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central portion of the site are the most impacted wells. The concentrations of TPHg detected in <br /> samples collected from these wells in June 2005 represent historical highs. The concentrations of <br /> petroleum hydrocarbons detected in the groundwater sample collected from deep well MW7 in June <br /> generally decreased with respect to the first time this well was sampled in March of 2005, and <br /> suggest that the vertical extent of impacted groundwater in the vicinity of this well is close to 120 <br /> ' feet bgs. <br /> The shallow groundwater plume appears to be adequately defined to the west and north in the <br /> ' vicinities of MW10 and MW11R, but is not defined to the east and south. The intermediate <br /> groundwater plume appears to be generally defined to the northwest in the vicinities of MW12 and <br /> MW4, but not well defined in other directions. Groundwater flow in the shallow zone in March and <br /> ' June of 2005 was variable with eastward and northward components flowing toward the center of the <br /> site. Groundwater flow in the intermediate zone in March and June of 2005 was towards the south. <br /> ' Additional investigation to the west and south is necessary to evaluate the extent of petroleum <br /> hydrocarbon impact. ATC is in the process of preparing a workplan for additional investigation <br /> pursuant to a request from the San Joaquin County Environmental Health Department dated August <br /> 31, 2005. W p d,� 1 v f 31 f o b <br /> Please contact our office at(209) 579-2221 if you have any questions or comments. <br /> . Respectfully submitted, <br /> ATC Associates Inc. <br /> Todd Hafner, P.G. '° <br /> Project Geologist ' <br /> . •. � { <br /> Jeanne Homsey, P.E. '�':-9 -, ��� F *s • <br /> CA Registered Civil Engineer No. 47410 '- '• Opt � t <br /> 1 <br /> cc: Mr. & Mrs. Ernest Foppiano <br /> Mr. Jim Barton, CRWQCB <br /> s:lenviromental1283491reports12005 1 &2 QMR.doc 6 ATC Associates Inc. <br />