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A.1 Borehole Design and Soil Sampling <br />A.1.1 Drilling and Soil Sampling <br />Boreholes will be advanced with a standard (8-inch diameter) hollow-stem <br />continuous flight auger so that 2-inch (nominal) diameter PVC casing can be <br />installed if conversion to a monitoring well is required. The hollow stem <br />allows the core sampler to be lowered in the hole while the auger is in place <br />to prevent caving. The hollow-stem sampling device used will be a modified <br />Diedrich 3-inch O.D. (2 1/2 inch I.D.) split barrel sampler with special <br />aluminum liners which become the sample containers; hence, soil samples are <br />not extruded and 'exposed to the atmosphere. Extruding soil samples into glass <br />jars in the field invalidates any purgeable analysis. Sample liner <br />preparation consists of the following: <br />Methanol wash to remove residual machine oil, <br />Air-dry at least one hour, <br />Wash in hot soapy water with Liquinox (or equivalent) non-phosphate <br />detergent, <br />Double rinse with organic-free distilled water, drain and air dry, <br />Place in polyethylene plastic bags to minimize atmospheric <br />contaminants. <br />The Diedrich sampler is a durable device that can be either hydraulically <br />pushed into soft materials or hammered into dense deposits. Four of these <br />samplers will be on the site to facilitate decontamination. To minimize <br />cross-contamination from loose cuttings in the hole, a knock-out plate will be <br />used on the tip of the auger and the sampler will be over-driven to a depth of <br />18 inches (three 6-inch liners). Then the main sample will be taken from the <br />A-2