�

Realistic, cost effective and sustainable remediation

Jane Dottridge, Contaminated Land Manager

�Issues

• Realistic and cost effective remediation

• Application of risk based (source-pathway-receptor) approach:– Remove source – traditional remediation approach

– Break pathway

– Remove receptors – but redevelopment may introduce moresensitive receptors

– Adjust master plan/design to most appropriate land use tominimise risks/remediation requirements

• Consider sustainability and carbon footprints ofremediation and future development

�Talk Outline

• Introduction – key issues

• Realistic remediation approach – common senseengineering

• Applying risk based criteria to define remediationstrategy

• Reducing volumes using on-site quick testing

• Sustainability and carbon footprints

• Forward look

�Realistic remedial strategy

Former waste water treatment works,Peterborough BEFORE

�Realistic and cost effectiveremediation

• Former waste water treatment works next to landfill

• Redevelopment of WWTW for housing

• Landfill and marshy area remain as open space

• Remediation strategy already agreed with regulators

• Modified to allow reuse of site won material, reduceimport of clean fill, lower costs, improve ‘buildability’

• Site owner, developer, regulators all accepted revisedapproach

�Realistic remedial strategy

Site remediation for housing development,Peterborough INITIAL TANK CLEANING

Fengate WWTW Remediation, Peterborough

�Realistic remedial strategy

Site remediation for housing development,Peterborough FILLING

�Realistic remedial strategy

Site remediation for housing development,Peterborough PREPARATION FOR BUILDING

�Realistic remedial strategy

Site remediation for housing development,Peterborough INFRASTRUCTURE AND BUILDING

�

• Focusing on groundwater impacts, but essential toconsider human health too

• Application of risk based (source-pathway-receptor)approach:

– Remove/reduce source – traditional remediation approach

– Break pathway – cover, vapour barriers, slurry walls

– Remove receptors – but redevelopment usually introducesmore sensitive receptors

– Adjust master plan/design to most appropriate use to minimiserisks/remediation requirements

– Demonstrate residual risks after remediation are insignificant

Risk based criteria for remediation

�Desk Study, Site data,

Literature Sources

Develop Conceptual Site Model

Derive and refine values torepresent physical and

chemical conditionsWater Resources

Modelling

(RTW, P20, Consim,MT3D)

Human Health Modellingeg BP Risc, CLEA

Derive ApplicableTarget Levels

Compare to on-site concentrations

Conclusions on risk andRecommendations for remediation

Site Specific Risk

Assessment Process

�Risk assessment approach

• Good Conceptual Site Model (CSM) to identify Source Pathway Receptor (SPR)Linkages and Contaminants of Concern (CoCs) using all available data.

On-site Resident Off-site Resident

Soil SourceVolatilisation

GroundwaterSource

Infiltration

Volatilisation

Groundwater flowLeaching

Abstraction

Which CoCs?

�

40 m

750 m

Lakes SSSI Former locationof free phase

product

Gault Clay Aquitard

Saturated ChalkAquifer

Dispersion ofcontaminants intogroundwater

8 m UnsaturatedChalk 0.5m

(depth ofsource)

Site boundary

100 m

Made Ground

Conceptual Site Model

�Groundwater risk models and results

• Range of software of varying complexity• Input site data, but inevitably many estimated values• Run sensitivity analyses to check influence of estimated and

uncertain values• BUT results tend to be over-estimate risks, due to inherently

conservative approach and many assumptions• Calibrate against measured concentrations in down

gradient/off-site wells• Verify against historical data if available• This often shows faster degradation and gives less

conservative results

�Model and measured concentrations

�Calibrated and measuredconcentrations

�Former Industrial Site

• Long history of contamination (from 1960s) with floatinghydrocarbons and chlorinated solvents

• Previous use for car parts manufacture

• In old industrial area, mostly blighted and derelict

• Previous skimming and SVE remediation to remove freephase hydrocarbons from water table but groundwater stillshows local contamination

• Current remediation to remove shallow contamination andstructures to address human health risks

• Large tanks still exist – holding fluids and clean underneath

�Former Industrial Site

�Development Proposalsns

Residential useProposed for mostcontaminated area

�Former Industrial Site - solvents inChalk

• 2007 groundwater analyses showed breakdown products but v low sourceconcentrations

• Regulators view– Investigation did not target most contaminated areas

– Analytical results low because missed contamination

– Need for large groundwater remediation due to historic contamination with hydrocarbons andchlorinated solvents

• Groundwater risk assessment used historical source concentrations

• 1999 - max concentration 4.5 mg/l TCA

• Calculated 2007 concentration 0.017-0.038 mg/l, after degradation and dilution

• Measured 2007 concentration 0.013-0.018 mg/l

• Range of half lives 12 d (lab) - 546 d (field) – 912 d (methanogenic)

• Results justify choice of 546 days and Monitored Natural Attenuation asgroundwater remediation technique

�Applying risk based remediation

Light aircraft crash site, Kent

�Residual Human Health andenvironmental impacts

• Unburnt jet fuel, combustion products and firefighting foam

• Aim to protect residents and neighbours, and

• Environment – rare designated area of meadow andwoodland in suburbs

• Tight access and public sensitivity

• Legal claims and confidentiality

�Applying risk based remediation

Receptors – residents, neighbours, environmentHuman Health and Environmental Risk Assessments

�

No.4No.5

BH02shallow

BH010.5-0.7

BH01B0.1-0.2BH03

0.3-0.5

BH040.1-0.3

BH050.3-0.5

BH060.1-0.3

BH070.3-0.5

BH080.2-0.5

BH090.3-0.5

BH100.3-0.5

BH120.3-0.5

BH130.2-0.4

BH140.2-0.4

BH170.1-0.2

BH210.2-0.4

0.7-1.0

STRICTLY CONFIDENTIAL – PRIVILEGED AND INCONTEMPLATION OF POTENTIAL CLAIMS ACTIVITY

BH1030.3-0.5

BH1040.3-0.5

BH1050.1-0.2

BH1120.3-0.5

BH1090.1-0.2

Project * Concentrations of any individual aliphatic oraromatic hydrocarbon fraction (e.g. aliphatic<C6-C8) found exceeding the SSV.

Location with exceedance* of theResidential (With Plant Uptake) SSVfor TPH (June 2008)

Borehole or Inspection Pit

No Exceedance of the SSV forTPH (June/ July 2008)

0.4-0.6 Depth of Sample (s) Analysed (mbgl)

Key

BH1080.1-0.3

BH1100.3-0.5

BH1110.5-0.6

BH1060.2-0.4

BH1070.3-0.5

Location with exceedance* of theResidential (With Plant Uptake) SSVfor TPH (May 2008)

No Exceedance of the SSV forTPH (May 2008)

Approximate area of soilsimpacted by hydrocarboncontamination

APPROXIMATE AREA OFCONTAMINATED SOILS

= 260m2

�Rapid on site assessment

• Helicopter crash onhilltop at farm

• Localised shallowimpacts – fuel,firefighting foam,some debris

• Difficult access

• Need for rapidaction

�Rapid on site assessment

• Soil samples in plastic bags,closed and left for 1 hour

• Vapour measured with PID

• Results only qualititative butclear definition of clean andcontaminated areas

• Assessed remedial volumesin < 1 day

• Also good for diesel spills

�Rapid on site assessment

�Rapid on site assessment

• On site labs for morecomplete assessment

• Rapid turnaround

• But results vary andrequires lab verification

• Technology evolving andreliability improvingrapidly Field Portable X Ray Fluorescence Analyser

From Forestry Research UK

�Sustainable Remediation ofContaminated Land

• Sustainable development is development that meets theneeds of the present without compromising the ability offuture generations to meet their own needs. (Brundtland,1987)

• .. to enable all people to satisfy their basic needs andenjoy a better quality of life without compromising thequality of life of future generations. (UK government)

What is sustainability?

�Can brownfield remediation besustainable?

• Redevelopment of brownfield land is a priority indicatorfor UK sustainable development agenda, to createSustainable Communities, with 60% of new homes onbrownfield.

• National Brownfield Strategy (March 2008):1. Identify, assess and prepare brownfield for next 15 to 20 years;

2. Safeguarding the environment - not all brownfield land is suitablefor redevelopment;

3. Enhancing communities, by tackling visual and economic blight

4. Accreditation and skills, ensuring a ‘joined up’ approach tobrownfield land reuse

�What is Sustainable Remediation?Is it green?

• Sustainable remediation (UK)

The practice of demonstrating, in terms of environmental,economic and social indicators, that an acceptablebalance exists between the effects of undertaking theremediation activities and the benefits the same activitieswill deliver.

• Green Remediation (US EPA)‘The practice of considering all environmental effects ofremedy implementation and incorporating options tomaximize net environmental benefit of cleanup actions’.

.

�Is sustainability considered forremediation

Sustainability considered ? Methods for selecting best technology

From SUBR: IM Bulletin 2, 2007

�Assessing sustainable of remedialapproaches

• Energy requirements,

• Air emissions,

• Water requirements and associated impacts on waterresources,

• Impacts on land and ecosystems,

• Material consumption and waste generation, and

• Impacts on long-term stewardship of a site.

Introducing Assessment of:

�Assessment Process

Excavation

Groundwater Treatment B

Groundwater Treatment A

Soil Treatment A

Others, as Identified

Vapor Treatment

Soil Treatment C

Soil Treatment B

Transportation

Air releases

Exposure hours

Treatment

Others, as Identified

Land use

Water losses

Off-site transfers

RemediationSustainabilityParameters------------------• Pollutants• Green House Gases• Air quality• Water• Waste• Resources• Energy• Water• Land• People

Remedial Options Calculation Data

RemediationProjectData------------------• Size• Volume• Quantity• Distance• Etc.

Ref: DuPont’s Conceptual Framework for Sustainability Analysis, SURF USA

�

Soil Wa 2 2 2

Electrok 1 3 3

1

5

Chemi

Res

ourc

es

Ene

rgy

Env

ironm

ent

Thermal

Bioreme

1

3

2

1

5

4

3

3

1

Was

te

2

1

4

Bioreme 4 2 4 3

Technologies and Impacts

etc…

Matrix of RemediationTechnologies andImpacts

�Initial results from research project

Ref: Michael Harbottle & Abir Al-Tabbaa, SUBR: IM

�Carbon FootprintingKey Components

Transportation

Direct CO, CO2Emissions

WasteDisposal

Other

Energy (IndirectCO2e)

CO2Chemicals/Consumables

�Sustainable brownfield remediationlinks

• CL:AIRE SuRF UK and SUBR:IM reportshttp://www.claire.co.uk/

• SURF USA http://www.sustainableremediation.org/

• NICOLE working group on Sustainable remediation,conferences March 2008 & June 2009http://www.nicole.org/

�Forward Look

• Progress in technology improvements, waste reductionand reuse, more appropriate remediation, acceptance ofinnovative and in situ techniques

• Current economic climate requires cheap techniques, butspeed and space are less critical

• Opportunity for slower, lower cost and lower energyoptions, e.g. phyto-remediation, in site bioremediation andMNA, PRBs

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