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r - <br /> k <br /> E <br /> Mr. Randall Stephenson <br /> January 27, 1994 <br /> Page 3 <br /> Ground Water Analytical Results <br /> 4n December 14, 1993, ground water samples were collected from monitoring wells MW-1, <br /> MW-2, and MW-3. Samples were collected as described in Enclosure A. Each ground water <br /> sample was analyzed for BTEX and TPHg by state and federal EPA-approved methods. <br /> Analytical results are summarized in Table 3. Copies of certified analytical reports are <br /> contained in Enclosure F. Dissolved benzene concentrations in water samples collected from <br /> monitoring wells MW-1, MW-2, and MW-3 ranged from less than 0.50 micrograms per liter <br /> (µg11) in monitoring well MW-1 and MW-3 to 20,000µg11 in monitoring well MW-2. Figure 4 <br /> presents benzene concentrations at individual monitoring wells. TPHg was detected at <br /> concentrations of 71 µg11 (MW-1) and 63,000 µg/l (MW-2); TPHg was not detected in the <br /> sample from monitoring well MW-3. <br /> Discussion <br /> Fourteen of the nineteen soil samples submitted for laboratory analysis did not contain detectable <br /> concentrations of TPHg. The remaining five soil samples contained TPHg concentrations <br /> ranging from 1.4 mg/kg to 7.7 mg/kg. Benzene concentrations in ground water samples ranged <br /> from less than 0.50 µg/l to 20,000 µg11 in samples collected from monitoring well MW-2. <br /> Conclusions and Recommendations <br /> Concentrations of dissolved petroleum constituents in ground water samples collected from <br /> monitoring well MW-2 indicate that additional investigation is warranted at this site. We <br /> recommend that a quarterly sampling program be initiated in the first quarter of 1994 and <br /> sampling results be evaluated to determine the scope of additional work(the number and location <br /> of additional monitoring wells). <br /> We recommend that copies of this report be submitted to: <br /> Mr. Mike Infurna Mr. Gordon Boggs <br /> Environmental Health Department California Regional Water Quality <br /> County of San Joaquin Control Board, Central Valley Region <br /> 445 North San Joaquin Street 3443 Routier Road <br /> Stockton, CA 95201 Sacramento, CA 95827-3098 <br /> LxrT057.ECD <br /> ACTON •NUCKELSON . van DAM,INC. Consul' Scientists,, Engineers, and Geologists <br />