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Department of Toxic Substances Control <br /> Maureen F. Gorsen, Director <br /> Linda S.Adams 8800 Cal Center Drive Arnold Schwarzenegger <br /> Secretary for Sacramento, California 95826-3200 Governor <br /> Environmental Protection <br /> December 21, 2007 <br /> Mr. Dan McGrade <br /> Director, Environmental <br /> SPX Corporation <br /> 13515 Ballantyne Corporate Place <br /> Charlotte, North Carolina 28277 <br /> APPROVAL OF THE REMEDIAL ACTION IMPLEMENTATION WORK PLAN (RAIWP), <br /> MARLEY COOLING TOWER COMPANY SITE, STOCKTON, CALIFORNIA <br /> Dear Mr. McGrade: <br /> The Department of Toxic Substances Control (DTSC) has completed review of the subject <br /> document dated December 2007, prepared by MWH Americas, Incorporated for the Marley <br /> Cooling Tower Company site. The RAIWP details the methodology and approach to conduct in- <br /> situ reduction described in the Remedial Action Plan Amendment adopted by DTSC on <br /> June 29, 2007. <br /> Based on our review, the RAIWP is approved. Prepare a Start Work Notification for our review <br /> for later distribution to the site specific mailing list. The following are comments on the RAIWP <br /> and recommendations for the monitoring program: <br /> 1. Elevated concentrations of chromium have been detected in groundwater <br /> samples from the intermediate zone. Injection is currently not planned for the <br /> intermediate zone. Elevated concentrations for the intermediate zone were <br /> detected in samples from monitoring wells MW-321, MW-214, and MW-213. It is <br /> anticipated that the cleanup of the shallower zones will allow for the intermediate <br /> zone concentrations to decrease at a faster rate than would be expected with just <br /> groundwater extraction. Recommend assessment with ongoing groundwater <br /> monitoring efforts as to the effectiveness of the injection to increase the rate of <br /> remediation of the intermediate zone. <br /> 2. A review of Figure 8 indicated that well screens for intermediate zone wells <br /> MW-214 and MW-213 are very long_ This could allow for dilution of chromium <br /> concentrations if samples are collected utilizing traditional purging methods. <br /> Recommend as chromium concentrations in groundwater samples from long <br /> screened wells approach cleanup goals then collect depth discreet samples from <br /> these wells at different depths within the screens. This sampling could be done <br /> with micropurging methods and possibly with the use of packers to help minimize <br /> mixing of groundwater. <br /> 0 Printed on Recycled Paper <br />