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ti _ r •. I Sal;._ ' ' 22 October'2004 ; '• 'AGE- j ; NC Project No. 95-0106 . Page 2 of 4 The .samples were transported `in a chilled container under chain of custody to• Cal Tech ' 'Environmental Laboratories (CTEL), a California:Department of Health Services (DHS)-certified analytical laboratory, and analyzed for: ; • Total ,petroleum hydrocarbons., quantified as gasoline (TPH-g) in accordance with EPA Method 8015-Modified; ' Benzene, toluene, ethylbenzene and xylenes (BTEX); and fuel additives methyl tertiary- butyl-ether'(MTBE), tertiary butyl alcohol'(TBA), diisopropylether(131PE), ethyl tertiary- butyl'ether(ETBE),tertiary-amyl methyl-ether(TAME), 1,2-dibromoethane(EDB),and 1,2- , dichloroethane (1,2-DCA) in accordance with EPA Method 8260B.- '3.0.1 ' FINDINGS. Groundwater:elevation and flow tion were inferred from field data. The hydrocarbon impact to ground waterwas quantified by laboratory'analysis of the ground water samples. 3.1. • GROUND WATER.ELEVATION AND FLOW DIRECTION r' The relative ground water elevation ranged from 32.17 feet (MW-6 upper) to 33.03 feet (MW-2), w, decreasing an average of 0.76 feet since the March 2004 monitoring event. The water table appears as a northerly plunging ridge; the east and west limbs of the ridge flow,toward the northeast and northwest,respectively,at a gradient of approximately 0.007'foot/foot,while the flow.gradient at the - " cel ter:of'the ridge is approximately'0.006 foot/foot toward the north. Ground water.elevation data Is presented ir'rable'l and the contoured ground water'elevation data•is shown on Figure 3. . 3.2. ANALYTICAL RESULTS OF GROUNDWATER SAMPLES TPH-g was detected at concentrations of 2,600•micrograznspei liter(µg/1)and 1;960µg/fin samples ; from'wells MW-f and'MW-4,-respectively(Figure 4). p g BTEX com ounds .were detected in��wells MW-1 and•1vIW-4' at -the.following concentrations: . benzene:at'190 µg/1 in MW-1 'and 39 µg11 in-MW-4,toluene at 5.3 µg11 in MW-1 only, ethylbenzene at 30,µg/1'in MW-4o' nly, and xylenes at 52 µg/l in MW-1' and 8.6 µg/1 in'MW-4. No additional analytes were detected at or above laboratory,detection limits in wells MWA and' MW-4.No:analytes were detected at or above laboratory detection limits in wells MW-2, MW-3,, '`Advanced GcoEnvironmental,-Inca