Kier Construction Desk Study Report

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Kier Construction

Desk Study Report

For

Adult Day Care Centre, Queensferry,

Deeside, Flintshire

October 2017

REPORT NO: 17KCN001/DS

� Desk Studies and Site Walkovers � Intrusive Contaminated Land Investigations � Geotechnical Appraisals and Ground Investigations � Landfill Gas Assessments and Remedial Design � Remediation Design and Implementation � Remediation Project Management and Supervision � Site Abnormal Assessments (Foundations and Contaminated Land)

© Betts Geo Environmental Ltd 2017

DOCUMENT ISSUE RECORD

Contract No: 17KCN001/DS

Client: Kier Group

Contract: Adult Day Care Centre, Queensferry

Document: Desk Study Report

Prepared by:

K Rodway

Checked by:

B Lewis

Approved by: B Lewis

Date: October 2017

REVISION RECORD

Revision Date Description Prepared by

0 October 17 Draft for issue and comments KR

1 October 17 FINAL BL

Adult Day Care Centre Kier Group Desk Study Report

17KCN001/DS 1 DRAFT Rev 0 © Betts Geo Environmental Ltd 2017

CONTENTS

1 EXECUTIVE SUMMARY 3

2 SITE DESCRIPTION 5

2.1 Introduction

2.2 Site Location

2.3 Site Description

3 SITE HISTORY 7

3.1 Site History from Ordnance Survey Maps

3.2 Summary of Site History

4 GEOLOGY 10

4.1 Published Geology

4.2 Geological Features

4.3 Hydrogeological and Hydrological Features

5 ENVIRONMENTAL DATA 17

5.1 Pollution Controls / Registers

5.2 Industrial Land Uses

6 SUMMARY OF ENVIRONMENTAL SENSITIVITY 20

6.1 Sources

6.2 Receptors

7 INITIAL CONTAMINATION CONCEPTUAL MODEL 22

7.1 Source-Pathway-Receptor-Linkages

7.2 Contamination Summary

7.3 Geotechnical Constraints

8 SCOPE OF GROUND INVESTIGATION 25

8.1 Objectives of the Ground Investigation

8.2 Proposed Ground Investigation Scope

9 REFERENCES 26



APPENDIX A i) Site Location Plan

APPENDIX B i) Historical Mapping

APPENDIX C i) Envirocheck Report ii) Coal Authority Report

APPENDIX D i) Conceptual Model

APPENDIX E i) Notes on Limitations



1 EXECUTIVE SUMMARY

Note – The following summary is not exhaustive and is to be used for guidance purposes only. The full report should be consulted for full details.

Site Location The site is located south west of Chester Road West, Queensferry, Deeside, Flintshire, CH5 1SE (coordinates for site is 331260, 368230).

Proposed Development The proposed construction of a new Adult Care Centre building.

Site Description: On Site The site is accessed via Chester Road East to the north of site. The site is currently part of John Summers High School and Infants School which comprises of multi-storey school buildings, car parking, and all-weather surfaces for sports and grassed sports fields to the north and east of site. The subject site is part of the grassed sports field Site levels undulate across the site however generally fall east to west.

Surrounding land uses for the site are as follows:

� North – Residential homes and commercial units beyond

� East - Commercial units and residential beyond

� South - Asda Supermarket, A494 and agricultural land beyond

� West - Residential homes

Site History The first map available of the site is the 1870 1:2,500 map which shows the site as a collection of fields, with a farm (shown as Aston Farm in 1899) and associated buildings (demolished by 1970), centrally to the southeast. Shotton Cottage is also shown to the northwest of the site; this is known to have been built circa 1820 and demolished in the 1960’s (anglefire.com/shotton/history8.html). Tennis courts are located to the south, along the southern boundary, no longer shown by 1996, replaced by a library. By 1970 the site had been developed into Deeside Senior High School and by 1996 it had been extended to the south of the original building and now named as John Summers High School and Queensferry Primary School. There have been no other significant changes since 1996. Surrounding Area A number of collieries were present within the immediate area circa 1870 – 1938/1968. Residential development began in the area circa 1938. A works is shown 20m N circa 1963 before being shown as a retail park circa 2006.

Published Geology The BGS map shows the geology beneath the site as the following:

� Drift – S (3/4 of site) - Devensian Till – Diamicton. N (1/4 of site) – Tidal Flat Deposits – Clay, Silt and Sand.

� Solid – Pennine Lower/Middle Coal Measures - Mudstone, Siltstone and Sandstone. Fault Lines There is one (1 No) fault line running east west across the site southern area of the site, with a further 4 coals seem crossing this the site as a whole. Two of which appear to be below the site of interest. Coal Mining The property is in a likely zone of influence from workings in 4 seams of coal at shallow to 150m depth and last worked in 1884.

Hydrogeology and Hydrology � The Devensian Glacial Till drift deposits are classed as Unproductive Strata (Negligible Permeability). � The Tidal Flat drift deposits are classed as Secondary Undifferentiated Strata (Low/Moderate Permeability). � The bedrock deposits of the Pennine Lower and Middle Coal Measures Formation are classed as a Secondary A Aquifer

(Moderate Permeability).



� The site does not lie within a Groundwater Source Protection Zone as defined by the Environment Agency. � The nearest surface water feature is located 1m NE of site in the form of a secondary river which flows along the north-

eastern boundary before connecting to a primary river flowing into the River Dee.

Radon Protection According to UKRadon mapping, the site boundary is in an area where 10-30% (higher probability) of the homes are above the action level. A radon report has confirmed that the site is within a higher probability area and that full radon protective measures are required in the new development.

Summary of Environmental Data Possible Contamination Sources;

� Current Land Use – Yes (localised to boiler house area). � Former Land Use – Yes. � Builders Yard – Adjacent to site (W) – No. � Former Colliery and Shafts – 20m to 50m N/NW – Yes. � Landfill – 420m W – No.

Pathways and Receptors;

� Aquifers – Below Site – Unlikely. � Secondary River – Adjacent N – Possible.

Qualitative Risk Assessment: In this qualitative risk assessment, a Low – Moderate risk for contamination and ground gas implies that remedial action may be necessary at the site, the likes of which cannot be confirmed until the geotechnical and contamination ground investigation has been completed.

Proposed Ground Investigation Scope: On assessing the potential risks on site, we have compiled the following recommendations for further initial investigation;

� Six (6 No) PRELIMINARY investigative rotary boreholes with water flush to 30.00 mbgl, at the four corners and centre of the proposed new layout. Coal Authority License will be required.

� Five (5 No) small diameter boreholes to 3.00 - 5.00 mbgl, installed with monitoring wells followed by 6 ground gas monitoring visits to assess risk of ground gas migration at anticipated foundation depth. At least two to target boiler house and two to target the north of site, adjacent to former Eleanor Colliery.

� Eight (8 No) soil samples (made ground and natural) taken for chemical analysis to benchmark contamination levels across the site targeted to garden areas which will be the key pathway. Proposed testing will include but not be limited to the following; heavy metals suite (comprising; As, Cd (low level), Cr Vi, Pb, Hg, Se, Ni, Cu, Zn), Organic Matter, Sulphate, pH, speciated polycyclic aromatic hydrocarbons, TPH CWG and asbestos (within Made Ground only).

� Should elevated determinant levels be encountered, additional leachate testing within soil and/or groundwater testing may be required.

� Should SVOC/VOC or other determinants be suspected within the holes, additional sampling will be required.

Following this initial investigation the Initial Site Conceptual Model should be updated to reflect the findings. Additional intrusive investigation may be required subject to this further assessment. The scope of works should be agreed with the Local Authority prior to the intrusive ground investigation and as such may change.



2 SITE DESCRIPTION

2.1 Introduction

This investigation was carried out on the instruction of Kier. The purpose of the work was to carry out a

Desk Study to provide geotechnical and contamination risk information for the proposed construction of a

new Adult Care Centre building. The mapping and datasets used to compile this report were obtained for

the wider John Summers High School site in January 2014. Focussed conclusions will be made at the end

of each section regarding the current area of interest within the wider site, where appropriate.

The current and proposed layouts are shown below;

Site Plan- Existing & Proposed- Dwg. no. 1480/KAD-LMA-XX-XX-DR-A-1001

2.2 Site Location

The wider site is located south west of Chester Road West, Queensferry, Deeside, Flintshire, CH5 1SE

(coordinates for site is 331260, 368230), and occupies an area of 8.69Ha. However, the site of interest

occupies an area of approximately 0.80ha in the west of the site.

See Site Location Plan in Appendix A.



2.3 Site Description

2.3.1 On Site

The site is accessed via Chester Road East to the north of site. The site is currently part of John Summers

High School and Infants School which comprises of multi-storey school buildings, car parking, and all-

weather surfaces for sports and grassed sports fields to the north and east of site. The subject site is part

of the grassed sports field Site levels undulate across the site however generally fall east to west.

The boundaries of the site and surrounding area are as follows:

� North – Deeside leisure centre

� East – Asda superstore

� South – Residential houses

� West – Residential houses

2.3.2 Surrounding Area

Surrounding land uses for the site are as follows:

� North – Residential homes and commercial units beyond

� East – Comemrcial units and rediential beyond

� South – Asda Supermarket, A494 and agricultural land beyond

� West – Residential homes



3 SITE HISTORY

3.1 Site History from Ordnance Survey Maps

A search of available historic OS maps was undertaken to establish the land use history of the site.

Extracts of the maps discussed below can be found in Appendix B of this report. All maps are Ordnance

Survey unless otherwise stated. All distances quoted on OS maps are taken from the site boundary, which

is marked on the map.

3.2 Summary of Site History

3.2.1 On Site

The first map available of the site is the 1870 1:2,500 map which shows the site as a collection of fields,

with a farm (shown as Aston Farm in 1899) and associated buildings (demolished by 1970), centrally to the

southeast. An extract of the 1870 map is shown below;

1870 1:2,500 map

Shotton Cottage is also shown to the northwest of the site; this is known to have been built circa 1820 and

demolished in the 1960’s (anglefire.com/shotton/history8.html). Tennis courts are located to the south,

along the southern boundary, no longer shown by 1996, replaced by a library.



1970 1:2,500 map

By 1970 the site had been developed into Deeside Senior High School and by 1996 it had been extended

to the south of the original building and now named as John Summers High School and Queensferry

Primary School.

There have been no other significant changes since 1996.

2006 1:10,000 map



3.2.2 Surrounding area

The following table summarises the significant changes in historical use surrounding the site:

Date First Shown Site

1870-1871

0m N – Road (still present). 35m N & 69m NW – Coal Mine Shafts of the Eleanor Colliery (1870-1878), replaced by buildings in 1963. Currently a petrol station and DIY store car park. 270m N/NE – Holyhead to Chester Railway line (still present). 430 SE – Colliery/Clay Pits (no longer shown by 1938). 670m N/NE – River Dee (still present). 700m W – Mill dam lake

1899-1900 50m E & 60m NE – Buildings (replaced by 1963). 465m W – Brick Works (no longer shown by 1938).

1911-1914 75m SE – Infants School (replaced by car park and petrol station by 2006). 180m-225m NW – St Ethelwold’s Church and Parsonage (still present). 180m W – Cricket Ground and Pavilion (still present).

1938 0m W – Residential dwellings (still present). 0m N – Building (replaced by residential dwellings and builders yard by 1969, still present). 55m E – Residential dwellings (still present).

1945 0m S – Residential dwellings (still present).

1963 20m N – Works & Depot (replaced by DIY store and retail park by 2006). 70m S – Aston County Secondary School (replaced by supermarket by 2006).

1970-1978 0m E – Fire and Ambulance Station (still present). 10m N – Training Centre (noted as special school and adult training centre by 1980 and still present). 98m NE – Deeside leisure centre (extended circa 1980, still present).

1978-2006 0m W – Apartment block (still present). 10m S – Supermarket with petrol station (75m SE). (Still present).

2014 No other significant changes.



4 GEOLOGY

The following section details the published and available geological data available for the site and the

surrounding area. All data is taken from the Envirocheck Data report located in Appendix C unless

otherwise stated. This report should be referred to for full details.

All distances are taken from the nearest site boundary, as shown by the pink boundary line.

4.1 Published Geology

The documented geology of the site is summarised on the British Geological Survey map principally, with

further site-specific details detailed below.

Geology Drift Solid

1:50,000, Sheet No 108

Flint (1999)

S (3/4 of site) - Devensian Till – Diamicton N (1/4 of site) – Tidal Flat Deposits –

Clay, Silt and Sand

Pennine Lower/Middle Coal Measures - Mudstone, Siltstone and Sandstone



4.1.1 Fault Lines

There is one (1 No) fault line running east west across the site southern area of the site, with a further 4

coals seem crossing this the site as a whole. Two of which appear to be below the site of interest.

Superficial Geology Bedrock Geology

Artificial Ground and Landslip



4.2 Geological Features

There are three (3 No.) Recorded Mineral Sites within 500m of site, this is detailed below:

4.2.1 Coal Mining



4.2.2 Radon

According to UKRadon mapping, the site boundary is in an area where 10-30% (higher probability) of the

homes are above the action level. A radon report has confirmed that the site is within a higher probability

area and that full radon protective measures are required in the new development.

4.3 Hydrogeological and Hydrological Features

The table below summarises the presence/absence of any hydrological licences and incidents within 500m

of the proposed site. If entries are present within 250m, further details are provided in the relevant

subsection below; For full details please refer to Appendix C.

All distances are taken from the nearest site boundary, as shown by the pink boundary line on mapping.

Data Type On Site 0 – 250m 250 – 500m

Hydrological

Discharge Consents - 2 12

Pollution Incidents to Controlled Waters - 4 5

Water Abstractions - - -



4.3.1 Discharge Consents

There are two (2 No) Discharge Consents within 250m of site, as detailed below.

4.3.2 Pollution Incidents to Controlled Waters

There are four (4 No) Pollution Incidents to Controlled Waters within 250m of site, as detailed below;



4.3.3 Hydrogeology

� The Devensian Glacial Till drift deposits are classed as Unproductive Strata (Negligible

Permeability).

� The Tidal Flat drift deposits are classed as Secondary Undifferentiated Strata (Low/Moderate

Permeability).

� The bedrock deposits of the Pennine Lower and Middle Coal Measures Formation are classed as a

Secondary A Aquifer (Moderate Permeability).

� The site does not lie within a Groundwater Source Protection Zone as defined by the Environment

Agency.

� The nearest surface water feature is located 1m NE of site in the form of a secondary river which

flows along the north-eastern boundary before connecting to a primary river flowing into the River

Dee.



5 ENVIRONMENTAL DATA

The following section details environmental data available for the site and the surrounding area. Full details

can be found in the EnviroCheck Report by Landmark located in Appendix C.

The table below summarises the presence/absence of any waste, hazardous substance sites and/or

industrial land uses within 500m of the proposed site. If entries are present within 250m, further details are

provided in the relevant section below.

All distances are taken from the nearest site boundary, as shown by the pink boundary line on mapping.

Data Type On Site 0 – 250m 250 – 500m

Pollution Controls/Registers

Integrated Pollution Controls - - -

Integrated/Local Authority Pollution Prevention and Controls - 2 -

Prosecutions Relating to Authorised Processes - - -

Registered Radioactive Substances - - -

Substantiated Pollution Incident Register - - -

Waste

BGS Recorded Landfill Sites - - -

Historic Landfill Sites - - 1

Integrated Pollution Control Registered Waste Sites - - -

Licensed Waste Management Facilities (Landfill Boundaries and Locations) - - 1

Local Authority Recorded Landfill Sites - - 1

Registered Landfill Sites - - -

Registered Waste Transfer Sites - - 1

Registered Waste Treatment or Disposal Sites - - -

Hazardous Sites

COMAH/Explosive sites/NIHHS/Planning Hazardous Substances - - -

Industrial Land Uses

Contemporary Trade Directory Entries - 15 38

Fuel Station Entries - 3 -



5.1 Pollution Controls / Registers

5.1.1 Integrated/Local Authority Pollution Prevention and Controls

There are two (2 No) Integrated/Local Authority Pollution Prevention and Controls within 250m of site, as

detailed below;

5.2 Industrial Land Uses

5.2.1 Contemporary Trade Entries

There are fifteen (15 No) contemporary trade entries within 250m of site, the closest of which are detailed

below;



5.2.2 Fuel Stations

There are three (3 No) fuel station entries within 250m of site, these are detailed below;



6 SUMMARY OF ENVIRONMENTAL SENSITIVITY

The following section is a review of the environmental sensitivity of the site as discussed in Sections 2 - 5.

Significant potential risks are discussed in the following subsections and will then be evaluated as part of

the Site Conceptual Model in Section 7.

Sources are defined as where pollution comes from, pathways are a route in which the pollution travels and

receptors are anything affected by a pollutant. Further details on Source-Pathway-Receptor methodology

can be found in Appendix D.

The table below focuses on significant site-specific sources, pathways and receptors. More ‘generic’

pathways and receptors (such as site end uses) will be covered as part of the full Site Conceptual Model in

Section 7.

6.1 Sources

Source Distance/ Direction

Details Significant

Risk

Current Land Use On Site

Current land use is as a secondary and primary school with playing fields. Possibility of localised Made Ground from 1990’s extension. There is a former boiler house located on the east of the old building. It is currently no longer in use, though metals, PAH’s and TPH’s could be potential contaminants. Ground Investigation and ground gas monitoring to confirm.

Yes (localised to boiler house

area)

Former Land Use On Site (S)

Former agricultural land until the late 1960’s when the school was built. Localised made ground potential. Given time since last farm, herbicides and pesticides are deemed negligible risk. Possibility of localised coal mining from unrecorded shallow workings, bell pits and surface mining. Two areas of buildings, possible foundations and localised Made Ground from Shotton Cottage and Aston Farm (see drawing in Appendix B). Targeted Ground investigation and ground gas monitoring to confirm.

Yes

Builders Yard Adjacent to Site (W)

Possibility of localised contamination along boundary. Ground investigation to confirm.

No

Former Eleanor Colliery & Shafts

20-50m N/NW

Former coal colliery and two shafts, operational 1870-1878. Both shafts have been built on, petrol station and DIY car park. Possibility of ground gas migration and localised contamination from colliery spoil along the northern part of site. Ground investigation including rotary boreholes for shallow workings and ground gas monitoring to confirm.

Yes

Landfill 420m W Shotton Lane Landfill, last backfilled in Dec 1940, given age >70 yrs since operational and anticipated cohesive glacial till, ground gas migration is deemed negligible.

No



6.2 Receptors

Source Distance/ Direction

Details Significant Risk

Secondary River Adjacent N

Surface water runoff to secondary river is possible, however no significant mobile contamination anticipated from site however ground investigation should be undertaken to confirm.

Possible

Aquifer Below Site

Devensian Till and Alluvium are susceptible to migration through sand bands within the aquifer and especially the Alluvium along the north of site (see Appendix B drawing) - no significant mobile contamination anticipated from site however ground investigation should be undertaken to confirm

Possible



7 INITIAL CONTAMINATION CONCEPTUAL MODEL

For details on how the conceptual model is evaluated please refer to Appendix D.

This section of the report aims to identify land which could potentially be affected by contamination, such

that it could affect the value or re-use of the land, or such that mitigation would be required for certain

proposed end uses of the land.

Potential contamination sources and environmentally sensitive receptors have been discussed in Section 5.

Potentially significant risks are evaluated as part of the subsequent sub-sections.

7.1 Source-Pathway-Receptor-Linkages

The risk assessment uses a ‘Source-Pathway-Receptor’ methodology for assessing whether a source of

contamination could potentially lead to harmful consequences. This means that there needs to be a

pollutant linkage from source to receptor for harm to be caused, this linkage consisting of: a source of

pollution; a pathway for the pollutant to move along; a receptor that is affected by the pollutant.

The current potential risks to site arising from various Source-Pathway-Receptor linkages are assessed

below. A risk may be considered significant if all three of the stages are present and therefore providing a

pollution linkage. The various sources, pathways and receptors are considered separately. The

assessment is based on the future use, which is understood to be a school building.

SOURCE Eg. Contaminated Soil

PATHWAY Eg. Groundwater, Ingestion, Gassing

RECEPTOR Eg. Groundwater,

Humans, Plant Life



Type of Contamination

Potential Sources

Potential Pathway

Potential Receptors

Pollution Linkage

Comment Estimated Level of

Risk

Ground Gas

Coal Mining Boiler House

Inhalation of Vapours

Construction/ Maintenance Workers

Potentially Active

PPE will reduce the risk significantly. Low

Vapours Penetrating Unprotected Buildings

Future Site Users

Potentially Active

Potential ground gas migration from Made Ground in location of former colliery to the north and Boiler house (fuel). Possibility of localised ground gas from boiler house. Ground Investigation and gas monitoring to confirm.

Moderate

Near Surface Contaminants Within Soils

Localised Made Ground Coal Mining Boiler House

Ingestion, Inhalation, Dermal Contact

Current Site Users

Potentially Active

Current land use is open land. PPE significantly reduces risk. Potential contamination risk. Localised Made Ground from extension and construction of school buildings/car parks/all-weather pitches. Boiler house been redundant for number of years, residual contamination. Ground investigation and gas monitoring to confirm. PPE significantly reduces risks. No significant contamination noted during the site walkover, therefore risk is lowered.

Low - Moderate

Construction/ Maintenance Workers

Potentially Active

Current land use is open land. PPE significantly reduces risk. Potential contamination risk. Localised Made Ground from extension and construction of school buildings/car parks/all-weather pitches. Boiler house been redundant for number of years, residual contamination. Ground investigation and gas monitoring to confirm. PPE significantly reduces risks. No significant contamination noted during the site walkover, therefore risk is lowered.

Low - Moderate

Future Site Users

Potentially Active

Site history has a moderate contamination risk from former unrecorded shallow mining workings, former buildings and former boiler house, within proposed garden areas. However a full ground investigation should be undertaken to confirm this.

Low - Moderate

Adjacent Land Users

Potentially Active

Adjacent site users could potentially be exposed to dust arising from construction, post construction risks are low.

Low

Direct Contact Structures Potentially Active

Structures within the ground are potentially susceptible to attack from aggressive ground conditions (colliery spoil) but may need to be protected, a ground investigation should be undertaken to confirm this.

Low

Absorption in Root Zone

Plants Potentially Active

Plants have the potential to be affected by phytotoxic contaminants within the made ground. Ground investigation should be undertaken to confirm this.

Moderate

Mobile Contaminants, Leachables e.g. from Pollution Sources on Site

Localised Made Ground Coal Mining Boiler House

Leaching into Groundwater

Groundwater Potentially Active

Published geology shows the underlying drift as Devensian Till as predominant superficial deposit, with alluvium in thin strip to north. The till is deemed by the EA to be an Unproductive Strata (Negligible Permeability) and secondary undifferentiated (low/moderate permeability). Beneath the till lies the Secondary A Aquifer coal measures formation. Significant leachable / mobile contamination associated with former use is possible.

Low - Moderate

Mobile Contaminants, Leachables e.g.

Localised Made Ground

Offsite Migration in Groundwater

Abstractions Potentially Active

The site is not within a Groundwater Source Protection Zone and there no sensitive abstractions within 500m.

Low



Type of Contamination

Potential Sources

Potential Pathway

Potential Receptors

Pollution Linkage

Comment Estimated Level of

Risk

from Pollution Sources on/off Site

Coal Mining Boiler House

Controlled Waters

Potentially Active

The nearest controlled water system is the adjacent north and flows to the River Dee River and the risk of migration is high due to anticipated alluvium; the risk to this receptor is moderate. However no significant risk of mobile determinants anticipated.

Low - Moderate

Organic and Inorganic Contaminants Within Soils/ Groundwater

Boiler House Potable Water Supply Pipes

Utilities Workers

Potentially Active

Low risk of significant contamination which may penetrate plastic pipes however ground investigation is needed to confirm this. Possibility of localised contamination around boiler house.

Low

7.2 Contamination Summary

In this qualitative risk assessment, a Low - Moderate risk implies that limited remedial action is likely to be

necessary at the site, the extent of which cannot be confirmed until a geotechnical and contamination

ground investigation is carried out.

7.3 Geotechnical Constraints

� Potential Tree Heave where cohesive stratum is encountered.

� Potential for unrecorded shallow mine workings across site (bell pits shafts etc).

� Recorded shallow mining to the north, potential for abnormal foundations in proposed location of

building.

� Former buildings of Shotton Cottage (to NW on site) and Aston Farm buildings (central), former

foundations.



8 SCOPE OF GROUND INVESTIGATION

8.1 Objectives of the Ground Investigation

The objectives of the intrusive ground investigation will be to:

� Clarify the ‘Initial Contamination Conceptual Model’.

� Clarify the initial risk assessment.

� Benchmark the contamination status of the site.

� Provide data for the design of any remedial works that may be required.

� Provide a geotechnical appraisal for the site.

8.2 Proposed Ground Investigation Scope

On assessing the potential risks on site, we have compiled the following recommendations for further initial

investigation;

� Six (6 No) PRELIMINARY investigative rotary boreholes with water flush to 30.00 mbgl, at the four

corners and centre of the proposed new layout. Coal Authority License will be required.

� Five (5 No) small diameter boreholes to 3.00 – 5.00 mbgl, installed with monitoring wells followed

by 6 ground gas monitoring visits to assess risk of ground gas migration at anticipated foundation

depth. At least two to target boiler house and two to target the north of site, adjacent to former

Eleanor Colliery.

� Eight (8 No) soil samples (made ground and natural) taken for chemical analysis to benchmark

contamination levels across the site targeted to garden areas which will be the key pathway.

Proposed testing will include but not be limited to the following; heavy metals suite (comprising; As,

Cd (low level), Cr Vi, Pb, Hg, Se, Ni, Cu, Zn), Organic Matter, Sulphate, pH, speciated polycyclic

aromatic hydrocarbons, TPH CWG and asbestos (within Made Ground only).

� Should elevated determinant levels be encountered, additional leachate testing within soil and/or

groundwater testing may be required.

� Should SVOC/VOC or other determinants be suspected within the holes, additional sampling will

be required.

Following this initial investigation, the Initial Site Conceptual Model should be updated to reflect the

findings. Additional intrusive investigation may be required subject to this further assessment.

The scope of works should be agreed with the Local Authority prior to the intrusive ground investigation

and as such may change.



9 REFERENCES

9.1 BS 5930:2015 Code of Practice for Ground Investigation.

9.2 Investigation of Potentially contaminated sites BS10175:2011 +A1:2013.

9.3 BS8576:2015 Guidance on investigations for ground gas.

9.4 R & D Publication CLR 8 (March 2002) Assessment of Risks to Human Health from Land Contamination: An

Overview of the Development of Soil Guideline Values and Related Research. Environment Agency.

9.5 R & D Publication CLR 10 (March 2002) The Contaminated Land Exposure Assessment Model (CLEA): Technical

basis and algorithms. Environment Agency.

9.6 Contaminated Land Risk Assessment; a Guide to Good Practice; CIRIA C552: 2001.

9.7 BRE 211 Radon: guidance on protective measures for new buildings (including supplementary advice for extensions,

conversions and refurbishment) (2007 edition).

9.8 Assessment of risks to human health from land contamination: an overview of the development of guideline values and related research. EA, 2002.

9.9 Health and Safety in Construction, HSG150, HSE, 1996.

9.10 Baker W (1987), Investigation Strategy - lecture at City of Birmingham Development Department Symposium on Methane Generating Sites, 9 December 1987, Industrial Research Laboratories, Birmingham.

9.11 NHBC Standards, Chapter 4.2, 2017 Building Near Trees.

9.12 ‘Guidance on Evaluation of Development Proposals on Sites Where Methane and Carbon Dioxide are Present’, Report Edition No.04 March 2007 NHBC – designed for use with low rise residential properties.

9.13 CIRIA C665 ‘Assessing risks posed by hazardous ground gases for buildings’ 2007 - for high rise residential / flats.

9.14 BS8485:2015 ‘Code of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings’.

9.15 BRE 414 ‘Protective measures for housing on gas-contaminated land’ Roger Johnson, Parkman Environment 2001.

9.16 BS 8500-2:2015+A1:2016 ‘Concrete British Standard to BS EN 206. Specification for constituent materials and concrete’.

9.17 CLR11 ‘Model Procedures for the Management of Land Contamination’ DEFRA 2004.

Kier Construction Desk Study Report

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