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08 October 1999 <br /> AGE-NC Project No. 95-0197 <br /> Page 2 of 5 <br /> 2.2. GROUND WATER SAMPLING <br /> Following well purging, ground water levels in monitoring wells MW-1, MW-2, MW-3 and MW-4, <br /> achieved a minimum of 80 percent recharge prior to sample collection. Ground water samples were <br /> collected from the purged wells utilizing new, disposable polyethylene bailers, 1-liter amber bottles <br /> and three EPA-approved 40-m1 VOA vials containing 0.5 ml 18% hydrochloric acid as a sample <br /> preservative. Care was taken to ensure that visible air bubbles were not present in the vials after <br /> filling and capping. Ground water sample containers were labeled with the well designation, date, <br /> 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 /> ' o Volatile aromatic compounds (benzene, toluene, ethyl benzene and xylene: BTEX) with <br /> methyl-tertiary butyl ether (MTBE)-by EPA Method'8020, and <br /> Tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tert butyl ether(ETBE),tert-amyl <br /> ' methyl ether (TAME) and MTBE by EPA Method 8260M. <br /> 3.0. FINDINGS <br /> ' AGE determined the ground water flow direction and gradient at the site from the field data collected <br /> on 13 July 1999. Laboratory.analysis of ground water samples collected from MW-.1,MW-2, MW-3 <br /> and MW-4 detected TPH-d in three ground water samples; MTBE was detected in two ground water <br /> ' samples. <br /> 1 .3.1. GROUNDWATER ELEVATION AND GRADIENT <br /> On 13 July 1999, the depths to first encountered ground water in wells MW-1, MW-2, MW-3 and <br /> . MW-4 ranged between 15.42 and 16.10 feet below the tops of well casings. Ground wafer elevations <br /> were calculated to lie between 10.70 feet and 10.82 feet below mean sea level; ground water <br /> Advanced GeoEnvironmental,Inc. <br />