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V t� Removal of Two 6,000 -Gallon Gasoline USTs (1987) Two 6,000 -gallon gasoline UST systems were located near the southwestern corner of the main building. Prior to 1987, the eastern -most 6,000 -gallon gasoline UST had been taken out of service and abandoned in-place by removing the fuel and filling the tank with sand. In December 1986, the western -most gasoline UST failed a tank integrity test. As a result of the ;r December 1986 tank integrity test failure, both 6,000 -gallon gasoline USTs were excavated and removed in April 1987 under the direction of Environmental Science and Engineering (ESE). The disposition of the product and vent pipelines is not known. During the tank removal, soil was initially excavated to 18 feet bgs. Soil samples collected from the excavation contained total extractable petroleum hydrocarbons at concentrations up to 2,900 milligrams per kilogram (mg/kg). The central portion of the gasoline UST pit was then excavated to 28 feet bgs. A confirmation soil sample collected from the floor of the excavation at 28 feet bgs contained total extractable petroleum hydrocarbons at 430 mg/kg (ESE, 1987). Approximately 450 cubic yards of soil was land -farmed with guidance from the San Joaquin Valley Air Pollution Control District (SJVAPCD). The excavation was backfilled with crushed rock and resurfaced with asphalt. The analytical data are contained as an appendix in Anderson Consulting Group's (ACG) December 19, 1991 Problem Assessment Report. Subsequent investigation, remediation, and monitoring activities are described in Section 2.5.2. Removal of 10 000 -Gallon Diesel UST System (1989) A 10,000 -gallon diesel UST system was also located near the southwestern comer of the main building. The UST system was removed for permanent closure in September 1989 (Campbell Taggart, Inc., 1989). Two soil samples (AA -1561 and AA -1562) were collected beneath the former tank at a depth of approximately 13 feet bgs. Total petroleum hydrocarbons quantified as gasoline (TPH-g), total petroleum hydrocarbons quantified as diesel (TPH-d), and benzene, �+ toluene, ethylbenzene and xylenes (BTEX) were not detected in the samples. Soil sample AA - 1563 was collected beneath the former dispenser at the fuel pump island at a depth of approximately 3.25 feet. Sample AA -1563 contained TPH-g at 89 mg/kg and TPH-d at 520 mg/kg. However, the laboratory noted that the hydrocarbons detected in the diesel range did not match a diesel standard. The BTEX compounds were not detected in soil sample AA -1563. Removal of 20,000 -Gallon Diesel UST System (1989) A 20,000 -gallon diesel UST system was located on the eastern side of the building and was used to fuel the bakery ovens. The UST system was removed for permanent closure in September 1989 (Campbell Taggart, Inc., 1989). The analytical data for soil samples collected • from the excavation of the UST system indicated no environmental issues. 5 L