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• <br /> (C c EPMPNP C BFIOWN Jn. <br /> -2v novrnuun <br /> - CLII.ONNI• <br /> Water Boards �ECEIVEH[ <br /> I4IAii HEv.� <br /> �r+viacrHw:rrn.l PnCrrrlinu <br /> 8 2012 <br /> Central Valley Regional Water Quality Control Board o <br /> ENVIRONMENTAL HEALTH <br /> 6 August 2012 PERMITISERVICES <br /> Mr. George Luxbacher <br /> Glenn Springs Holdings, Inc. <br /> 5005 LBJ Freeway, Suite 1350 <br /> Dallas, TX 75244-6119 <br /> REVIEW OF WELL INSTALLATION AND HYRAULIC TESTING REPORT AND ADDITIONAL <br /> WELL INSTALLATION WORK PLAN, FORMER OCCIDENTAL CHEMICAL CORPORATION <br /> FACILITY, LATHROP, SAN JOAQUIN COUNTY <br /> Staff of the California Regional Water Quality Control Board, Central Valley Region (Central <br /> Valley Water Board) has reviewed the Well Installation and Hydraulic testing Report(Report) <br /> and Additional Well Installation Work Plan (Work Plan), dated 28 February 2012. The Work <br /> Plan was prepared by ARCADIS US, Inc. (ARCADIS) on behalf of Glenn Springs Holdings, Inc., <br /> (GSH) for the former Occidental Chemical Corporation manufacturing facility (Site). The Site is <br /> located at 16777 South Howland Road in Lathrop, San Joaquin County. <br /> Background <br /> Historical operations onsite resulted in a release of the pesticides 1,2-dibromo-3-chloropropane <br /> (DBCP) and ethylene dibromide (EDB), and the solvent 2,3,4,5-tetrahydrothiophene-1,1-dioxide <br /> (sulfolane) to soil and groundwater underneath the Site. GSH has operated a groundwater <br /> extraction and treatment system since 1982 to remediate the groundwater. In 2011 and early <br /> 2012, the treatment system was optimized by reconfiguring the granular activated carbon (GAC) <br /> units from up-flow parallel to down-flow series operation, separating the bioreactor and GAC <br /> unit processes, and adding supplemental dissolved oxygen (DO) to the influent stream to <br /> improve sulfolane biodegradation. <br /> Investigation <br /> In December 2011, GHS performed soil borings and well installation activities onsite. Soil <br /> samples were collected from boring EW-09 at five-foot intervals from 10 feet (ft) to 40 ft below <br /> ground surface (bgs). Soil samples were analyzed for sulfolane using a gas chromatograph. <br /> Sulfolane was detected in soil at 70,000 pg/kg from 10 ft to 25 ft bgs and at 520 pg/kg from <br /> 30 to 40 ft bgs soil. <br /> Extraction well EW-09 was installed at 40 ft bgs in the sulfolane investigation area near well <br /> PW26-154. Permanent wells PW27-40, PW38-40, and PW29 40 were also installed at the <br /> KARL E. LONQLEY SCD, F.E.. CHAIR I r AWLA C. CRCCDON P.E., BCEE, Ex EGUTIVIL OFFICER <br /> 17020 Sun Center Drive 11200,RanChO Cordova,CA 95670 I www_waterooards.ca.00v/centrals all Py <br /> Ci nr, cl co r.rr.n <br />