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18 August 2004 <br /> AGE-NC Project No 95-0142 <br />' Page 2 of 4 <br /> a <br /> 2 2 GROUNDVATER SAMPLE COLLECTION <br /> After allowing the monitoring wells to achieve a minimum of 80%recovery of the pre-purge water <br /> volume, water samples were collected from each well using the dedicated polyethylene tubing <br /> , <br /> „ The waterway then transferred into EPA-approved 40-milliliter(ml)volatile organic analysis(VOA) <br />' vials containing 0 5 ml hydrochloric acid(18%)as a sample preservative The vials were labeled and <br /> placed in a chilled container for subsequent transport under chain of custody to McCampbell <br /> Analytical, Inc (MAI), a State of California Department of Health Services (DHS) certified <br />' laboratory Ground water samples were analyzed for the following , <br /> • Total petroleum hydrocarbons as gasoline (TPH-g) in accordance with EPA Method 8015 <br />' Modified, <br /> Benzene, toluene, ethylbenzene and total xylenes (BTEX) in accordance with EPA <br />' Method 8021, and <br /> • The oxygenated fuel additives methyl tertiary-butyl ether(MTBE),di-isopropyl ether(DIPE), <br /> ethyl tertiary-butyl ether (ETBE), tertiary-amyl methyl ether (TAME) and tertiary butanol <br /> (TBA) in accordance with EPA Method 8260B <br />' 3.0. FINDINGS <br />' Ground water elevation, flow direction and gradient were determined from field data collected on <br /> 27 May 2004 The contaminant impact to ground water was quantified by the ground water <br /> laboratory`data <br /> 3 1 . GROUND WATER GRADIENT AND DIRECTION f _ <br /> Depth to ground water at the site ranged between 28 89 feet and 29 96 feet below the tops of the <br /> monitoring well casings,depth to'ground water data from the extractions wells were not utilized due <br />' to modification of the casing tops as a result of remediation system installation The ground water <br /> elevation in the wells ranged from 16 60 feet(MW74) to 17 70 feet(MW-3)below mean sea level <br /> (MSL), the averageground water elevation increased in well MW-4 through MW-8 and decreased <br /> in well MW-3 since the previous monitoring event The elevation and ground water depth data is , <br /> summarized in Table 1 <br /> L , <br /> 1 } 1 L , <br /> At the time of the Second Quarter 2004 monitoring event,the ground water potentiometric surface <br /> appears as a southwesterly-plunging ridge, flowing southwest at a hydraulic gradient of 0 007 ft/ft <br /> Advanced GeoEnvironmentai,Inc <br /> , <br />