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LAPPENDIX A LSTANDARD OPERATING PROCEDURES The standard operating procedures for drilling and soil sampling, decontamination, installation of soil gas probes, and disposal of rinsate and soil cuttings are described in this appendix. The following procedures are supervised under the direction of a California registered geologist. LA-1 Drilling. and Soil Sampling: Subsurface assessment permits will be filed with the appropriate regulatory agencies before conducting field operations. Underground Service LAlert will be notified at least 48 hours prior to initiation of field activities. The soil borings will be drilled using a Central Mine Equipment Company 75 truck-mounted drill rig equipped with 6-5/8-inch outside diameter, continuous-flight, hollow-stem augers. Twining is a licensed drilling contractor under C-57 classification (Contractor's License No. 506159). The soil borings will be drilled under the direction of a Twining geologist. Soils encountered during drilling will be logged consistent with the Unified Soil Classification System. The soil boring logs will note soil types encountered at depth including consistency, soil moisture, particle size, color, and other distinguishing features. LSoil samples will be collected using a 1-1/2-inch inside diameter split-spoon sampler. Samples will be obtained by attaching the sampler to the drive rod, followed by driving the Lsampler into undisturbed soil below the lead auger with a 140-pound hammer that is continuously dropped 30 inches until the sampler penetrates 18-inches of soil. The number L of drops will be recorded for each six-inch increment the sampler is driven into the soil and recorded on the field log of soil borings. The values for the bottom two six-inch increments will be added together to obtain a standard penetration resistance value for each sample. L Upon completion of the drilling and soil sampling, each borehole will be backfilled with L bentonite neat cement to site grade. Soil cuttings from the borings will be sealed in United States Department of Transportation (DOT) approved 55-gallon steel drums. The drums will be labeled with information on the source of their contents and stored on site in a Llocation remote from public access. The disposal of the drill cuttings is discussed below. A-2 Decontamination: Decontamination procedures will be implemented to reduce the potential for cross-contamination between soil borings. Before, during, and following drilling operations, the augers and associated drilling and sampling equipment will be thoroughly cleaned using a high pressure hot water (steam) washer. The hot water washer has a pressure of approximately 1,200 pounds per square inch and a water temperature of approximately 100 degrees Centigrade (°C). The sampler and brass sleeves will be washed in a Alconox® detergent solution, rinsed with clean tap water, and air-dried prior to initial use and between each sampling event. The augers will be steam cleaned prior to the drilling of each soil boring. L