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ai <br /> I01 October 2004 <br /> • AGE-NC Project No 99-0657 <br /> Page 2 of 4 <br />' 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES <br /> Water samples were collected from each purged well using new disposable plastic bailers after <br />' allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume Each water <br /> sample was transferred into one 1-liter amber bottle without sample preservative and into three <br /> 40-milliliter(ml)volatile organic analysis(VOA)vials containing 0 5 ml 18%hydrochloric acid as <br />' a sample preservative After collection, the samples were properly Iabeled, placed in a chilled <br /> container and transported under chain-of-custody to Cal Tech Environmental Laboratories(CTEL), <br /> a California Department of Health Services (DHS)-certified analytical laboratory, for analysis The <br />' samples were analyzed for <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) and diesel (TPH-d) in <br />' accordance with EPA Method 8015 Modified, and <br /> • Benzene,toluene,ethylbenzene and total xylenes(BTEX)and the fuel additives di-isopropyl <br />' ether(DIPE),ethyl tertiary-butyl ether(ETBE),methyl tertiary-butyl ether(MTBE),tertiary- <br /> amyl methyl ether(TAME),tertiary butyl alcohol(TBA), 1,2-dichloroethane(1,2-DCA)and <br /> 1,2-dibromoethane (EDB) in accordance with EPA Method 8260B <br />� i <br />' 3:0. FINDINGS <br /> Ground water elevation, flow direction, and gradient were determined from field data collected on <br />' 19 April 2004 The contaminant impact to ground water was quantified from the laboratory <br /> analytical data <br />' 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION <br />' At the time of the April 2004 sampling event, depths to ground water ranged from 36 84 (MW-7) <br /> feet to 38 81 (MW-6) feet below the tops of the well casings Ground water elevation at the site <br /> averaged approximately 3 58 feet above mean sea level (MSL) which indicates a decrease in <br />' elevation of approximately 1 78 feet since the January 2004 monitoring event (Table 1) During this <br /> monitoring event, the ground water levels in the wells were at least six feet below the tops of the <br /> well screens, indicating that the wells are screened properly to yield representative shallow ground <br />' water samples <br /> Ground water flow was inferred to be flowing towards the southwest with an average hydraulic <br />' gradient of 0 003 foot/foot This flow direction remains consistent with the previous monitoring <br />' Advanced GeoEnvironmental,Inc <br /> 1 <br />