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{ <br /> 3 _ 19 February 1993 <br /> Memorandum <br /> Geweke, 16 S. Cherokee, Lodi <br /> 3. The consultant preparing remediation proposals must have the most <br /> current soil and ground water data in order to design effective <br /> remediation systems. <br /> 4. No explanation was given for not proposing the ng <br /> useion the <br /> the exist <br /> 1nnew extraction <br /> extraction well , EW1 . A map <br /> well was not provided. <br /> 5. The proposal to use MW2 for reinjection was not accompanied by a <br /> discussion of the merits and drawbacks of using an existing well , nor <br /> did it include estimates and maps of the projected zone of influence. <br /> Recent laboratory results showed contamination in MW6, upgr <br /> adient of <br /> MW2. It may be necessary to install an additional well specifically for <br /> injection so that adverse impacts on the contamination plume can be <br /> minimized. <br /> because not <br /> 6 The constiarterlytuentswreportsere submied,tthereforeted by WeGeweke iseke are coutlOfecompliance with <br /> l <br /> the C&A. The. existing monitoring program is inadequate because several <br /> wells have not been sampled for several years. <br /> 7. Some of the constituents that have not been analyzed as required are <br /> denser than water and have a tendency to sink, unlike the petroleum <br /> constituents that are lighter than water and tend to remain near the <br /> water surface. Several of these dense constituents were detected in a <br /> previous sampling event. If the analyses had been conducted as <br /> required, we would have additional information to determine whether <br /> monitoring wells are necessary to determine the vertical extent of <br /> contamination. Once we have additional data, deeper monitoring wells <br /> may be necessary. <br /> 8. It may be necessary to install additional monitoring wells to define the <br /> upgradient extent of contamination. Additional monitoring wells would <br /> also refine the extent of downgradient contamination and may make the <br /> extraction/injection system more efficient. However, the extraction <br /> system could be designed to impact the current downgradient clean wells. <br /> 9. Geweke was initially informed in a letter dated 9 September 1991 that <br /> additional aquifer/pumping tests were required if they proposed to <br /> reinject but no additional aquifer/pumping tests were conducted and none <br /> have been proposed. <br /> 10. No other remediation options were discussed or presented to us. <br /> 11. No feasibility studies were conducted to determine the best remedial <br /> options. <br />