ARCHIVED REPORTS XR0000746 - Laserfiche WebLink

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1 - - ' UNDERGROUND STORAGE TANK REMOVAL • ' The UST system was removed in 1988.Groundwater was encountered in the tank excavation during removal. Subsequently,one soil and one grab water sample were collected from the tank excavation in August 1988. Both samples were p analyzed for total petroleum hydrocarbons quantified as gasoline (TPH-g), stoddard solvents,paint thinner, diesel,kerosene,motor oil(TPH-ss, TPH-thinner,TPH-d, TPH-k and TPH-mo)and volatile aromatics(benzene,toluene and total xylene).TPH-g,toluene and xylenes were detected in the soil sample at concentrations of 560 milligrams per kilogram(mg/kg),21 mg/kg and 79 mg/kg,respectively.TPH-g,benzene,toluene and xylenes were detected in the water sample at concentrations of 117,000 micrograms per liter(gg/1), 10,100 gg/l, 11,300 gg/l and 9,330 gg/l, respectively. EXCAVATION OF UNDERGROUND STORAGE TANK AREA The former UST area was excavated on 24 August 1995 to remove impacted soil. Excavation procedures were supervised by a representative of AGE. Soil was excavated to a depth of 12 feet below surface grade(bsg). Approximately 100 cubic yards of impacted soil were removed from the former UST area. lie TPH-g was detected in the soil sample collected at a depth of 8 feet bsg from the sidewall of the excavation at concentrations as high as 5,800 mg/kg and benzene was detected in the samples at a maximum concentrations of54 mg/kg. Petroleum hydrocarbons were not detected in soil samples collected from the floor of the excavation at a depth of 12 feet bsg. TPH-g was detected in stockpile soil samples at a concentration of 440 mg/kg and volatile aromatic compounds - benzene, toluene, ethylbenzene and total xylenes(BTEX)were detected at concentrations of 1.1 mg/kg, 12 mg/kg, 8.1 mg/kg and 40 mg/kg,respectively.. The excavated soil was stockpiled adjacent to the excavation on plastic sheeting. On 09 October 1996, approximately 100 cubic yards of stockpiled soil were transported to Forward Incorporated, a Class II landfill located in Manteca, California. Soil was loaded into transport vehicles by Stokley Construction of Tracy,California and hauled to Forward by Bob Evans Trucking of Manteca, California. The disposal of the soils was summarized in the Quarterly Report prepared by AGE, dated 21 November 1996, SITE ASSESSMENT ACTIVITIES Six soil probe borings were advanced at the site on 20 December 1996. Soil and water samples were collected at discrete depth intervals from the majority of the probe borings. Figure 2 depicts the locations of the probe borings. • TPH-g was detected in three of the soil samples analyzed at concentrations as high as 2,800 mg/kg Advanced GeoEnvironmentals Inc.