Assessing Vapor Instrusion Risk


When previous investigations by other consultants were insufficient, Farallon worked with stakeholders to obtain closure for an investment property.

Farallon conducted necessary soil gas and indoor air samples to demonstrate that tetracloroethene (PCE) was not present at a commercial building at levels that would represent a risk to occupants. These findings allowed the client to lease and subsequently sell the property.

A client purchased an industrial building formerly used as an environmental laboratory and encountered difficulty with stakeholders in obtaining regulatory case closure for historical contamination to soil and groundwater. Environmental investigations conducted by other consultants were insufficient to delineate the extent of PCE contamination in soil gas and predicted unacceptably high costs to attain case closure. Farallon collected subslab soil gas and indoor air samples in close consultation with representatives of the California Department of Toxic Substances Control (DTSC) and was able to demonstrate to DTSC satisfaction that PCE and other contaminants were not a threat to indoor air at the building.

“The seller established an environmental escrow account with limited funds,” recalls Farallon Senior Engineer Matt Nusenow, the project manager. “We communicated the scope of work and the results of sampling with the client, client’s counsel, seller’s consultant, seller’s council, and DTSC. Because of this close collaboration, we were able to secure a No Further Action determination from DTSC in a timely and cost-efficient manner. No investment from the client was necessary, and remaining money from the escrow account was returned to the seller. Best of all, our client was able to lease and ultimately sell the property for office use with no environmental concerns.”