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Lee Higgins -2- 10 August 2011 <br /> Chevron <br /> Tracy Byron Road <br /> The non-cancer health hazard index for Area 3 is 0.04 and well below 1; this level indicates an <br /> acceptable non-cancer health hazard for a potential construction worker. <br /> The shallow background water quality at the Site exceeds State and Federal standards for <br /> total dissolved solids (TDS) for some drinking water and agricultural purposes. SAIC <br /> concluded groundwater is not likely to be used as a drinking water source. Thus, the direct <br /> exposure pathway to COPCs was considered incomplete and the report did not quantitatively <br /> evaluate that pathway in the Screening Evaluation. <br /> Based a review of an ecological sensitive receptors database, SAIC concluded the ecological <br /> screening indicates that a threat to ecological receptors does not appear to be present. <br /> Consequently, SAIC concluded that Site conditions do not pose a health risk to future <br /> residents or to sensitive species and therefore no further action required is appropriate. <br /> Central Valley Water Board staff concur with the Report and have the following comments: <br /> • Consistent with other OVP/TAOC sites, separate Soil and Groundwater Management <br /> Plans (SGMP's) are needed for each area. <br /> • A request for No Further Action Required (NFAR) determination maybe prepared; <br /> separate NFAR documentation should be completed for each area. <br /> • Chevron's Surland Homes project should not be included in the Area 2 NFAR; the <br /> Surland Homes evaluation and risk assessment is being addressed separately. <br /> • Documentation to support a NFAR closure determination should be completed in <br /> accordance with California Regional Water Quality Control Board, Central Valley <br /> Region's 16 April 2004 update to Appendix A of the Tri-Regional Board Staff <br /> Recommendations for Preliminary Investigation and Evaluation of Underground Tank <br /> Sites - No Further Action Requests. Section 6.5 - NFAR for Cases Exceeding Water <br /> Quality Objectives should be followed for documenting Site conditions. <br /> By 20 December 2011, please provide documentation to support the request,for NFAR <br /> determination for each of the three areas; the SGMP's may be submitted at the same time. <br /> If you have any questions or comments, please call Dean Hubbard at (559) 445-5179 or by <br /> email at: dhubbard(a�waterboards.ca.gov. <br /> SHELTON R. GRAY C. DEAN HUBBARD <br /> Senior Engineering Geologist Engineering Geologist <br /> P.G. No. 6357 <br /> cc: Michael Infurna, San Joaquin County EHD, Stockton <br /> Michael Hurd, SAIC, Oakland <br />