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0.8/25/92 08:45 $916 366 7013 SACR9MENTO Q006/011 _.._ KIFI \ etoek Task 2 - Drilling and Sampling of Three Borings If a 20,000-gallon underground fuel storage tank were to be excavated and removed, State and County guidelines would require that three soil samples be collected beneath the tank. The samples would be collected near each end of the tank and near the middle of the tank. Since the tank is to be abandoned inplace, Kleinfelder recommends that, at a minimum, the same sampling approach for tank removal be incorporated for the inplace tank abandonment. The bottom of the 20,000-gallon tank sits on top of a concrete slab at a depth of approximately 14 feet below the ground surface. Potential petroleum hydrocarbons migrating vertically from the tank would migrate laterally to the edge of the concrete slab and then migrate vertically from the edge of the slab. For this reason, Kleinfelder recommends three vertical borings at each end and the middle of the tank as opposed to angle drilling beneath the tank. Kleinfelder proposes to drill three soil borings along the tank; one adjacent to each end of the tank and one adjacent to the middle of the tank near the fuel line piping (Plate 1). The borings will be drilled to a depth of approximately 25 feet. It is anticipated that ground water is approximately 30 to 35 feet below the surface and will not be encountered in the borings. The borings will be terminated if ground water is encountered at a depth less than 25 feet. Soil borings will be advanced using a truck-mounted drill rig equipped with 6-inch hollow stem augers. The borings will be drilled, logged, and sampled following the Protocol described in Attachment A, Sections A-2.1 through A-2.4, and closed as described in Section A-2.7. Task 3 - Laboratory Analysis and Database Management Two soil samples from each boring will be selected for laboratory analysis (six total): The samples will be selected based on field observations, qualitative screening results with an organic vapor detector, and the objectives of the investigation. The six soil samples will be submitted to a laboratory certified by the State of California Department of Toxic Substances Control (DTSC) for the proposed analyses. The samples will be analyzed for: o Extractable Total Petroleum Hydrocarbons (TPH) o Purgeable TPH o Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) The samples will be analyzed on a regular turnaround schedule, usually requiring 15 working days for completion. If water is encountered in one or more of the borings, Kleinfelder can collect representative water samples from the borings with a BAT Probe without installing ground water monitoring wells. Task 4 - Prepare a Report of Findings Upon completion of soil sampling and receipt and review of analytical results, a report of findings will be prepared for client review. The report will include: o A description of field activities, observations, and protocols. o Lithologic logs. FP3-92.35 Page 2 of 6 Copyright 1992 Kleinfelder, Inc.