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6131 Pacific Avenue August 9, 2011 <br /> Page 2 <br /> In January 2006, additional DPE wells were installed onsite. A soil vapor extraction (SVE) <br /> system, rather than a DPE system, was operated from July through November 2006. <br /> In January 2007, DPE equipment was brought to the site and in April 2007, the DPE <br /> system was started. The system was shut down in February 2009 without prior notification <br /> to the EHD. <br /> In April 2009, CRA submitted on your behalf 'Remediation System Shutdown Request', <br /> two months after they shut the DPE system down. <br /> When notified by CRA after the fact that they had shut the remediation system down, the <br /> EHD directed submission of the contingency plan for remediation of the groundwater <br /> contamination that had been proposed in the approved CAP. Instead, the above <br /> referenced 'Remediation System Shutdown Request', which did not contain a plan for <br /> remediation of the groundwater contamination, was submitted. <br /> Most recently CRA has submitted on your behalf Updated Site Conceptual Model (SCM) <br /> dated June 10, 2011, and Groundwater Monitoring Report 2nd Quarter 2011 (GMR) dated <br /> July 15, 2011. Again the focus is on the offsite solvent plume, now with the suggestion <br /> that well MW-3 does not represent part of your plume. Wells MW-3, MW-4, MW-6 and <br /> MW-7 all historically had high concentrations of petroleum hydrocarbon constituents <br /> including benzene, toluene, ethylbenzene, xylenes and fuel oxygenates. All four of these <br /> wells appear to be part of your plume, whether or not there is a co-mingled solvent plume <br /> also present. The EHD notified you in 2003 that we agreed there appeared to be a solvent <br /> plume near your site, and now urges you to not expend additional resources on this issue <br /> that is not thought to be part of your unauthorized release. <br /> CRA is now recommending that additional groundwater monitoring wells be installed in <br /> the southeast area of your site, screened from 54-64 feet bsg, and is apparently already <br /> preparing a work plan. The EHD recommends focusing your resources on remediation of <br /> the source area contamination. Please proceed with submittal of the contingency plan for <br /> remediation of the source area groundwater contamination as originally proposed by CRA <br /> in the CAP. The contingency plan is due to the EHD no later than September 30, 2011. <br /> If you have any questions please contact Lori Duncan at (209) 468-0337 or by email at <br /> Iduncan@sjcehd.com. <br /> Lori Duncan, REHS Nuel C. Henderson, Jr. PG <br /> Senior Registered Environmental Health Specialist Engineering Geologist <br /> c: James Barton, CVRWQCB, 10020 Sun Center Drive#200, Rancho Cordova, CA 95670 <br /> Joe Neely, CRA, 19449 Riverside Drive #230, Sonoma, CA 94576 <br />