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' 12 December 2005 AGE-NC. Project No. 95-4137 Page 2 of 4 22. - COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES t Ground water samples were collected from the purged wells using new disposable plastic bailers after allowing the wells to achieve a minimum 80% recovery of the pre-purge water volume. Each sample was transferred into three, 40-milliliter (ml) EPA-approved volatile organic analysis (VOA)vials and into one 1-liter amber bottle. Samples were properly labeled, stored in a chilled container, and transported under chain of custody to Cal Tech Environmental Laboratories (CTEL), a California Department'of Health Services (DHS)-certified laboratory, for analysis. Each sample was 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 methyl tertiary-butyl ether(MTBE), tertiary-butyl alcohol (TBA),di-isopropyl ether (DIPS), . ' ethyl tertiary-butyl ether(ETBE),tertiary-amyl methyl ether (TAME), 1,2-dibromoethane (EDB), and 1,2-dichloroethane (1,2-DCA) in accordance with EPA Method 8260B. 3.0, FINDINGS ' Ground water elevation, flow direction, and gradient were determined from field data collected . on 17 August 2005.and;the contaminant impact to ground water was quantified from laboratory data. 3.1. GROUNDWATER GRADIENT AND FLOW DIRECTION Depths to ground water during the August 2005 monitoring event ranged from 23.09 feet (MW- 3)to 25.68 feet (MW-9) below the tops of the well casings; the depth to ground water decreased approximately 0.9 feet since t��Wfy 2005 qu erly monitoring event. The calculated ground water elevations ranged fromgg��feet(MW,� to 33.68 feet (MW-6); which was an average 7 ' ground water elevation calculated. The ground water flow direction was inferred to be west to northwest, at a ground water gradient of 0.0009 foot/foot(ft/ft) across the farmer'UST release area(Figure 3). 3.2. ANALYTICAL RESULTS OF GROUND WATER SAMPLES tTPH-d were detected in the ground water samples from two on-site wells at Ripon Farm Service. Advanced GeoEnvironmentaf,Inc.