ARCHIVED REPORTS_FIRST QUARTER 2011 STATUS SUMMARY REPORT

Home Browse Search

Stantec First Quarter 2011 Status Summary Report Former Tosco Bulk Terminal No. 10013 April 29, 2011 SITE DESCRIPTION The site is located on the northeastern portion of Rough and Ready Island in Stockton, California (Figure 1). The 4.3-acre Site is bounded on the east by the Lyons Club Golf Course, on the south by the access road of Navy Drive, and on the west and north sides by vacant land. The Stockton Deep Water Channel is located beyond adjacent vacant land, approximately 500 feet north-northeast of the site. The San Joaquin River is located approximately 1,500 feet to the southeast. PREVIOUS ASSESSMENT ACTIVITIES The site was initially occupied and used as a bulk storage facility by Mobil Oil Corporation in 1938. British Petroleum (BP) acquired the Site from Mobil in 1989 as a bulk gasoline and diesel storage facility. Tosco Refining Company acquired the Site from BP in August 1994, and subsequently transferred ownership to ST Services in October 1998. Valero (currently named as NuStar Energy) acquired the Site in 2005, and is the current Site operator. Since 1998, the facility has been used only for diesel storage. Historical site operations have resulted in petroleum hydrocarbon impact to the soil and groundwater beneath the site. Constituents of concern for the site include: total petroleum hydrocarbons as gasoline and diesel (TPH-g and TPH-d, respectively); benzene, toluene, ethylbenzene, and total xylenes (BTEX); methyl tertiary butyl ether (MTBE); and other oxygenates. The facility currently includes six aboveground storage tanks (ASTs), two underground storage tanks (USTs) (UST Nos. 4 and 6), a fuel-loading rack in the central portion of the site, two metal buildings in the southeastern portion of the site and a small enclosure that formerly contained a groundwater extraction and treatment system (GWETS) connected to wells MW-8 and MW-14. The GWETS and associated piping were installed in June and July of 2003. Groundwater extraction was terminated on July 31, 2006; the rental portions of the GWETS were dismantled in August 2006. Mobile oxygen injections were started in December 2007, as part of a pilot study to determine if this process would be effective in further remediating the tert- butyl alcohol (TBA) and MTBE plumes at the site. Figure 2 shows the locations of above- and below-grade structures and equipment at the site. The site currently has 19 monitoring wells, including MW-1 through MW-6, MW-8 through MW- 11 and MW-14 through MW-22C. Well MW-7 was abandoned in 1996, and wells MW-12 and MW-13 were abandoned in May 2006, due to a relative absence of any detection of constituents of concern. Wells MWA through MW-6 and MW-9, MW-10, MW-11, MW-14 and MW-19C are located within the site property boundary or in the adjacent vacant lot to the west. Wells MW-8, MW-15 through 18C and MW-20 through MW-22C are located approximately 120 to 500 feet down-gradient from the southern site boundary. Groundwater monitoring well locations are shown on Figure 2. Well construction details are provided in Table 2. 1