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28 March 2005 <br /> AGE-NC Project No 98-0511 <br /> Page 2 of 4 <br /> I 18%hydrochloric acid solution as a sample preservative After collection,the samples were properly <br /> labeled, placed in a chilled container, and transported under chain of custody to Cal Tech <br /> Environmental Laboratories (CTEL), a California Department of Health Services (DHS)-certified <br />' laboratory, and analyzed for <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br />' Method 8015M, <br /> • Benzene, toluene, ethylbenzene, and total xylenes (BTEX) and fuel additives di-isopropyl <br />' ether(DIPE),ethyl tertiary-butyl ether(ETBE),methyl tertiary-butyl ether(MTBE),tertiary- <br /> amyl methyl ether(TAME), tertiary-butyl alcohol (TBA), 1,2-dibromoethane (EDB), 1,2- <br /> dichloroethane (1,2-DCA), ethanol, and methanol in accordance with EPA Method 8260B <br /> 3.0. FINDINGS <br /> Ground water elevation and flow direction were determined from field data Hydrocarbon impact <br /> to ground water was inferred from laboratory analysis of ground water samples <br /> 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION <br /> For the December 2004 ground water monitoring event, the elevation of ground water in each well <br />' was calculated by subtracting the depth to ground water from the surveyed casing elevation <br /> (Table 1) Depths to ground water ranged from 17 02 feet to 18 25 feet below the tops of the well <br /> casings Ground water elevations at the site ranged from 0 01 feet below mean sea level (MSL) in <br /> well MW-7 to 0 40 feet above MSL in well MW-4 Ground water at the site was inferred to flow <br /> generally toward the south and southwest under a hydraulic gradient of approximately <br /> 0 003 foot/foot (ft/ft) or less <br /> 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br />' TPI -g was detected in the ground water sample collected from monitoring well MW-1 at a <br /> concentrations of 6,500 micrograms per liter (µg/1) BTEX was detected in well MW-1 at <br /> concentrations of 120 µg/l benzene,41 µg/l toluene, 150 Vig/1 ethylbenzene,and 6,100 µg11 xylenes <br /> Maps showing the approximate distributions of dissolved TPH-g and benzene at the site are <br /> illustrated on Figures 4 and 5, respectively <br /> MTBE was detected in the ground water samples collected from wells MW-3 and MW-5 at <br /> Advanced GeuEnviromnental,Inc <br />