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1.0 METHODS ' 11 Soil Sampling and Contamination Reduction Soil borings and soil sampling were performed under the direction of a Delta engineer or geologist The soil bonngs were advanced using a truck-mounted drill ng utilizing hollow-stem augers To reduce the chances of cross-contamination between boreholes, all downhole drilling equipment was ' steam-cleaned between each boring To reduce cross-contamination between samples, the split-barrel I sampler will be washed in a soap solution and double-nnsed between each sampling event Soil sampling was done in accordance with ASTM 1586-84 Using the procedure, a 2-inch outside-diameter split-barrel sampler or a 2-inch inside-diameter California-type sampler was driven into the soil by a 140- point 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 recorded The number of blows required to drive the sampler is known ' as penetration resistance, or the "N" 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 was placed into a glass jar and sealed for later screening with a phototonuation detector {PID) Another portion of the soil sample was used for classification and description That part of the soil sample collected in brass tubes with the Californta-type sampler was stored ' at approximately 4°C for transport to the laboratory 1.2 Soil Classification ' As the samples were obtained in the field,they were classified by the crew chief/geologist in accordance with ASTM D2488-84 Representative portions of the samples were then retained for further examination and ' for verification of the field classification Logs of the borings indicating the depth and identification of the various strata, the N value, water-level information and pertinent information regarding the method of ' maintaining and advancing the borehole was made in the field during drilling activities 13 Soil-Sample Screening(PID Method After soil sample jars were brought to room temperature, the headspace vapors of the soil sample jars were screened with a PID, equipped with a 10 2 eV lamp calibrated to benzene for direct reading in ppm The sample jar lid was opened and the hNu probe was immediately placed through the foil cap within the head- space of the jar The highest observed reading was recorded in the field notebook. 1