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Ile 25 October 2005 AGE-NC Project No 95-0167 ' Page 2 of 4 ' purged well to ensure that a minimum 80%of the initial well volume had recharged A ground water sample was collected from each purged well using the dedicated disposable plastic bailers Each water sample was transferred 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 California Department of Health Services (DHS)-certified analytical laboratory in Paramount, California The samples were analyzed for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA ' Method 8015 Modified, and • Benzene, toluene, ethylbenzene, and total xylenes (BTEX) and the fuel additives methyl ' tertiary-butyl ether MTBE, di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), tertiary-amyl methyl ether(TAME),tertiary-butyl alcohol(TBA), 1,2-dibromoethane(EDB), and 1,2-dichloroethane(1,2-DCA) in accordance with EPA Method 8260B 3.0. FINDINGS Ground water flow direction elevation and gradient were determined from data collected in the field during the December 2004 quarterly monitoring event The hydrocarbon impact to groundwater was quantified by laboratory data obtained from ground water samples 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION ' On 15 December 2004, depths to ground water ranged from 16 40 feet (MW-5 and MW-7) to 17 20 feet(MW-2)below the tops of the well casings Ground water elevations at the site averaged approximately 5 35 feet below mean sea level (MSL), indicating an average elevation decrease of ' 0 20 feet since the last monitoring event in September 2004(Table 1) During this monitoring event, ground water was within the screened interval of each well,thus producing an accurate sampling of the first encountered ground water ' The ground water flow direction was determined by plotting and contouring the ground water elevation data The shape of the water table at the time of the December 2004 monitoring event was in the form of a mound centered over monitoring well MW-2,_w1th a trough on the west end of the site Ground water at the site was determined to be flowing radially outward from the mound under an average hydraulic gradient of approximately 0 0035 foot/foot (ft/ft) Data collected from well MW-2 has exhibited excessively high ground water elevation values for the past two quarters,and may not represent the true ground water level or possibly indicate a surface water intrusion or utility Advanced GeoEnvironmental,Inc 1