Vapor Intrusion Rises in Importance in 2010
Eight years after issuing “draft” guidance on vapor intrusion, the EPA will issue an “interim” guidance this year that is supposed to move the organization closer to issuing a final guidance in 2012. This sudden rise in importance was prompted by an evaluation that the lack of final guidance on vapor intrusion by the organization impedes efforts to assess indoor air risks. Since 2002, more than half the states and other governmental bodies have issued their own vapor intrusion standards, leading to ad hoc and inconsistent standards across the board. So why not finalize the draft? Well, the times have changed and so has the EPA’s approach. This new risk based approach no longer supports some of the assumptions inherent in the draft guidance. For instance, the EPA will use updated toxicity values, beginning with trichloroethylene (TCE) and tetrachloroethylene (PCE) toxicity values, to determine at what level an indoor risk exists, and consider more significantly atmospheric and building specific effects. But, alas, there are many more than assessment questions to be answered in the final guidance. Again, not waiting for the answers, ASTM International announced last week that it will soon release its ASTM E 2600 Guide: Vapor Encroachment Screening standard for conducting due diligence for sale of properties where potential vapor intrusion is a concern, a revision of its 2008 standard that was criticized for being overbroad. The ASTM standard will focus on identifying potential sources in the surrounding areas of the real estate property rather than broad assessment of an existing vapor intrusion problem. Years after the 2002 guidance, many thought the final guidance would be immediately forthcoming, but it was not. While more certainty is definitely desired by all parties involved on this issue, what we hope is that the “interim” guidance does not dance to the same tune as the “draft” guidance…one step forward and two steps back!
