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' 15 September 2000 AGE-NC Project No. 98-0450 ' Page 2 of 4 ' 2.2. GROUND WATER SAMPLE COLLECTION The ground water levels in all six wells were allowed to recharged to a minimum of 80%of the initial ' well volume prior to sample collection. Ground water samples were collected from each well using new disposable plastic bailers. Each water sample was then transferred into one 1-1 amber bottle and three 40-m1 volatile organic analysis (VOA) vials containing 0.5 ml 18% HCl as a sample preservative. The samples were then labeled and placed in a chilled container for transport under chain-of-custody to McCampbell Analytical, Inc. (MCAI) of Pacheco, California, a Department of Health Service (DHS)-certified laboratory. The samples were analyzed for the following: • Total petroleum hydrocarbons quantified as gasoline (TPH-g) and total petroleum hydrocarbons quantified as diesel(TPH-d) in accordance with EPA method 8015-modified ' for gasoline and diesel, respectively, • Volatile aromatics(benzene,toluene,ethyl benzene and xylene; BTE&X) with methyl tert- butyl ether (MTBE) in accordance with EPA method 8020, • Fuel oxygenates [MTBE, di-isopropyl ether(DIPE), ethyl tert butyl ether(ETBE),tert amyl . methyl ether (TAME) and tertiary butanol (TBA)] in accordance with EPA method 8260- lmodified. ' 3,0. FINDINGS ' 3.1. RELATIVE GROUND WATER ELEVATION AND GRADIENT The depths to ground water from the ground water monitoring wells were measured at 46.25 to 47.00 feet from the tops of the well casings. The corresponding ground water elevations ranged from 0.92 to 1.23 feet below mean sea level. Over the last quarter, ground water elevation has increased an average 0.28 to 0.30 feet at the site. The ground water elevation data for the well network during the latest ground water monitoring event is depicted in Figure 3. The ground,water flow direction determined during this monitoring event is in a southerly and south-southwesterly direction with a hydraulic gradient of 0.003 feet/feet or 15.8 feet per mile (Figure 3). 1 Based on a southerly to southwesterly flow direction within the area contained by the six monitoring wells,well MW-5 is in the most down-gradient position from the former dispenser system and wells BMW-1 -and-BMW-2 are down gradient from theTbdr ier UST area: ' Table I shows the screen intervals for monitoring wells BMW-3, BMW-4 and BMW-5 and the assumed screen intervals for monitoring wells BMW-1 and BMW-2. Well MW-5 may be screened . approximately 3 feet below the ground water table.The analytical results obtained are believed to be ' Advanced GeoEnviron mental,Inc.