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

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.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.

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.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