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placed in a triangular pattern to enable a three-point determination of the ground water gradient to be made Following is a discussion of drilling, soil sampling, monitoring well construction, monitoring well development, surveying, and ground water sampling activities for the Phase I investigation field activities. tDrilling Affivitigs and 52H The three soil borings located outside of the warehouse (MW-1A, MW-2A and M-3) cont nwere uous led using a CME-55 truck-mounted drill rig equipped flight hollow stem augers. The inside boring (MW-4A) was drilled using a CME-45 drill rig. Prior to drilling each well boring, the ' augers were cleaned and decontaminated by the use of steam. The borings were drilled to depths ranging between 15 and 25 feet below the ground surface. Borings MW-1A and MW-2A were sampled at 2 5-foot intervals within the unsaturated zone. MW-3A and MW-4A were sampled at 5-foot intervals. Soil samples were collected during drilling utilizing a modified California split-spoon ' sampler equipped with precleaned brass sampling tubes. The sampler was cleaned prior to each use in an Alconox0 solution and rinsed with deiomzed water. Soil samples were retained in brass ' tubes by covering the ends of the tubes with TeflonO film and plastic caps. During drilling, soil samples were labelled with a unique sample number, the project name and location, the date and time, and the sampler's initials. Sample identification numbers reference the boring number and the sample depth from the ground surface. Samples were then placed in Zip-LockO type plastic bags, sealed, and placed in an iced cooler Information noted on the label was recorded on a chain-of-custody form. After completion of drilling, the samples ' were delivered under chain-of-custody to Superior Analytical, Inc , a California-certified laboratory Soil samples and drill cuttings were visually inspected and classified according to the Unified Soil Classification System (USCS) by a qualified ERM-West geologist Boring logs were constructed to record ' vertical variations in lithology, moisture content, color, and texture of the soil Appendix M contains the drilling logs for the Phase I ' investigation. All soil removed from the boreholes and all rinsate generated was stored in sealed 55-gallon drums pending the results of laboratory ' analyses Each drum drasclearly mlabelled lred adjacent totthe stockpiled its contents and boring number. us were stored soil near the east end of the loading dock. ' Monitoring Well construrti Well completion forms are provided in Appendix M. MW-2A, located in the center of the former tank site, 5-5