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-z R :3 1.0 FIELD TTLTFIODS ANT) PROCEDURES 1.1 Drillin and Soll Sampling - Soil borings were advanced and Soil samples were collected under the direction of a qualified Delta representative. Soil borings were drilled using a truck-mounted rotary drilling rig utilizing hollow-stem augers. Soil sampling was conducted in accordance with ASTM 1586-84 using a 3.0-inch inside-diameter California-type sampler driven into the soil by a 140-pound weight falling 30 inches. After an initial set of 6 inches,the number of blows required to drive the sampler an additional 12 inches,known as penetration resistance or the"N"value,was recorded. The "N"value is used as an empirical measure of the relative density of cohesionless soils and the consistency of cohesive soils. The sampler is lined with three brass sample tubes, each 6 inche, long with an outside diameter equal to the inside diameter of the sampler. Samples were collected at 5400t intervals or as directed by the geologist based on geologic and site specific conditions. All soil samples were examined in the field by a geologist and described by color,grain size,and moisture -ontent, and classified in accordance with the Unified Soil Classification System. A portion of the soil sample was placed into a plastic bag and sealed for headspace analysis for the presence of the organic vapors using a photoionization detector (PID). The soil sample collected in the leading brass tube within the California-type sampler was labeled, sealed, and stored on ice pending selection and transport to the laboratory for analysis. Representative portions of the samples were retained for furtber examination and for verification of the field classification. Logs of the borings indicating the depth and identification of the various strata,the"N"value,and pertinent information regarding the method of maintaining and advancing the borehole were made. All drilling and sampling equipment was cleaned before drilling each boring using a high-pressure,steam- cleaning apparatus. The split-spoon sampler was cleaned with phosphate-free soap and rinsed with water following each sample collection. Soil cuttings generated during drilling operations were placed on and covered with visquine on site until Iaboratory results are obtained and an appropriate disposal method is selected. l.z Soil Sample Screening After the soil samples in the plastic bags were warmed to approximately ambient temperature,the organic vapors within the headspace of the soil sample jars were screened with a PID equipped with a 10.2 eV lamp calibrated to benzene. The sample bag was opened and the detector probe immediately plateal within the headspace of the bag. The highest observed reading was then recorded on the boring logs.