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�. <br /> 1;3 <br /> WORK PLAN <br /> ATLANTIC RICHFIELD COMPANY, STATION 2133 <br /> µ- 2908 BENJAMIN HOLT DRIVE <br /> STOCKTON, CALIFORNIA <br /> This work plan has been prepared. for Atlantic Richfield Company <br /> (ARCO) Station 2133, located at 2908 Benjamin Holt Drive in Stockton, <br /> California. The work plan will be submitted to ARCO and the San <br /> Joaquin County Environmental Uealth Department (County) . The <br /> necessary permits have been acquired, and an Underground Storage Tank <br /> Unauthorized Release (Leak)/Contamination Site Report (Form HSC 05 <br /> 110/85) ) has been completed and filed. <br /> w Boreholes <br /> T Brown and Caldwell (BC) will supervise the drilling of seven <br /> boreholes at the site. The locations are shown on the plot plan <br /> (Attachment A) . The boreholes will be drilled using a truck-mounted <br /> drilling rig equipped with 8-inch-outside-diameter, 4-inch-inside- <br /> diameter hollow-stem augers. A typical borehole diagram is shown on <br /> Figure 1. <br /> The depth to groundwater is approximately 3, feet. Borehole <br /> "- depth is not expected to he deeper than 10 feet. Soil samples will <br /> be collected at 5-foot intervals. Each borehole will be sealed with <br /> cement-bentonite grout. The grout will be pumped through a tremie <br /> pipe into the bottom and filled to the top of each borehole, <br /> Soil Sampling Procedures <br /> Soil samples will be taken at the surface and every 5 feet during <br /> drilling. Samples will be obtained using an 18-inch split-spoon <br /> drive sampler. Three 2-inch-diameter by 6-inch-long brass tubes will <br /> be fitted into the drive sampler. The sampler will be driven into <br /> undisturbed soil to obtain the soil samples. Sample tubes will then <br /> be removed from the sampler, the ends visually inspected in the field <br /> to identify lithology, and capped with aluminum foil, plastic caps, <br /> and tape to provide an airtight seal. If visible hydrocarbons or <br /> odor are present, it will be noted. Before sealing, the soil samples <br /> will be tested for hydrocarbon vapor concentrations using a <br /> photoionixation detector. Lithologic logs will be constructed for <br /> each borehole. Each sample will be labeled on site to show the date, <br /> project number, sample location, and depth interval. The sealed <br /> '- samples will be stored on ice ' in closed chests and protected from <br /> meltwater. <br /> { <br /> r�` <br />