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KLEINFELDER 3.1.4 Soil Boring Closure Each boring was closed after the completion of sampling activities. A cement-bentonite slurry was used to seal each boring to the ground surface. 3.2 LEACHATE ASSESSMENT Two soil samples were collected to assess the potential presence and characteristics of leachate from the landfill, following the protocol discussed in Appendix A. One soil sample was collected from B-1 at the contact between the fill material and the native soil, at a depth of 65.5 feet. This sample was chosen because it is from older, thicker portion of the landfill. The second leachate soil sample, was composited from three soil samples collected at depths of 4.0, 9.0 and 14.0 feet from B-5, at the request of the RWQCB. B-5 was drilled in a topographic low on the east side of the landfill. Both samples were submitted for chemical analysis. 3.3 GROUNDWATER ASSESSMENT Due to the expected depth of 200-300 feet for ground water, the monitoring wells were installed using an air-rotary casing hammer drill rig. Monitoring well MW-1, was positioned near B-4 and MW-2 was positioned near B-3 (refer to Plate 3-1). The subsurface lithology logged from the upper 100 feet in B-3 and B-4 was compared to the cuttings obtained during the drilling of MW-1 and MW-2. 3.3.1 Drilling Procedures Field activities commenced June 15 and continued through June 23, 1989. The holes were advanced with the air-rotary casing hammer rig at an average rate of 20 feet per 40 minutes. Grab cuttings were obtained and logged at approximate five foot intervals by an experienced environmental geologist. To avoid the introduction of contaminants or cross contamination between holes, all of the equipment was steam cleaned or washed with Trisodium phosphate and rinsed with distilled water prior to the initiation of drilling activities. FOOTHILL 18