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Commingled Plume#35 $ E C 0 R
<br /> Chevron 9-4275/ARCO#2133
<br /> Site Conceptual Model
<br /> September 1,2006
<br /> Page 6
<br /> 3.0 UST REMOVAL -CHEVRON
<br /> In June 2005, five USTs, and associated product lines and dispensers were removed at the
<br /> Chevron 9-4275 facility. In addition, during site grading for the new station building, a previously
<br /> unknown concrete UST (approximately 1,000-gallon capacity) was encountered. Chevron
<br /> subcontracted Wendt Construction to remove the site facilities. A summary of the UST removal
<br /> and soil sampling activities is provided below.
<br /> Permitting
<br /> Wendt Construction obtained permits from the SJCEHD to remove four 10,000-gallon and one
<br /> 5,000-gallon capacity, fiberglass lined, single-walled, steel USTs.
<br /> Dispenser, Fuel Line, and UST Removal
<br /> Prior to starting the UST removal project, personnel from SECOR and Wendt reviewed and
<br /> signed the site specific Health and Safety Plan that outlined the specific site-related hazards.
<br /> On June 9, 2005, the dispenser island and associated product lines were exposed and
<br /> removed.
<br /> On June 9, 2005, Wendt removed the USTs from the excavation for inspection.
<br /> The USTs appeared to be in good condition, with no observable holes or cracks. Some slight
<br /> rusting was noticed on each tank. The USTs were disposed of at Ecology Control Industries
<br /> (ECI) in Richmond, California. A SJCEHD representative observed the UST removal and
<br /> directed the soil sample collection activities.
<br /> On June 30, 2005, a 1,000-gallon concrete UST was discovered in the northwest portion of the
<br /> site during grading for the new station building. With concurrence from SJCEHD, the concrete
<br /> UST was crushed onsite and disposed of with the remaining site debris.
<br /> 3.1 Soil Sample Collection
<br /> On June 9, 2005, a total of nine UST confirmation soil samples were collected in native soil at
<br /> the ends of the USTs (Figure 2). Soil samples TP-1 through TP-5 were collected at 12 feet bgs
<br /> from each end of the individual USTs. An excavator was used to retrieve the native soil from
<br /> the tank pit floor. Clean two-inch-diameter by six-inch long brass sample liners were driven into
<br /> the native soil held in the excavator bucket. Soil samples were also collected from beneath the
<br /> dispensers (D-1A through D-6A and D-113 through D-613) and the product lines (PL-1 through
<br /> PL-13) at depths between three and five feet bgs. On June 30, 2005, one soil sample was
<br /> collected from each end of the 1,000-gallon concrete UST.
<br /> Soil samples collected for chemical analysis were retained in brass liners, labeled, and capped
<br /> with Teflon® sheets and plastic end caps. The samples were then sealed in zip-lock bags,
<br /> placed on ice, and transported to the laboratory accompanied by the appropriate chain-of-
<br /> custody documentation. The soil samples were analyzed for TPHg, benzene, toluene,
<br /> ethylbenzene, and xylenes (BTEX), and the fuel oxygenates: MtBE, EtBE, TAME, DIPE, TBA,
<br /> ethanol, 1,2-DCA, and 1,2-dibromoethane (EDB) by Environmental Protection Agency (EPA)
<br /> Method 82608.
<br /> 94275-ARCO 2133 SCM 9-2006 6
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