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Liquors (1980-1986), vacant (1991), and Delta Kajukenbo School Self Defense and Tracy Guns & Ammo (2000). EFI concluded that none of the former uses at the subject property were likely to be of concern. Offsite Vapor Intrusion Risk(s) The adjoining property to the west (hydrologically cross-gradient) is listed on the UST, LUST, and Historical Hazardous Waste & Substance Site List (HIST CORTESE) databases. According to the regulatory database report and records provided by the SJCEHD, the west adjoining property was developed as a gasoline station from the 1920s through the 1960s. A LUST case investigation began in 1994 for an unauthorized release of other solvent or non-petroleum hydrocarbon, total petroleum hydrocarbons (TPH), and benzene, toluene, ethyl benzene, and xylenes (BTEX). Between 1995 and 2000, eight groundwater monitoring wells (U-1 through U-8) were installed at the site and down- gradient of the site in order to determine the extent of contamination. Remedial actions included excavation of 75 cubic yards of impacted soil and purging water from monitoring wells. Maximum documented groundwater concentrations following cleanup activities included 0.195 parts per million (ppm) total petroleum hydrocarbons as gasoline (TPHg), 0.113 ppm total petroleum hydrocarbons as diesel (TPHd), 0.0017 ppm benzene, 0.000597 ppm toluene, 0.00315 ppm ethyl benzene, and 0.000899 ppm xylene, and less than 0.002 ppm methyl tert-butyl ether (MTBE). Based on the foregoing concentrations, the site was granted closure in October 2001. However, volatile organic compounds (VOCs) including tetrachloroethylene (PCE) and trichloroethylene (TCE) were detected in multiple ground water monitoring wells located within 100 feet to the west of the subject property. The presence of PCE and TCE in groundwater was attributed to an off-site, up-gradient source or a former waste oil UST. From 1995 through June 2000, concentrations of PCE and TCE appeared to be declining. However, according to the most recent sampling data (September 2000), concentrations of PCE and TCE increased during this latest sampling event, with maximum concentrations of 17.8 parts per billion (ppb) and 8.42 ppb, respectively. The presence of VOCs in the subsurface within the critical distance of 100 feet from the subject property is considered a potential vapor intrusion condition (pVIC), which represents a recognized environmental condition (REC) for the subject property. Based on the risk of vapor intrusion from the west adjacent property, a subsurface investigation is proposed. Note that the proposed sampling is being conducted only on the western parcel at 18 E. I l th Street. Scope of Work/Field Investigations A geophysical scan utilizing ground-penetrating radar will be performed to investigate the subsurface for potential USTs, buried drums, product lines, and/or utilities on the subject property. A total of 4 soil borings will be advanced in the western border of the subject property and other suspect areas of concern. The four soil borings will be advanced to 5 feet below ground surface (bgs). A total of 4 soil samples (1 from each soil boring) will be placed on hold for analysis of total petroleum hydrocarbons (TPH) as oil, diesel, and gasoline range Fulcrum Resources Environmental 18-22 East 116 Street, Tracy California Site Assessment Work Plan 3