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' 19 January 2004 S AGE-NC Project No 95-0173 ' Page 3 of 10 ' 2 3 LABORATORY ANALYSIS OF GROUND WATER SAMPLES After labeling, each ground water sample was logged on a chain of custody form,placed in a chilled ' container,and transported to Castle Analytical Laboratory(CAL),a California Department ofHealth Services (DHS)-certified laboratory, to be analyzed for • Total petroleum hydrocarbons quantified as gasoline(TPH-g)by EPA Method 5030/8015M, • Benzene, toluene, ethylbenzene, and total xylenes (BTEX) and methyl tertiary-butyl ether (MTBE) by EPA Method 8020, and • MTBE, tertiary-amyl methyl ether (TAME), tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), 1,2-dichloro ethane (1,2-DCA), and ethylene ' dibromide (EDB) by EPA Method 5030/8260 24 QUARTERLY GROUND WATER MONITORING AND SAMPLING FINDINGS ' . AGE determined ground water flow direction and gradient from the field data collected on 06 October 2004, the contaminant Impact to ground water was assessed from the laboratory data collected on 07 October 2004 2 4 1 Ground Water Elevation and Gradient ' During the October 2004 ground water monitoring event, the depths to ground water ranged from ' 32 25 feet(MW-1) and 35 50 feet (MW-13C) below the tops of the well casings (Table 2), ground water elevations were calculated to be between 22 89 feet (MW-1) and 25 59 feet (MW-5) below mean sea level Figure 3 Illustrates the ground water elevations plotted and contoured on a scaled ' site map Generally,groundwater flow direction was inferred to be east-northeast at an apploxlmate hydraulic gradient of 0 006 fl/ft or less (Figure 3), typically, ground water elevation at the site decreased an average 2 73 feet between the July and October 2004 ground water monitoring events ' Based on the historical ground water data collected at the site, it Is likely that the ground water . elevatlolls measured from Vveils lv/ VV -i ar'ld tYl TV-U YY4117 Q �Lrle 111LL<.cur"a e, eitllVl UU%A LV 1aLL1LY L,.L.ILL1V111G11L and/or technician error Therefore,ground water elevation measurements collected from wells MW-1 ' and MW-8 were not utilized In contouring the October 2004 ground water elevations (Figure 3) GeoTracker confirmation pages of the submitted ground water monitoring electronic deliverable format (EDF) files are Included In Appendix B Advanced GeoEnvironmental,Inc I