Laserfiche WebLink
al til <br /> t, <br /> CAMBRIA <br /> i <br /> wells, it became apparent that groundwater flow is actually easterly to northeasterly and the wells <br /> are located cross-gradient from the site <br /> Historically total petroleum hydrocarbons as gasoline (TPHg)have been detected in wells MW-6 <br /> through MW-11, and benzene has been detected in wells MW-6 through MW-10 The highest <br /> concentrations south of the subject site are found in well MW-7 There are two wells (MW-3 <br /> and MW-6) located between MW-7 and the subject site TPHg and benzene concentrations are <br /> much lower in wells MW-3 and MW-6 than in well MW-7 This suggests that the petroleum <br /> hydrocarbons detected in MW-7 are from a separate source and did not originate at the Shell <br /> station <br /> Historical laboratory analytical reports indicate that the hydrocarbons reported as TPHg for the <br /> wells south of the site do not exhibit a typical gasoline chromatographic pattern This atypical <br /> pattern has been noted several times in MW-6 since December 2001, was noted once for MW-7 <br /> during September 2002, and has been noted in wells MW-8 through MW-11 since they were <br /> installed Cambria requested that the laboratory review the chromatographs for these wells The <br /> laboratory responded that the samples collected from wells MW-6 and MW-8 through MW-11 <br /> contain tetrachloroethene (PCE), which is the primary contributor to the TPHg value in these <br /> wells Based on a telephone conversation with a project coordinator at the laboratory, well <br /> MW-7 also contains PCE, although the primary contributor to the TPHg value in this well is <br /> gasoline range hydrocarbons <br /> Analytical results and TPHg chromatographs from the onsite wells and wells located adjacent to <br /> the subject site (MW-1 through MW-5) do not indicate the presence of PCE at the subject site <br /> This demonstrates that the TPHg reported in wells MW-6 and MW-8 through MW-11 are not a <br /> result of Shell's operations at the subject site and did not originate from the Shell service station <br /> Based on the analytical data, groundwater flow direction, and the chromatographs, the petroleum <br /> hydrocarbons detected in wells MW-6 through MW-11 did not originate as a result of Shell's <br /> operations at the subject site and Shell should not continue monitoring these wells Shell <br /> requests that, beginning with the third quarter 2003 sampling event, gauging and monitoring <br /> these wells be discontinued <br /> �t <br /> 0854 2 <br />