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Mr Michael Infurna Page 2 of 3 Laboratories (ELAP #2359) The samples were analyzed for gasoline oxygenate additives, EDB and 1,2-DCA using EPA method 8260B, BTEX using EPA method 8020, TPHg using EPA 8015M, and lead using EPA method 200 7 Groundwater monitoring data and purge logs are included in Attachment A Monitoring Well Survey As required by AB 2886, all monitoring wells were surveyed by a Registered Surveyor to a horizontal accuracy of less than one meter and a vertical accuracy of 0 01 feet In February 2002, Morrow Surveying surveyed the latitude and longitude of the site wells relative to the North American Datum(NAD83), and surveyed the wellhead elevations relative to City of Tracy Benchmark located at the intersection of Grant Line Road and East Street A site map showing monitoring well locations, latitude and longitude coordinates and wellhead elevations is included in Attachment B GROUNDWATER ANALYTICAL RESULTS TPHg was detected in wells MWI and MW2 at concentrations of 320 parts per billion (ppb) and 73 ppb, respectively Benzene was detected in wells MWI and MW2 at concentrations of 23 ppb and 6 8 ppb, respectively Ethylbenzene was detected in wells MWI and MW2 at aconcentrations of 6 3 ppb and 7 4 ppb respectively No toluene, xylenes, MTBE, lead, or any other target analytes were detected in wells MWI or MW2 No gasoline constituents of any kind were detected in well MW3 Analytical data are summarized in Table 2 Laboratory reports and chain-of-custody documentation are included in Attachment C SUMMARY Groundwater flow beneath the site was toward the northeast, which is consistent with historical measurements Low levels of TPHg, benzene, and ethylbenzene were detected in groundwater samples collected from wells MWI and MW2 No gasoline constituents were detected in well MW3 No oxygenated gasoline additives, lead, or lead scavengers were detected in any site well CONCLUSIONS AND RECOMMENDATIONS The current levels of TPHg in wells MWI and MW2 represent reductions of 85% and 99%, respectively from historic highs The current levels of benzene represent reductions of 89% and 97%, respectively from historic highs, which demonstrates that natural attenuation processes are actively reducing contaminant concentrations Time vs Concentration plots of benzene and TPHg for these wells are presented in Figures 3 and 4 G 1Data1GROUNDZfi\PESTANAIPESTANA 0361REP0RTSIclosurc02 doc