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r <br /> Site Assessment Report , <br /> Former Texaco Service Station <br /> Chevron Site ID 309075 <br /> March 18, 2010 <br /> 5.0 CONCLUSIONS <br /> The site assessment activities completed November 9 through November 13, 2009 have further <br /> delineated the petroleum hydrocarbon impacts at the site. The soil samples collected from <br /> MW-6D did not contain concentrations above the respective ESLs for any analytes. <br /> TPH-DRO was detected in groundwater samples collected from both monitoring wells (MW-6 <br /> and MW-6D) screened by 8015B. TPH-DRO was detected in monitoring well MW-6D screened <br /> by 8015B with silica gel clean-up. The groundwater sample collected from MW-6D also <br /> contained concentrations of toluene, ethylbenzene and total xylenes above the respective <br /> laboratory MDLs, but not above the respective MCLs. Groundwater samples collected from <br /> monitoring wells MW-6 and MW-6D did not contain concentrations of TPH-GRO, benzene, <br /> MTBE, ethanol, DIPS, ETRE, TAME, TBA, 1,2-DCA, EDB and ethanol above the respective <br /> laboratory MDLs. The distribution of TPH-DRO concentrations across the site (e.g. similar <br /> concentrations in the upgradient, crossgradient and downgradient wells), are indicative of a <br /> regional TPH-DRO issue. <br /> V <br /> 6.0 RECOMMENDATIONS <br /> Based upon the findings of the installation of the additional groundwater monitoring wells down <br /> gradient to monitoring well MW-1, ARCADIS recommends that MW-6 and MW-6D are <br /> incorporated into the semiannual monitoring and sampling program during the first semiannual <br /> event of 2010. Gettler-Ryan Incorporated (G-R) will conduct semiannual monitoring and <br /> sampling of wells MW-6 and MW-6D beginning with the first semiannual event of 2010. <br /> Prepared by. <br /> Sherrie Lang <br /> Assodl—ate Project Mager <br /> Licensed Approver: COGS <br /> a DAVID LAY -4 <br /> David W. Lay, P.G., C.P.G. • No.8545 • <br /> Principal Geologist <br /> March 18, 2010 OP CA1-�FO� <br /> Yul <br /> V <br /> \\CA5FP\Data\Aproject\ENV\CHEVRON1309075\6 Deliverables\Reports\DG Wells Assessment\Assessment Report_4741010950.doc 8 <br />