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STEWART CHEANG -2- 1/19/99 , <br /> UST 517, 816D, SUMP 617 <br /> NCTS,STOCKTON <br /> additives are not detected using EPA Method 8260, then we recommend continued use of EPA <br /> Methods 8015/8020 (including MTBE) during quarterly monitoring. Furthermore, we request <br /> 1, 2-Dichloroethane (1,2-DCA), a gasoline additive to clean carburetors, be analyzed as well. <br /> Please clarify what parameters will be included in the analysis for the intrinsic remediation study <br /> and the rationale for each parameter. We agree with the Navy that two years of seasonal <br /> groundwater monitoring data will provide sufficient data upon which to base sound remedial <br /> action alternatives. <br /> 3. For purposes of referencing lead detection limits, rather than STLC results, we provide the <br /> following information. The Board has recently updated the Recommended Limits in Water for <br /> Petroleum-Based Fuel. Components to Protect. the Beneficial Use of Municipal and Domestic <br /> Supply , dated 17 August 1998 (see attached). The recommended water quality goal for lead is <br /> 2 pg/L (CA Public Health Goals in drinking water- OEHHA). This level protects groundwater <br /> designated for use as municipal, domestic, and agricultural supply. <br /> Site 8I6D <br /> 1. Site 816D has extremely high levels of both organic and inorganic constituents in soil and <br /> groundwater. We concur with the Navy's decision to incorporate Site 816D into the Installation <br /> Restoration Program. STLC results were discussed in the Navy's comments with regards to total <br /> chromium and trivalent chromium. Because of the more mobile and carcinogenic aspects of <br /> hexavalent chromium, we also concur with the Navy's proposal to speciate chromium samples in <br /> future sampling events in soil and groundwater. Characterization of the lateral and vertical extent <br /> of a potential hexavalent chromium plume is necessary and should be expeditiously investigated. <br /> If you have any questions please contact me at (916) 255-3078 or schwabk@rb5s.swrcb.ca.gov. <br /> KIM A. SCHWAB <br /> Associate Engineering Geologist <br /> DoD, Cleanup Unit <br /> Enclosure(s) <br /> cc: Mr. Jim Austreng, DTSC, Region 1, Sacramento <br /> Mr. Ron Rowe, San Joaquin County Environmental Health Department, Stockton <br /> Ms. Gail Qatsha, Naval Communication Station, Stockton <br /> Mr. Brad Beeman, Naval Communication Station, Stockton <br /> Mr. Jay R. Jahangiri, Port of Stockton, Stockton <br /> kas:NCS UST 517,816D,Sump 617 <br />