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31 July 2000 <br /> AGE-NC Project No 97-0249 <br /> Page 2 of 5 <br /> 2 2 GROUND WATER SAMPLING <br /> Following well purging, ground water levels in monitoring wells MW-1 through MW-6 were <br /> allowed to achieve a minimum of 80 percent recharge prior to sample collection Ground water <br /> samples were collected from the purged wells utilizing new, disposable polyethylene bailers, one <br /> 1-liter amber bottle without a preservative and four 40-m1 EPA-approved VOA vials containing 0 5 <br /> ml 18%hydrochloric acid as a sample preservative Care was taken to ensure that visible air bubbles <br /> were not present in the vials after filling and capping Ground water sample containers were labeled <br /> with the well designation, date, time, and sampler's initials <br /> 2 3 LABORATORY ANALYSIS OF GROUND WATER SAMPLES <br /> Each ground water sample was logged on a chain-of-custody form, placed in a chilled container and <br /> transported to a California Department of Health Services (DHS)-certified laboratory for analysis <br /> for <br /> • • Total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d, <br /> respectively) by EPA Method 8015M, <br /> Volatile aromatic compounds benzene, toluene, ethyl benzene and xylene (BTEX) with <br /> methyl-tertiary butyl ether (MTBE) by EPA Method 8020, and <br /> Fuel oxygenated compounds tertiary butanol (TBA), di-isopropyl ether(DIPE), ethyl tert <br /> butyl ether(ETBE), tert arnyl methyl ether(TAME) and MTBE by EPA Method 8260M <br /> 3.0. FINDINGS <br /> Ground water elevation, flow direction and gradient were determined from field data collected on <br /> 26 May 2000, the contaminant impact to ground water was assessed from the ground water <br /> laboratory data <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> The depths to ground water in wells MW-1 through MW-6 were measured between 8 52 and 11 30 <br /> feet below the tops of well casings, ground water elevations were calculated to be between 1 38 feet <br /> and 175 feet below mean sea level Ground water elevation at the site decreased an average 3 98 feet <br /> between the February 2000 and the May 2000 ground water monitoring events The ground water <br /> elevation data for MW-1 through MW-6 during the May 2000 ground water monitoring event is <br /> Advanced GeoEnvironmental,Inc <br />