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- i <br /> Environmental <br /> Mr.3-larlin Knoll �7 Resources <br /> 24 March 2010 Management <br /> Page 4 <br /> media. That document includes ESLs for.groundwater to be protective <br /> of human health based on exposures to chemicals via the vapor intrusion <br /> pathway (ESL Table E-1; Groundwater Screening Levels for Evaluation of <br /> Potential Vapor Intrusion Concerns). The ESLs are considered to be <br /> conservative, and under most circumstances, the presence of a chemical <br /> in soil, soil gas or groundwater at concentrations below the <br /> corresponding ESL can be assumed to not pose a significant long-term <br /> (chronic) threat to human health and the environment. The ESLs for this <br /> pathway are also provided in Table 1. As shown in Table 1, none of the <br /> current groundwater concentrations for the primary risk drivers (BTEX <br /> constituents) exceed the groundwater ESL for the evaluation of potential <br /> vapor intrusion concerns, under either a commercial/industrial or <br /> residential land use scenario. ESLs have also been developed for soils <br /> for both human health exposures and threats to groundwater (via <br /> leaching). Because all of the impacted soils have been removed during <br /> the prior tank excavations, soil ESLs do not apply to this site. <br /> Based on the current concentrations relative to either site-specific RBSLs <br /> or more recent ESLs, no further action appears warranted to address the <br /> vapor intrusion pathway. <br /> We hope that these responses adequately address your comments. <br /> Heinz would appreciate your concurrence with these conclusions, or any <br /> specific comments regarding the scope for any future activities that can <br /> bring this site closer to regulatory closure. If you have any questions, <br /> please call me at (925) 946-0455. <br /> Sincerely, <br /> Brian Bjorklund, PG, CHG <br /> Partner <br /> BSB/bsb/0106834 <br /> cc: Mr. Mickey Frantz, Heinz North America <br /> Mr. Marty Hartzel, CVRWQCB <br /> Mr. James F. Davenport, The Cranbrook Group <br />