landfill and ground-gases - vocs and vapour intrusion - the assessment and management of gas...
TRANSCRIPT
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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
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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
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Why bother about LFG?
• Cranbourne landfill case, in context of urban sprawl, demand for housing, brownfieldsdevelopment
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Why bother about LFG?
• Cranbourne Landfill LFG CSM
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Why bother about GG?
• Loscoe, Derbyshire, 1986
• Abbeystead, Lancashire, UK 1984
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Why bother about VOCs and SVI?
• Barkley Street Case, Brunswick• Redfield, Colorado
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Why bother about VOCs and SVI?• Endicott, Upstate New York
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“Hypothetical” Case GG
Former Landfill1960s-1970s
Proposed ResidentialDevelopment
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“Hypothetical” Case SVI
Primary School
Possible Sources for SVI
Car Dealership
Service Station
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Sources, pathways, receptors & risks of GG and SVI (CSM)
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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
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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)
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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)
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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)
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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)
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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 )
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GG Risk classification & Mitigation
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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)
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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
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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
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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
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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
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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
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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.
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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.
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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.
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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/
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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