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Vapor Intrusion Guidance

Overview for Stakeholders 

By

EPA’ Offi f S lid W t d E R EPA’s Office of Solid Waste and Emergency Response

Office of Superfund Remediation and Technology Innovation

Office of Underground Storage Tanks

April 2013 U.S. Environmental Protection Agency 1

Briefing j Ob ectives

• Provide broad overview of two forthcoming 

vapor intrusion guidance documents

– OSWER general vapor intrusion guidance (VIG)

– ‘Petroleum vapor intrusion’ (PVI) guidance

• Discuss public review and input process

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Purp p ose & Scope of VIG

• Addresses vapor intrusion for

– CERCLA and RCRA corrective action sites and 

associated residential and non-residential 

buildings

– Full range of vapor Full range of vapor-forming chemicals found at forming chemicals found at

these and other sites (e.g., PCE, TCE, other 

chlorinated solvents, petroleum hydrocarbons 

(PHCs))

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Purp p ose & Scope of VIG

• Also intended for brownfield redevelopment 

sites subject to EPA grants (where state and 

tribal agencies opt to implement the VIG)

• Will supersede and replace

– 2002 draft VI guidance

– Existing Regional guidances for VI assessment

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Development Process for VIG

• Public comments considered from past 11 

years

– 2002 draft VI guidance 

– 2011 Federal Register solicitation

– 2012 on-line technical support documents

• Intra-agency work group (representing EPA 

regions and program offices) prepared 

consensus document

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Exp p anded VIG Components

• Flexible framework for planning and 

conducting investigations to evaluate sites 

and buildings

• Methods to account for ‘background’ 

contributions to indoor air concentrations

• Risk management decision-making 

framework

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Exp p anded VIG Components

• Community involvement 

• Engineered exposure controls (i.e., building 

mitigation)

– Operation and maintenance

– Monitoring, including termination criteria

– Pre-emptive mitigation option

• Institutional controls

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Additional Features of Interest

• Updated screening levels, attenuation factors 

• Emphasis on multiple lines of evidence (e.g., 

to support no-further-action decisions)

– Biodegradability in the vadose zone

– Geology and hydrology in the vadose zone

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VIG Technical Support Documents

• Published and available online 

– ‘Background’ concentration document

– Conceptual model scenarios document

– Database paper 

• Forthcoming

– Document about engineered exposure controls for 

buildings (building mitigation)

– Case studies to illustrate concepts and guidance

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Additional VIG Technical Resources 

• Published and available online 

– Vapor intrusion screening level calculator (to be 

updated)

• Forthcoming

– Enhanced spreadsheet tool for implementing 1-D 

(Johnson-Ettinger) model

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PVI Guidance: Background 

• EPA’s draft 2002 Vapor Intrusion Guidance did 

not address petroleum

• Interest from states and regulated community

• PVI effort initiated in 2009

• EPA Inspector General noted need for 

petroleum vapor intrusion guidance 

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Overview of PVI Guidance

• Companion document to VIG

– Focus is on typical corner gas stations (USTs that 

are regulated under 40 CFR 280)

– Petroleum hydrocarbons biodegrade aerobically 

relatively quickly over short distance relatively quickly over short distance

• Simple screening criteria to better focus 

scarce resources on UST sites with greater 

potential for PVI

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Step g s in PVI Investigation

• Assess and mitigate immediate threats to 

safety

• Conduct a site characterization and develop a 

conceptual site model 

• Construct a lateral inclusion zone

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Step g s in PVI Investigation

• For buildings within the lateral inclusion zone, 

determine vertical separation distance – thickness of 

clean, biologically active soil:

– 6 feet for dissolved PHC plumes; 15 feet for LNAPL PHC sources

– If these thicknesses are not met, then EPA recommends sub-slab 

sampling

• Identify preferential transport pathways

• Mitigate petroleum vapor intrusion

• Community Engagement 

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PVI Guidance: Supp g ortin Documents

• An Approach for Developing Site-Specific Lateral and Vertical 

Inclusion Zones within which Structures Should be Evaluated for 

Petroleum Vapor Intrusion due to Releases of Motor Fuel from 

Underground Storage Tanks (EPA/600/R-13/047) December 

2012

• Evaluation Of Emp pp p irical Data To Support Soil Vapor Intrusion 

Screening Criteria For Petroleum Hydrocarbon Compounds (EPA 

510-R-13-001) January 2013

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PVI Guidance: Supp g ortin Documents 

• Forthcoming 

– Technical supporting information for PVI sites 

addressing vapor intrusion modeling (ORD 

technical paper)

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Lateral Inclusion Zone

Vertical Separation Distances

For Dissolved PHC sources = 6 feet
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Vertical Separation Distances

For LNAPL PHC sources = 15 feet PHC sources = 15 feet

Next Steps

• External review drafts available on-line April 

16, 2013 

http://www.epa.gov/oswer/vaporintrusion/

• Public input due to docket [EPA-HQ-RCRA2002-0033-0071] by May 24 2013 0071] by May 24, 2013

http://www.regulations.gov/

• Inter-agency review planned

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VI Guidance Contacts VI Guidance Contacts

• VIG

– Rich Kapuscinski Kapuscinski.rich@epa.gov (703) 

305-7411

– Helen Dawson Dawson.helen@epa.gov (703) 603-

8833

• PVI Guide

– Hal White White.hal@epa.gov (703) 603-7177

– Will Anderson Anderson.will@epa.gov (703) 603-

7156

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On-line Vapor Intrusion Resources line Vapor Intrusion Resources

• http://www.epa.gov/oswer/vaporintrusion/

• http://www.epa.gov/oswer/vaporintrusion/guid

ance.html

• http pg p ://www.epa.gov/oust/cat/pvi/index.htm

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