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TE* . Fe 62 ,93 9 04 No .004 P .05 <br /> w Memorandum - 3 - 19 February 1993 <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 to use the existing <br /> extraction well , EW1 . A map showing the location of the new extraction <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, upgrad,ent of <br /> MW2. It may be necessary to install an additional well specifically for <br /> injection so that adverse impacts on the contamination plume tan be <br /> minimized. <br /> 6. The quarterly reports submitted by Geweke are incomplete because not all <br /> constituents were analyzed, therefore, Geweke is out of compliance with <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 nut been analyzed as required are <br /> denser than water and have a tendency to sink, unlike the petroleum <br /> constituents that are lirhter than water and tend to rer•ain 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 ,ystei: r•ore 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/pumpirig 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 /> n: <br />