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' 17 April 2000 AGE-NC Project No 00-0696 ' Page 2 of 7 ' total petroleum hydrocarbons quantified as gasoline (TPH-g), and volatile aromatic compounds - benzene, toluene, and total xylenes (BTEX) The soil sample collected from beneath the former regular gasoline UST was also analyzed for total lead and ethylene dibromide (EDB) The two 550-gallon gasoline USTs were located at the south end of the site Immediately following the UST removal, a total of two soil samples, one from beneath each UST were collected from the ' floor of the UST excavation Total petroleum hydrocarbons quantified as gasoline (TPH-g) were reported in soil sample R-1 collected from beneath the 550-gallon regular gasoline UST at a concentration of 570 milligrams per kilogram (mg/kg) Toluene and xylenes were also reported in ' soil sample R-1 at concentrations of 84 mg/kg and 250 mg/kg,repectively Benzene was not reported in any of the soil samples submitted for analysis Ethylbenzene and methyl tertiary butyl ether (MTBE)were not analyzed in either of the soil samples collected 23 REGIONAL GEOLOGIC SETTING The property is situated within the Great Valley Geomorphic Province of California, a large, �. elongate, northwest trending, asymmetric structural trough The Great Valley Province has been filled with thick sequences of sediment ranging in age from Jurassic to Recent, creating a nearly flat- lying alluvial plain, extending from the Tehachapi Mountains in the south to the Klamath Mountains in the north The western and eastern boundaries of this province are comprised of the California Coast Range and the Sierra Nevada, respectively Rocks composing the basement complex of the province have not been completely defined but are believed to be metamorphic and igneous in origin The northern and southern portions of the Great Valley Province have been designated the Sacramento and San Joaquin Valleys, respectively The Modesto, Riverbank, Turlock Lake Formations and overlying recent alluvium are the principal source of domestic ground water in the 13,500-square-mile San Joaquin Valley Ground Water Basin (Basin 5-22) This basin is drained primarily by the San Joaquin River 2 5 GROUND WATER DEPTH AND GRADIENT Based on the location, the estimated depth to ground water in the vicinity of the site is 5 to 15 feet below surface grade (bsg) The prevailing ground water flow direction in the vicinity of the site is inferred to be toward the Mokelumne River west of the site However, flow direction may be both locally and seasonably variable • Advanced GeoEnvironmental,Inc