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Stockton 99 Speedway Preliminary Endangerment Assessment Workplan April 12,2007 s,,., overall site as the Stockton Speedway Site. The second string will consist of the sampling point identification code (e.g., SB-10). The final string will identify the upper limit of the sample interval. Thus, the code SSS-SB10-25 represents a sample collected from sample point SB-10 from the sample interval with an upper limit of 25 feet. Duplicate samples will be indicated by inserting the number 9 as the first digit of the sample identification code (e.g., the sample identification code SSS-SB910-25 would be used to identify a duplicate sample of sample SSS-SB10-25). 4.3 Sampling Equipment Shallow soil samples (i.e. 6 inches to 2 feet bgs) will be collected using a drive core sampler equipped with clean brass or stainless steel tubes. The ends of the tube will be covered with Teflon tape, capped, and then sealed with tape/Parafilm. Deeper soil samples (i.e. 5 and 10 feet bgs) will be collected using a DPT percussion rig equipped with a dual-tube sampling system using the following procedure: • The sampling location will be accessed by the DPT rig and the drive hammer will be positioned to bore vertical holes; • The drive rods will be equipped with inner sample sleeves to collect soil from desired depths; • The sampler will be driven into the ground using the percussion; • The desired sampling depth will be achieved by adding a series of drive rods; 14� • Soil collects and compacts in the sample sleeve as the drive rods are advanced. Sand catcher devices will be fastened to sampling sleeves to retain loose soil, if necessary; and • The soil sampling sleeves containing the desired samples will be retracted from the borehole. Soil samples are retrieved in a 4-foot long acetate sleeve, which allows viewing of the collected sample. Once the sample liner is extracted from the sampler, the contents are examined through the clear liner. The portion of the liner that is selected for analysis is prepared by cutting the liner, bracketing the desired interval. The ends of the selected interval are covered with Teflon tape, capped, and then sealed with tape/Parafilm. Upon completion of sampling, boreholes will be backfilled with neat cement. Soil sample locations will be recorded in the field logbook when sampling is completed. Locations will also be marked and assigned GPS coordinates. 4.4 Decontamination Procedures Disposable soil sampling equipment, such as small tools and disposable gloves, will be either decontaminated or disposed of after each use. The decontamination procedure will consist of: • Wash in a phosphate-free soap and water mixture; • Rinse thoroughly in distilled water following washing; and PEA Workplan.Flnal.doc 4-4 The Source Group,Inc.