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February 1, 2011 |
USEPA Releases Review of the Draft 2002 Subsurface Vapor Intrusion GuidanceFederal and state environmental and public health agencies are beginning to formally regulate vapor intrusion.1 For example, the Illinois EPA is in the process of promulgating amendments to the state's clean-up methodology (the "TACO" Guidelines) to include vapor intrusion as a pathway for exposure to hazardous substances. If these amendments are adopted, any evaluation or remediation of a site will be required to address the vapor intrusion pathway along with the other pathways for human exposure. Other states such as Alaska, California, Colorado, Indiana, Pennsylvania, New Hampshire, New Jersey and New York have also taken action towards addressing this issue. At the federal level, USEPA's Office of Solid Waste and Emergency Response ("OSWER") has reevaluated its 2002 Subsurface Vapor Intrusion Guidance ("2002 Guidance"). The 2002 Guidance was never finalized and in December 2009, USEPA's Office of Inspector General ("OIG") published a report titled "Lack of Final Guidance on Vapor Intrusion Impedes Efforts to Address Indoor Air Risks." In this report, the OIG suggested, among other recommendations, that USEPA should "identify and publicly report" what portions of the 2002 Guidance remain valid and what sections of the Guidance will be updated in a future final guidance document. In December 2010, USEPA responded to this recommendation by publishing a "Review of the Draft 2002 Subsurface Vapor Intrusion Guidance." The 2002 Guidance consists of a three-tier screening process. Tier 1 uses general knowledge of the site to determine whether there is a "potential for unacceptable vapor intrusion." Review of the Draft 2002 Subsurface Vapor Intrusion Guidance, p. 2. The second tier compares "contaminant concentrations for single environmental media . . . to their appropriate concentration screening values" to determine whether vapor intrusion conditions can be "screened out" as an issue for the site. Review of the Draft 2002 Subsurface Vapor Intrusion Guidance, p. 3. If the data exceed the Tier 2 screening values, the environmental professional must proceed to Tier 3 to conduct a site-specific analysis of air quality within the building. Review of the Draft 2002 Subsurface Vapor Intrusion Guidance, p. 5. According to the Review published in December, USEPA anticipates making at least five major changes to the 2002 Guidance. First, the 2002 Guidance required only a single line of evidence to conclude that a site does not need further vapor intrusion screening. The final guidance will require that "multiple lines of evidence" be used to make this determination. Second, in the 2002 Guidance, site-specific indoor air samples are not taken until the last step of the screening process; the final guidance will require that indoor air samples are taken earlier in the process. Third, the 2002 Guidance is primarily designed to address vapor intrusion in residential properties; however, the final guidance will be expanded to cover all types of buildings as well as undeveloped land. In addition, the new guidance will also provide a clearer definition of when "pre-emptive mitigation" should be used to address potential vapor intrusion conditions in new buildings. Finally, USEPA has proposed changing the standard 24-hour duration indoor air sample to allow other sampling durations and methods. USEPA has committed to finalizing the Subsurface Vapor Intrusion Guidance by November 2012. In the meantime, there is some ambiguity as to whether one should follow the 2002 Guidance or the Review of the Draft 2002 Subsurface Vapor Intrusion Guidance in anticipation of the more stringent final guidance. In other vapor intrusion news, on January 25, 2011, USEPA requested oral comments on whether vapor intrusion should be included in the CERCLA National Priorities List ("NPL") site evaluation process. The first listening session will take place in Arlington, Virginia on February 24, 2011 and registration to present oral comments on that date is required by February 17, 2011. If you have any questions about how the Vapor Intrusion Guidance applies to your company, how to interpret USEPA's recent publication, or how to present your comments to USEPA, please contact an environmental lawyer at Schiff Hardin.
1 Vapor intrusion is a potential pathway for human exposure to hazardous substances through the "migration of volatile chemicals from the subsurface into overlying buildings." 2002 Guidance p. 4.
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