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First Quarter,2003 Quarterly Groundwater Monitoring Report Canepa's Car Wash Pacific Avenue Stockton,CA Page 3 Table 2 Groundwater Elevation Data(January 14, 2002) Well Casing Well Collar Depth to Groundwater WELL Screen Elevation Water Elevation Interval (feet) (feet) (feet) feet-h s MW-1 50-70 1548 3662 -21 14 MW-2 50-70 1529 36 18 -2089 MW-3 50-70 1553 3715 -21 62 MW4 50-70 1583 3747 -2164 MW-5 50-70 1471 3661 -21 90 MW-6 45-65 1499 3553 -2064 MW-7 45-65 15 80 3653 -2073 MW-8 45-65 1531 3653 -21 22 MW-9 25-45 1484 3669 -2185 MW-10 25-45 1472 3568 -2096 MW-1 1 25-45 15 12 3594 -2082 MW-12D 100-110 1 1499 3578 -2079 LABORATORY ANALYTICAL RESULTS The groundwater samples collected from the monitor wells and SV-4 were analyzed for BTEX by EPA Method 8020, TPH-G by Method 8015M, and selected gasoline oxygenates/additives by EPA Method . 8260B by Excelchem Laboratories, Inc of Roseville, California (Excelchem) The selected oxygenates/additives included methyl tert butyl ether (MTBE), ethanol (EtOH), tertiary-butanol (TBA), dl-isopropyl ether (DIPE), ethyl-tert butyl ether (ETRE), tert-amyl methyl ether (TAME), 1,2- dichloroethane(1,2-DCA), and 1,2-dibromoethane (EDB) The current monitor well groundwater analytical results presented in Table 3, on the following page, are generally consistent with the historical results (Attachment C) The groundwater analytical results for SV- 4 indicate increased concentrations of MTBE, ethyl benzene, total xylenes, and TPH-G with respect to the previous monitoring event conducted in October 2002 Benzene and toluene concentrations decreased relative to the previous groundwater analytical results reported for SV4 during the October 2002 monitoring event The highest concentrations of BTEX constituents, MTBE, and TPH-G were detected in the samples from SV-4 The groundwater sample analytical results from well MW-12D continue to indicate a trend of lower contaminant concentrations since the initial sampling event for this well conducted on October 25, 2001 The BTEX concentrations detected In the groundwater sample collected from MW-1 are higher than previously detected, however, the MTBE concentration was louver than previously detected Benzene and MTBE isoconcentration contour maps are included as Figure 4 and Figure 5, respectively, in Attachment A The MTBE concentration detected in the groundwater sample collected from MW-3 is slightly higher than detected in October 2002 (Figure 6, Attachment A) None of the analytes of interest were detected at or above the laboratory reported detection limits In the groundwater samples collected from MW-5 through MW-10 Laboratory certificates of analyses and chain of custody record are included In Attachment E • �1, CONDOR