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' QUARTERLY MONITORING REPORT,JULY 1997 CANEPA'S CAR WASH 248E Park Street Stockton CA Aubust 12, 194197 Page 3- ' 4 0 INVESTIGATION RESULTS ' 4 1 Laboratory Analyses The groundwater samples were analyzed for total petroleum hydrocarbons, quantified as gasoline (TPH-G) by Method 5030/LUFT and for benzene, toluene, ethyl benzene, and xylene (BTEX) ' and methyl tertiary butyl ether (MTBE) by EPA Method 602 EPA Method 8260 was used to attempt confirmation of MTBE in the sample from MW-5 The laboratory certificates of analyses and chain- of-custody are located in Appendix C ' 4.2 Results of Analyses ' Gasoline was detected in the groundwater samples from MW-1 at 0 30 mg/L, MW-2 at 21 mg/L, MW-3 at 0 88 mg/L, MW-5 at 14 mg/L, MW-6 at 0 10 mg/L, and MW-7 at 0 13 mg/L Gasoline was not detected at or above the laboratory reported detection limits in the sample from MW- 4 BTEX constituents were detected in groundwater samples collected from all the monitor wells ranging from 0 3 pg/L to 3,000 p,g/L MTBE was detected in groundwater samples from all seven monitor wells using EPA Method 602 However, EPA Method 8260 was used to attempt confirmation I of MTBE in MW-5 EPA Method 8260 indicated that MTBE was not present in the groundwater sample collected from MW-5 at or above the laboratory reported detection limit This result suggests that MTBE may not be present in groundwater samples at or above the laboratory reported detection limits collected from the other monitor wells during this and the previous monitoring events Additional analysis with EPA Method 8260 during future monitoring events may substantiate the potential absence of MTBE at the site The laboratory results are presented In Section 4 2, Table 1, and Figure 2, Appendix A 3-t Page -3- 41% • CONDOR