Did EPA overstep in applying soil vapour intrusion guidance to commercial buildings? - .PDF file.
By Reza S Zarghamee, Sheila M Harvey, Peter H Wyckoff and Jeffrey A Knight
In April 2013, the US Environmental Protection Agency’s (EPA’s) Office of Solid Waste and Emergency Response issued two guidance documents on soil vapour intrusion. One addresses general soil vapour intrusion issues, while the other is specific to petroleum vapour intrusion at leaking underground storage tank sites. This alert focuses on the first one — the ‘2013 Guidance’. Although the 2013 Guidance was issued as ‘final’, the US EPA solicited public comments through 24 June 2013. The 2013 Guidance changes the US EPA’s basic approach to addressing soil vapour intrusion and raises important jurisdictional issues regarding the interplay between the US EPA and the US Department of Labor, Occupational Safety and Health Administration (OSHA). These features of the 2013 Guidance underscore the need for careful legal attention to clean-up sites involving soil vapour intrusion, which has become an important factor in both remedy selection and toxic torts litigation.
The phrase ‘soil vapour intrusion’ refers to the migration of volatile chemicals from a subsurface source into buildings. This migration occurs through cracks or perforations in floors and walls, when there is a difference in interior and exterior vapour pressure or concentration. Soil vapour (i.e. the gas between soil particles) can become contaminated when chemicals evaporate or migrate from contaminated soil or groundwater, non-aqueous phase liquid, buried wastes and underground storage tanks or drums. The potential harm to humans posed by soil vapour intrusion depends on several factors, including the length, amount and frequency of exposure, as well as the toxicity of the volatile chemicals and the individual’s sensitivity…
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