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## Vapor Intrusion Guidance

Overview for Stakeholders By EPA’ Offi f S lid W t d E R EPA’ s Offi ce o f S o lid W as t e an d E mergency R esponse Office of Superfund Remediat ion and Technology Innovation Office of Underground Storage Tanks

April 2013 1 U.S. Environmental Protection Agency



## Briefin g Ob ectives j • 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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## Pur p ose & Sco p e of VIG p • Addresses vapor intrusion for – CERCLA and RCRA corrective action sites and associated residential and non-residential buildings Full range of vapor forming chemicals found at

– Full range of vapor - forming chemicals found at these and other sites (e .g., PCE, TCE, other chlorinated solvents, pet roleum hydrocarbons (PHCs))
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## Pur p ose & Sco p e of VIG p • 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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## Develo p ment 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 April 2013 U.S. Environmental Protection Agency 5



## Ex p anded VIG Com p onents p • 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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## Ex p anded VIG Com p onents p • 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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## A dditional 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 Su pp ort 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 April 2013 U.S. Environmental Protection Agency 9



## A dditional VIG Technical Resources • Published and available online – Vapor intrusion screening le vel calculator (to be updated) 

### • Forthcoming

– Enhanced spreadsheet tool for implementing 1-D (Johnson-Ettinger) model

April 2013 U.S. Environmental Protection Agency 106 

## PVI Guidance: Back g round • 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 April 2013 12 U.S. Environmental Protection Agency7 

## Ste p s in PVI Investi g ation g • 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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## Ste p s in PVI Investi g ation g • For buildings within the lateral inclusion zone, determine vertical separati on 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 preferentia l transport pathways • Mitigate petroleum vapor intrusion • Community Engagement

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## PVI Guidance: Su pp ortin Documents g

• 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 Em p irical Data To Su pp ort Soil Va p or Intrusion pp p Screening Criteria For Petrol eum Hydrocarbon Compounds (EPA 510-R-13-001) January 2013

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## PVI Guidance: Su pp ortin Documents g • 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 feet10 

## Vertical Separation Distances For LNAPL PHC sources = 15 feet PHC sources = 15 feet



## Next Ste p s • 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

April 2013 U.S. Environmental Protection Agency 2011 

## 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 April 2013 21 U.S. Environmental Protection Agency



## On
- line Vapor Intrusion Resources line Vapor Intrusion Resources

• http://www.epa.gov/oswer/vaporintrusion/
• http://www.epa.gov/oswer/vaporintrusion/guid ance.html
• htt p ://www.e p a. g ov/oust/cat/ p vi/index.htm pg p

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