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1.0 METHODS AND PROCEDURES 1.1 Soil Sam lin and Contamination Reduction Soil borings and soil sampling was performed under the direction of a Delta geologist. The soil borings will be advanced using a truck-mounted hollow-stem auger drill rig. ' To reduce the chances of cross contamination between boreholes, all downhole drilling equipment will be steam-cleaned between each soil boring. To reduce cross contamination between samples, the ' split-barrel sampler is washed in a soap solution and double rinsed between each sampling event. ' Soil sampling conducted in accordance with ASTM 1586-84, will use a 2-inch outside-diameter split-barrel sampler or a 2-inch inside-diameter split-barrel 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. 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 inches long and the outside-diameter equal to the inside-diameter of the sampler. Upon recovery, a portion of the soil sample is placed into a plastic bag and sealed for later screening with a photoionization detector (PID) as described in Section 1.3. A representative portion of the soil sample will be used for classification and description. The soil sample collected in the leading brass tubes within the California-type sampler will be labeled, sealed, and stored on ice for transport to the laboratory. 1.2 Soil Classification As the samples are obtained in the field, they will be classified in accordance with the Unified Soil Classification System. Representative portions of the samples will be retained for further examination 1 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 will be made. 1.3 Soil-Sample Screening/hNu Portable Photoionization.Detector Method ' After the soil samples in the plastic bags are warmed to approximate ambient temperature, the organic vapors within the headspace of the soil sample jars will be screened with a portable PID equipped with a 10.2 eV lamp calibrated to benzene. The sample bag will be opened and the detector probe immediately placed within the headspace of the bag. The highest observed reading will be recorded. RPT049.TA