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Quarterly Monitoring Report,October 1998 Canepa s Car Wash(Pacific Avenue) November t7, 1998 Page -3 I4 d GROUNDWATER MONITORING RESULTS 4 1 GROUNDWATER ELEVATION CONTOURS On October 22, 1998, the depth to groundwater was measured in each monitor well prior to the collection of groundwater samples The average depth to groundwater was approximately 35 7 feet below the well measuring points (slightly below the ground surface) The average depth to groundwater increased approximately 0 3 feet since the previous monitoring event conducted in July, 1998 The groundwater elevation ranged from 22 17 to 24 21 feet below mean sea level (bmsl) The groundwater elevation contour map (Figure 3, Appendix A) indicates groundwater mounding to the center of the site in the vicinity of N4W-1 See 'fable 1, below, for groundwater elevation data A hydrograph of groundwater elevations is included as Figure 4,Appendix A TABLE 1 Groundwater Elevation Data (October 22, 1998) IMW-1 through MW-8 Well Well Casing Well Collar Depth to Groundwater ID Screen Elevation Water Elevation Interval (feet) (feet) (feet) (feet- bgs) MW-1 50- 70 1345 3569 -2224 MW-2 50- 70 13 27 3544 -22 17 IMW-3 50- 70 13 50 3598 -2248 I MW-4 50-70 13 82 36 11 -2229 MW-5 50- 70 1269 3504 -2235 MW-6 45 - 65 11 62 35 83 1 -2421 MW-7 45 -65 13 18 35 86 -2268 MW-8 45 -65 13 26 3584 }_ -2258 l 4 2 LABORATORY ANALYSES (TPH-G, BTEX,OXYGENATES/ADDITIVES) The groundwater samples were analyzed by GeoAnalytical Laboratories, Inc for total petroleum Ihydrocarbons - quantified as gasoline (TPH-G) by Method 5030/LUFT, for benzene, toluene, ethyl j benzene, and total xylenes (B 1'EX) by EPA Method 602, and for selected gasoline oxygenates/additives by EPA Method 8260 The gasoline oxygenates/additives include methyl tertiary-butyl ether (MTBE), ethanol, tertiary-butanol, di-isopropyl ether (DIPS), ethyl terttary-butyl ether (ETBE), and terttary-amyl methyl ether(TAME) D•r i� CONDOR i I