WORK PLANS - Laserfiche WebLink

Home Browse Search

ameO • Section 6 outlines the schedule for completing the work. • Section 7 lists references used in preparing this work plan. 2.0 BACKGROUND INFORMATION This section describes the Site setting and its geographic location, the regional and Site v geology and hydrogeology, and the historical investigation and remedial activities conducted at the Site to date. 2.1 SITE DESCRIPTION AND SETTING The Site is located at 1604 South B Street, Stockton, California (Figure 1). Since the 1900s, the majority of businesses in the Site vicinity have included gas stations, equipment and machine shops and manufacturers, and light industrial development. The Site contains various maintenance buildings, warehouses, several office buildings, and two aboveground fuel storage tanks (Figure 2). The Site is surrounded by residential properties to the east and south and commercial use properties to the north and west. The Caltrans Shop 10 w Maintenance Station is located immediately west of the Site. 2.2 SUMMARY OF RELEASE AND INVESTIGATIONS In December 1989, one 5,000-gallon diesel UST, one 10,000-gallon gasoline UST, two fueling islands, and associated product piping were removed from the Site. Analytical results of soil samples collected from the UST excavation indicated maximum total petroleum hydrocarbons quantified as gasoline and diesel (TPHg and TPHd) concentrations of 2,000 and 58 milligrams per kilogram (mg/kg), respectively. In September 1993, one 115-gallon backup diesel generator UST was removed from behind the Electricians and Radio Shop Building (Figure 2). Soil discoloration and odors were not noted during the UST removal activities. Soil analytical results collected from the soil stockpile generated during removal activities and from beneath the UST did not contain concentrations v of TPHd and benzene, toluene, ethylbenzene, and total xylenes (BTEX) (Geocon, 2009a). Two investigations were completed at the Site between 1992 and 1996. A map showing the location of the former UST pit and boring locations, a cross section of the source area, and tabulated soil data from these two investigations is provided in Appendix A. During these investigations, soil samples were collected from one boring within the former UST pit(VW-1) and from seven borings adjacent to the former UST pit and near the former fueling islands (SB-1 through SB-3, VW-2, and MW-1 through 3). The highest concentrations of petroleum hydrocarbons were detected in VW-2 at 46 feet below ground surface (bgs) (TPHg at 550, AMEC Geomatrix, Inc. P:\Project\14000s\14443_Caltrans\TO 10\11000PLAWAS WP—March 2010\AS WP.doc 2 v