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i • 17 May 2005 AGE-NC Project No 96-0263 Page 2 of 5 allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume Each water sample was transferred into three 40-m1 volatile organic analysis(VOA)vials containing 0 5 ml 18% hydrochloric acid 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 State of California Department of Health Services (DHS)-certified analytical laboratory The samples were analyzed for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 5030/8015 Modified, and • Benzene,toluene, ethylbenzene and total xylenes(BTEX),fuel additives di-isopropyl ether (DIPS),ethyl tertiary-butyl ether(ETBE),methyl-tertiary-butyl ether(MTBE),ternary-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 09 March 2005, the contaminant impact to ground water was quantified from the laboratory analytical data 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 well casing elevations (Table 1) For the March 2005 sampling event, depths to ground water ranged from 6 87 feet to 7 91 feet below the tops of the well casings Ground water elevations at the site ranged from 28 91 feet above mean sea level(MSL)in well MW-9 to 29 82 feet above MSL in well MW-11 ' The ground water flow direction was determined by contouring the ground water elevation data The ground water at the site was inferred to be flowing to the north-northwest at an average gradient of ' 0 004 foot/foot The ground water contours are depicted on Figure 3 Elevation data from deep- screened well MW-6(screened between 27 and 32 feet bsg)was not used to determine ground water flow direction ' Advanced GeoEnvironmentel,Inc 1