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' 26 November 2002 • AGE-NC Project No 95-0184 ' Page 2 of 5 ' 2 2 COLLECTION OF GROUND WATER SAMPLES Water samples were collected from each monitoring and vapor extraction well using new disposable ' bailers after allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume Each water sample was transferred Into laboratory-supplied 40-m1 VOA vials containing 0 5 ml 18% hydrochloric acid as a sample preservative,the sample from MW-4 was also transferred Into a 1-liter ' amber bottle without 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 and diesel (TPH-g and TPH-d) In ' accordance with EPA Method 8015m, Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether (MTBE) in accordance with EPA Method 602/8020, ' - The fuel oxygenates dl-Isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), MTBE, tertiary-amyl methyl ether (TAME), tertiary butanol (TBA), and other volatile organic ' compounds (VOCs) by GC/MS (full-scan 8260) ' 3.0. FINDINGS ' Ground water elevation and flow direction were Inferred from field data, hydrocarbon-Impact to ground water was quantified by laboratory analysis of theground water samples ' 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION ' The elevation of ground water In each well was calculated by subtracting the depth to ground water from the surveyed casing elevations (Table 1) Depths to ground water ranged from 32 49 feet to 33 17 feet below the tops of the well' casings, however, ground water levels are as high as ' approximately 22 feet above the screened Interval Ground water elevations at the site ranged from 19 89 feet In VW-2B to 20 35 feet In VW-5C below mean sea level (MSL) ' The ground water appears to flow generally northeast across much of the site at a gradient of approximately 0 007 ft/ft (Figure 2), however, an apparent north-northeast finger In the northern quarter of the site separates the flow pattern Into a northerly flow direction (gradient of about ' 0 023 ft/ft) and an easterly flow direction (gradient of about 0 017 ft/ft) ' Advanced GeoEnvi ron mental,Inc 1