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FIELD PROCEDURES FOR DRILLING, SOIL SAMPLING, AND TEMPORARY GROUNDWATER MONITORING WELL INSTALLATION Drilling The shallow soil borings used for lateral groundwater assessment were drilled using 4-inch-diameter hand augers. To avoid cross-contamination,drilling equipment in contact with potentially contaminated material was washed using a phosphate-free detergent followed by tap water and deionized water rinses between each use. Decontamination fluids were placed into a tank truck for disposal at an appropriate recycling facility. Soil Sampling During drilling,samples were collected at varying intervals. Before and after each use,the sampler was washed using a phosphate-free detergent followed by tap water and deionized water rinses. Soil was sampled using a hand sampler with stainless steel tubes. A slide hammer was used to advance the sampler approximately 6 inches into undisturbed soil. After retrieval from the boring, the sampler was opened, the sample tubes were removed,and a soil sample was selected for possible chemical analysis. The sample was retained within the stainless steel tube, and both ends were immediately covered with Teflon sheeting and polyurethane caps. The caps were sealed with tape and labeled with the following information: Alisto's project number,boring number, sample depth interval, sampler's initials, and date of collection. The sample was immediately placed in a waterproof plastic bag and stored in a cooler containing blue ice. Possession of the samples was documented from the field to a state- certified analytical laboratory by using a chain of custody form. Soil samples and,when representative, drill cuttings were described by Alisto's personnel using the Unified Soils Classification System;and field estimates of soil type, color,moisture,density, and consistency were noted on the boring logs. The logs were reviewed by a civil engineer registered in the State of California. Temporary Monitoring Well Installation and Sampling Construction of the temporary monitoring wells used for lateral groundwater assessment was based on the stratigraphy encountered in the soil borings and the depth to water in the boring. Prior to inserting the temporary well casing into the boring, the depth to water was measured so that the screened interval of the temporary well casing was within one foot of the stabilized water level. The 3/a-inch-diameter PVC well casing consisted of 0.010-inch slotted casing from the ground surface to approximately 14 feet below grade.