwater
A, B, C, E,
F, G, J, L, N,
O, P, Q, R,
S
As above plus W32, W33, W34, W78, W81,
[W2, W3]
Contaminated
Soils*2
A, C, E, F,
H, J, L, M,
N, O, P, Q
W70, W71, WS73, W74, W112, W113, W116,
W117, [W26, W28, W29]
Ground Gas
and/or Vapours
A, B, C, E, I,
K, N, O, P,
Q, R
W41, W50, W52, W87, W96, W98, [W12,
W14]
LNAPL B, C, G, L,
N, O, P, Q
Area C – Widnes
Loops
W36, W45, W48, W51, W53, W56, W59,
W82, W91, W94, W97, W99, W102, W105,
[W4, W10, W13, W15, W16, W19]
Contaminated
Groundwater
A, B, D, E,
F, G, J, L, N,
O, P, Q, R,
S
As above, plus W32, W33, W34. W78, W81,
[W2, W3]
Contaminated
Soils*2
A, D, E, F,
H, J, L, M,
N, O, P, Q,
U
W70, W71, WS73, W112, W113, W116,
W117, [W26, W28, W29]
Ground Gas
and/or Vapours
A, B, D, E, I,
K, N, O, P,
Q, R
W51, W53, W97, W99, [W13, W15] DNAPL B, D, G, L,
N, O, P, Q
W61, W63, W64 Surface Water E, D, E, R,
S, T
*1 SPR (Source-Pathway-Receptor) linkage numbers as shown in Tables 7.4 to 7.9, and in Figures
MG_EIA_REP_009/094 to 097.
*2 Contaminated soils, including Galligu and other chemical wastes.
SPR numbers in square brackets ([ ]) relate to risks from the Do Nothing scenario.
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Table 8.1 (continued) – Summary of Specific Contaminants of Concern, Effects and
Viable Remediation Measures (Updated)
Area SPR No. *1
Nature of
Contaminants
Potential
Mitigation
Measures
Area I2 – De-Linking
Works
W32, W33, W34, [W2] Contaminated
Soils*2
A, E, F, H,
I, L, N, O,
P, Q
W61 Surface Water R, S, T
Area D – Widnes
Saltmarsh
W36, W48, W82, W94, [W4, W10] Contaminated
Groundwater
A, E, F, G,
L, N, O, P,
Q, R
As above, plus W32, W33, W34, W78, W81 Contaminated
Soil/Sediment
A, E, F, H,
L, N, O, P,
Q, V
W61, W64 Surface Water A, E, R, S,
T
W70, W116 Ground Gas E, I, N, O,
P, Q, R
Area D – Runcorn
Saltmarsh/Wigg Island/
Kemet Works
R41, R43, R47, R48, R50, R78, R83, R84,
R86, [R6, R9, R11]
Contaminated
Groundwater
A, E, F, G,
L, N, O, P,
Q, R
As above, plus R35, R37, R72, [R3] Contaminated
sediment/soils
A, E, F, H,
L, N, O, P,
Q, V
R35, R37, R41, R43, R47, R48, R50, R56,
R65, R66, [R3, R6, R9, R11, R26, R27]
Landfill*2 A, B, E, F,
G, H, L, M,
N, O, P, Q,
R, T
R65, R66, R99, R100, [R26, R27] Ground Gas E, I, N, O,
P, Q, R
R55, R56 Surface Water A, E, R, S,
T
Area E – Astmoor
Industrial Estate
Area F – Bridgewater
Junction
Area G1 – Lodge Lane
Junction
Area G2 – Lodge Lane
Junction
Area H – M56 Junction
12
R56 Surface Water E, R, S, T
*1 SPR (Source-Pathway-Receptor) linkage numbers as shown in Tables 7.4 to 7.9, and in Figures
MG_EIA_REP_009/094 to 097.
*2 Contaminated soils, including Galligu and other chemical wastes.
SPR numbers in square brackets ([ ]) relate to risks from the Do Nothing scenario.
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8.8 Risks arising from the Project
8.8.1 The majority of significant risks associated with the Project arise during the construction stage
and mitigation measures have been proposed for these. Many of these mitigation measures will
continue or continue to have an effect into the operation phase. Further significant risks have
been noted during the operation phase and mitigation measures have been outlined to address
these.
8.8.2 The overall approach to mitigation for site users is based on the premise that wherever possible
contaminated soils will remain in place beneath the road and that the road construction and
landscaping will act as a barrier between human receptors and contaminants. The proposed
end use is not a sensitive one in terms of human health and on this basis it is considered that
widespread removal and/or remediation of contaminated soils would not be an appropriate
means of managing this risk. In some cases, the construction of the road will provide benefits
as areas of contamination will be covered and risks to some receptors will be reduced when
compared to the current situation. The fact that substantial parts of the development in Widnes
would be elevated on embankment will further assist in reducing these risks. This has not
changed for the Project including the Proposals.
8.8.3 With the exception of Wigg Island, the pile types already identified for the scheme are not
considered to be likely to result in new pathways or cause contaminants to move. On this basis,
there are no risks that require mitigation relating to the installation of piles within the Project
area. The requirement for specific mitigation measures at Wigg Island has been identified in
Section 8.4.15 to 8.4.17 above.
8.9 Existing risks associated with the Project
8.9.1 There are existing risks that have been identified in the do nothing scenario and these will
continue regardless of whether the Project is constructed or not. These principally relate to
contamination of the groundwater due to past industrial activities in Areas A, B, C and part of
Area D (Wigg Island landfill) together with sources of LNAPL (in Area B) and DNAPL (in Area
C).
8.9.2 The development should not create new pathways for the migration of contaminants or
introduce any new vulnerable receptors. The proposed use of replacement piling and
displacement ground improvement techniques are techniques which are acknowledged in EA
guidance as presenting a low risk of introducing pathways. If other methods of piling are
considered, these would need to comply with EA guidance and gain approval from the EA. On
this basis it is considered that the Project would should not represent a significant additional
impact on the existing issue of groundwater contamination.
8.9.3 In areas where there are specific contaminants of concern such as DNAPLs, the proposed
ground improvement methods will would lie within the alluvial soils that have already been
heavily impacted and are likely only to extend for a minimal distance (200mm to 300mm) into
the underlying glacial clay. No piles penetrating a greater distance into the glacial clay are
proposed in any identified areas of DNAPL contamination. The proposed foundation solution
will need to be agreed with the EA. In addition to this, alternative construction proposals have
been assessed that could remove the need for ground improvement altogether if necessary.
Remediation is also proposed as part of the advanced works for DNAPL in the Project area.
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8.9.4 However, The presence of groundwater contamination has to be considered as part of the
planning process especially as the Project will cover areas of the site and might affect the ability
to remediate such areas in the future. However, agreement has been obtained from the EA that
other than treatment of DNAPL in Area C, remediation of groundwater would not be required to
prevent off-site migration
8.9.5 The Project is a long, linear feature that cuts across site boundaries and any remediation
proposed for groundwater would need to be considered in the context of the wider contaminated
land and groundwater issues in Widnes and on Wigg Island. Potential remedial measures for
groundwater beneath the footprint of the scheme have been outlined in the preliminary remedial
options appraisal and this includes various groundwater remediation techniques together with
options for cut off walls (with and without reactive barriers) and the option of allowing natural
attenuation to continue. Any proposals will need to be practical, effective, durable, provide a
benefit and not result in adverse environmental impacts. A key issue in this respect is that it will
be important to ensure that any remediated areas are not re-contaminated by neighbouring
areas of contamination.
8.9.6 Consultation with the EA has indicated a preference for avoiding extensive cut off structures
across the Project area as they could interfere with overall groundwater flows and the
implementation of more widespread groundwater remediation in the future. It is questionable
whether remediation beneath the footprint of the Project in isolation offers any substantial
benefit without measures to prevent recontamination in the future.
8.9.7 The final approach that is adopted will need to be part of an overall remediation strategy that
takes account of, although does not necessarily remediate in full, the wider contaminated land
and groundwater issues in Widnes and at Wigg Island. This would be developed and approved
by the relevant regulators from the preliminary options appraisal conducted for this report.
8.9.8 Consideration of the individual issues that are likely to require mitigation in each of the Areas A,
B, C and D is given below:
Area A
8.9.9 In Area A the route of the Project crosses part of a wider area of former landfilling, although
much of this is outside the proposed construction works, many of the existing issues would still
remain. It is underlain predominantly by made ground, though alluvium is also present and this
forms a minor aquifer and is therefore a sensitive receptor. The groundwater in the made
ground and alluvium has been impacted by a wide range of contaminants; there is evidence of
further contamination beyond the boundaries of the Project area across the St Michaels Golf
Course.
8.9.10 Potential mitigation measures to address the effects on groundwater directly beneath the
Project have been outlined and could be implemented as part of the works, although this should
not be required for construction compounds. However, it is unlikely that remediation of
groundwater beneath the footprint of the development alone would contribute significantly to the
wider issues associated with this Area especially given the very limited extent of the
development on the golf course. These wider issues, if they require further remediation, are
more likely to be addressed as part of an overall strategy for the remediation of St Michaels Golf
Course rather than at the location of the Project itself, which does not extend to wholesale
remediation of the area.
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Areas B and I1
8.9.11 Areas B and I1 are is underlain by relatively limited depths of made ground that rest directly
upon glacial clay. Alluvium has been identified in the south of Areas B and I1, underlying the
made ground. This forms a minor aquifer. The groundwater in the made ground and alluvium
has been impacted by a wide range of contaminants; there is evidence of further contaminated
made ground beyond the boundaries of the Project area.
8.9.12 There is evidence of LNAPL in this area and this contamination appears to be located within the
Project boundaries. The DQRA does not indicate that remediation of LNAPL will be required to
prevent off-site migration and this has been agreed with the EA. However, it is considered that
it would be prudent to remove remediate the LNAPL as far as is practicable where it is
encountered in excavations and mitigation measures have been proposed for this.
8.9.13 Consideration would need to be given to the benefits of groundwater remediation as part of any
wider remediation strategies in the area. If such remediation is undertaken in isolation then it
may be necessary to take steps to prevent recontamination of the Project area and this could
potentially impact on future remediation efforts within the wider area.
Area C
8.9.14 This area includes Catalyst Trade Park, where possible DNAPLs and associated dissolved
phase contaminants have been identified in made ground, alluvium and upper glacial sands.
There is evidence in this area that natural attenuation of these products is taking place.
However, the available information also shows that these contaminants are migrating outside
the Project area and any remediation scheme would have to acknowledge this. There is
evidence to suggest that the Project area may represent the source area for these
contaminants.
8.9.15 The requirement for treatment of DNAPL has been identified in order to reduce the risk to
Bowers Brook from off-site migration and in areas where DNAPL will be covered by the Project.
This is being developed at present as part of the advanced works and will be implemented
shortly. Options to treat DNAPL have been identified and these are being refined as part of the
advanced works. However, remediation of DNAPLs is complex and EA guidance acknowledges
that it is rarely completely successful. Consultation with the EA has acknowledged this by
noting that they would only expect improvement over the Do-Nothing scenario in this regard.
This approach has been agreed with the EA, the remediation strategy is being developed in
consultation with the LPA and EA to deliver the best practicable option for remediation of
DNAPL.
8.9.16 In addition to the DNAPL, consideration would need to be given to the benefits of groundwater
remediation as part of any wider remediation strategies in the area and within the context of the
fact that at least some natural attenuation does appear to be taking place at present. It is
possible that following source removal monitored natural attenuation could be adopted for future
remediation. If remediation is undertaken then it may be necessary to take steps to prevent
recontamination of the Project area. However, it has been agreed with the EA that remediation
of groundwater to prevent off-site migration (other than DNAPL) would not necessarily be
required.
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Area D Wigg Island Landfill & Former Kemet Works
8.9.17 Current proposals involve the need to construct piers through the existing Wigg Island Landfill
and at the former Kemet Works. Measures have been defined to mitigate potential impacts
arising from the Project on groundwater at this location. Once again, there are wider issues of
groundwater contamination in this area. However, it is considered that the construction
proposals would not interfere with the ability to remediate these in the future if necessary.
8.10 Remediation Strategy
8.10.1 The remediation strategy would be incorporated into the COPE for the site. The Remediation
Strategy would be secured by planning condition that would require the strategy to be approved
by the LPA and EA prior to commencing work. The remediation strategy prepared by the
Project Company would need to take into account the advanced works.
8.10.2 The mitigation measures will need to be implemented as part of an overall Remediation
Strategy which will depend on the method/s adopted for the construction of the scheme and the
overall programme. Viable mitigation measures have been outlined. However, there will be a
need for a detailed evaluation of the remedial options to develop the detailed Remediation
Strategy. Mitigation measures should be the Best Practicable Techniques taking account of the
following factors:
a. Practicability including constraints arising from practicability, the site itself, the time
available and regulatory factors;
b. Effectiveness;
c. Durability;
d. Benefit;
e. Adverse environmental impacts; and
f. Overall sustainability.
8.10.3 The interactions between remedial techniques will also need to be considered to ensure that the
overall objectives are achieved without one method compromising any others.
8.10.4 The Remediation Strategy should be incorporated into the Construction Environmental
Management Plan (CEMP) for the site.
8.10.5 Additional site investigation and detailed quantitative risk assessment together with laboratory
and/or site trials of mitigation measures will could still be required to define the final remediation
strategy. The Remediation Strategy will require regulatory approval before it is implemented on
site and sufficient time will need to be allowed in the programme for this to be achieved.
8.10.6 The Remediation Strategy will need to include an Implementation Plan defining in detail how the
mitigation measures will be implemented on site. This will include details of the methods to be
adopted and any measures to be implemented in parallel with the remedial works to ensure that
possible impacts are managed adequelty.
8.10.7 A Verification Plan will be required describing how the effectiveness of the mitigation measures
will be verified on site during the Works and any longer term verification measures that may be
necessary.
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8.10.8 A Monitoring Plan will be required. This will need to include monitoring during the
implementation of the mitigation measures, to confirm that there are no adverse impacts from
the remedial works themselves, and longer monitoring to measure the efficacy of the remedial
works.
8.10.9 An Action Plan will need to be associated with the Monitoring Plan defining actions that will be
taken if the monitoring indicates that any parameters are diverging from those anticipated in the
Remediation Strategy.
8.10.10 On completion of the remedial works a Verification Report will have to be prepared
demonstrating that the mitigation measures have been implemented and that the goals of the
strategy have been achieved. If long term monitoring is required as part of the process, for
example, associated with monitoring natural attenuation, then there may need to be a series of
Verification Reports at regular intervals throughout this process.
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9. MONITORING REQUIREMENTS
9.1.1 The following measures should be undertaken in order to assess risks during the construction
and operation of the Mersey Gateway. This will allow mitigation measures to be fine tuned once
in place if necessary.
9.1.2 Groundwater level monitoring and chemical testing should be continued in the run up to the
construction works, during construction and post-construction to monitor trends in groundwater
and assess whether the works are likely to have impacted on groundwater. It may be
appropriate to increase the frequency of monitoring nearer to and during the construction works.
9.1.3 It would be appropriate to undertake chemical testing of surface water courses as well as
making daily visual inspections when working close to such features during the remedial and
construction works to look for signs of possible contamination. The possibility of causing
contaminant migration through existing drains in some areas would need to be considered by
the Contractor.
9.1.4 Ground gas monitoring should be continued to assess whether additional protection measures
for foundations may be required.
9.1.5 Vapour, gas, dust and odour monitoring should be undertaken during the construction works to
ensure that workers are not exposed to contaminants and off-site fugitive emissions are not
being produced. Provision for dust and odour abatement will need to be included during the
construction works for excavations and stockpiled material.
9.1.6 Protocols for the Earthworks will need to be put in place by the Contractor in order to assess
suitability of material for re-use, dealing with areas of contamination, disposal and re-use of
waste and any areas of unexpected contamination.
9.1.7 Screening of arisings on and adjacent to the Catalyst Trade Park during construction works
should include radiological monitoring for health and safety and to assess the possible re-use or
disposal of arisings.
9.1.8 Additional monitoring may be undertaken by the Contractor, such as groundwater level
monitoring for detailed modelling or prior to undertaking excavations.
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10. SUMMARY
10.1 Introduction
10.1.1 An assessment of contaminated land has been undertaken for the Project area. The objective
of the assessment was to establish baseline conditions and assess the potential risks related to
the proposed development. Potential mitigation measures have been outlined where
appropriate.
10.1.2 The scope of works comprised the following:
a. Review of published information, archive sources and previous investigations
b. Intrusive site investigation
c. Soil and groundwater sampling
d. Chemical analysis of samples
e. Groundwater monitoring
f. Ground gas and vapour monitoring
g. Assessment of results against generic and site specific criteria
h. Development of a Conceptual Site Model defining source-pathway-receptor linkages
i. Qualitative risk assessment for Do Nothing, Construction and Operational stages
j. Identfication of mitigation measures during each stage of the Project
10.1.3 This section of the report summarises the information gathered for the study and the findings of
the risk assessment. The potential mitigation measures that have been identified are also
summarised together with a commentary on the issues relating to planning and policy.
10.2 Historical Information
10.2.1 The historical information obtained by Gifford shows evidence of widespread potentially
contaminating land uses in Widnes and, to a more limited extent, on the saltmarshes and Wigg
Island in Runcorn.
10.2.2 Former chemical works that have been identified in Widnes include the sites currently occupied
by Catalyst Trade Park in Area C and Gussion Transport and former Anglo Blackwells site in
Area B2. On the saltmarshes the site of a former chemical works has been identified in the
north west of Widnes Warth in Area D. The site of a further former chemical works has also
been identfied on Wigg Island in Area D immediately to the north of the Manchester Ship Canal.
10.2.3 The Project area also includes the eastern end of the former Wigg Island Landfill in Area D
where material tipped included alkali waste. Evidence of significant waste disposal was also
identified in Area A at St Michaels Golf Course in Widnes. Evidence of historical waste disposal
has also been identified in other parts of the project area from the updated Envirocheck Report,
in particular Ditton Junction (Area B1), the former Anglo Blackwells site, Gussion Transport and
S Evans & Sons scrapyard (Area B2) and northern part of the Thermphos site (Area C).
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10.3 UXO
10.3.1 The desk top threat assessment undertaken by BACTEC considered the risk from UXO to be
moderate in Area D on the saltmarshes and estuary, and low elsewhere. A detailed risk
assessment was prepared by BAE Systems on the moderate risk areas identified by BACTEC
for the proposed construction works. The results of this assessment identified a moderate
probability of encountering German air dropped UXO and a low to moderate probability of
encountering UXO of an anti-aircraft origin during the construction works in this part of the
project area. However, if UXO was found, the likelihood of initiating the device and causing an
explosion was considered substantially lower. No evidence of UXO was encountered during the
site investigations.
10.3.2 A former chemical weapons production facility has been identified at Randle Island in Runcorn
to the east of the Project area. This would have been located at the site of the existing Randle
Island Landfill. No evidence has been obtained that indicates the former chemical weapons
production facility at Randle Island is likely to have extended into the Project area.
10.4 Ground Conditions
10.4.1 The ground conditions encountered during the Phase 1 to 67 site investigations comprised
made ground, alluvium, glacial deposits and bedrock. The alluvial materials were associated
with the Estuary and the saltmarshes. Alluvium was also encountered underlying the made
ground in parts of Areas A to C in Widnes. Underlying the made ground and/or alluvium were
glacial deposits, these comprised predominately cohesive glacial clay with interbedded glacial
sands and gravels, which in turn were underlain by Sandstone bedrock. Mudstone bedrock was
encountered within the Runcorn area.
10.4.2 The made ground was highly variable in the Project area. There was widespread evidence of
„galligu‟, a chemical waste/by-product from the former alkali industry, from Area A at St Michaels
Golf Course to Area C at the Catalyst Trade Park. Waste from the alkali industry was also
encountered in localised areas in the north of Widnes Warth saltmarsh in Area D and the Wigg
Island Landfill in Area D.
10.4.3 Alluvial material associated with the River Mersey was located within the saltmarsh areas and
as recent materials (Runcorn Sands) within the Mersey Estuary in Area D. The alluvium on the
saltmarshes comprised cohesive sediment (clay or clay/silt) near surface overlying silty sand.
The alluvium in the Estuary was also a silty sand.
10.4.4 Alluvium was also encountered in exploratory holes to the north of St Helens Canal extending
northwards to the golf course across Areas A to C. The extent of alluvial material in this area is
in broad agreement with that shown on the BGS drift geology map.
10.4.5 Glacial deposits were encountered across the majority of the study area. North of the St.
Helens Canal and south of the Manchester Ship Canal, where the alluvium was absent, the
glacial materials were found immediately underlying the made ground. Closer to the Mersey
Estuary, the glacial material was encountered underlying the alluvial materials. The glacial
deposits typically comprised the following:
a. Firm and stiff clay with varying amounts of granular constituents;
b. Medium dense to very dense silt; and
c. Medium dense to very dense sand and/or gravel.
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10.4.6 Areas where glacial materials were noted to be absent in the Project area or only present
intermittently were as follows:
a. Wigg Island (bedrock at relatively high elevation and directly underlying alluvium); and
b. Runcorn Sands – across the Estuary (alluvium directly onto bedrock).
10.4.7 The near surface bedrock in the Project area typically comprised very weak to moderately weak
red sandstone with evidence of weathering at the interface between the drift deposits and solid
strata. The weathered rock was generally encountered within the top 3m of bedrock, although it
was encountered to a maximum thickness of 15.9m in the north of Area E in Runcorn.
Mudstone was encountered underlying the glacial deposits to the south of the estuary in Area
G1.
10.4.8 The bedrock was typically encountered at shallower depths (<20 m bgl) south of the River
Mersey and at greater depths to the north (between 20m and >40 m bgl). Outcrops of rock
were noted to the west of the Project area in the Estuary at West Bank in Widnes and the
southern bank of the Manchester Ship Canal in Runcorn.
10.4.9 The boreholes on the Widnes Warth saltmarsh in Area D indicate that the depth to rockhead
increases from the edge of the saltmarsh northwards to the St Helens Canal and then continues
to increase to the north into the Catalyst Trade Park in Area C. The base of the glacial deposits
was not encountered at a depth of 53m bgl at the Ditton Junction in Area B1. Historical
boreholes in Area C proved the rock at depths of between 40m and 48m bgl. This increase in
depth to bedrock in Areas A to C is considered to be related to the buried glacial channel shown
on published information.
10.5 Surface Water
10.5.1 A number of surface water features have been identified within the Project area; River Mersey,
St Helens Canal, Stewards Brook and Bowers Brook in Widnes, and the Manchester Ship
Canal, Bridgwater Canal and former Latchford Canal spur in Runcorn. The largest surface
water feature is the River Mersey.
10.5.2 Available information indicates the St Helens Canal in the north of Area D was constructed on
embankment onto the cohesive alluvium (shallow saltmarsh deposits). Given the age of this
part of the Canal it is likely that some form of lining, such as puddle clay, would have been used
on the base and sides of the Canal. Therefore, the St Helens Canal may not be in continuity
with shallow groundwater.
10.5.3 The available information indicates the majority of Bowers Brook in Area C is located in a culvert
along the southern edge of Area C. This culvert is brick lined adjacent to the Catalyst Trade
Park. This is thought to have been constructed onto or within the fine grained alluvial deposits.
Information also indicates that contaminated silt is likely to be present within Bowers Brook.
This water course is considered to be in hydraulic connection with shallow groundwater which
chemical testing shows is contaminated in Area C. Testing on samples of water and sediment
obtained from drains during previous investigations at Catalyst Trade Park showed metals,
solvents and radiological contaminants to be present, with solvents and radiological
contaminants also having been encountered in Bowers Brook.
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10.5.4 Stewards Brook flows in a southerly direction through St Michaels Golf Course, although it is
located outside of the Project area in Area A. Information obtained from the Council indicates
the Brook was is being affected by contamination from the northern part of the golf course,
although in the Project area itself the Brook has been lined to prevent contaminants migrating
into the watercourse. Remediation on the northern part of the golf course was completed in
2010. This involved re-capping the site remove pathways to site users and introducing a
leachate collection to improve water quality in the Brook.
10.5.5 The Manchester Ship Canal was cut through glacial deposits into the Sherwood Sandstone.
Groundwater in bedrock is considered to be in hydraulic continuity with the Manchester Ship
Canal. The spur to the former Latchford Canal on Astmoor saltmarsh has also been impacted
by contamination arising from the former Wigg East Works. Remedial measures have been
implemented for the Latchford Canal including removing sediments and the construction of a
leachate treatment system.
10.5.6 Information obtained from contained in the ES indicates the Bridgewater Canal could be lined.
However, information provided subsequently by the Manchester Ship Canal Company in May
2008 states the Bridgewater Canal was not lined. A review of the logs from exploratory holes
located immediately adjacent to the canal indicates the base of the Bridgewater Canal is likely
to be situated in glacial clay. The presence of glacial clay would reduce hydraulic continuity with
groundwater.
10.5.7 A DQRA has been undertaken for controlled waters for contaminants in groundwater at Gussion
Transport (Area B2) and Catalyst Trade Park (Area C) where free product has been identified.
The DQRA established that contaminants arising from LNAPL at Gussion Transport did not
represent a risk to surface water at Marsh Brook 350m to the southwest from off-site migration.
In Area C, the contaminants arising from DNAPL in made ground and alluvium at Catalyst Trade
Park were not considered to represent a risk to the River Mersey. However, a risk was
identified from contaminants in the made ground at Catalyst Trade Park to Bowers Brook.
10.5.8 The outputs from the DQRA have been agreed with the EA and this has informed the
requirements for advanced works remediation.
10.6 Groundwater
10.6.1 The northern and north western parts of the scheme in Widnes (Area A to C) are located in a
source protection zone which is associated with the abstraction of groundwater for public
drinking water. This relates to the sandstone bedrock at depth and extends to the north of the
Project area.
10.6.2 Shallow groundwater has been identified in the made ground, alluvium and glacial deposits.
Groundwater is also present in the sandstone bedrock, this is considered to be separated from
the shallow groundwater where glacial clay is present. Groundwater flow in the bedrock
appears to follow the rockhead profile towards the buried glacial valley identified in Widnes.
Groundwater flow in the alluvial deposits on both sides of the estuary is towards the River
Mersey. The difference in groundwater flow directions indicates separate groundwater bodies.
10.6.3 Groundwater in the bedrock is considered to be in continuity with the Mersey Estuary,
particularly within the Mersey Estuary where estuarine alluvium lies directly over the Sherwood
Sandstone. Evidence of saline intrusion is apparent from the conductivity and chloride results
for groundwater which show increased salinity closer to the estuary.
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10.6.4 Groundwater testing results obtained from the EA indicate that chlorinated solvents are present
in the bedrock in the wider Runcorn and Widnes area which relate to historical industrial activity.
None of the monitoring results relate to the Project area. The data shows the concentration of
these solvents to be less than previously observed, although there is still some impact within the
bedrock south of Area A.
10.7 Soil and Sediment Contamination
10.7.1 The guidance relating to assessing risks to human health and buried water pipes have been
updated since the Orders ES. The soil testing results have been compared against this
updated guidance and this has resulted in a number of changes to the exceedances identified.
10.7.2 Concentrations of soil contaminants have been obtained from the made ground and alluvium
which exceed the assessment criteria derived for a commercial/industrial land use in Area A to
C in Widnes. Exceedances of the GAC for commercial/industrial land use was highly localised
in Runcorn (lead in BH127).
10.7.3 Widespread exceedances of the assessment criteria derived for construction workers were
encountered in the made ground and alluvium in Widnes and the cohesive alluvium on the
saltmarshes. Only localised exceedances of assessment criteria for construction workers were
encountered in Runcorn, these were associated with made ground and metals in sediments
from Astmoor Saltmarsh.
10.7.4 Fragments of asbestos were encountered in isolated areas in Area A at St Michaels Golf
Course in Widnes, in Area F at the Bridgewater Junction and Area G1 at the Lodge Lane
Junction in Runcorn.
10.7.5 Elevated concentrations of potentially phytotoxic metals (namely copper, nickel, zinc) were
identified in the made ground in Widnes and at one location in Runcorn.
10.7.6 Elevated concentrations of sulphate have been identified requiring protection measures for
buried concrete. Comparison of the soil test results from Area A to C showed exceedances of
the threshold values for plastic water supply pipes. No assessment of the results from Runcorn
for plastic water supply pipes was undertaken as no buildings are proposed for this part of the
Project area. In Runcorn, localised exceedances of the threshold values for water pipes were
obtained for petroleum hydrocarbons and/or SVOCs in Area E, F and G.
10.7.7 The sediments from the saltmarshes and estuary were compared to the interim sediment quality
guidelines to assess risks to aquatic fauna. Exceedances were obtained within the estuary for
metals/metalloids and PAHs, and from the saltmarshes for metals/metalloids, PAHs, and
ammonia. Locally elevated concentrations of pesticides were present in shallow sediments on
Widnes Warth. Concentrations of contaminants within the shallow fine grained saltmarsh
sediments were higher than those within the underlying granular alluvium or estuarine intertidal
deposits.
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10.8 Groundwater Contamination
10.8.1 There have been a number of changes to the EQS for water since the Orders ES. The soil
leachate and groundwater testing results have been compared against this updated guidance
and this has resulted in a number of changes to the exceedances identified. In addition, further
groundwater sampling has also been undertaken and these results have also been included in
the groundwater assessment.
10.8.2 The results obtained show widespread contamination of groundwater by metals/metalloids at
shallow depth. These contaminants are typically encountered at highest concentrations to the
north of the Mersey estuary in Widnes and associated with shallow groundwater in the made
ground and alluvium. The concentrations of metals/metalloids in the Sherwood Sandstone
aquifer were lower than in the shallow deposits.
10.8.3 Widespread evidence for groundwater contamination by sulphate and ammonia/ammonium was
obtained. Concentrations were generally higher in Widnes than Runcorn.
10.8.4 The distribution of organic contaminants is more complex. The area of shallow groundwater
beneath the proposed route alignment in Widnes north of the St Helens Canal has been
impacted to a varying degree by organic contaminants. These include dissolved phase organic
hydrocarbons and both light and dense free phase product.
10.8.5 The highest concentrations of petroleum hydrocarbons in the shallow groundwater were
identified in Area B2 at Gussion Transport and Area C at the Catalyst Trade Park.
10.8.6 Elevated concentrations of petroleum hydrocarbons and BTEX were encountered in
groundwater from the made ground at Gussion Transport in Area B2. LNAPL as floating
product was identified at four locations in the made ground on the Gussion Transport site during
subsequent groundwater monitoring.
10.8.7 Significantly elevated concentrations of VOCs including chlorinated solvents were noted in
groundwater from the made ground, alluvium and upper glacial sands on and adjacent to the
Catalyst Trade Park in Area C and on Spike Island in Area D. Elevated concentrations of
solvents were also encountered in groundwater from the made ground at Gussion Transport
(Area B2) and at St Michael‟s Golf Course (Area A) in the made ground and alluvium.
10.8.8 The concentrations of chlorinated solvents at Catalyst Trade Park are indicative of free phase
contamination being present as a dense non-aqueous phase liquid (DNAPL) in groundwater
within the made ground, alluvium and upper glacial sands. The occurrence of possible free
phase DNAPL contamination in the upper glacial sand was limited to one borehole at the south
of Catalyst Trade Park Thermphos, although significantly elevated concentrations (but not
considered indicative of possible DNAPL) were also obtained from another well installed into the
upper glacial sands in this area. Subsequent sampling did not indicate that DNAPL was likely to
present within the monitoring wells themselves.
10.8.9 Organochlorine pesticides were encountered on and adjacent to the Catalyst Trade Park in
Area C in groundwater from the made ground, alluvial and glacial deposits. Acid herbicides
were also detected within the alluvium at Catalyst Trade Park.
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10.8.10 A localised exceedance for naphthalene was recorded in groundwater from the alluvium
underlying the Wigg Island Landfill in Area D and sandstone on one occasion in bedrock in Area
G. Localised exceedances were obtained for PAHs in Area A to D in Widnes and Area F and G
in Runcorn.No other evidence of organic contaminants was found in groundwater samples
obtained from Area E to G in Runcorn
10.9 Soil Leachate Contamination
10.9.1 The distribution of contaminants identified in soil leachate showed similar trends to the
groundwater contamination identified.
10.10 Ground Gas and Volatile Vapours
10.10.1 Elevated concentrations of ground gas and vapours were recorded in the area of the proposed
toll plazas and associated office buildings. Elevated levels of ground gas and vapours were
also recorded in proposed areas of excavation in Widnes, on the saltmarshes and on Wigg
Island Landfill. Elevated results were noted during the screening of soil arisings for the
presence of VOCs, the highest concentrations were obtained from Area C in Thermphos and
Catalyst Trade Park.
10.11 Risk Assessment
10.11.1 A qualitative risk assessment was prepared on the basis of a conceptual site model which is
included in Section 7 and summarised on Drawing No. MG_REP_EIA_009/093 to 096. The
figures show Source-Pathway–Receptor linkages and these are referenced to the risk
assessment tables.
10.11.2 The conceptual site model was based on the following information:
a. Current land use;
b. Historical land uses;
c. Ground conditions;
d. Hydrogeology and water abstractions;
e. Contaminants in soil, leachate and groundwater;
f. Ground gas and volatile vapours;
g. UXO and radiation; and
h. Construction proposals.
10.11.3 The risk assessment was undertaken for the Do-nothing, Construction and Operational Stages
to identify where significant pollutant linkages might exist or could be introduced during the
project. The risk assessment was undertaken on the basis that no mitigation measures were
present.
10.11.4 Potentially significant risks have been identified for the Do Nothing, Construction and
Operational Stages. At this stage it has been assumed that for the Do Nothing scenario
mitigation measures would not be introduced as the Project would not go ahead. On this basis
the potentially significant risks in the Construction and Operational stages have been assessed
as follows:
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Construction Stage
Widnes
a. Human health with regard to ingestion, inhalation or dermal contact by construction/
ground workers, site visitors and trespassers;
b. Human health with regard to ingestion, inhalation or dermal contact by local residents
c. Migration of ground gas and volatile vapours into excavations;
d. Leaching and vertical migration of contaminants between groundwater horizons in the
shallow groundwater including where foundations are removed;
e. Transfer of LNAPL and DNAPL to groundwater and off-site migration of free product;
f. Off-site migration of contaminants in shallow groundwater;
g. Vertical migration of contaminants where existing foundations are removed;
h. Vertical migration of contaminants along disused water wells;
i. Migration along buried drains or services;
j. Migration of contaminants in groundwater to Stewards Brook and Bowers Brook; and
k. Migration of contaminants through run-off into surface water courses;
Runcorn
a. Human health with regard to ingestion, inhalation or dermal contact by construction/
ground workers, site visitors and trespassers at Wigg Island;
b. Migration of ground gas and volatile vapours into excavations;
c. Leaching and vertical migration of contaminants between made ground and shallow
groundwater at Wigg Island;
d. Migration of contaminanted groundwater to bedrock beneath Wigg Island;
e. Off-site migration of contaminated groundwater beneath Wigg Island;
f. Migration of contaminants through run-off into surface water courses; and
g. Vertical migration of contaminants due to installation of piled foundations;
Operational Stage
Widnes
a. Human health with regard to ingestion, inhalation or dermal contact by service
maintenance workers;
b. Migration of ground gas and volatile vapours into buildings on-site or confined spaces
including excavations.
c. Human health from contaminated water supplies in new buried services;
d. Leaching and vertical migration of contaminants between groundwater horizons in the
shallow groundwater;
e. Potential for vertical migration of DNAPLs towards the major aquifer;
f. Transfer of LNAPL and DNAPL to groundwater and off-site migration of free product;
g. Off-site migration of contaminants in shallow groundwater;
h. Vertical migration of contaminants where existing foundations are removed;
i. Additional risk of off-site migration of shallow groundwater or gas due to placing
embankments;
j. Migration along buried drains or services; and
k. Migration of contaminants in groundwater to Stewards Brook and Bowers Brook;
Runcorn
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a. Human health with regard to ingestion, inhalation or dermal contact by service
maintenance workers;
b. Leaching and vertical migration of contaminants between groundwater horizons in the
shallow groundwater at Wigg Island;
c. Vertical migration of contaminated groundwater to bedrock at Wigg Island;
d. Off-site migration of contaminated groundwater beneath Wigg Island; and
e. Migration of ground gas and volatile vapours for health of people entering excavations
at Wigg Island.
10.11.5 On the basis of the modifications incorporated in the Updated Reference Design it is considered
that the potential pathways and receptors remain appropriate. No new potential sources of
contamination, pathways or receptors have been identified. The receptor workers in toll booths
and offices will not be present in the Project including the Proposals and there are changes to
the Project area for Area A. A number of options are available for the construction works in
Area C. The results from the DQRA for controlled waters have also been considered. These
changes have been included in the risk and effect assessment and mitigation measures
identified where necessary.
10.12 Mitigation Measures
10.12.1 A range of possible mitigation measures have been identified for the risks identified during the
Construction and Operational Stages. Consideration has also been given as to how mitigation
could be introduced during the design phase as well.
10.12.2 Alternative proposals may be considered by any future Project Company Concessionaire.
However, an assessment of the possible risks and mitigation associated with alternative
proposals would need to be undertaken by the Concessionaire and the alternative measures
approved by the regulators.
Detailed Design Stage
10.12.3 The following mitigation measures will need to be considered during the detailed design stage
for the potentially significant risks identified:
a. Construction Environmental Management Plan (CEMP);
b. Additional site investigation and detailed risk assessment associated with the setting of
remedial targets and detailed evaluation of remedial options;
c. Design of specific remediation measures for soil and groundwater;
d. Minimisation of intrusive works;
e. Design measures to protect surface water features from contamination;
f. Design of measures to prevent vertical migration of contaminants
g. Locating the former works water wells;
h. Design measures for contaminants remaining beneath sections of the route to be
covered;
i. Design measures to take into account recontamination of treated areas from outside of
Project area;
j. Migration of contaminants outside the Project area;
k. Design of protection measures for buried services;
l. Drainage design; and
m. Design of protection measures for ground gas and vapours such as for buildings and
possibly confined spaces.
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10.12.4 In addition to the mitigation measures outlined above, the following will also need to be
considered:
a. Design of specific measures to prevent migration of contaminants following
embankment or structural loading;
b. Further investigation to delineate areas of radioactive contamination if it is to be
disturbed as part of the construction works;
c. Prior to commencing work on site an Implementation Plan and a Verification Plan will be
required to describe how the remedial work will be undertaken and how the work will be
verified against the remedial strategy;
d. A Monitoring plan will need to be put in place as part of the design to define how the
remedial works will be monitored to ensure that there are no adverse impacts from the
remedial works themselves;
e. Design of landscaping and capping measures; and
f. Obtaining regulatory approval.
Construction Stage
10.12.5 The following mitigation measures are likely to be required during the construction stage for the
potentially significant risks identified:
a. Implementation of a Construction Environmental Management Plan (CEMP);
b. Soil and groundwater remediation works;
c. LNAPL and DNAPL remediation works and management of LNAPL where encountered
in excavations;
d. Implementation of measures to prevent recontamination of treated areas;
e. Implementation of measures to prevent migration of contaminants outside the Project
area;
f. Minimisation of intrusive works;
g. Measures to mitigate exposure to contaminated soil and water including site security,
dust suppression, control of odours and vapours, and site hygiene and personal
protective equipment for construction workers;
h. Inclusion of information on contamination within the site health and safety file;
i. Measures to prevent vertical migration of contaminants including where old foundations
are removed;
j. Grouting of former works water wells;
k. Implement protection measures for buried pipes;
l. Implement gas and vapour protection;
m. Aggressive ground conditions;
n. Implement suitable capping for areas of landscaping;
o. Protocols to deal with unexpected contamination;
p. Protocols to deal with accidental spillages or releases;
q. Protection or removal of existing drains;
r. Protection of surface water features;
s. Measures to address radioactive contaminated land if it is to be disturbed.
t. Mitigation measures for radioactive contamination within drains at Catalyst Trade Park
which may require removal, grouting or sealing to prevent migration from the Project
area;
u. Disposal of radioactive contaminated material to a suitably licensed disposal facility; and
v. Monitoring for unexploded ordnance.
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10.12.6 In addition to the mitigation measures outlined above, the following will also need to be
considered:
a. Measures to control the temporary storage of contaminated arisings prior to re-use or
off-site disposal;
b. Implementation of measures for contaminants remaining beneath sections of the route
to be covered;
c. Implementation of specific measures to prevent migration of contaminants following
embankment or structural loading;
d. Implement suitable protection measures for landscaped areas;
e. Protocols to deal with unexpected contamination;
f. Removal and grouting of recently installed groundwater monitoring wells in Widnes and
Runcorn;
g. Implementation of the Monitoring Plan during the construction phase to ensure that the
remedial works are not having an adverse impact and, where necessary, assess the
effectiveness of any mitigation measures;
h. Appropriate licensing and authorisations for specialist remediation works.
i. Appropriate authorisations and/or licensing for re-use and disposal of contaminated
materials and pre-treatment of material prior to disposal; and
j. Implementation of the Verification Plan and production of a Verification Report following
completion of any remedial works.
Operational Stage
10.12.7 The following mitigation measures are likely to be required during the operational stage:
a. Mitigation measures for maintenance workers who could come into contact with soil or
water contamination or ground gas and vapours;
b. Monitoring to ensure effectiveness of mitigation or remediation measures;
c. Maintenance of any long term soil and/or groundwater remediation system;
d. Action plans should monitoring indicate remediation or mitigation are not performing as
anticipated; and
e. Completion of Verification Report as required. This should be submitted to the
regulators for approval as appropriate and kept with the site Health & Safety file.
Existing Risks Associated with the Project
10.12.8 As previously noted, there are existing impacts relating to contaminated land that have been
identified in the do nothing scenario and these will continue regardless of whether the Project is
constructed or not. These principally relate to contamination of the groundwater due to past
industrial activities in Areas A, B, C and part of Area D (Wigg Island landfill) together with
sources of LNAPL (in Area B) and DNAPL (in Area C). It is a benefit of the Project that it will
provide for at least some reduction of the risks identified for the do-nothing scenario. It has
been agreed with the EA that remediation of LNAPL to prevent off-site migration to surface
water would not be required.
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10.12.9 The presence of groundwater contamination will have to be considered as part of the planning
process especially as the Project will cover areas of the site and might affect the ability to
remediate such areas in the future. Agreement has been obtained from the EA that other than
treatment of DNAPL, remediation of groundwater would not be required to prevent off-site
migration. Remediation of the DNAPL is proposed as advanced works comprising source
reduction using best practicable techniques for a fixed period. This approach has been agreed
by the EA. However, contaminants would still remain in the Project area that may need to be
addressed during the construction works, in particular where they are encountered during
excavations.
10.12.10 The Project is a long, linear feature that cuts across exisiting site boundaries and any
remediation proposed for groundwater would need to be considered in the context of the wider
contaminated land and groundwater issues in Widnes and on Wigg Island. Potential remedial
measures for groundwater beneath the footprint of the scheme have been outlined in the
preliminary remedial options appraisal and this includes various groundwater remediation
techniques together with options for cut off walls (with and without reactive barriers) and the
option of allowing natural attenuation to continue. Any proposals will need to be practical,
effective, durable, provide a benefit and not result in adverse environmental impacts. A key
issue in this respect is that it will be important to ensure that any remediated areas are not re-
contaminated by neighbouring areas of contamination.
10.12.11 Consultations with the EA indicate a preference not to have extensive cut off structures
across the Project area, as they could interfere with overall groundwater flows and the
implementation of more widespread groundwater remediation in the future. It is also
questionable whether remediation beneath the footprint of the Project in isolation would offer
any substantial benefit without measures to prevent recontamination in the future. The final
approach that is adopted will need to be part of an overall remediation strategy that takes
account of the Project wide contaminated land and groundwater issues in Widnes and at Wigg
Island. This would need to be developed and approved by the regulators from the preliminary
options appraisal.
Potential Risks Arising from the Project
10.12.12 The majority of the potentially significant risks associated with the Project arise during the
construction stage and mitigation measures have been proposed for these. Many of these
mitigation measures will continue or continue to have an effect into the operation phase.
Further significant risks have been noted during the operation phase and mitigation measures
have been outlined to address these.
10.12.13 The overall approach to mitigation for site users is based on the premise that wherever
possible contaminated soils will remain in place beneath the road and that the road construction
and landscaping will act as a barrier between human receptors and contaminants. The
proposed end use is not a sensitive one in terms of human health and on this basis it is
considered that widespread removal and/or remediation of contaminated soils would not be an
appropriate means of managing this risk. In some cases, the construction of the road will
provide benefits as areas of contamination will be covered and risks to some receptors will be
reduced when compared to the current situation. The fact that substantial parts of the
development in Widnes would be elevated on embankment will further assist in reducing these
risks.
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10.12.14 The pile types already identified for the scheme are not considered likely to result in new
pathways or cause contaminants to move with the exception of Wigg Island. On this basis,
there are no effects that require mitigation relating to the installation of piles within the Project
area, including the options being considered at Victoria Road, Widnes Loops and St Helens
Canal. However, for the options being considered it would still be necessary to consider
whether other impacts from contamination could exist, for example the use of embankments
would provide greater coverage of existing soils in the construction area than viaducts requiring
less additional areas of landscaping.
10.12.15 Specific mitigation measures will be required for Wigg Island such as the use of specialist
piles to minimise the potential for contaminant migration along the piles. Alternatively, it would
be possible to excavate the landfill beneath the footprint of the pier, and have the piles/pile caps
founded within natural soils only. This would remove any risk of vertical migration of landfill
leachate along the piles. The waste material from the landfill could either be sent off-site for
disposal or re-interred as part of the subsequent landfill re-instatement works. This would be
subject to EA approval, and an authorisation or possibly an exemption from the Environmental
Permitting Regulations is likely to be required.
10.12.16 At Wigg Island, the need to remove material around the piers will have a greater
environmental impact than installing piles through the landfill assuming that the risk of
contaminant migration is mitigated. There are wider issues of groundwater contamination in this
area, the construction proposals should not interfere with the ability to remediate these in the
future.
Remediation Strategy
10.12.17 The remediation strategy would be incorporated into the COPE for the site. The
Remediation Stragegy would be secured by planning condition that would require the strategy
to be approved the by LPA and EA prior to commencing work. The remediation strategy
prepared by the Project Company would need to take into account the advanced works
10.12.18 The mitigation measures specifically associated with land affected by contamination must
ensure that significant pollutant linkages are addressed by either removing or treating the
source, breaking or removing the pathway or protecting or removing the receptor. It should be
noted that this standard would require that the possibility of off site migration of contaminants
from the Project area is taken into account even where the contaminants are not potentially
impacted by the scheme but lie within the footprint of the Project. Other mitigation measures
will need to comply with relevant guidance and legislation, in particular Health and Safety
legislation for the protection of construction workers.
10.12.19 A detailed evaluation of the remedial options will be required to develop the detailed
remediation strategy. However, mitigation measures for land affected by contamination should
be the Best Practicable Techniques taking account of the following factors:
a. Practicability including technical constraints, site constraints and regulatory constraints
b. Effectiveness
c. Durability
d. Cost
e. Benefit
f. Adverse environmental impacts
g. Sustainability
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10.12.20 Time constraints can be a factor in the practicability of the techniques. However, this should
be taken into account in the project programme rather than be used to define the remedial
measures. The interactions between remedial techniques will also need to be considered to
ensure the overall objectives are achieved without one method compromising any others.
10.12.21 In the project area there are instances where the Best Practicable Techniques may not in all
cases be capable of fully achieving the tests outlined above and will not therefore fully remedy
the effects that have been observed. This is likely to apply to the presence of Dense Non
Aqueous Phase Liquids on and in the vicinity of Catalyst Trade Park (Area C) where it may not
be possible to achieve risk derived remedial targets. In this situation the guidance provided by
DEFRA Circular 01/2006 notes that the measures should be those that mitigate as far as
practicable.
10.12.22 The information obtained for the Project area indicates there are a broad range of
contaminated land issues that will require mitigation. For users of the proposed crossing the
risks associated with land affected by contamination are not considered to be significant.
However, other issues do exist that will need to be taken into account in the construction of the
crossing. A key issue in this respect is the potential impact on groundwater and the possibility
of groundwater migration. In many cases the need to address the impacts on groundwater will
ultimately drive the remediation strategy.
10.12.23 The remediation strategy should be incorporated into the Construction Environmental
Management Plan (CEMP) for the site. The options for the construction works and remediation
strategy prepared by the Project company will need to take into the advanced works
remediation works.
10.13 Policies and Plans
10.13.1 In order to comply with wider policies and plans it will be necessary to ensure that the standard
of any mitigation for land affected by contamination meets the following tests.
10.13.2 The principal tests are those outlined in Planning Policy Statement 23 and Part IIA of the
Environmental Protection Act 1990, namely:
a. The land is “suitable for use” and unacceptable risks have been addressed
b. The land is not capable of being determined as statutory contaminated land
c. The effects of any significant harm, harm attributable to radioactivity or pollution of
controlled waters has been remedied
10.13.3 The requirements of the Water Framework Directive and the Water Resources Act will need to
be taken into account, particularly the fact that in the future the Water Framework Directive will
requirement that water is brought to specific standards. Mitigation measures must take this into
account and ensure, as far as practicable, that this objective is not jeopardised. The
requirement under the Groundwater Directive to control List 1 and List 2 substances will also
need to be taken into account in the design of mitigation measures.
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10.13.4 Local and regional policies are largely governed the principles outlined above; in particular the
mitigation measures will need to address the following policies:
Regional Policy
RPG 13 Ensuring High Environmental Quality - Policy EQ1 Tackling Derelict Land and
Contamination Issues
10.13.5 This policy states “Local Authorities should work in partnership with the North West Regional
Assembly (NWRA), North West Development Agency (NWDA) and the EA To identify and
prioritise a major programme of schemes for the restoration and remediation of derelict and
contaminated sites to support urban renaissance and reduce sources of pollution and
environmental impact in the North West.”
RPG 13 Ensuring High Environmental Quality - Policy EQ3 Water Quality
10.13.6 This policy states that “measures to improve and sustain the quality of the Region‟s rivers,
canals, lakes and sea will be promoted. Local authorities and other regional agencies should
co-ordinate their strategies and programmes to:
a. maintain or improve the quality of groundwater, surface or coastal waters;
b. avoid development that poses an unacceptable risk to the quality of groundwater,
surface or coastal water;
c. ensure that adequate foul and surface water provision and infrastructure is available to
serve new development and minimise the environmental impact of discharges;
d. ensure that adequate pollution control measures to reduce the risks of water pollution
are incorporated into new developments;
e. discourage the proliferation of private sewage disposal facilities;
f. locate development in locations where the necessary sewerage infrastructure will be
available or can be provided at an affordable cost and without environmental harm;
g. discourage diffuse pollution of water from agriculture and from landfill sites; and
h. ensure that the construction of roads and other transport infrastructure does not
unnecessarily add to diffuse pollution.”
10.13.7 Policy EQ3 also considers that emphasis should be placed on protecting the quality of
groundwater resources as, once contaminated, they can be difficult or even impossible to
remediate. This text has been removed as RPG13 no longer exists.
10.13.8 The Regional Spatial Strategy (RSS) for North West England was prepared by the Government Office for the North West in 2008 and provides a framework for development and investment in the region. It establishes a broad vision for the region and its sub-regions, priorities for growth and regeneration, and policies to achieve sustainable development across a wide range of topics from jobs, housing and transport to climate change, waste and energy. The RSS is part of the statutory development plan for every local authority in the North West.
10.13.9 The Government intends to abolish the RSS under the Decentralisation and Localism Act. Until this is enacted the RSS remains part of the statutory development plan.
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10.13.10 Policy DP7 relates to Promote Environmental Quality which states that environmental quality
(including air, coastal and inland waters) should be protected and enhanced. This includes the following:
a. Reclaiming derelict land and remediaton contaminate land for end-uses to improve the
image of the region and use if land resources efficiently
b. Maximising opportunities for the regeneration of derelict and dilapidated areas
Local Policy
Halton Borough Council‟s Contaminated Land Inspection Strategy
10.13.11 The Council‟s contaminated land inspection strategy has identified a number of sites along
the proposed route, and potentially extending outside the Project area as potentially
contaminated. The locations of these sites are consistent with the findings of the study and no
new sites have been identified.
Unitary Development Plan
10.13.12 The following policies relating to contamination from the UDP have been saved:
PR6 Land Quality
10.13.13 This policy states that “Development will not be permitted if it is likely to cause contamination
of the soil or sub-soil on a development site or on surrounding land uses as a result of pollution.
This includes consideration of:
a. The unacceptable effects of deposits and emissions
b. Whether development, through its potential to pollute, is likely to have a serious impact
upon investment confidence.
c. The risk of damage to health”
10.13.14 The justification provided for PR6 is that „it is essential to avoid the possibility of new land
uses which may themselves be a future source of land contamination‟.
PR7 Development Near to Established Sources of Pollution:
10.13.15 This policy states that “Development near to existing sources of pollution will not be
permitted if it is likely that those existing sources of pollution will have an unacceptable effect on
the proposed development and it is considered to be in the public interest that the interests of
the existing sources of pollution should prevail over those of the proposed development.
Exceptions may be permitted where the applicant submits satisfactory proposals to substantially
mitigate the effects of existing sources of pollution on the development proposal.”
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PR13 Vacant and Derelict Land:
10.13.16 This policy states that “Development and reclamation of derelict and vacant land will not be
permitted unless all of the following criteria can be satisfied.
a. Reclamation/decontamination works are carried out to ensure the safety and health of
people and the environment on and around the land.
b. The proposal is a suitable after use of the site.
c. Any proposal complies with other relevant policies within the Plan including urban
regeneration initiatives by the Council.”
10.13.17 Information posted on HBC‟s website on 4th April 2008 indicates that Policy PR13 expired
after 6th April 2008. This text has been removed as this policy has not been saved. However, in
terms of the implications of removing Policy RP13, the requirements relating to ensuring the
safety and health of people and the environment from contamination are included in PPS23 and
Part IIA. Therefore, these have still been considered as part of this assessment.
PR14 Contaminated Land
10.13.18 This policy states that “before determining any planning applications for development on or
adjacent to land which is known or suspected to be contaminated, the applicant will be required
to satisfy all of the following:
a. Submit details to assess the nature and degree of contamination (type, degree and
extent of contamination).
b. Identify remedial measures required to deal with any hazard to safeguard future
development and neighbouring land uses.
c. Submit details of a programme of implementation for the roll out and completion of
mitigation measures to be agreed with the Council.”
10.13.19 The UDP states that it is “therefore necessary to assess any risks and identify remediation
measures to make the land developable or to reduce harm to the existing environment, and so
that new receptors and pathways are not introduced.”
10.13.20 The UDP also states “The Council will require that the implementation of mitigation
measures is enforceable through either planning conditions or by the forms of planning
obligations.”
PR15 Groundwater
10.13.21 This policy states that “Proposals that are likely to lead to an adverse impact on groundwater
resources in terms of their quantity, quality and ecological features they support will not be
permitted.”
10.13.22 The justification for PR15 is that “there are many developments that have the potential to
pose a direct or indirect threat to groundwater quality‟. PR15 states that „many of the types of
development likely to pose a risk to groundwater will fall under the requirements of the Town
and Country Planning (Environmental Impact Assessment) Regulations 1999. Where relevant,
environmental statements will fully address the potential impacts of any proposal upon the
groundwater environment. Wherever groundwater is vulnerable to land use activities the site-
specific considerations of both the geology and proposed operation controls must be considered
at the planning stage to ensure adequate protection.”
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10.13.23 The justification also states that “within the boundary of Halton a single major aquifer
underlies approximately two thirds of the area [Borough]. The groundwater is extensively
exploited for public and industrial supply and past over abstraction has led to saline intrusion
from the Mersey Estuary.”
10.14 Concluding Comments
10.14.1 On the basis of the assessment undertaken it is considered that meeting the overriding tests
from Part IIA and Planning Policy Statement 23 will also meet many of the regional and local
policies.
10.14.2 The test of “suitable for use” can be met as there are few risks to site users associated with the
proposed development. Measures hav e been identified to mitigate the risks that have been
identified in this case.
10.14.3 Consideration will need to be given to mitigation of With regards to existing impacts, i.e. those
effects that already exist and are not caused by the project and, in particular, groundwater
contamination it is considered that the project would not increase the significance of the risks
following the implemention of mitigation. Agreement has been obtained from the EA that other
than treatment of DNAPL in Area C, remediation of groundwater would not be required to
prevent off-site migration. Remediation of DNAPL is proposed as part of the advanced works.
However, contaminants would still remain and under Part IIA consideration may still need to be
given to remediation of such issues in order to meet the requirement that the site cannot be
considered as statutory contaminated land and to ensure potential effects to controlled waters
are managed. This would need to be addressed as part of an overall remediation strategy to
provide practical, effective and durable remedial measures within the context of the wider
contamination issues in Widnes and at Wigg Island.
10.14.4 Depending on the approach that is adopted to the mitigation of existing issues, residual impacts
may could still remain during the Construction and Operation Stages of the Project and these
could be significant. This is because it may not be technically possible or cost effective to fully
mitigate all of the issues relating to the contamination of groundwater identified in Area A, B, C
and D (Wigg Island).
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