Landfill and Ground-Gases –VOCs and Vapour Intrusion –

The Assessment and Management of Gas Contamination in Australia

Peter Gringinger & Anthony Lane

EcoForum 2010, 23-24 February 2010, Sydney

Contents

• Why bother about Landfill Gas (LFG), Ground Gas (GG), VOCs and Soil Vapour Intrusion (SVI)?

• Sources, pathways, receptors & risks of GG & SVI• Current guidance on GG and SVI in Australia (?)• Development and status of guidance in UK and

North America• GG and SVI assessment as part of the LCM cycle• Australian GG and SVI Guidance Framework• Conclusions

Why bother about LFG?

• Cranbourne landfill case, in context of urban sprawl, demand for housing, brownfieldsdevelopment

Why bother about LFG?

• Cranbourne Landfill LFG CSM

Why bother about GG?

• Loscoe, Derbyshire, 1986

• Abbeystead, Lancashire, UK 1984

Why bother about VOCs and SVI?

• Barkley Street Case, Brunswick• Redfield, Colorado

Why bother about VOCs and SVI?• Endicott, Upstate New York

“Hypothetical” Case GG

Former Landfill1960s-1970s

Proposed ResidentialDevelopment

“Hypothetical” Case SVI

Primary School

Possible Sources for SVI

Car Dealership

Service Station

Sources, pathways, receptors & risks of GG and SVI (CSM)

Sources and Risks of GG

• Landfills• 1990s and 2000s: Moderate to very high (but

mostly lined and controlled)• 1960s to 1990s: Moderate to very high risk• <1960s: Low to moderate

• Fill (with high organic content), foundry sands, sewage sludge: Low to moderate

• Coal mine workings: Low to high• Peat and coal measures: Low

Sources and Risks of SVI

• Service Stations and Drycleaners: High• Workshops and small factories: Moderate to

high (incl. bakeries, engineering shops etc)• Petro-chemical industry: Very High • Landfills: Low to High• NOTE: Organic sources and plumes can emit methane due to

biodegradation (i.e. 1mg/L of CH4 in GW could result in up to 4% in soil vapour but flow rates likely low)

Current guidance on GG and SVI in Australia

• EPA Vic Pub 722 – Reduction of GHG from Landfills (?)

• EPA Vic Pub 788 – Siting, Design, Operation and Rehabilitation of Landfills

• EPA SA – Env Mgmt of landfill facilities• EPA NSW Technical Note on VI• Revised NEPM? (noting that VI criteria for

Petroleum Hydrocarbons will be included)

Overseas Guidance on GG – UK• Developed over last 25 years after incidents in 1980s• Mature guidance, regularly updated, extensive practical

experience• GG assessments are required and integral part of LCM

cycle and development policies (planning, building, environmental regulations)

• Main Guidance documents• Construction and Industry Research and Information

Association – CIRIA C665, 2008 and C682 (SVI), 2009• British Standard BS8485: 2007• National House-Building Council NHBC 2007• (Ground Gas Handbook, 2009)

GG Assessment Approach (UK)• Initial Desk Study (Phase 1) with CSM on sources,

potential pathways, receptors critical (including good knowledge of Geology & Hydrogeology) & initial screening

• Intrusive assessments (Phase 2)• Detailed soil (organic material) descriptions• TOC/DOC & gas generation tests• Gas monitoring wells

• Spacing depends on gas risk and sensitivity of end use• Bore installation determined by CSM (i.e. permeable

strata)• Periods and frequency of monitoring determined by gas

risk and sensitivity of end use (range from 4x1 to 24x24)

GG Risk Assessment Approach (UK)• Tier 1: CSM & S-P-R approach and likelihood and

consequences (i.e. similar to AS on Env RA) and can include generic screening criteria

• Tier 2: Qualitative Assessment for CH4 and CO2• Gas screening value (GSV) = Borehole flow rate x

gas concentration (%)• GSV determined risk classification (NHBC or CIRIA)• GSV determines scope of protection measures

(types, design, construction & validation)• Tier 3: Quantitative Risk Assessment for high risk

cases using fault tree analysis, models, continuous gas monitoring (e.g. Gasclam – www.gasclam.co.uk )

GG Risk classification & Mitigation

SVI Guidance Approach (US/UK)• Can largely be based on ASTM, ITRC, USEPA &

CIRIA guidance (and few others) and include phased and tiered risk based approach (see GG)• Sources, transport and pathways of VOCs may differ

to GG (VOCs are complex from a process perspective)

• Hence CSM’s account for this and in detailed investigations (e.g. bore locations, screen depths, screen lengths, use of multilevel installations etc)

• Mitigation measures largely similar to GG (with differences in detailed design; e.g. resistance of barriers against VOCs)

SVI Guidance Approach (US/UK)• Preliminary Risk Assessments (Tier 1) use Soil

Guidance Values for Groundwater and/or Soil Vapour data (few jurisdictions)

• Generic Risk Assessments (Tier 2) for SVI rely either on Attenuation Factors (AF between sub-surface and indoor air vapour concentrations) to determine risk levels or generic vapour transport models (i.e. most commonly the Johnson & Ettinger (1991) model)

• Detailed Risk Assessments (Tier 3) use site specific models, numerical models, indoor air data etc

Australian Framework Guidance to GG and SVI Assessment and Mgmt

• Integrate with existing guidance (i.e. NEPM) and consideration from start of assessment process

• Use phased and tiered risk based approach• Emphasise use of CSM and S-P-R approach• Use of GSV and AF plus models* • Reference to best available UK/US guidance for assessment

to provide technical details• Has to be an iterative multiple lines of evidence approach• Include comprehensive coverage of mitigation and

management measures (including design, construction and validation)

• Who to develop? – e.g. CRC CARE, CSIRO

Undertake additionalintrusive

investigationsand/ or

monitoring & sampling

No

Review data

Is data reliable? (e.g. appropriate response zones,

variable/ unrepresentative groundwater levels)

Has monitoring been carried out

under varying conditions likely

to influence the gas vapour regime?

Results sufficientlyconsistent/ reliable?

Source(s) ofgas(es)/ vapour(s)

identified?

Extent of source(s) established?

Refine conceptual site model

Consider odour & toxicity and incorporate

into risk assessment as appropriate

Undertake appropriate risk assessment modelling. Define gas

regime

Does risk assessmentdemonstrate

corrective actionrequired?

No

No

No

No

Yes

No

Yes

Yes

Yes

Yes

Yes

Amber Red

NO FURTHER ACTION REQUIRED

Green

Define the context & set the objectives

Carry out Phase One Desk Study

Develop initial conceptual site model& undertake preliminary risk assessment

Has development of modelincluded site specific factors

that may influence gas/vapour regime

Are there potential unacceptable risks?

Identify further actions to clarify potential unacceptable risks

Establish objectives of any further investigations

Carry out further investigation[desk based/intrusive/ Monitoring]

NO FURTHER ACTION REQUIRED

Yes

No

Yes

Identify remedial objectives to mitigate

unacceptable risks

Identify feasible remedial options

Has sufficientdata been

obtained to allowthe selection/ design

of appropriateremedial

solutions?

Undertake additional intrusive

investigations

Detailed evaluation of remedial options

Develop a remedial strategy

Design, implementation & verification of

remedial measures

Is post installation/ construction

monitoring required?

Undertake post installation/construction monitoring

Is the monitoringdata acceptable?

Yes

No

No

Yes

Yes

NO FURTHER ACTION REQUIRED

Site Characterisation Assessment of Risk Determination / Validation of Remediation

Have these factors identified the

potential presence of gas/vapour?

Yes

No

No

Completion/Validation Report

Figure 1. The Process of Managing Risks Related to Hazardous Ground Gases

No

Review/amend

remedial strategy

CIRIA C665GG

Australian Framework Guidance to GG and SVI Assessment and Mgmt• Staged Assessment

• Site Assessment• Desk Study (Screening)• Intrusive Investigation• Monitoring & Sampling

• Data Assessment• CSM• Risk Assessment

• Tier 1, 2 and 3• Mitigation Design &

Implemention• Verification

CIRIA C682SVI

ASTM E2600SVI

ITRC, 2007SVI

Australian Framework Guidance to GG and SVI Assessment and Mgmt

Data Analysis

•Remedial Objectives• Options Screening & evaluation• Remedial Strategy• Design, implement & verification• Monitoring and Validation

(Potentially) Contaminated Site

Preliminary (GG/SVI) Site Assessment (Desk Study & Walkover)

Site Investigation

Risk Assessment

Risk Mitigation and Remediation

Site Close Out

• Site History (on- & offsite)• COPC’s (Gases and VOCs) • Initial CSM & preliminary RA

• Work Plan based on CSM• Intrusive Investigation• Monitoring Program

• Collate Data• Analyse & Review (incl QA/AC)• Refine CSM• Include odour and toxicity issues

• Tier1: Generic guideline levels• Tier 2: GSV or AF & generic models• Tier 3: Site specific DQRA

Conclusions• Not only landfills produce ground gases• Not only servos and drycleaners have SVI issues• GG and SVI issues are common• It’s the Geology (pathway) stupid• Hence know your CSM and S-P-R (stupid)• Phased and tiered Risk based Assessment• Integration of GG and SVI from start of Land

Contamination (just like soil and GW) Assessment• Mitigation and Mgmt details are part of the deal• National guidelines needed (to avoid another

Cranbourne) & minimise litigation potential

References and Links• CIRIA, 2007: Assessing risks posed by hazardous ground gases to

buildings, C665.• CIRIA, 2009: The VOCs Handbook, Investigating, assessing and

managing risks from inhalation of VOCs at land affected by contamination. C682.

• Wilson, S.; G. Card & S. Haines, 2009: Ground Gas Handbook. Whittles Publishing, UK.

• ASTM, 2008: E2600-08 Standard Practice of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions.

• British Standard, 2007: BS8485:2007 Code of practice for the characterization and remediation from ground gas in affected developments.

• NHBC, 2007: Guidance on Evaluation of Development Proposals on Sites where Methane and Carbon Dioxide are Present. Report Edition No. 04, March 2007.

References and Links• API, 2005. Collecting and Interpreting Soil Gas Samples from the

Vadose Zone, A Practical Strategy for Assessing the Subsurface Vapor-to-Indoor Air Migration Pathway at Petroleum Hydrocarbon Sites. Publication No. 4741.

• EPRI, 2005. Reference Handbook for Site Specific Assessment of Subsurface Vapor Intrusion to Indoor Air. March 2005.

• ITRC, 2007: Vapor Intrusion Pathway: A Practical Guide. Technical and Regulatory Guidance, January 2007.

• CALEPA/DTSC, 2004. Guidance for the Evaluation and Mitigation of Subsurface Vapor to Indoor Air, Interim Final, December 2004.

• CALEPA/DTSC, 2009. Vapor Intrusion Mitigation Advisory. April 2009.• USEPA, 2008: Brownfields Technology Primer: Vapor Intrusion

Considerations for Redevelopment. EPA/542/R-08-001, March 2008.• USEPA, 2008. Engineering Issue: Indoor Air Vapor Intrusion Mitigation

Approaches. EPA/600/R-08-115, October 2008.• USDOD, 2009. DoD Vapor Intrusion Handbook. January 2009.

References and Links• NYSDOH, 2006. Guidance for Evaluating Soil Vapor Intrusion in the

State of New York. October 2006.• USEPA, 2002. OSWER Draft Guidance for Evaluating the Vapor

Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance). EPA/530/D02-004, November 2002.

• USEPA, 2005. Guidance for Evaluating Landfill Gas Emissions from Closed or Abandoned Facilities. EPA/600/R05-123a, September 2005.

References and Links

• Clu-In Vapor Intrusion Focus Area www.clu-in.org/issues/default.focus/sec/Vapor_Intrusion/cat/Overview/

• EnviroGroup Vapor Intrusion Links www.envirogroup.com/links.php

• Indoor Air Vapor Intrusion Database iavi.rti.org/• ITRC Vapor Intrusion Site

www.itrcweb.org/teampublic_Vapor.asp• The Landfill Gas Expert www.landfill-gas.com/

GG Training

• ACLCA Vic is planning a 4-day short course on “Landfill Gas investigation, risk assessment and remediation” some time between July to September 2010

• Watch for details on www.aclca.org.au