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SOIL SAMPLING PROCEDURES SOIL BORING LOCATION AND CLEARANCE Soil boring locations are marked by Tetra Tech in white paint with a circle denoting the boring . location and an alpha-numeric sample location identifier (i:e., TtBl, etc.)..Sampling locations are evaluated for possible underground obstructions by, at least, Underground.Service Alert, and/or one or more geophysical means (EM, GPR, :etc.). Soil borings that must be relocated due to li subsurface obstructions are kept as close ose as possible to the original feature under investigation. DRILLING AND SAMPLING The soil borings are completed using a CME 75 or 95 drill rig where possible. All drill rigs will use 8-inch diameter hollow-stem augers, Only dry drilling methods are used (i.e., no drilling mud or water is introduced into the boreholes). Undisturbed .soil samples are collected by driving a split-spoon sampler ahead of the augers. No overdrilling (drilling past the depth of the split-- spoon) of the sampler is allowed. The augers are prior to use and between each. I � e steam-cleaned boring location. Soil samples are collected from.the borings with an 18-inch.long, 2%2-inch diameter, California split-spoon sampler. The split-spoon sampler is washed in a solution of soap (non-phosphate TSP) and clean tap water, rinsed in clean tap water and final rinsed in distilled water between each sample. Water from decontaminating the sampling equipment is stored in 55-gallon drums on-site pending characterization and proper disposal. The split-spoon sampler is loaded with.clean stainless steel or brass sari le liners. All sample p p liners are washed as described in the decontaimination procedures section prior to use. Advancement of the auger is halted at the desired sample depth and the sampler is lowered inside the hollow stem auger.The sampler is then driven into the soil using a 140 pound hammer falling a distance of 30 inches. The number.of blows required to advance the hammer 18 inches is r recorded as anindication of soil density or.consistency. . Only sample sleeves with close to 100% recovery (completely filled with soil so that there is no jvoid space) are delivered to the laboratory for chemical analysis. The liners are loaded into the sampler according to the following sequence: Liner Sequence Length Purpose (beginning at bottom of sampler) #1 3-inch Headspace analysis #2 34nch Laboratory analysis #3 64nch Logging/ Archivirig #4 6-inch Lithological Logging I ` C-1 1