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r 23 December 1999 AGE-NC Project No. 95.0197 Page 2 of 4 2.2. GROUND WATER SAMPLING Following well purging, groundwater levels in monitoring wells MW-1,MW-2,MW-3, and MW-4 achieved a minimum of 80 percent recharge prior to sample collection. Ground water samples were collected from the purged wells utilizing new, disposable polyethylene bailers, I-liter amber bottles and three EPA-approved 40-m1 VOA vials containing 0.5 ml 18% hydrochloric acid as a sample preservative. Care was taken to ensure that visible air bubbles were not present in the vials after pilling and capping. Ground water sample containers were labeled with the well designation, date, time, and sampler's initials. 2.3. LABORATORY ANALYSIS OF GROUND WATER SAMPLES Each ground water sample was logged on a chain-of-custody form,placed in a chilled container and ' transported to a California Department of Health Services (DHS)-certified laboratory for analysis for: • Total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d, respectively)by EPA Method 8015M, Volatile aromatic compounds (benzene, toluene, ethyl benzene and xylene: BTEX) with methyl-tertiary butyl ether(MTBE)by EPA Method 8020, and Tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tert butyl ether (ETBE), tert amyl methyl ether(TAME) and MTBE by EPA Method 8260M. 3.0. FINDINGS AGE determined a north-northeast ground water flow direction•at a gradient of 0.001 ft/ft at the site from the field data collected on 08 October 1999. Laboratory analysis of ground water samples collected from MW-1, MW-2, MW-3, and MW-4 detected MTBE'and TBA in one ground water sample (MW-2). TPH-g, TPH-d, and BTEX were not detected in any of the ground water samples above the laboratory reporting limits. 3.1. GROUND WATER ELEVATION AND GRADIENT On 08 October 1999,the depths to first encountered ground water in wells MW-1, MW-2, MW-3, and MW-4 ranged between 16.17 and 16.77 feet below the tops of well casings. Ground water elevations were calculated to lie between 11.45 feet and 11.52 feet below mean sea level; ground Advanced GeoEnvironmental,Inc.