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06 September 2005 AGE-NC Project No 01-0877 Page 2 of 4 analysis(VOA)vials containing 0 5 ml 18%hydrochloric acid solution as a sample preservative,and one l-liter amber bottle without preservative After collection, the samples were properly labeled, placed in a chilled container, and transported under chain of custody to Cal Tech Environmental r ' Laboratories (CTEL), a State of California Department of Health Services (DHS)-Environmental Laboratory Accreditation Program certified(#2424)analytical laboratory,for analysis The samples were analyzed for I Total petroleum hydrocarbons quantified as gasoline(TPH-g),diesel(TPH-d),and motor oil p Y 4 (TPH-mo) in accordance with EPA Method 8015 Modified, and • Benzene,toluene, ethylbenzene, and total xylenes(BTEX)and volatile organic compounds methyl-tertiary-butyl ether(MTBE),tertiary butyl alcohol(TBA),di-isopropyl ether(DIPS), ethyl tertiary-butyl ether (ETBE), tertiary-amyl methyl ether (TAME), 1,2-dichloroethane (1,2-DCA) and 1,2-dibromoethane (EDB) in accordance with EPA Method 8260 3.0. FINDINGS • Ground water flow direction, elevation, and gradient were determined from data collected in the field The hydrocarbon impact to ground water was quantified by the laboratory data obtained from the ground water samples 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION At the time of the April 2005 sampling event, depths to ground water ranged from 25 63 to 26 98 feet below the tops of the well casings(Table 1) The average ground water elevation at the site was approximately 16 15 feet below mean sea level (MSL), which indicates an Increase in the static ground water elevation of approximately 125 feet since the last monitoring event The ground water ' table formed a shallow west-trending plunging-ridge,with ground water flow toward the northwest under a gradient of approximately 0 014 foot/foot and to the southwest under a weaker gradient of approximately 0 008 foot/foot (Figure 3) During previous ground water sampling events, ground ' water has generally flowed toward the northeast During the April 2005 monitoring event, ground water levels were within the screened Interval of each well, indicating that the wells were screened ' properly to yield representative ground water samples ' 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES • TPH-g was detected in all water samples at concentrations ranging from 58,000 micrograms per liter Advanced GeoEnvironmental,Inc