On September 25, EPA sent two draft guidance documents on vapor intrusion to the Office of Management and Budget (OMB). OMB review is the last step before publication of the guidance. One guidance generally addresses vapor intrusion issues for all compounds, and the other focuses on petroleum hydrocarbons released from underground storage tanks (USTs). The purpose of the guidance is “to provide technical and management guidance to field investigators when conducting vapor intrusion investigations and response actions.” Drafts of the guidance were issued for public comment in 2013.
The guidance addressing all compounds, including chlorinated solvents, describes a framework for investigating sites and recommends long term sampling of indoor air. The petroleum hydrocarbon guidance contains separation distances—the amount of clean soil which should exist between petroleum contamination and overlying buildings to allow petroleum hydrocarbons to dissipate, in order to mitigate the risk of indoor air contamination. Commenters on the draft guidance asserted that the guidance would be a game-changer for chlorinated solvent sites, increasing cleanup liability for PRPs, and causing additional assessment at many of the estimated 440,000 vapor intrusion sites in the country.