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0 0 <br /> page 2, 6131 Pacific Ave. <br /> that groundwater flow direction places these wells cross gradient to the source area. <br /> SJC/EHD does not agree with this conclusion at this time. The wells were placed at <br /> locations proposed by your consultant, to cover the down gradient flow direction known <br /> at the time of their installation. Review of the reported groundwater flow directions at <br /> this site show variation in all directions over time. The laboratory data submitted with <br /> this report did not include quantitative analysis for PCE in any of the wells, nor were <br /> chromatograms provided. Review of the historical groundwater monitoring reports for <br /> this site did not show any analysis for PCE performed on groundwater samples. In <br /> addition, while concentrations of contaminants in MW-3 and MW-6 have decreased in <br /> recent years, they have historically shown high levels of contamination. <br /> You are directed to complete the following tasks: <br /> 1. Submit a work plan to complete the definition of the groundwater contaminant <br /> plume at this site, both vertically and laterally. <br /> 2. Submit a site conceptual model (SCM)for this site, including maps and cross <br /> sections showing the site hydrogeologic framework, potential contaminant <br /> migration pathways and a rose diagram of the historical groundwater flow <br /> direction. <br /> 3. Submit copies of chromatograms discussed in the Cambria report. <br /> 4. Verify and quantify the presence of PCE by having all samples collected at the <br /> next quarterly monitoring and sampling event analyzed by EPA method 8260B. <br /> Report results for 1,2 dichloroethane and ethylene dibromide also. <br /> 5. Continue routine quarterly groundwater monitoring and sampling of all site wells, <br /> until directed otherwise by this agency. <br /> Both the work plan and the SCM are due in this office by October 3, 2003. If you have <br /> any questions please call Lori Duncan at (209)468-0337. <br /> Donna Heran, REHS, Director <br /> Environmental Health Department <br /> Lori Duncan, Senior REHS Nuel C. Henderson, Jr., RG <br /> LOP/Site Mitigation Unit IV LOP/Site Mitigation Unit IV <br /> cc: James Barton, CVRWQCB <br /> Joe Neeley, Cambria <br />