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i Quarterly Monitoring Report April 2000 Canepa s Car Wash(Pacific Avenue) Page -> TABLE 2 LABORATORY ANALYTICAL RESULTS (APRIL 2000) B T E X TPH-G MTBE Detection limits 03 03 1 03 06 005 10 Monitor Well I D dig/L fig/L µg/L µg/L mg/L µg/L €707-M W I-4/12/00 940 620 81 310 5 840 1707-M W2-4112/00 38,000 2,100 1,500 5,900 61 N D(400) 1707-MW3-4/13/00 ND ND ND ND ND 15 1707-MW4-4/12/00 ND 13 ND ND 012 ND 1707-MW5-4/11/00 ND ND ND ND ND ND 1707-MW6-4112/00 ND ND ND ND ND ND 1707-MW7-4/12100 ND ND ND ND ND ND 1707-MWS-4/11/00 ND ND ND ND ND ND ILI 707-SV9-4/12/00 ND(150) ND(150) ND(150) ND(300) ND(25) 9,700 Unit Conversions Analytical µglL parts per billion(ppb) B T E X=benzene toluene ethyl benzene,and total xylenes mg/L parts per million(ppm) TPH-G=total petroleum hydrocarbons quantified as gasoline MTBE=Methyl tertiary Butyl Ether . ND=not detected at or above the laboratory reported detection limit ND(X)=not detectLd at or above a laboratory reported detection limit of X raised due to elevated concentrations of other analytes 1 5 0 DISCUSSION OF RESULTS 5.1 DISCUSSION OF GROUNDWATER ELEVATIONS 1 The average depth to groundwater measured during the April 2000 groundwater monitoting event was approximately 31 8 teet below the monitor well measuring points, which is approximately 13 to 19 feet above the top of all well screens The groundwater elevation ranged from 18 29 to 19 36 feet bmsl Since 1 November 1993, the depth to groundwater at the site has ranged from approximately 54 5 feet to 31 0 feet bgs The groundwater elevation contour map (Figure 2, Appendix A) Indicates groundwater mounding in the center of the site in the vicinity of MW-1 and MW-2 with a primary groundwater 1 gradient to the west, but with a northeast groundwater gradient reversal on the east side of the mound The groundwater mounding effect identified during the April 2000 quarterly groundwater monitoring event is general ly consistent with previous monitoring results 1 5 2 DISCUSSION OF ANALYTICAL RESULTS 1 The second quarter, 2000, laboratory analytical results (see Figures 3-5, and 7-9, Appendix A) are generally consistent with recent historical laboratory analytical results The laboratory analytical results indicate that none of the analytes of interest were detected at or above the laboratory reported detection 1 limits in the groundwater samples collected from MW-5, MW-6, MW- 7, and MW-8 BTEX, TPH-G, and MTBE were detected in the groundwater sample collected tram MW-1 Elevated concentrations of BTEX and TPH-G were detected in the gioundwater sample collected from MW-2 There was a significant decrease in the concentrations of BTEX, TPH-G, and MTBE in the groundwater sample 1 collected horn SV-9 on April 12, 2400, compared to the groundwater sample collected from SV-lk k 1 t� CONDOR