Did EPA Overstep in Applying Soil Vapor Intrusion Guidance to Commercial Buildings?

Pillsbury Winthrop Shaw Pittman LLP
Reza Zarghamee, Sheila McCafferty Harvey, Peter H. Wyckoff
and Jeffrey A. Knight

October 21, 2013

In April 2013, U.S. EPA’s Office of Solid Waste and Emergency Response issued two guidance documents on soil vapor intrusion. One addresses general soil vapor intrusion issues1, while the other is specific to petroleum vapor intrusion at leaking underground storage tank sites 2. This alert focuses on the first one – the “2013 Guidance.” Although the 2013 Guidance was issued as “final,” U.S. EPA solicited public comments through June 24, 2013. The 2013 Guidance changes U.S. EPA’s basic approach to addressing soil vapor intrusion and raises important jurisdictional issues regarding the interplay between U.S. EPA and the U.S. Department of Labor, Occupational Safety and Health Administration (“OSHA”). These features of the 2013 Guidance underscore the need for careful legal attention to cleanup sites involving soil vapor intrusion, which has become an important factor in both remedy selection and toxic torts litigation.

What Is Soil Vapor Intrusion and Why Is It Important?

The phrase “soil vapor 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 vapor pressure or concentration. Soil vapor (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 vapor 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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