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Ms Lori Duncan <br /> Page 3 of 3 <br /> Groundwater analytical results are summarized on Table 3 Attachment 3 contains laboratory reports and <br /> P <br /> chain of custody documentation <br /> 4.0 SUMMARY <br /> Groundwater levels and the direction of groundwater flow beneath the site were generally consistent with <br /> historical measurements An average of 0 03 feet of free product was measured in well MW3 during the <br /> reporting period A passive skimmer was installed in well MW3 on April 28, 2003 to remove free product <br /> Several VOCs were present in groundwater at levels exceeding their primary Maximum Contaminant Levels <br /> (MCLS) Benzene, cis-1,2-DCE, and TCE were present at levels exceeding their respective MCLS of 1 0 ppb, <br /> 6 0 ppb, and 5 0 ppb only in well MW3 (14 ppb, 19 ppb, and 5 8 ppb, respectively) PCE was present at levels <br /> exceeding its MCL of 6 0 ppb in each site well except MW3 (<2 0 ppb)and MW5 (5 0 ppb) <br /> 5 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 Iack 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 except well MW3, which was completed at the location of <br /> the former waste oil UST, and well MW5, which is upgradient of the former UST However, dissolved <br /> concentrations detected in groundwater samples collected from wells MW1, MW2 and MW4 have generally <br /> been decreasing since first sampled in December 2000 Groundwater samples collected from newly <br /> installed wells indicate that PCE is present upgradient (well MW5), downgradient (well MW6), and cross- <br /> 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 EI Dorado Streets, suggests that there may be an off- <br /> site source of PCE contamination in groundwater PCE concentrations in all site wells have steadily <br /> declined since groundwater monitoring began <br /> Please feel free to contact John 1ie_of Ground Zero at (209) 838-9888 if you have any questions regarding <br /> this submittal ' <br /> ED GFO <br /> Respectfully, �5 C0 <br /> Ground Zero Analysis,Inc JOIN P GN <br /> L.;iii= 0 <br /> No G195 ° <br /> N <br /> John P Lane _P1 <br /> CA Registered Geologist No 6795 OF CA\Y <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 /> G IGROUNDZEIGABBARDIreports\QMRV00314QM2003 doc <br />