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(t <br /> Ms Lori Duncan <br /> Page 3 of 3 <br /> ppb, toluene at 32 ppb, ethylbenzene at 10 ppb, and xylenes at 46 ppb Well MW3 also contained several <br /> additional VOCs associated with petroleum hydrocarbons Groundwater analytical results are summarized <br /> on Table 3 Attachment 3 contains laboratory reports and chain of custody documentation <br /> The distribution of dissolved PCE, TCE, and cis-1,2-DCE beneath the site are presented on Figures 3, 4, and <br /> 5, respectively The figures were created by plotting the average concentration of the target analyte over the <br /> last four sampling events, the results of which are noted on each figure Although the contours are based on <br /> the composite value, the contours for a given sampling round would be very similar if plotted separately <br /> The concentration of dissolved PCE in all site wells over time is illustrated on Figure 6 <br /> 4.0 CONCLUSIONS <br /> Although groundwater beneath the site has consistently flowed northeast (Figure 2), the highest <br /> concentrations of PCE in groundwater were detected in well MW7, located. northwest (cross-gradient) of the <br /> former UST Further, no PCE has been detected in well MW3, which was completed through the former <br /> UST's location The distribution of dissolved PCE in site wells (Figure 3) strongly suggests that the primary <br /> source of PCE in groundwater is off-site <br /> Although measurable free product remains in well MW3 in the form of oily hydrocarbons, no dissolved <br /> petroleum hydrocarbon constituents have been detected in any other site well <br /> Based upon the distribution of PCE in groundwater beneath the site, we conclude that the primary source of <br /> PCE contamination in groundwater beneath the site is located off-site <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 /> Ground Zero Analysis, Inc <br /> 0i0 <br /> Joseph L Vasquez d P U' <br /> Staff Geologist j''t`�r <br /> y�Q to No 6�'095 <br /> John P Lane O� C �"�� <br /> CA Registered Geologist No 6795 <br /> Attachments <br /> cc Mr John Gabbard <br /> Mr James L L Barton, RWQCB-Central Valley Region <br /> Mr Patrick Riddle, Attorney at Law <br /> G 1GROUNDZEIGABBARDIreports\QMR1200413QM2004 doe <br />