ARCHIVED REPORTS_XR0012661 CASE 2

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r� rrt During the sample collection, an experienced environmental geologist classified the subsurface soil and logged the boreholes. A copy of the Unified Soil Classification System used to classify the soil and a log key are included in Plates A-1 and A-2. Descriptions of the soil encountered in each boring and the identification of the sampling intervals are presented on the Log of Borings, Plate A-3 through A-8 (Appendix A). The soil encountered in the borings consisted of clay, clayey silt, silt, sandy silt; silty sand, and clayey sand. In general clay and silt was encountered from 0 to 25 feet. Some sand. and gravel was encountered between 25 and 40 feet in borings B-1 and B-2. Soil samples were generally moist, except for the sample collected at the bottom of B-1 which was wet. Free water was observed in B-I at a depth of 56.5 feet below ground surface. The remaining five borings were drilled to a depth of 41.5 feet or less and did not encounter free water. At each boring location, a truck mounted drill rig equipped with 6-inch hollow stem augers was used to reach the desired sampling depths. Samples were collected by advancing the - boring to a point immediately above the desired sampling depth and then driving a Modified California Sampler lined with three brass tubes into the undisturbed soil. The ,:... sampler was removed from the bottom of the boring,and the bottom tube was sealed with Teflon sheeting and tight fitting plastic caps, labeled, and placed inside an iced cooler. At ,. the end of drilling operations, selected soil samples were delivered under chain-of-custody to California Analytical Laboratories/Enseco Inc.in West Sacramento. The remaining soil samples were retained in refrigerated storage for future reference or analysis. JA To reduce the potential for cross-contamination between borings, the augers and associated equipment were steam cleaned prior to drilling each boring. .The sampling -' equipment was cleaned with a trisodium phosphate wash and a distilled water rinse prior to collecting each soil sample. At the completion of the sampling operations,each boring was backfilled to the surface with a bentonite-cement slurry. Soil cuttings removed from the borings was placed in 55-gallon steel drums and left onsite. 3.2 QUALITATIVE FIELD SCREENING To provide a qualitative indication of contamination and to assist in selecting samples to be analyzed, a portable organic vapor detector was used to screen the samples in the field. A 241-89-2196 4