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' 14 May 2002 AGE-NC Project No. 97-0327 Page 2 of 4 2.2. GROUND WATER SAMPLING Following well purging, ground water levels in the wells achieved a minimum of 80 percent recharge ., prior to sample collection. Ground water samples were collected from the purged wells utilizing disposable polyethylene bailers and transferred to 40-m1 EPA-approved VOA vials containing 0.5 ml 18%hydrochloric acid as a sample preservative and 1-liter amber bottles without preservative. ' Care was taken to ensure that visible air bubbles were not present in the vials after filling 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 5030/8015M and LUFT/EPA 8015B, • Benzene,toluene,ethyl benzene and xylene(BTEX)with methyl-tertiary butyl ether(MTBE) ' by EPA Method 8020, and • Ethylene dibromide (EDB), dichloroethane (1,2-DCA), methanol, ethanol, tertiary butanol (TBA), di-isopropyl ether(DIPE), ethyl tert butyl ether(ETBE) and tert amyl methyl ether (TAME), and MTBE by EPA Method 5030/8260. 0. FINDINGS NGS tGround water elevation, flow direction and gradient were determined from field data collected on 18 December 2001; the contaminant impact to ground water was quantified by the laboratory data. 3.1. RELATIVE GROUND WATER ELEVATION AND GRADIENT The-depths-to ground water in wells-MW-1, MW-2 and-MW-3 were between•55:7$ and 57.84 feet below the tops of the well casings; ground water elevations at the site were calculated to be between ' 30.31 feet and 31.00 feet below mean sea level. Ground water elevation at the site decreased an average 1.05 feet between the September 2001 and the December 2001 ground water monitoring events. Ground water elevations are depicted in Figure 3. ' Advanced GeoEnvironmental,Inc.