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California P-gional Water Quality Contril Board <br /> Central Valley Region <br /> ion <br /> � <br /> Karl E. Longley,ScU, P.E.,Chair <br /> Linda S.Adams 11020 Sun Center Drive x200. Rancho Cordova.California 95670-6114 Arnold <br /> Secreraty'for Phone(916)464-3291 •FAX(916)464-4645 Schwarzeneg <br /> I_'17riron menlal Gorenlor <br /> Protection http:/'++++++ ++aterboards.cago+'/centralvallev �� <br /> 13 March 2009 <br /> ��AR 1 g 2009 <br /> Mr. Nam Baek <br /> Glenn Springs Inc. E�1V�RONMENT 1i�A�-TH <br /> Holdings, <br /> 5005 LBJ Freeway, Suite 1350 Q�an�,T��ERVICES <br /> Dallas, TX 75244-6119 <br /> GROUNDWATER REMEDIATION ANNUAL REPORT 2008, FORMER OCCIDENTAL <br /> CHEMICAL COMPANY, 16777 HOWLAND ROAD, LATHROP, SAN JOAQUIN <br /> COUNTY <br /> The California Regional Water Quality Control Board, Central Valley Region (Regional <br /> Water Board) staff has reviewed the 2008 Annual Report (Annual Report), dated <br /> February 2009, prepared on behalf of Glenn Springs Holdings, Inc. (GHSI) by <br /> Conestoga-Rovers & Associates (CRA). In the Annual Report, CRA describes the <br /> groundwater treatment system performance, monitoring, and sampling for January <br /> through December 2008. We appreciate GHSI's continued efforts to reduce the mass <br /> and extent of pollution caused by past operational practices at this facility. <br /> I have reviewed the Annual Report and concur with the findings that hydraulic capture <br /> of the groundwater plume has been maintained, and that the plume continues to shrink <br /> with the operation of the groundwater extraction and treatment system. <br /> We continue to be concerned that the aquifer that receives treated groundwater <br /> (injection zone) may be impacted by sulfolane concentrations. Currently four <br /> monitoring wells completed in the injection zone (PW09-338, PW12-315, PW16-329, <br /> and PW20-500) are sampled quarterly. Two of the wells have had no detectable <br /> concentrations of sulfolane in at least the last eight monitoring events. However, these <br /> wells (PW-20-500 and PW12-315) are located thousands of feet from injection wells <br /> IW-01 and IW-02. Therefore. we request that GHSI evaluate the adequacy_ of the <br /> monitoring network to characterize the injection zone, and prepare a Work Plan to <br /> analyze impacts to groundwater closer to the injection wells themselves. <br /> Given the lack of detections of sulfolane in wells PW20-500 and PW12-315, we are <br /> willing to consider a reduction in the frequency of monitoring of these wells. When we <br /> revise the Monitoring and Reporting Program for this project, we can incorporate this <br /> change. <br /> California Environmental Protection Agency <br /> H",Ir/e"l Pnprr <br />