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' 10 December 2004 • AGE-NC Project No 02-0950 ' Page 4 of 4 ' containers without a preservative, and 16-oz plastic bottles containing 5 ml nitric 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, Inc (CTEL), a ' California Department of Health Services-certified analytical laboratory, for analysis The samples were analyzed for ' • Total petroleum hydrocarbons quantified as gasoline (TPH-g) and diesel (TPH-d) 1n accordance with EPA Method 8015 Modified, and • Benzene, toluene, ethylbenzene, and total xylenes (BTEX) and the volatile organic compounds methyl-tertiary-butyl ether(MTBE),tertiary-butyl alcohol(TBA), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), tertiary-amyl methyl ether (TAME), I 1,2-dichloroethane (1,2-DCA), and 1,2-dibromo ethane (EDB) in accordance with EPA Method 8260 ' 3.0. FINDINGS ' • Ground water elevation, flow direction, and gradient were determined from field data collected on 28 September 2004 The contaminant impact to soil and ground water was quantified from the laboratory analytical data 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION At the time of the September 2004 sampling event, depths to ground water ranged from 20 49 feet I (MW-3)to 20 89 feet(MW-1)below the tops of the well casings Groundwater elevation at the site averaged approximately 12 92 feet below mean sea level (MSL), which indicates a decrease in ground water elevation of approximately 2 31 feet between April and September 2004 (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 northeast under a hydraulic gradient of approximately 0 007 foot/foot (ft/ft), the direction rotated to the north since the last quarter, while fthe gradient was steeper Figure 3 illustrates the contoured ground water elevations as measured on ■ 28 September 2004 Ground water directions and gradients can vary greatly, as they are influenced by seasonal changes to the static water table Advanced GeoEnvironmental,Inc