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' 16 March 2005 AGE-NC Project No 99-0657 ' Page 2 of 4 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 State of 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 accordance with EPA Method 8015 Modified, and • Benzene, toluene, ethyl-benzene, and total xylenes (BTEX) and the fuel additives di- isopropyl ether (DIPS), 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 25 October 2004 The contaminant impact to ground water was quantified from the laboratory analytical data 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION At the time of the October 2004 sampling event,depths to ground water ranged from 35 40(MW-7) feet to 37 52 (MW-6) feet below the tops of the well casings Ground water elevation at the site averaged approximately 4 98 feet above mean sea level (MSL),which is an increase in elevation of approximately 13 feet since the July 2004 monitoring event(Table 1) During this monitoring event, the ground water levels in the wells were at least five 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 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 shows the contoured ground water elevations as measured on 25 October 2004 and a rose diagram showing ground water flow directions from previous monitoring events IAdvanced GeoEnvironmental,Inc