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' QUARTERLY MONITORING REPORT,July 1998 CANEPA CAR WASH 6230 Pacific Avenue,,Stockton,CA August 24 1998 ' Page -4 MW-1, MW-2, MW-4, MW-6, and SV-4 at concentrations ranging from 0 4 (MW-6) to 71,000 µg/l (SV- 4) MTBE was detected in samples collected from MW-1, MW-3, and SV-4 at concentrations of 220, ' 6 5, and 70,000 µg/l, repetitively A summary of the current groundwater sample laboratory analytical results is presented in fable 2, below, and in Figure 2, Appendix A Laboratory report sheets indicating analytical methods used, detection limits, and the results of the analyses are contained in Appendix C The historical groundwater analyses are presented in Table A, Appendix B ' TABLE 2 LABORATORY ANALYSES (July, 1998) ' B T E X TPH-G MTBE Other Oxygenates* Detection limits 03 03 03 06 005 1 0 See Labortary Monitor Well Pg/l lig/l pg/1 µg/1 Mg/1 µg/1 Report Sheets ' 1707-MW1-7/22/98 4,900 1 200 400 1 ND** 32 220 ND** 1707-MW2-7/22/98 34,000 1 4,200 1 ND** 1 3,400 ND** I ND** ND** ' 1707-MW3-7/22/98 ND ND ND ND ND 6 5 ND 1707-MW4-7/21/98 ND 19 ND ND 01 ND ND 1707-MW5-7/21/98 ND ND ND ND ND ND ND ' 1707-MW6-7/21/98 ND 0 4 ND ND ND ND ND 1707-MW7-7/21/98 ND ND ND ND ND N= ND ' 1707-MW8-7/21/98 ND ND ND ND ND ND ND 1707-SV4-7/22/98 71,000 47,000 1,700 9,400 390 170,000 ND** Unit Conversions Analvtical pg/I parts per billion(ppb) B T,F X=benzene,toluene,ethyl benzene,and xylene inV] parts per million(ppm) TPH-G=total petroleum hydrocarbons quantified as gasoline tvi rBE=Methyl tertiary Butyl Ether *Other Oxygenates/Additives=ethanol,Di-isopropyl ether Ethyl tertiary- Butyl Ether tertiary-amyl Methyl Ethel and tertiary-Butanol ND=none detected at or above reported laboratory detection limit ND**=detection limit raised due to elevated concentrations(See ' Laboratory Report Sheets) ' 5 0 DISCUSSION OF RESULTS The average depth to groundwater was approximately 35 4 feet below the well measuring points at the site The groundwater elevation ranged from 21 96 to 22 96 feet bmsl During tine past four years, the depth to groundwater at the site has ranged from approximately 53 feet to 36 feet bgs The groundwater elevation contour map (Figure 3, Appendix A) indicates groundwater mounding in the center of the site • in the vicinity of MW-1 and MW-2 This is generally consistent with previous monitoring results 01ill, Na6lw- ;� CONDOR