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California Regional Water Quality Control Board. <br /> .p <br /> Central Valley Region <br /> ,. <br /> Robert Schneider,Chair <br /> Alan C.Lloyd Ph.D. Arnold Schwarzenegger <br /> Secretary for Sacramento Main Office - Governor <br /> Environmental Internet Address: http://www.waterboards.ca.gov/centralvalley � "�"���D <br /> 11020 Sun Center Drive#200 Rancho Cordova,CA 95670.6114 C�11 ,J <br /> Protection Phone(916)464-3291 Fax(916)4644797 <br /> MAR 3 1 2006 <br /> 28 March 2006 ENVIRONMENT HEALTH <br /> PERMIT/SERVICES <br /> Mr. Thomas Kosel <br /> ConocoPhillips <br /> 76 Broadway <br /> Sacramento, CA 95818 <br /> REVIEW OF REQUEST TO TERMINATE OPERATION OF GROUNDWATER <br /> EXTRACTION AND TREATMENT SYSTEM, FORMER TOSCO BULK TERMINAL #10013, <br /> 3505 NAVY DRIVE, STOCKTON, SAN JOAQUIN COUNTY <br /> Staff of the Central Valley Regional Water Quality Control Board (Water Board)reviewed the 8 March <br /> 2006 letter(Letter) submitted by Earth Tech, Inc. on behalf of ConocoPhillips Petroleum Company for <br /> the former Tosco Bulk Terminal No. 10013 at 3505 Navy Drive in Stockton(site). The Letter requests <br /> Water Board approval to terminate operation of the groundwater extraction and treatment system <br /> (GWETS) currently operating at the site. Alternative treatment methods would be evaluated during <br /> shutdown of the existing system. <br /> The GWETS well network consists of two extraction wells, well MW-8 completed in the shallow <br /> groundwater zone and well MW-14 completed in the deeper zone. Extracted groundwater is treated <br /> through chemical oxidation using a HiPox treatment system. Effluent is discharged to the City of <br /> Stockton sewer system under a discharge permit. The permit sets limits on chemical concentrations in <br /> the effluent. ConocoPhillips has been treating the groundwater in batch mode in order to meet the <br /> effluent discharge limit for tertiary butyl alcohol (TBA). ConocoPhillips requests that the treatment <br /> system be shutdown due to diminishing returns in the rate of contaminant removal versus cost of system <br /> operation. <br /> The Letter focuses on providing an unsubstantiated justification for shutdown of the remediation system. <br /> Little information on how other remedial approaches will be evaluated is provided. The Letter states <br /> that enhanced in situ biodegradation opportunities via oxygen injection are currently being evaluated and <br /> groundwater samples have been collected and analyzed for various geochemical parameters. Also <br /> briefly mentioned is the intention to perform an oxygen injection pilot study and/or install a full-scale <br /> oxygen injection system once the existing system is shutdown. <br /> Water Board staff does not concur with shutdown of the remediation system until such time as a <br /> remedial alternative has been selected and approved by the Water Board. ConocoPhillips needs to <br /> submit a detailed feasibility study (FS) work plan describing which remedial alternatives will be <br /> evaluated and how this work will be performed. The FS work plan should include a list of remedial <br /> alternatives to be considered and an associated schedule to perform the evaluation. An outline of <br /> requirements for a typical FS is attached to this letter. The FS work plan can focus on alternatives that <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />