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5.0 MITHCD8 1 I 5.1 Sail Borings Soil borings will be drilled and soil samples collected under the direction hof a California-registered professional geologist or engineer. Initially;' the soil borings gill be advanced to a depth oiz,'approximatelY five feet below grads by hand auger. The soil borings will then be advanced to total depth using atruck-mounted hollow-steal auger drilling rig. To reduce the potential for cross-contamination between boreholes, all downhole drilling equipment will be cleaned with a high pressure hot water Iwash between each boring. Rinsate will be captured and contained for proper disposal. To reduce cross- contamination between samples, the split-barrel sampler will be washed in , a tri-sodium phosphate solution and double-rinsed :in distilled water between each sampling event. i 5.1.1 8oi18ampling l Soil sampling will be conducted in accordance with ASTM 1586-84. Using this procedure, a two-inch O.D. split-barrel sampler or a two-inch I.D. California-type sampler is driven into the soil by - a 140-pound weight falling 30 inches. After an initial set of 6 inches, the number lof blows required to drive the sampler an additional; 12 inches is known as penetration resistance, or the value: The N value is used as an empirical measure of the relative density of cohesionless soils and the consistency of cohesive soils. 1 Upon recovery, a portion of the soil sample will be placed into an air-tight disposable"container and sealed for later screening with a portable PID or TLV organic vapor sensor. Another portion of the li soil sample will be used for classification and description. That part , of the soil sample collected in a brass tube within the sampler will be stored on ice in an ice chest for transport to the laboratoryi. 5.1.2 Soili Classification i w As ,:the samples are obtained in the field, they are classified in accordance with the Unified Soil Classification System (USCs) . Representative portions of the samples are then submitted to a soil mechanics 'I laboratory for further examination and for verification ofjthe field classification. Logs of the borings indicating the depth and identification of the various soil types, the N value and -• pertinent I information regarding the method of maintaining and advancing the borehole are also made. n I L .