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Mr. Nathan Esformes - 2 - 18 July 1997 <br /> Triple E's Proposals <br /> Increased Pumping from XW-1 <br /> Triple E should be more specific with regards to the proposal to increase the pumping rate from XW-1. <br /> Triple E should discuss the proposed increase in pumping in relation to the capacity of the extraction <br /> pumps, aeration pond, treatment plant, and apricot spray orchard, and predict the effect of the increased <br /> pumping on the extraction system's capture zone. <br /> Triple E's original prediction of the capture zone of the extraction system extended beyond MW-7. We <br /> still expect Triple E to achieve capture of the chloroform plume to beyond MW-7, which has chloroform <br /> concentrations exceeding the remedial goal of 5 µg/1. If it is not possible to increase the pumping rate of <br /> XW-1 to achieve capture of the full lateral or vertical extent of chloroform, then Triple E must consider <br /> another alternative for achieving capture. <br /> Resampling 42B <br /> Triple E proposes to conduct additional sampling in 42B and assess possible sources of chloroform in the <br /> domestic water system during the June sampling event. In a letter dated 7 April 1997, Triple E proposed <br /> to sample 42B and two other domestic wells downgradient of MW-7 in June. The depth of these two <br /> wells are similar to that of 42B. Water quality data from these wells may help to characterize the vertical <br /> extent of chloroform in groundwater. <br /> The extent of chloroform should be evaluated upon receiving the results of this additional sampling. The <br /> effectiveness of extraction well XW-1 should then be re-evaluated with respect to any elevated <br /> chloroform beyond Triple E's current monitoring well network, both vertically and laterally. The <br /> evaluation should include recommendations to modify the extraction system or use some other alternative <br /> remedial approach, if necessary, to capture the full extent of the chloroform contamination. The specific <br /> details of any modifications to the extraction system or other remedial approach and the predicted capture <br /> zone should be discussed. <br /> Bob Dixon has informed me that the three domestic wells are to be sampled the week of 14 July 1997. <br /> By 22 August 1997, please submit your evaluation of the extent of chloroform in groundwater, the <br /> effectiveness of XW-1 to capture the full extent of chloroform, and any recommendations for improving <br /> the remediation system's ability to capture the chloroform plume. This should allow sufficient time to <br /> include the results of the domestic well samples in the evaluation. <br /> If you have any questions, you may call me at (916) 255-3048. <br /> a�� <br /> -4y-POLL <br /> 4y-POLLY OWRY <br /> Associate Engineering Geologist <br /> PAL:njjss <br /> cc: OW. Mike Infurna, San Joaquin County Public Health Services, Stockton <br /> Mr. Tom Guido, Triple E Produce, Tracy <br /> Mr. Michael Campos, Graham&s James, Sacramento <br /> Mr. Bob Dixon, Condor Earth Technologies, Inc., Stockton <br /> Mr. John Kramer, Condor Earth Technologies, Inc., Sonora <br />