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' 30 January 2006 <br /> . AGE-NC Project No 98-0511 <br />' Page 2 of 4 <br />' laboratory-supplied,40-milliliter(ml)volatile organic analysis (VOA)vials containing 0 5 ml 18% <br /> 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 /> analytical 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), and <br /> 1,2-dichloroethane (1,2-DCA) 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 /> I3 1 GROUND WATER GRADIENT AND FLOW DIRECTION <br />' For the September 2005 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 06 feet(MW-1)to 17 56 feet(MW-7)below the <br /> tops of the well casings Ground water elevations at the site ranged from 0 31 feet above mean sea <br /> level (MSL) in well MW-5 to 1 16 feet above MSL in well MW-2 <br /> Ground water at the site was inferred to flow toward the southwest on the southern portion of the site <br /> and radially inward toward a depression in the potentiometric surface near well MW-5 on the <br /> northern portion of the site, calculated gradients ranged between 0 007 foot/foot (ft/ft) and <br /> 0 015 ft/ft The historical ground water flow direction is generally observed from the Th Street area <br /> towards the UST area and west to well MW-6 <br /> 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> ITPH-g was detected in the ground water samples collected from monitoring wells MW-I and MW-5 <br /> • at concentrations of 15,000 micrograms per liter (µg/1) and 2,400 µg11, respectively BTEX <br /> Advanced GcoEnvironmental,Inc <br /> I <br />