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Frontier Transpoticaion. lire. B23502.01 October 16, 1996 Page A-2 Soil boring are drilled using an appropriate method. The method selected will depend upon project objectives and subsurface conditions. Typically soil boring are drilled using a Central Mine Equipment Company model 75 (CME-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 boring are drilled under the direction of a Twining geologist. Drilling and Sampling equipment are thoroughly cleaned before, during and after each use. Cleaning procedures are described in a subsequent paragraph. Soil samples are collected using a continuous-coring device, by driving a split-spoon sampler, or by grabbing samples from the drilling cutting returns. The sampler or coring device is lined with brass, stainless steel, or acrylic tubes, in which samples may be retained for subsequent chemical analyses. To collect samples using the split-spoon sampler, the sampler is initially lowered to the bottom of the soil boring and driven 6 inches into undisturbed soil. It is then driven 12 inches deeper by repeatedly dropping a 140-pound weight from a height of 30 inches. The number of blows required to advance the sampler 12 inches is recorded on the boring logs as "blows per foot". This information is used in estimating soil density. 1. Soil samples are examined for, the purpose of preparing lithologic logs Soils are logged consistent with the Unified Soil Classification System (USCS). The soil boring logs note soil types encountered at depth including consistency, soil moisture, particle size, color, and other distinguishing features. The soil samples are field screened for evidence of volatile organic chemicals (VOCs) and/or other contaminates. The field screening consist of; visual observation for straining or free fluids, unusual odor, and head space analysis using a photoionization detector (PID) or drager tube. The procedure for performing head space analysis are describe in a subsequent paragraph (if pertinent to this investigation). Generally, soil samples selected for analyses typically represent those which the field screening indicated will be most likely to contain the contaminate of concern. In most instances the deepest two samples and/or and sample collected from just above groundwater are selected for analyses. Samples intended for chemical analyses are sealed with Teflon tape and plastic end caps, labeled, placed on ice, and delivered to a laboratory, along with chain-of-custody documentation. The soil boring may be completed as groundwater monitoring wells, or abandoned by grouting with a sand-cement slurry. Abandonment procedures depend upon the boring depth, depth to groundwater, project objectives, and regulatory requirements. For boring greater than 15 feet deep, `rout is emplaced through the hollow augers which will extend to within 15 feet of the bottom of the boring. If required by the Iocal regulatory agency, grout is emplaced by pumping through a tremie pipe which extends to within 15 feet of the