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' 16 February 2005 • - AGE-NC Project No 98-0465 Page 2 of 4 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Water samples were collected from each monitoring well using dedicated,disposable plastic bailers after allowing the well to achieve a minimum 80% recovery of the pre-purge water volume The - ' samples from each well were transferred into three 40-'milliliter(ml)volatile organic analysis(VOA) vials containing 0 5 ml 18% hydrochloric acid solution as a sample preservative and one 1-liter ' amber bottle without preservative The samples were labeled with the monitoring well designation, date,time of sampling,and the sampler's initials and transported in a chilled container under chain of custody to Cal Tech Environmental Laboratories (CTEL), a Department of Health Services- certified analytical laboratory, for analysts The samples were analyzed for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) and diesel (TPH-d) in ' accordance with EPA Method 8015-modified, • Volatile aromatic compounds benzene, toluene, ethylbenzene, and xylenes (BTEX) in ' accordance with EPA Method 8260B, and • Fuel oxygenates methyl tertiary-butyl ether (MTBE), di-isopropyl ether (DIPS), ethyl tertiary-butyl ether(ETBE),tertiary-amyl methyl ether(TAME),and tertiary butanol(TBA) lie in accordance with EPA Method 8260B, and • Fuel scavengers ethylene dibromide(EDB)and 1,2-dichloroethane(1,2-DCA)in accordance ' with EPA Method 8260B 3.0. FE4DINGS Ground water elevation and flow direction were inferred from field data collected on 15 October ' 2004,hydrocarbon impact to ground water was quantified by laboratory analysis of the ground water samples 1 3 1 , GROUND WATER GRADIENT AND FLOW DIRECTION 1 The elevation of ground water in each of the monitoring wells was calculated by subtracting the depth to ground water from the surveyed relative casing elevations(Table 1) Depths to ground water ' averaged about 13 20 feet below surface grade(bsg)-Ground water elevations at the site ranged from 9 91 feet (MW-4) to 10 07 feet (MW-1) below mean sea level (MSL) Ground water elevations at the adjacent site (Sanchez Property) ranged from 7 87 feet below mean sea level (MSL) in well 1 MW-5 to 8 19 feet below MSL in wells MW-6B(Table 1) During this monitoring event,the ground water elevations were within the screened intervals of the wells r Advanced GcoEnvironmental,Inc x