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Ms Lori Duncan <br /> Page 3 of 3 <br /> • No petroleum hydrocarbons or gasoline additives were detected above method detection limits in <br /> groundwater samples collected from any site well, except well MW3 Well MW3 contained TPHg at 880 <br /> ppb, benzene at 17 pg/L, toluene at 37 µg/L, ethylbenzene at 15 pg/L, and xylenes at 88 pg/L Well MW3 <br /> also contained several other VOCs associated with petroleum hydrocarbons Groundwater analytical results <br /> are summarized on Table 3 Attachment 3 contains laboratory reports and chain of custody documentation <br /> The distribution of dissolved PCE beneath the site is presented on Figure 3 The figure was created by <br /> plotting the average concentration of the target analyte over the last four sampling events, the results of <br /> which are noted on the figure Although the contours are based on the composite value, the contours for a <br /> given sampling round would be very similar if plotted separately The concentration of dissolved PCE in all <br /> site wells over time is illustrated on Figure 4 <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 /> 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 /> j00 <br /> � <br /> PEp GAO <br /> Joseph L Vasquez <br /> Staff Geologist Q, JOHN P <br /> LANE a <br /> No 61795 <br /> John P Lane <br /> CA Registered Geologist No 6795 7�cs`QP C P,Ll�O�p <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 1GROUNDzE1GABBARi)Ireports\QMR1200511QM2005 doe <br />