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• Former Unocal Station No 0187 February 14, 1995 SITE DESCRIPTION AND BACKGROUND Site Description The subject site is a vacant lot situated on the northwest corner of East Miner Avenue and California Street in the City of Stockton, California, as shown on the Vicinity Map (Figure 1) The subject site is situated in an area of retail stores and hotels. Topography in the site vicinity is flat-lying, at an elevation of approximately 15 feet above mean sea level (MSL) McLeod Lake and the Stockton Deep Water Channel are situated approximately one-half mile to the west The site was an operating Unocal Service Station from 1922 until 1992. The most recent service station consisted of a three-bay service station building, three product dispenser islands (D-1 through D-3), and two gasoline and one waste oil underground storage tanks (USTs) in a common excavation The site is currently an unpaved vacant lot Pertinent features of the former service station are shown on the Site Plan (Figure 2) Previous Environmental Work . Two 1,000-gallon gasoline and one 550-gallon waste oil USTs were removed from the southeast corner of the subject site in 1967 Data related to soil testing at the time of UST removal is not available These USTs appear to have been replaced with two 10,000-gallon gasoline and one 280-gallon waste oil USTs situated in a common excavation in front of the station building The two 10,000-gallon gasoline and one 280-gallon waste oil USTs and associated product piping were removed and the station building demolished in January, 1992 Petroleum hydrocarbons were not detected in soil samples collected beneath the USTs, hydraulic lifts, or oil/water separator Total Petroleum Hydrocarbons as Gasoline (TPHg) and benzene were detected in one soil sample collected from the product piping trench between dispenser islands D-1 and D-3 at concentrations of 150 and 0 81 parts per million (ppm), respectively. This trench area was overexcavated, and a confirming soil sample collected from the base of the excavation Petroleum hydrocarbons were not detected in this confirming soil sample Toluene, ethylbenzene, and xylenes were detected in one soil sample from the product pipe trench adjacent to dispenser island D-1 at concentrations of 0.070, 0 017, and 0.087 ppm, respectively This area was not overexcavated A second 130-gallon waste oil UST was removed from the eastern portion of the property in May 1992 Petroleum hydrocarbons were not detected in the soil sample collected from beneath this UST Results of the UST removal investigation were presented in GSI Report No 782701-1, dated September 11, 1992 i 482704-1 2 GeoStrategies Inc.