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SOIL SAMPLING DURING DRILLING Soil samples will be collected during the drilling operations for three reasons: (1) for field identification of the borehole lithology, (2) for qualitative field screening for the presence of contaminants, and (3) for chemical analysis. For purposes of collecting soil samples for lithologic identification and for field screening, each borehole will be continuously cored. The soil cores will be examined in the field and classified according the Unified Soil Classification system. In addition to evaluating the borehole lithology, the soil cores will be screened in the field with a photoionization detector (PID) or similar instrument, and the relative permeability of the soil will be qualitatively estimated. The lithology, PID reading, and estimated permeability of each sample will be recorded on the borehole log next to the depth interval from which the sample was obtained. Soil samples for laboratory chemical analysis will be collected at 5-foot intervals, at a minimum, to the total depth of the boring. The samples will be obtained using a 2-inch-diameter by 18-inch-long split-spoon sampler lined with three 6-inch-long thin-walled brass tubes. The sampler will be driven its entire length into undisturbed soil, either hydraulically or by a 140- pound drop hammer. When the sampler is extracted from the borehole, the brass tubes will be removed and the ends of the tubes will immediately be screened for the presence of hydrocarbons with a PID or equivalent instrument. One sample per 5-foot sampling interval will be selected for possible chemical analysis on the basis of the highest PID reading. The ends of the selected brass tube will be (1) covered with aluminum foil and plastic caps, which will then be taped with plastic tape to provide an air-tight seal; (2) labeled and placed into zip-lock plastic bags, and (3) stored in a cooled ice chest for delivery to the analytical laboratory. These procedures minimize the potential for cross contamination and volatilization of volatile organic compounds prior to chemical analysis. To prevent cross contamination during sampling, all equipment will be washed with laboratory-grade detergent, rinsed with tap water, and rinsed with deionized water before and between collecting each sample.