EPA Plans to Issue Final Subsurface Vapor Intrusion Guidances

EPA has made substantial progress during the past year in preparing its final guidances for the vapor intrusion pathway. EPA has extensively engaged stakeholders and considered extensive and substantive public comments received in 2011 and 2012. Additionally EPA has prepared external review drafts of the guidance documents for public input through May 24, 2013 (see above). EPA is working to complete its work expeditiously and issue final subsurface vapor intrusion guidances so that it can be applied in forthcoming decisions. Prior comments as well as new comments can be viewed at Regulations.gov (EPA-HQ-RCRA-2002-0033).

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EPA Technical Documents and Tools Prepared to Support Guidance Development

EPA has prepared several documents and tools, shown below, to support development of its Final Subsurface Vapor Intrusion Guidance. In addition, relevant research publications prepared by the EPA Office of Research and Development (see Related Links) will also be considered.

• Background Indoor Air Concentrations of Volatile Organic Compounds in North American Residences (1990 – 2005): A Compilation of Statistics for Assessing Vapor Intrusion.
• EPA's Vapor Intrusion Database: Evaluation and Characterization of Attenuation Factors for Chlorinated Volatile Organic Compounds and Residential Buildings.
• Conceptual Model Scenarios for the Vapor Intrusion Pathway.
• Indoor Air Vapor Intrusion Mitigation Approaches.
• Frequently Asked Questions about Vapor Intrusion
• Vapor Intrusion Screening Levels
• Petroleum Hydrocarbons And Chlorinated Hydrocarbons Differ In Their Potential For Vapor Intrusion.

Some EPA Tools:

• EPA Spreadsheet for Modeling Subsurface Vapor Intrusion
• Vapor Intrusion Database - Contains site-specific measurements of vapor attenuation factors, which express the reduction in vapor concentrations as volatile contaminants  move from sub-surface sources into indoor air.

EPA Guidance Documents That May Be Helpful

In 2002, EPA released the OSWER Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance) - This document presents technical and policy recommendations of the Office of Solid Waste and Emergency Response for evaluation subsurface vapor intrusion. Until EPA issues a final version of its vapor intrusion guidance, we recommend using the 2002 draft and other available sound scientific information to address vapor intrusion.

In August 2010, EPA released its Review of the 2002 Draft OSWER Subsurface Vapor Intrusion Guidance PDF (7 pp, 79K, About PDF).

The Brownfields and Land Revitalization Technology Support Center has developed a primer for land revitalization stakeholders concerned about vapor intrusion, including property owners, municipalities, and real estate developers; see Brownfields Technology Primer: Vapor Intrusion Considerations for  Redevelopment (PDF) (49 pp, 1.2MB,  About PDF) .  This document provides an overview of vapor intrusion and how it can affect redevelopment. It also summarizes techniques for quickly and cost effectively assessing the potential for vapor intrusion, which can be implemented in consultation with qualified scientists and engineers.

Fact Sheet for Correcting the Henry's Law Constant for Temperature (PDF) (9 pp, 186K,  About PDF)

EPA HRS Rule-Making Effort

EPA is working toward a proposed rulemaking to add a new screening component to OSWER's Hazard Ranking System (HRS), which would allow sites impacted by vapor intrusion or intrusion of other subsurface contamination to be evaluated for placement on the Superfund National Priorities List (NPL). Through this change, the HRS could directly consider the human exposure to contaminants that enter building structures from the subsurface environment.