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Vapor Intrusion and the Superfund Program

Vapor Intrusion

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This website provides some key information on vapor intrusion and the Superfund program for members of the public who may be interested in this topic and U.S. Environmental Protection Agency (EPA or Agency) professionals who have responsibilities for implementing the program. The page is divided into two sections. The first features general information about vapor intrusion, while the second features information specific to the addition of Subsurface Intrusion (SsI), which includes vapor intrusion, to the Hazard Ranking System (HRS). The information in the two sections overlap considerably but contact information for each area is different. All covered subjects can be accessed through the following links:

Additional information about vapor intrusion can be found on the EPA's Office of Solid Waste and Emergency Response (OSWER) Vapor Intrusion website.

General Information

Vapor Intrusion Screening Levels

The EPA's Office of Superfund Remediation and Technology Innovation has developed a spreadsheet tool, the Vapor Intrusion Screening Level (VISL) Calculator, that: (1) lists chemicals considered to be volatile and sufficiently toxic through the inhalation pathway; and (2) provides VISLs for ground water, soil gas and indoor air, which are generally recommended, media-specific, risk-based screening-level concentrations. The primary purpose of the VISL calculator is to assist Superfund site managers and risk assessors in determining, based on an initial comparison of site data against the VISLs: whether chemicals found in ground water or soil gas can pose a significant risk through vapor intrusion; and, if so, whether a site-specific vapor intrusion investigation is warranted. Other Agency cleanup programs may also find it helpful to consider the VISLs for their own specific needs.

For further information, please contact Alicia Frame, phone: 703-603-8777, email: Alicia Frame (frame.alicia@epa.gov)

Trichloroethylene and Vapor Intrusion

Trichloroethylene, or TCE, is a widely used industrial chemical frequently found at Superfund sites as a contaminant in soil and groundwater. Scientific evidence indicates TCE poses potential cancer and non-cancer human health hazards. The Office of Superfund Remediation and Technology Innovation has compiled information (Compilation of Information Relating to Early/Interim Actions at Superfund Sites and the TCE IRIS Assessment) regarding existing EPA guidance on early or interim actions at Superfund sites where investigations of indoor air contamination identify site-related TCE concentrations.

Community Involvement and Vapor Intrusion

Community and stakeholder involvement is a key component of any Superfund site investigation and response action. It is particularly important for Superfund sites with vapor intrusion issues, where the exposures to toxic vapors in homes, workplaces, schools and places of commerce may be unavoidable (in the absence of mitigation systems). Community and stakeholder involvement activities should, therefore, be initiated as soon as possible after the determination that VI concerns exist at a particular site.

The EPA has developed a Superfund Community Involvement website devoted to describing the Superfund community involvement process and providing planning resources. Other Agency cleanup programs may also find it helpful to consider these materials.

If you have concerns about vapor intrusion where you live or work, please contact your state health department.

Five-year Reviews and Vapor Intrusion

Section 121 of the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA), requires that remedial actions which result in any hazardous substances, pollutants or contaminants remaining at the site be re-evaluated every five years to determine if the remedy is and will continue to be protective of human health and the environment. OSWER Directive 9200.2-84 provides a recommended framework for assessing vapor intrusion in the context of the Superfund five-year review process, Assessing Protectiveness at Sites for Vapor Intrusion (PDF)(13 pp, 188 K).

For further information, please contact Rich Kapuscinski, phone: 703-305-7411, email: Rich Kapuscinski (kapuscinski.rich@epa.gov)

Addition of Subsurface Intrusion (SsI) to the HRS

Related Links | Listening Sessions | Contacts

Subsurface intrusion is the migration of hazardous substances, pollutants and contaminants from the unsaturated zone and/or the surficial ground water into overlying structures. While subsurface intrusion can take multiple forms, the most common form of subsurface intrusion is vapor intrusion. The EPA is considering the addition of a new screening mechanism to the Hazard Ranking System (HRS) to enable sites with subsurface intrusion contamination to be evaluated for placement on the National Priorities List (NPL).

In a May 2010 report (EPA's Estimated Costs to Remediate Existing Sites Exceed Current Funding Levels, and More Sites are Expected to Be Added to the National Priorities List, GAO Report to Congressional Requesters, GAO-10-380, May 2010), the Government Accountability Office (GAO) concluded that if vapor intrusion sites are not assessed and, if needed, listed on the NPL, there is the potential that contaminated sites with unacceptable human exposure will not be acted upon. GAO recommended that the EPA Administrator determine the extent to which the EPA will consider vapor intrusion in listing NPL sites and how this will affect the number of NPL sites listed in the future. The HRS is Appendix A to the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), which the EPA promulgated on July 16, 1982 (47 FR 31180) pursuant to section 105(a)(8)(A) of CERCLA. The HRS is the principal mechanism the EPA uses to place sites on the CERCLA NPL.

The addition would enable the HRS to directly consider the human exposure to contaminants that enter building structures through the subsurface environment. When hazardous substances, pollutants or contaminants are spilled on the ground or otherwise migrate to the subsurface, they can move in the subsurface environment and eventually enter buildings as a gas or vapor, or even as a liquid in some cases. Dry cleaning solvents and industrial de-greasers are products that contain hazardous substances that when released to the environment, can migrate into the soil and subsurface environment, enter buildings by seeping through cracks in basements, foundations, sewer lines and other openings and ultimately result in human exposures. Vapor intrusion is a particular concern because concentrations of vapors can rise to a point where the health of residents or workers in those buildings could be at risk. Intrusion of contaminants in a non-vapor state may also be a pathway of concern because of the potential for human exposure to the liquids, the resulting precipitates, or associated vapors.

Many sites on the NPL that have subsurface intrusion problems were placed on the NPL by evaluation of pathways other than a subsurface intrusion mechanism. There are other contaminated sites that did not qualify for placement on the NPL under the current HRS. However, these sites may qualify for placement on the NPL if the threat from subsurface intrusion was included in the HRS. A new HRS mechanism would enable the EPA to identify situations in which individuals are exposed or potentially exposed to vapor or other contaminant intrusion in dwellings, work places or other structures or enclosures.

The Agency conducted public outreach activities, including facilitating public listening sessions, providing public information documents and establishing a website with more information regarding this rulemaking. The Agency considered the information gathered from the January 31, 2011, Federal Register Notice, listening sessions and other sources before making the decision to issue a proposed rulemaking to add subsurface intrusion to the HRS. The Agency requested comments only regarding this addition to the HRS, and it is not considering changes to the remainder of the HRS. Please note that the comment period for the January 31, 2011, Federal Register Notice ended on April 16, 2011, 11:59 PM ET.

HRS SsI Related Links

HRS SsI Listening Sessions

The EPA held four listening sessions following publication of the January 31, 2011, Federal Register Notice to allow interested parties to present feedback on the potential HRS addition. This input was considered by the Agency as it determined whether to move forward with this addition to the HRS.

The first listening session was held in Arlington, VA on February 24, 2011. The second listening session was held in San Francisco, CA on March 16, 2011. The third listening session was held in Albuquerque, NM on March 30, 2011, and the fourth listening session was held in Edison, NJ on April 7, 2011.

For a transcript and copy of the slide presentation from the Arlington, VA listening session, click here:

HRS SsI Contacts

For further information, please contact the following:

General Issues - Terry Jeng, phone: (703) 603-8852, email: Terry Jeng (jeng.terry@epa.gov)
Technical issues - Brenda Nixon-Cook, phone: (214) 665-7436, email: Brenda Cook (cook.brenda@epa.gov)
                            Jennifer Wendel, phone: (404) 562-8799, email: Jennifer Wendel (wendel.jennifer@epa.gov)
                            Lorie Baker, phone: (215) 814-3355, email: Lorie Baker (baker.lorie@epa.gov)

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