ARCHIVED REPORTS XR0012794 - Laserfiche WebLink

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BOREHOLE DRILLING Boreholes are drilled by a licensed drilling subcontractor, using a truck-mounted drilling ng equipped with nominal 8-inch-diameter hollow-stem augers During dnlling, soil samples for lithologic identification and possible laboratory analysis are collected every five feet in the borehole The samples will be obtained using a 2-inch-diameter by 18-inch-long split-spoon sampler lined with three b-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 In addition to evaluating the borehole lithology, the soil samples 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 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 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 Boreholes are drilled to a predetermined depth below the ground surface or are terminated when two consecutive readings indicating hydrocarbons are not present in the soil are collected Borehole depths are based on site conditions, including but not limited to conditions such as depth-to-water, depth of identifiable contaminants, and depth to bedrock To prevent cross contamination during drilling, all equipment is steam cleaned prior to and between use at each borehole