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Mr. ,John Ewing -2- 19 November 1992 <br /> property just prior to sampling MW-1 and EW-1. " The report does not include <br /> any water level measurements. Even though access to the Mobil Oil wells may <br /> not have been possible at the time of sampling EW-1 and MW-1, the water levels <br /> in EW-1 and MW-1 should have been measured prior to sampling these two wells. <br /> The installation of only two wells, rather than three, at Leprino was allowed <br /> only because the Mobil Oil wells on the Leprino property would make it <br /> possible to determine the ground water flow direction. However, if it is not <br /> possible to measure the water levels in the Mobil monitoring wells at the same <br /> time as the water levels in EW-1 and MW-1, then it will be necessary to <br /> install another monitoring well on the Leprino property in order to determine <br /> the local ground water flow direction. <br /> The work pian proposed to install extraction well EW-1 approximately 15 feet <br /> downgradient of where a B.A.T. probe ground water sample had found free <br /> product, in the area near the leaky fuel lines. The assessment report shows <br /> EW-1 was actually placed 30 feet downgradient of the leaky fuel lines. <br /> Therefore, it is likely that higher levels of TPHd exist upgradient of EW-1, <br /> closer to the leaky fuel lines. <br /> By 7 December 1992, Please submit a schedule for resampling EW-1 and MW-1 and <br /> reporting the results and inform us whether the Mobil Oil wells will be <br /> available for measurement. Water level measurements shall be taken prior to <br /> sampling these wells. If water levels cannot be measured in the three Mobil <br /> Oil monitoring wells on the Leprino property at the same time as measurements <br /> are taken in EW-1 and MW-1, then it will be necessary to install an additional <br /> monitoring well to allow a determination of the local ground water flow <br /> direction. In this case, a work plan to install the additional wells is due <br /> by 28 December 1992. If it is possible to sample the three Mobil Oil monitor- <br /> ing wells at the same time as EW-1 and MW-1, then, as stated in my 11 June <br /> 1992 letter, the water levels from those wells, EW-1 and MW-1 shall be plotted <br /> on a ground water contour map and included in the determination of the local <br /> ground water flow direction. <br /> In addition, by 11 December 1992, please submit an addendum to the "Initial <br /> Ground Water Assessment Report" which describes the construction details of <br /> EW-1 and MW-1 and includes any. results of field screening of the soil samples <br /> from EW-1 and MW-1. <br /> If you have any questions, please call me at (916) 255-3048. <br /> POLLY LOWRY <br /> Associate Engineering Geologist <br /> PAL: ldj <br /> cc: San Joaquin Public Health Services, Stockton <br /> Mr. Roy Greengrass, Leprino Foods, Tracy <br /> Mr. Dana Booth, Kleinfelder, Sacramento <br /> I <br />