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Work Plan for Additional Site Assessment <br /> and Interim Remediation/Feasibility Testing <br /> ARCO Facility No,5469 <br /> Stockton,California <br /> Page 8 <br /> borings using a California-type, split-spoon sampler equipped with three precleaned brass <br /> tubes. The ends of the bottom-most, intact tube from each sample interval will be lined <br /> with Teflon TM sheets, capped, and sealed. Each sample will then be labeled, placed in a <br /> resealable plastic bag and stored in an ice-chit-led cooler. The samples will remain chilled <br /> until relinquished to a state-certified analytical laboratory. Strict chain-of-custody <br /> procedures will be followed from the time the samples are collected until the time the <br /> samples are relinquished to the laboratory. Soil contained in the remaining brass tubes will <br /> be screened for volatile organic compounds using field instrumentation equipped with a <br /> photoionization detector(PID). <br /> Delta will record PID readings, soil types, and other pertinent geologic data on the borehole <br /> log. A minimum of three soil samples from each boring will be submitted for chemical <br /> analyses; the sample exhibiting the highest PID response, the sample from just above first <br /> encountered groundwater, and the sample from the' bottom of the boring. Additional <br /> samples may be collected at the discretion of the registered geologist overseeing the project. <br /> C-Sparger'Well Installation <br /> Delta will oversee the drilling of five onsite soil borings using a drilling rig equipped with <br /> 8-inch diameter hollow stem augers. The borings will subsequently be converted to ozone <br /> injection wells (IW-1 thxough TW-5). The actual locations of the borings will be based on <br /> accessibility and the location of underground utilities. <br /> Wells TW-1 through IW-5 will be installed to a depth of approximately 55 feet bgs. Each <br /> sparge well will consist of a C-Spargei""point(a permeable PVC membrane approximately <br /> two feet in length placed at a depth of 55 feet bgs), connected to a 3/4 inch PVC riser that <br /> extends to the ground surface. A filter pack of LonestarTm 92112 sand will be placed in the <br /> annular space around the injection point. Two feet of bentonite will be placed on top of the <br /> filter pack and hydrated with clean water to provide a sanitary seal for the well. The <br /> borehole will be backfilled with neat cement up to surface grade. A traffic rated vault box <br /> will be placed over the well and a water-tight locking cap will be placed on top of the well. <br /> The actual well construction may be modified in the field based on conditions encountered <br /> at the time of the investigation. <br /> Because previous or proposed subsurface investigations will have adequately characterized <br /> the subsurface conditions onsite, soil samples will not be collected for logging purposes or <br /> for chemical analysis. <br /> P:1kRCO\54691Work Plan15469 wTkpin 03-2002.doc <br />