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24 May 2006 • AGE-NC Project No 01-0886 ' Page 2 of 4 23 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Ground water samples were collected from each well using the dedicated Waterra tubing after ' allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume Each water sample was transferred into three laboratory-supplied, 40-milliliter (ml) volatile organic analysis (VOA) vials containing 0 5 ml 18% hydrdchloric acid solution as a sample preservative, and one ' 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 in Paramount, California The samples were analyzed for • • Total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d, ' respectively) In accordance with EPA Method 8015 Modified, and • Benzene,toluene,ethylbenzene,and total xylenes(BTEX)and fuel oxygenates di-isopropyl ether (DIPE), methyl tertiary-butyl ether (MTBE), ethyl tertiary-butyl ether (ETBE), tertiary-amyl methyl ether (TAME), tertiary-butyl alcohol (TBA), 1,2-dichloroethane(1,2- DCA), and 1,2-dibromoethane (EDB) by EPA Method 8260B r • v ' 3.0. FINDINGS Ground water elevation, flow direction, and gradient were determined from field data The tcontaminant Impact to ground water was quantified by laboratory analytical data 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION At the time of the March 2006 sampling event, depths to ground water ranged from 63 35 feet ' (MW-1)to 63 89 feet(MW-2)below the tops of the well casings(Table 1) Ground water elevation at the site ranged from 33 03 feet(MW-2)to 33 28 feet(MW-1)below mean sea level (MSL), and averaged approximately 33 15 feet below MSL,Indicating an Increase in elevation of approximately ' 2 36 feet since the last ground water monitoring event in December 2005 During this monitoring event, the ground water levels In all three wells were within the screened Intervals, indicating that the wells are properly screened to yield ground water samples representative of shallow ground water conditions Ground water at the site was inferred to be flowing toward the west-southwest under a hydraulic ' gradient of approximately 0 005 foot/foot (ft/ft) Figure 3 Illustrates the contoured ground water • elevations as measured on 08 March 2006 ` Advanced GeoEnvironmental,Inc 1