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i ' 13 Hutchins Street, and Rimby Avenue area are shown on Figures 5, b, 7, and 8. Underground Services Alert (USA) will be notified prior to drilling. USA's :.member utilities will then mark the locations of their underground lines in the drilling area. The locations of the USTs, associated piping, and overhead canopy at Station 434 are shown on Figure 2. On-Site Soil Characterization This section describes the borehole drilling and soil sampling methods for the on-site soils characterization. Borehole Drilling. BC will supervise the chilling of nine soil boreholes at Station 434 (see Figure 2). The boreholes will be dril ed using a truck-mounted drilling rig equipped with 8-inch-outside-diameter, hollow-ste augers. Borehole depths are not expected to be greater than 50 feet. Borehole cut ings will be temporarily placed on and covered by plastic sheeting. The disposal of these cuttings is the responsibility of ARCO. Boreholes will be grouted with a bentonite-cement out mixture placed by tremie pipe. Soil Sampling. Continuous soil cores for li hologic classification will be ;collected from all boreholes to the total depth of the borehole using a 5-foot-long, split-sampling barrel inside the auger. Samples for laboratory analysis will be collected using a'1.5-foot- long, split-spoon drive sampler, lined with 2-inch-diameter brass liners. The sarripler will be, driven into undisturbed soil ahead of the augers. The litbology of each borehole will be de cribed according to the Unified Soil Classification System. The boreholes will be logged by an experienced field 1geologist working under the direct supervision of a registered geologist. Observations of visible hydrocarbons and hydrocarbon odors will also ben ted. The soil samples will be screened on site with a portable vapor meter to detect hydrocarbon vapors. These data will be recorded on the log. A soil sample will be collected for laboratory analysis in every 10- foot interval. The sample analyzed will be that sample having the highest detected vapor reading in that interval. Brass liners containing soil samples selected for laboratory analysis will be covered with aluminum foil and plastic caps and sealed ith plastic tape. Each sample will be labeled on site to show the date, project number, sample location, and depth interval. The sealed samples will be stored on ice in closed chess and protected from meltwater. Selected soil samples will be analyzed for BTX and gasoline by U.S. Environmental Protection Agency (EPA) Method 8015, modified, Extraction Method 5030. The samples will be delivered to Eureka Laboratories, Inc., in S icramento. Groundwater Extraction Well This section describes the methods for the groundwater extraction well construction and development and aquifer testing. ARCO will be responsible for the proper well abandonment when the Regional Board and/or the County determine that groundwater extraction is no longer necessary.