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r r30 October 2005 AGE-NC Project No 98-0511 rPage 2 of 4 r 18%hydrochloric acid solution as a sample preservative After collection,the samples were properly labeled, placed in a chilled container, and transported under chain of custody to Cal Tech Environmental Laboratories (CTEL), a California Department of Health Services (DHS)-certified rlaboratory, and analyzed for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA rMethod 8015M, • Benzene, toluene, ethylbenzene, and total xylenes (BTEX) and fuel additives di-isopropyl ether(DIPE),ethyl tertiary-butyl ether(ETBE),methyl tertiary-butyl ether(MTBE),tertiary- amyl methyl ether (TAME), tertiary-butyl alcohol (TBA), 1,2-dlbromoethane (EDB), 1,2- dichloroethane(1,2-DCA), ethanol, and methanol In accordance with EPA Method 8260B r 3.0. FINDINGS rGround water elevation and flow direction were determined from field data Hydrocarbon Impact to ground water was Inferred from laboratory analysis of ground water samples r • 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION r For the March 2005 round water monitoring event the elevation of round water in each well was o g g � g r calculated by subtracting the depth to ground water from the surveyed casing elevation (Table 1) Depths to ground water ranged from 13 45 feet to 14 29 feet below the tops of the well casings Ground water elevations at the site ranged from 3 76 feet below mean sea level(MSL)In well MW-7 r to 4 33 feet above MSL in well MW-4 Ground water at the site was Inferred to flow generally toward the west-northwest on-site at gradients ranging between 0 002 foot/foot(ft/ft)and 0 006 ft/ft and toward the southwest,off-site In the areas of wells MW-7 and MW-8,under a hydraulic gradient ' of approximately 0 005 foot/foot (ft/ft) or less ' 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g was detected in the ground water sample collected from monitoring well MW-1 at a concentrations of 7,200 micrograms per liter (µg11) BTEX was detected In well MW-1 at concentrations of 78 µg/l benzene, 110 pg/l toluene, 1,400 µg/l ethylbenzene, and 6,100 µg/l xylenes Maps showing the approximate distributions of dissolved TPH-g and benzene at the site are rIllustrated on Figures 4 and 5, respectively rAdvanced GcoEnvironmental,Inc r