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Californigegional Water Quality Cov#ol Board <br /> Central Valley Region , <br /> Karl E.Longley,ScD,P.E.,Chair <br /> Arnold <br /> Linda S.Adams Sacramento Main Office <br /> Schwaver negger <br /> Secrerog far <br /> 11020 Sun Center Drive 9200,Rancho Cordova,California 95670-6114 Governor <br /> Environmental Phone(916)464-3291 •FAX(916)464-4645 <br /> Protection http;//www.waterbouds.ca.gov/ceniralvalley <br /> 21 March 2008 REEVED <br /> Mr. Nam Baek MAR 2 5 2008 <br /> Glenn Springs Holdings, Inc. ENVIRONMENT HEALTH <br /> 5005 LBJ Freeway, Suite 1350 PERMIT/SERVICES <br /> Dallas, TX 75244-6119 <br /> COMMENTS ON 2007 ANNUAL REPORT, GROUNDWATER REMEDIATION PROJECT, <br /> OCCIDENTAL CHEMICAL COMPANY, LATHROP, SAN JOAQUIN COUNTY <br /> The California Regional Water Quality Control Board, Central Valley Region (Regional Water <br /> Board) staff has reviewed the 2007 Annual Report (Annual Report), dated February 2008, <br /> prepared on behalf of Glenn Springs Holdings, Inc. (OxyChem) by Conestoga-Rovers & <br /> Associates. The Annual Report describes the groundwater treatment system performance, <br /> monitoring, and sampling for January through December 2007. We appreciate Glenn Springs <br /> Holdings' continued operation of the treatment system. It is evident that the system is <br /> effective in reducing the overall footprint of the contaminant plumes. <br /> The groundwater treatment system was shut down in a planned operational cycling from <br /> January 1 to April 1, 2007. The system was re-started on April 2 and taken off line December <br /> 3, 2007. The system will remain off line until June 2008. <br /> 1 have the following specific comments. <br /> 1 . Please clarify capture zone geometry as shown in Figures 7.4, 7.5, 7.8, 7.9, 7.10, 7.11, <br /> and 7.12. In most of these figures the capture zone boundary does not extend to create a <br /> northern or southern boundary. How do you interpret the extent of the capture zones in <br /> the shallow, intermediate, and deep zones to the north and south of the site? <br /> 2. We have a concern regarding the more frequent detections and increasing trend in <br /> sulfolane concentrations in the injection zone since 1995. Although the statistical analysis <br /> presented in Appendix D identifies no significant trend in the last eight monitoring events or <br /> in the overall data set, wells such as PW9-338 and PW12-315 have exhibited sulfolane <br /> detections well above the permitted discharge limit since the injection program began. The <br /> rising concentrations indicate either untreated sulfolane in the treatment system effluent, or <br /> an undetected breach in the confining layer that has allowed impacts from the upper zones <br /> to infiltrate the injection zone. As sulfolane is apparently the most intractable of the <br /> constituents of concerns at the site, mitigating sulfolane impacts to the injection zone <br /> should be a high priority. We request that Glenn Springs Holdings propose corrective <br /> measures to address the source of sulfolane loading to the injection zone. <br /> California Environmental Protection Agency <br /> P.o� Reryded Paper <br />