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�N ' 05 July 2000 AGE-NC Project No 00-0696 ' Pages 2 of 9 ' 2 2 UNDERGROUND STORAGE TANK REMOVAL On 27 April 1988,two 550-gallon gasoline USTs,were removed from the site by the property owner, Mr Charles Jacobs The approximate locations of the former USTs are shown on Figure 2 Soil samples were collected at a depth of four feet below surface grade (bsg), and were analyzed for ' 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, respectively 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 PREVIOUS SUBSURFACE INVESTIGATION On 22 March 2000, four soil borings(B-1 through B-4)were advanced at the site to assess the lateral and vertical extent of petroleum-Impacted soil TPH-g was detected in the soil sample collected from probe boring B-2 at 10 feet bsg at a concentration of 14 mg/kg No other analytes were detected above laboratory reporting limits in the soil samples collected and analyzed from B-1 through B-4 TPH-g was detected in the grab ground water samples collected from B-1 and B-2 at concentrations of 120,000 ,ug/1 and 15,000 ,ug/l, respectively BTEX compounds were also detected in the grab ground water samples collected from B-1 and B-2 at concentrations as high as 56,000,ug/l(xylenes) and 600 µg/1 (xylenes) 24 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 Advanced CeoEnvironmentai,Inc