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1.0 M1;'TIiODS 1.1 Soil Samnlinr and Contaminadon Reduction Soil borings and soil sampling was performed under the direction of a Delta engineer or geologisL The soil borings were advanced using a truck-mounted d:iL rig utilizing hollow-stem augers. •i To reduce the chances of cross contamination between boreholes,all down-hole drilling equipment were cleaned between each soil boring. To reduce cross contamination between samples, the split-barrel sampler was washed in a soap solution and double rinsed between each sampling event. Soil sampling was done in accordance with ASTM 1586.84. Using this procedure, a 2-inch outside- diameter split-barrel sampler or a 2-inch inside-diameter California-type sampler is driven in.o 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 is known as penetration resistance, or the "N" value. The N x�. value is used as an empirical measure of the relative de Hairy of cohesionless soils and the consistem. of cohesive soils. Upon mcovery, a portion of the soil sample was, placed into a glass jar and sealed for later screening ' with a'photoioniaation detector (PID). Another portion of the soil sample was used for classification and description. That part of the soil sample collected in brass tubes within thn California-type sampler was stored at approximately 4oC for transport to the laboratory. 1.2 alt Classiticatlan As the samples are obtained in the field, they were classified by the crew chieflgeologist in accordance with ASTM:D2488-84. Representative portions of the samples were returned to the laboratory for further ' examination and for verification of the Held classification. Logs of the borings indicating the depth and identification oC the various strata, the N value, water-level information and pertinent information regarding the method of maintaining and advancing the bore hole were made. i 13 Soil-Sample ScreeninnElhNu Photoionization Detector Method After soil-sample jars have been brought to room temperature,the head-space vapors of the soil-sample jars were screened with an hNu photoionixation detector equipped with a 102 eV lamp calibrated to benzene for direct reading in parrs per million (ppm). The sample jar lid will be opened and the hNu probe immediately placed within the head space of the jar._ The highest observed reading was recorded.