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' 23 April 2002 AGE-NC Project No 97-0301 Page 2 of 5 1 i 1 2 2 GROUND WATER SAMPLING Following well purging, ground water levels at all wells achieved a minimum of 80 percent recharge prior to sample collection, however, ground water recharge was not documented at MW-4 Ground ' water samples were collected from the purged wells utilizing new,disposable polyethylene bailers and transferred into 1-liter amber bottles without sample preservative and 40-m1 EPA-approved VOA vials containing 0 5 ml 18%hydrochloric acid as a sample preservative Care was taken to ensure that visible 1 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 ' Following collection and labeling, 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, diesel, kerosene and motor oil (TPH-g, TPH-d, TPH-k and TPH-mo respectively)by EPA Methods 8015M/5030/3550/3510, • Benzene, toluene, ethyl benzene and xylene (BTEX) and methyl tertiary-butyl ether(MTBE) by EPA Method 8020, and • The fuel additives 1,2-Dichloroethane(1,2-DCA),ethylene dibromide(EBD),di-isopropyl ether (DIPE), ethyl tert butyl ether(ETBE),MTBE,tert amyl methyl ether(TAME), tertiary butanol (TBA), methanol and ethanol by EPA Method 8260M ' 30. FINDINGS ' Ground water elevation, flow direction and gradient were determined from field data collected on 20 December 2 00 1, the contaminant impact to ground water was quantified by the ground water laboratory data 3 1 GROUND WATER ELEVATION AND GRADIENT The depths to ground water in wells MW-1 through MW-7 were measured at between 30 41 and 3122 feet below the tops of well casings, ground water elevations were calculated to be between 18 01 feet (MW-6) and 18 21 feet(MW-5 and MW-7)below mean sea level Ground water elevation at the site . increased an average 1 41 feet between the September 2001 and the December 2001 ground water Advanced GeoEnvlronmentai,Inc 1