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12 November 2004 AGE-NC Project No 99-0657 Page 2 of 4 ' 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Water samples were collected from each purged well using the disposable plastic bailers after allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume Each water sample was transferred into one 1-liter amber bottle without sample preservative and into three 40-milliliter (ml) volatile organic analysis (VOA) vials containing 0 5 ml 18% hydrochloric acid ' solution as a sample preservative After collection, the samples were properly labeled, placed in a chilled container, and transported under chain of custody to Cal Tech Environmental Laboratories (CTEL), a California Department of Health Services (DHS)-certified analytical laboratory, for analysis The samples were analyzed for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) and diesel (TPH-d) in Iaccordance with EPA Method 8015 Modified, and • Benzene,toluene,ethylbenzene,and total xylenes(BTEX)and the fuel additives di-Isopropyl ether(DIPE),ethyl tertiary-butyl ether(ETBE),methyl tertiary-butyl ether(MTBE),tertiary- amyl methyl ether(TAME),tertiary butanol(TBA), 1,2-dichloroethane(1,2-DCA),and 1,2- dibromoethane (EDB) in accordance with EPA Method 8260B 3.0 FINDINGS Ground water elevation, flow direction, and gradient were determined from field data collected on 26 July 2004 The contaminant impact to ground water was quantified from the laboratory analytical data I3 1 GROUND WATER GRADIENT AND FLOW DIRECTION At the time of the July 2004 sampling event,depths to ground waterranged from 36 69(MW-7)feet to 38 88 (MW-6)feet below the tops of the well casings Ground water elevation at the site averaged approximately 3 67 feet above mean sea level (MSL), which is an Increase in elevation of I approximately 0 09 feet since the April 2004 monitoring event (Table 1) During this monitoring event, the ground water levels in the wells were at least six feet below the tops of the well screens, indicating that the wells are screened properly to yield representative shallow ground water samples Ground water flow was inferred to be flowing toward the south to southwest under an average hydraulic gradient of approximately 0 005 foot/foot (ft/ft) This flow direction remains consistent with the previous monitoring events Figure 3 illustrates the contoured ground water elevations as • Advanced Geo E nviron mental,Inc