Scope of PresentationRiver Rother in the final alignment (0- 100m, 100-200m and >200m). Divided in...
Transcript of Scope of PresentationRiver Rother in the final alignment (0- 100m, 100-200m and >200m). Divided in...
The Avenue former Coking Works Remediation andRegeneration Project
Hugh Masters-WilliamsMartin WestwoodNorthWest Brownfield Regeneration ForumChartered Institution of Water and Environmental Management (CIWEM)
29th September 2015
Scope of Presentation
1. Introductions2. The Problems3. Site Investigations4. The Conceptual Site Model5. Evolution of the CSM6. Controlled Water Risk Assessments7. Remediation Strategy and Techniques8. Post Completion landform
1. Introduction Project Team and Roles
Client & Project Promoter
Project and Cost Management
NEC Supervisor and Designer
Remediation ContractorJoint venture between Volker Stevin, Sita Remediation and DEC NV
Geotechnical, Mining & Landscaping Designer
History and Works StagesYear Activity
1890s Avenue Colliery and Lime & Iron Works operational on site
1930s Avenue Colliery and Lime & Iron Works become disused
1952 Construction of The Avenue Coking Works commenced
1956 The Avenue Coking Works is operational
1992 The Avenue Coking Works are closed
1999 Emda take ownership of the site and become responsible for delivering its reclamation
1999 –2005 Stage 1: Plant area drain-down and demolition, site surveys, ground investigations, H&S and environmental improvement works, desk studies, PRA, DQRA, remediation trials, development of outline remediation strategy
2005-2006 Stage 2: Pre-qualification exercise and tender for detailed design of remediation strategy / Appointment of VSD for detailed design of remediation strategy
2006 –2009 Stage 2: Detailed design of earthworks and remediation strategy, value engineering, economic appraisal( Early
Contractor Involvement/ OJEU Procurement/ NEC:EEC Option C Target Contract with Activity Schedule
2009 Stage3: Appointment of VSD for remediation of The Avenue site (Stage 3)
2009 - due to be completed2016
Stage 3: Remediation and landscaping works
Site Zones98 Hectares
Type Narrative
Former Uses Zone 1A to 5B which broadly correspondto the primary historical contaminative land-use areas.
Grid Cells In order to manage the earthworks, VSD further spit the site up into over 2000 grid cells
Material ReuseZones
Structural PerformanceZones
The placement of fil material has been undertaken across zone in three re-use zone denoted from the distance from the River Rother in the final alignment (0- 100m, 100-200m and >200m).
Divided in to a range of zonesassociated with structural performance of placed fil material.
2. The ProblemsProject Objectives
To discharge HCA’s legal obligations by removal of the source contamination, cleaning up the River Rother, cleaning up the shallow groundwater
Prepare the site for the planned redevelopment in accordance with the planning consent for the project
Maximise re-use of site won material with treatment as needed and minimise off-site disposal
Incorporate flood protection measures and SUDs (of which the Environment Agency is the promoter)
Pollution of Controlled Water
Voluntary remediation to avoid any regulatory action under Part IIA of the EnvironmentalProtection Act /the Water Resources Act (1991) / EU Groundwater Regulations
Planning Permission CW4/0507/39 remediation of the site via on-site treatment of contaminatedsoils and sediments, with landform reinstatement to a variety of end-uses, including public open space, formal and informal leisure areas, nature conservation areas and a development platform.
Under the planning and development control regime, the aim is to ensure that there are no unacceptable risks to either receptors relevant to Part IIA, or to others that may be covered by other regimes, taking into account the proposed new use of the land.
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.JACOBSFormer Land Use - the Lagoons 3 Site Investigation
3 Site InvestigationBetween 1991and 2007: 22 Phases of investigation.
415 Boreholes 750 Trial Pits Numerous Environmental Monitoring Programmes (Ground gas, Vapour, Air Quality,
Surface Water, Groundwater, leachate) Source characterisation: Identified Contaminants of Concern : PAHs (Poly Aromatic
Hydrocarbons), Phenols, DROs (Diesel Range Organics), PROs (Petrol Range Organics), BTEX (Benzene, Toluene, Ethylene, Xylene), Cyanide, Thiocyanate, Ammonia, Heavy Metals (Arsenic, Nickel, Cadmium, Chromium), Asbestos Geological / Hydrogeological Characterisation Material Re-Use /Earthworks /Mass Haul Assessment Sumps and Structure Surveys Coal Mining and Ground Stability Conditions
Exploratory Hole Plan- North of Site
Findings - Example Benzene
River Rother
Lago
on2
4 Conceptual Site Model Lagoon 2 (Controlled Waters)
ID Zone Contaminants Exposure Routes Receptor
Naphthalene, Phenol, PRO, DRO,CW 1 Benzene, Ammoniacal Nitrogen,
Thiocyanate, Cyanide
Groundwater transport via saturated Made Ground, superficial clays/alluvium to Coal Measures
Coal Measuresminor aquifer
Naphthalene, Phenol, PRO, DRO, Groundwater transport via superficial clays/alluvium to Coal Coal MeasuresCW 2 Benzene, Ammoniacal Nitrogen,Thiocyanate, CyanideNaphthalene, Phenol, PRO, DRO,
Measures minor aquifer
CW 3
CW 4
Benzene, Ammoniacal Nitrogen, Thiocyanate, Cyanide Naphthalene, Phenol, PRO, DRO, Benzene, Ammoniacal Nitrogen, Thiocyanate, CyanideNaphthalene, Phenol, PRO, DRO,
Groundwater transport via saturated Made Ground to River River Rother
Groundwater transport via superficial clays/alluvium, CoalMeasures to River River Rother
Groundwater transport via saturated Made Ground,CW 5 Benzene, Ammoniacal Nitrogen,
Thiocyanate, Cyanidehistorical pipework, drains (including possible rubble drain)and culverts to River
River Rother
CW 6 Phase Separated Hydrocarbons 1 Groundwater transport via saturated Made Ground,superficial clays/alluvium to Coal Measures
Coal Measures minor aquifer
CW 7 Phase Separated Hydrocarbons 1 Groundwater transport via superficial clays/alluvium to Coal Coal MeasuresMeasures minor aquifer
CW 8 Phase Separated Hydrocarbons 1 Groundwater transport via saturated Made Ground to River River Rother
CW 9 Phase Separated Hydrocarbons 1 Groundwater transport via superficial clays/alluvium, CoalMeasures to RiverGroundwater transport via saturated Made Ground,
CW 10 Phase Separated Hydrocarbons 1 historical pipework, drains (including possible rubble drain)and culverts to River
River Rother
Geology/Hydrogeology
§
.JACOBSConceptual Site Model (contronedwaters>
SOUTH NORTHHighlevel stocking area/Waste tip
Recllarge
........ River RotherLagoon4
Made Gnx.nd AJiwiU'n Superfici31cl3ys
0 'tiddie Cool Mea511eS0Sandstone inCool MeaS .reS•Sattr.1tedsediment
--_ Baseol wealhen!dCo3l Measl.res
Gromdwater flowinfluencedby wrJaflthorpe dewatering
(1) Predorrinmtly due to cessation of Mortondewatering(2)Infiltration spatially variable;dependent on Coal Measu--es
sequencelpropertiesof localhardrock/weatheredCoal Measu-es(3)Cofr1>1exverticaland lateral groundwater movement; function
of nlliti ered rrthology(4) Aux to river constrained by da}'ey supemcialslaluvium
5 Evolution of the CSM Unrecorded Sources / Materials Tar in lagoon base Alluvial deposits-pathway River channels and former alignments Service corridors in plant area- oily preferential pathways Unrecorded tar lagoon Unrecorded solvent disposal pit Impacts upon Mass Haul Cross Boundary Issues (CPL)
Groundwater Issues River NAPL Springs Rising groundwater- aquitard reinstatement /weathered mudstone Groundwater Pump and Treat System TDU output material (additional groundwater risk assessment)
6. Controlled Water Risk Assessment and Remedial Targets
Based on four main phases of modelling and risk assessment:
1. Babtie Group 2002, The Avenue Coking works, Groundwater Risk Assessment
2. Jacobs Babtie, 2004, The Avenue Coking works, Controlled water risk Derivation of Leachable Soil Threshold Concentrations, (using consim version 1.06).
3. Jacobs 2008, The former Avenue Coking Works and Chemical Plant ConceptualSite model and Detailed Quantitative Risk Assessment.
4. Jacobs 2012, Ground and Surface Water Environmental Risk Assessment (PostRemediation), Fill Verification Assessment (using ConSim2.5)
5. 2016 Final reporting
Risk AssessmentKey DQRA Facts Free phase excluded (Visible Free Product (VFP) Protocol requires treatment mandatory) EA agreed risk to groundwater need not be considered on the basis of cost benefit and therefore the River
Rother is the key Receptor in RA terms The Controlled Waters Risk Assessment using ConSim v1.06 was completed to derive SSACs (benzene,
phenol , cyanide and thiocyanate) through an iterative process of varying leachate concentrations until notheoretical impact was observed in the water quality of the River Rother.
The 0-100 m zone for the river remedial target was agreed to be equal to the EQS and was therefore not originally modelled given the conservative SSACs.
In-situ natural biodegradation was not included within the modelling - conservative final scheme verification using ConSim model v2.5 has been run (model multiple sources) with the river in its
final alignment and the 3 source areas Conceptual agreement that any material above the Coal measures lithology will migrate to river and there
would be no water/contaminant loss to the aquifer i.e. modelling of the coal measures is not required The EA agreed that plume concentration could be diluted by a factor of 175 (low flow river dilution factor) and
compared to 1/10th of the Environmental Quality Standard (EQS) Remediation strategy is only possible with the support of the Regulators
0.3 3 3
Soil Leachate Re-use Criteria
Determinand
Units
Reuse within 100m of River Rother
Reuse between100m and 200m of River Rother
Reuse more than 200m from
the RiverRother
Ammoniacal Nitrogen(NH4)
mg/l 2.5 n/a n/a3
Benzene mg/l 0.03 1.75 8.75
Cyanide (CN) mg/l 0.05 175 175
Naphthalene mg/l 0.01 n/a3 n/a3
Phenol mg/l 0.03 0.7 1.75
Diesel Range Organics(DRO) mg/l n/a n/a
Thiocyanate (SCN) mg/l 1 17.5 17.5
Groundwater Remedial Objectives and WasteWater Management
The removal and treatment of made ground and soils where contaminant concentrations exceed defined leachable or free product thresholds
The removal and treatment of shallow groundwater and surface water encountered in the existing lagoons, ponds, and entering open excavations
Non-Aqueous Phase Liquids entering excavations removed as far as is reasonable and practicable prior to backfilling the excavation
Where possible, the weathered coal measures shall be kept in place to protect the material
Contaminated wastewater arising from the removal of materials from Lagoons 2 and4 and other contaminated groundwater arising from any excavation shall not beallowed to contaminate Controlled Waters and hence must be collected and treated to make it suitable for disposal to foul sewer (Yorkshire Water).
Site Water Management Plan Groundwater and Surface water monitoring programme during the works and for two
year after completion.
Post Completion Source AreasExcavation and Restoration Profile
Post Completion Source AreasExcavation and Restoration Profile
Post Completion Source AreasExcavation and Restoration Profile
Predicted Surface Water Results 7 Remediation Strategy / RemediationTechniques
Remediation Strategy and Masterplan Source removal Material recovery (re-use) Waste minimisation On-site treatment Development and POS Land use
Earthworks
Plant area trawl
Shallow made ground
Deeper structures retained
Structural fill in development area
Thermal Treatment Pre-mixing soils homogenise for CV/MC Indirect pre-dryer heated by off gases to
evaporate water & some hydrocarbons Direct kiln heating by gas burner 450-600ºC
to volatilise/oxidise hydrocarbons Gases have dust removed in cyclones Gases heated up to 1200ºC in oxidiser Hydrocarbons convert to carbon dioxide and
water Cyanides oxidise into carbon dioxide, water
and N2/NOx inject ammonia to DeNOx Sulphur converts to SO2 Gases quenched to 8000C for pre-dryer Gases to heat exchanger 2200C to bag
house filter Gas scrubbers to remove SO2 and other acid
gases Carbon filters to remove mercury Stack monitoring Heat recovery and recycling
Screening (Waste Tip Recovery)Mixed solid waste Co-disposal with liquid Lime solids/ Tar oil tank
cleaning/ Napthalene /Spent oxide wooden grids/Dust from cyclones/ Solids from river discharge/Acid plant residues/Building materials/scrap/clay/Ferric hydrate slurry mixes Asbestos
Selective excavation at face <600mm to Separator
>75mm oversize 30-75mm to picking station 0-30mm to sentencing
Picking station Second Separator >75mm oversize 50-75mm for re-screening 0-50mm to sentencing
Bioremediation Treatment of
leachable Phenols Thiocyanate
Biobeds 250-500m3
10% green waste ALLU mixing
bucket Process Samples Environmental
monitoring
Waste WaterManagement Plan Sustainability Contaminated water (Surface , Groundwater ,Operationally
generated water ) collected and treated Holding Ponds/ (17,000m3 capacity) Water Transfer/Silt +Oil
Traps Monitored Surface water from adjacent site Monitored Discharge to foul sewer under consent (480m3
day) Monitored Consent to River via surface water sewer Clean /storm water used for operations (dust/thermal) Groundwater , Surface water Sewer and River monitoring
programme during work and for two year after completion. WWTW
WWTW Chemical and Biological treatment
Oil / water separator Coagulation tank with NaOH dosing Lamella classifiers for settlement of suspended
solids. Settlement of flocs in B06 (previously interim
output buffer). Biological treatment plant (Sequenced Batch
Reactor) Hypo dosing with pH correction Two continuous sand filters in parallel Up to four activated carbon filter in series Two ion exchange filters in series
Predicted and Final Treatment VolumesTechnique Original Designs Volume Final /Forecast
Treatment (m3)Thermal desorption 270,300 257,266Soil screening /sorting/washing 237,600 203,485Bioremediation 74,000 181,206Total 581,900 641,497
Off-Site Disposal (Tonnes)Asbestos 2352 913Metal 3000 550Other waste 4600 2470Recovered Timber 1450 10,000Tar 0 19,000Total 11, 402 32,020
All Earthworks (m3)Total Material volume (cut) 1,883,377 2,244,989Total Material volume (Fill) 1,934,896 2,178,200Total 3,818,273 4,423,189
Material Import to Create Landform 0 80,000
Groundwater and Surface Water Treated in WWTW Discharge to Sewer/River 80:20
?? 635,654
8 Post Completion Landform
• 28 hectares of residential led mixed use development• Flood alleviation scheme (Dam and Reservoir)• Realigned River Rother and Backwater• 65 hectares of public open space & nature reserve• Sports Facilities• Sustainable Urban Drainage (SUDS)• Access Road and Car Park
Masterplan – the outcome
SUDS and FAS• SUDS series of channels, reed bed pond, a fisherman’s pond, slot
weirs and cascades- river discharge• Embankment dam and culvert to create the FAS• Designed to accommodate a 1 in 100 year flood event.• Water levels in the reservoir to be between 80.5mAOD and
81.47mAOD, (i.e. 1-2m of water).• The inundation of the flood plain will be temporary and periods of
inundation are expected to last for 6-8 hours• The storage capacity of the reservoir is approximately 240,000m3.
.JACOBS
1953JACOBS 1965JACOBS
JACOBS 1992 .JACOBS 2007
.JACOBS 2010 .JACOBS 2012
.JACOBS 2013 .JACOBS 2014
.JACOBS 2015
Conclusions Planned site investigation is essential Multiple phases are needed – we are still doing
GI’s The CSM must evolve – gather data; test your
hypothesis; revise the CSM…. Major projects demand a wide range of skills - a
multidisciplinary team is essential. Regulatory engagement and agreement is vital. Early contractor Involvement A client who understands the remediation
process is a big help too!
Thank you for your attention.
Any questions?
www.theavenueproject.co.uk