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First Quarter Groundwater Monitoring Report March 2003 Bnyett Petroleum,419 S.Main,Manteca,CA Page 4 LABORATORY ANALYTICAL RESULTS The groundwater samples were analyzed for benzene, toluene, ethyl benzene, and total xylenes (BTEX) and selected gasoline oxygenates/additives by EPA Method 826013, and total petroleum hydrocarbons quantified as gasoline (TPH-G) by Method 8015B by Argon Laboratories, Inc. of Ceres, California. The selected oxygenates/additives included methyl tertiary-butyl ether (MTBE), ethanol (EtOH), tertiary- butanol (TBA), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), tertiary-amyl methyl ether (TAME), 1,2-dichlorocthane(1,2-DCA), and 1,2-dibromoethane (EDB). Laboratory analytical results for the groundwater samples collected at the site on March 21, 2003, indicate that BTEX constituents and TPH-G were not detected at or above the laboratory reported detection limits in any of the groundwater samples collected from the monitor wells. Gasoline oxygenates/additives were not detected at or above the laboratory reported detection limits in the groundwater samples collected from MW-2, MW-3, MW-6, and MW-8. MTBE was detected in the groundwater samples collected from MW-1, MW-7, and MW-9. TAME was detected in the groundwater samples collected from MW-1 and MW-7. The laboratory analytical results for the March 2003 monitoring event indicate a decrease in the concentration of MTBE detected in samples collected from MW-1, MW-2, MW-3, and MW-8, and an increase in the concentration of MTBE detected in MW-7 and MW-9 relative to the previous sampling event conducted in December 2002. The laboratory analytical results for the first quarter 2003 quarterly groundwater monitoring event are presented in Table 4, on the following page. A map representing MTBE isoconcentration contours in shallow groundwater is included as Figure 5, attached. A graph showing MTBE concentrations versus time in monitor wells MW-1 and MW-7 is presented as Figure 6, attached. A graph showing MTBE concentrations and groundwater elevations in monitor wells MW-1 and MW-7 is presented as Figure 7, • attached. Historical groundwater monitoring data, laboratory certificates of analyses, and chain of custody record are also attached. ILA CONDOR