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The USTs were removed in November 1988. RDM performed a file review at the San Joaquin County Environmental Health Department (SJCEHD) and was able to locate a copy of SJCEHD's Underground Tank Program Official Inspection Report dated November 8, 1988 (the date the USTs were removed, and confirmation soil samples collected) and another document titled Underground Storage Tank, dated February 16, 1989. This latter document appears to be a summary of the tank pull activities and includes a hand sketch illustrating the locations of the USTs, site features, and confirmation soil sample locations and identification names. Based on the SJCEHD documents, there were three 850 -gallon gasoline USTs located along the western property boundary and one 550 -gallon `oil" UST (assumed to have been waste oil) located along the eastern property boundary between the "lawn mower repair shop" building and Golden Gate Avenue. Based on SJCEHD's observations, the three 850 -gallon gasoline USTs appeared to be in good condition, but the piping to the south UST was in poor condition. The east (waste oil) UST and piping were observed to be in poor condition and the UST was corroded with holes in it and spilling contents. Four soil samples, one beneath each UST, were collected and identified as: NT - 1 North Tank, MT -2 Middle Tank, ST -3 South Tank, and ET -1 East Tank. The soil samples were collected at 10 feet below ground surface (fbgs) beneath each UST, except for the middle UST, which was collected at 14 fbgs. In addition, one soil sample, identified as PL -1 Pipeline, was collected from beneath the product piping between the USTs and the dispensers. Soil samples collected from beneath the former gasoline USTs located along the western property boundary reported concentrations of total petroleum hydrocarbons (TPH) up to 4,700 milligrams per kilogram (mg/kg), and benzene up to 7.8 mg/kg. The soil sample collected beneath the waste oil UST reported benzene at 0.12 mg/kg; TPH apparently was not analyzed in this sample. In addition to benzene, toluene, ethylbenzene, and total xylenes (BTEX), additional VOCs were analyzed in soil samples ST -3 South Tank and ET -1 East Tank and were below the laboratory's detection limits. The UST basins were reportedly excavated to a depth of 10 to 14 fbgs. Approximately 80 cubic yards of soil were reportedly excavated from the gasoline UST excavation and 12 cubic yards were excavated from the waste oil UST excavation during removal activities. The SJCEHD documents did not indicate whether this soil was hauled off-site or used to backfill the excavations. The dispensers were not investigated during the UST removal activities. Groundwater was not encountered in the UST excavations. No additional soil excavation has occurred since this initial excavation. In 2011, W&K was awarded a contract by the State of California UST Cleanup Fund Emergency, Abandoned, and Recalcitrant (EAR) Account Program to continue the environmental investigation of the subject site. Work included a subsurface investigation and subsequent quarterly monitoring activities. During the September 2011 subsurface investigation, petroleum hydrocarbons were identified in soil borings SB -1 through SB -4 with the highest concentration reported in SB -4, located adjacent to the former fuel dispenser island. Soil concentrations for TPHg ranged from 3.9 to 11,000 mg/kg and total petroleum hydrocarbons as diesel (TPHd) ranged from 30 to 2,800 mg/kg. Benzene, toluene, ethylbenzene and xylenes were also detected at low concentrations, which suggest the release was relatively older and some natural attenuation was occurring. During the September 2011 subsurface investigation,