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Comfort Air, Incorpi rated Page 2 <br /> 1607 Turnpike Road June 16, 2008 <br /> Stockton, California 5206-1960 <br /> • Electronic to interpretations for the interval between 80 and 100 feet for CPT-1, <br /> located appro imately twelve feet from the proposed monitoring well, were described <br /> as "clayey si , stiff fine grained, silty clay, clay, and silt." The pore pressure log <br /> displayed this interval as low pore pressure with intermittent, slightly increased pore <br /> pressure inter als. Low pore pressure is interpreted to be an indicator of a permeable <br /> unit. <br /> • High conc: ations of contaminants of concern detected in grab groundwater samples <br /> collected fro CPT-1 at depths of 96 to 100 feet bsg, and 113 to 117 feet bsg, may <br /> have been the result of cross contamination from shallower impacted zones. <br /> • Analytical res ilts for groundwater samples collected quarterly from MW-6, screened <br /> between 60 aid 65 feet bsg, and located approximately ten feet from the proposed <br /> monitoring 11, have demonstrated significant increases in concentrations of total <br /> petroleum h ocarbons quantified as gasoline (TPH-g), benzene, toluene, ethyl <br /> benzene, and total xylenes (BTEX); tertiary-amyl methyl ether (TAME), and <br /> 1,2-dichloroe ane (1,2-DCA) during the last three sampling events. If groundwater <br /> collected firon the proposed monitoring well is not impacted with COC, the EHD will <br /> consider the p ume to be vertically delineated. <br /> Please respond and s bmit your comments to the EHD by July 25, 2008. If you have any <br /> questions, please c ntact Vicki McCartney, Senior Registered Environmental Health <br /> Specialist, at(209) 46 -9852 or by email at vmccartney@sjcehd.com. <br /> Sincerely, <br /> Victoria L. McCartney, REHS Nuel C. Henderson,Jr., PG <br /> Senior Registered En ironmental Health Specialist Engineering Geologist <br /> c: Ms. Ally L. Co vita, Advanced GeoEnviromnental, Inc., 837 Shaw Road, Stockton, <br /> California 95215 <br /> Mr. James L.L. I larton, PG, California Regional Water Quality Control Board Central <br /> Valley Region, 11 20 Sun Center Drive, Suite 200, Rancho Cordova, California 95670 <br />