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u �� <br /> � Ms Lori Duncan <br /> Page 4 of 4 <br /> PCE, cis-1,2-DCE, and chloroform were detected in the groundwater samples collected from monitoring wells <br /> t MW1, MW2, MW4, MW5, MW6, and MW7 No sample was collected from well MW3 due to the presence <br /> of free product TCE was only detected in wells MW I,MW6, and MW7 <br /> Detected concentrations of chloroform and cis-1,2-DCE in each site well were below the Primary Maximum <br /> Contaminant Levels (MCLs) of 80 ppb for chloroform and 6 ppb for cis-1,2-DCE, which were established by <br /> the State of California Department of Health Services The detected concentrations PCE exceeded the primary <br /> MCL of 5 0 ppb in all site wells <br /> 6.0 CONCLUSIONS <br /> Petroleum hydrocarbon contamination, in the form of free product (oil) in well MW3, is apparent in <br /> groundwater within close proximity to the former UST The contaminant plume associated with the former <br /> UST appears to be stable as evidenced by the lack of free product and/or dissolved petroleum hydrocarbon <br /> constituents in any perimeter wells <br /> PCE exceeds its MCL of 5 ppb in each site well However, dissolved concentrations detected in <br /> groundwater samples collected from wells MW1, MW2 and MW4 have generally been decreasing since first <br /> sampled in December 2000 Groundwater samples collected from newly installed wells indicate that PCE, <br /> as well as chloroform and cis-1,2-DCE are present upgradient (well MW5), downgradient (well MW6), and <br /> cross-gradient(well MW7) from the former waste oil UST <br /> The distribution of PCE in groundwater beneath the site, with the highest concentration detected in the <br /> cross-gradient well nearest the intersection of Park and El Dorado Streets, suggests that there may be an off- <br /> site source of PCE contamination in groundwater <br /> The next monitoring and sampling event is scheduled for September 2003 EHD will be notified at least 48 <br /> hours prior to conducting any fieldwork <br /> Please feel free to contact John Lane of Ground Zero at (209) 838-9888 if you have any questions regarding <br /> this submittal <br /> Respectfully, <br /> Gro d Z nalysis, Inc <br /> y <br /> 0 GG/ <br /> S arveO <br /> �cr� Ciao <br /> Staff Geologist rr .OPN P <br /> LAv <br /> No 6795 <br /> John P Lane <br /> CA Registered Geologist No 6795 <br /> OF CR�i <br /> Attachments <br /> cc Mr Gary Gabbard <br /> Mr James L L Barton, RWQCB-Central Valley Region <br /> Mr Patrick Riddle, Attorney at Law <br /> GIGROUNDZEIGABBARDIreports\QMR12003UQM2003 doc <br />