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VAPOR INTRUSION

We have been involved in some of the first vapor intrusion cases in California, dating back to the Middlefield-Ellis-Whisman (MEW) site in Mountain View. At present, vapor intrusion continues to be a driver for many remediation projects, with adoption of U.S. EPA's conservative attenuation factor for soil gas expanding the scope of the cleanup at many sites.  We are also seeing more extensive vapor intrusion investigations required, more frequently involving off-site properties implicating not just access issues but creating other potential liabilities.

 

We managed one of the state's first evacuation directives in light of the short-term exposure risks believed to be associated with the presence of TCE. Since then, we have worked with both DTSC and a RWQCB on mandatory evacuation of tenants and/or residents. We also advise on routine vapor intrusion investigations, including reporting and disclosure requirements, and negotiating third-party access agreements.

 

We also see vapor intrusion impacting other areas of our practice, including Proposition 65 (both private and public agency requirements) and due diligence.

 

We are closely tracking the new draft guidance for vapor intrusion investigation and evaluating how these new requirements will affect our clients both as to sites previously closed, about to be closed, or from an acquisition and financing perspective. 

DEVELOPMENTS 

The DTSC, SWRCB, and the San Francisco Bay RWQCB have issued
long-awaited new draft guidance for the investigation of vapor intrusion. Some agencies are already following the guidance even though the guidance is not final.

Getting Tough on Vapor Intrusion:

Enforcement for Failure to Mitigate 

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