On April 15, 2013, EPA made available to the public its highly anticipated guidance documents on vapor intrusion. Both documents are external review drafts subject to further review and revision, and they may not be adopted at all. EPA is seeking public input and comment between April 16 and May 24, 2013. The first document, “OSWER Final Guidance For Assessing And Mitigating The Vapor Intrusion Pathway From Subsurface Sources to Indoor Air – External Review Draft” is a general guidance for all compounds. Separately, EPA is also seeking comment on its guidance regarding petroleum hydrocarbons released from underground storage tanks, “Guidance For Addressing Petroleum Vapor Intrusion At Leaking Underground Storage Tank Sites – External Review Draft.”
Businesses that build or own property near contaminated sites, such as Brownfield sites and industrial sites, should consider reviewing these external draft guidance documents to determine how these new guidance documents may impact their operations. Some businesses may require vapor intrusion assessments and a vapor barrier or a vapor migration system (active or passive) that diffuses vapors from the building.
Vapor intrusion refers to the upward and side-ward migration of chemicals that volatilize into buildings that overlie contaminated soils and groundwater plumes through dirt floors and cracks in foundations. EPA and state regulators are concerned that the vapors from the volatile chemicals that can migrate into in the indoor air may pose an unacceptable risk of chronic health effects due to long-term exposures, even when present at extremely low levels.
Sites that present the potential for vapor intrusion include those where there have been spills and releases of the common industrial solvent trichloroethylene (TCE), such as metal parts cleaning and parts washing, degreasing operations, automotive and jet engine cleaning, and electronic and semi-conductor manufacturing, as well as releases and discharges of the industrial solvent perchloroethylene (PCE or PERC) widely used in commercial dry-cleaning operations.