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Mate of California ` ?�Ci1 y;� a1 J— Department of Health Services <br /> Memorandum <br /> To Jim Tjosvold, P.E. Date July 3 , 1987 <br /> Senior Engineer <br /> Subject: COMMENTS TO <br /> McCORMICK & <br /> BAXTER WORKPLAN <br /> MAY 1987 <br /> From Jeff Van Slooten,{�G <br /> Associate HazarMlls Materials SpE�cialist <br /> Department of Health Services���/_� <br /> G <br /> Gary Reents <br /> Associate Water Resources Control. Engineer <br /> Central Valley Regional Water Quality Control Board <br /> The workplan submitted by McCormick and Baxter to complete the <br /> Site Assessment Plan and the Pollution Control and Mitigation <br /> Plan generally meets all of the investigation objectives <br /> established by the State. However, there are a number of <br /> relatively minor issues that need resolution. The comments <br /> and requirements of the Regional Board and the Department are <br /> as follows: <br /> Well Construction <br /> 1. The length of the well screens are to be similar to <br /> previous installations. There should be only minimum <br /> deviation in this criteria. <br /> 2 . The filter pack for wells shall extend no more than five <br /> feet above the top of the screen. <br /> 3 . Commercially produced grout must be mixed in accordance <br /> with manufacturer's recommended guidelines. If bentonite <br /> is used in the mix, cement and bentonite must be <br /> thoroughly dry blended and then "jet" or "venturi" mixed <br /> into a prescribed amount of water. All materials are to <br /> be pumped through a tremie pipe from the bottom to the <br /> top of the borehole. Material should not be poured in <br /> from the top or gravity fed through the pipe. <br /> 4 . Prior to installation of wells, the galvanic reaction <br /> between stainless steel screens and carbon steel casings <br /> should be investigated to determine if the rate of <br /> corrosion of the carbon steel casing is acceptable. <br /> 5. The primary method for well development should use a <br /> vented surge block with bailing and/or pumping to remove <br /> the fines. Air development should be avoided, but may be <br /> used as a last resort. <br /> 6. The Department requests that the pilot bore hole for <br /> wells DSW-4D, 2E, 6C, and 05-4C be continuously <br /> cored/sampled with mud rotary drilling techniques, using <br /> .,., .. .,... .,, . ;: "', ire„nrv,-. -!' .. _. .- : •,...., ... dx. t^,io4^�$*._+5�"�:°.i.�:�L+a-: .._.— ,. ... <br />