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\WNW ,..WW extent of hydrocarbon contamination. The results of this program will help to determine whether the contaminated soil can be quickly removed by excavation or whether additional drilling and in-situ remediation will be required to mitigate the contamination. The locations of the proposed borings are shown in Figure 1. One boring would be drilled within the former UST cavity, preferably near soil sample A2. A second boring would be located next to the sump, and the third would be located near the septic tank. Because of existing subsurface structures, the second and third borings will be drilled at an angle of 25° from vertical. The estimated depth to groundwater was 80 feet in 1990, and perhaps 50 to 55 feet during the high-water year of 1986. Therefore, GeoAudit proposes to continuously core to 35 feet in the tank pit area. If no contamination is detected between 30 and 35 feet, then it can be assumed that a buffer zone of at least 20 feet of uncontaminated soil is present above the former water table. The risk to groundwater would be very low, any contaminated soil above 30 feet could be quickly excavated and disposed of, and the site could proceed rapidly to closure. For this reason, this work plan includes excavation procedures in addition to drilling procedures. However, should contamination be detected at this depth, not only would a groundwater investigation be required by PHS/EHD, the contaminated soil would be too deep to be excavated. Either of these conditions would prevent expeditious site closure and delay the site renovations. We propose to core the slant borings to a vertical depth of 10 feet below the sump and septic tank, respectively. Should contamination be encountered at this depth, these borings will be extended as needed to identify the vertical extent of contamination. 4.0 PROCEDURES Details of the drilling, sampling, and analytical program are provided below. Optional procedures for soil excavation are also included. 1) Submit an Executive Summary for possible soil excavation to the PHS/EHD for public participation (Attached).. 2) Notify PHS/EHD 48 hours prior to field work. 3) Drill three soil borings using truck-mounted, continuous-flight, 8-inch hollow-stem augers at locations shown in Figure 1. 4) Collect discrete soil samples at five-foot intervals from 5 to 35 feet using a split- spoon sampler loaded with three brass tubes. 5) Decontaminate sampling equipment in a tri-sodium phosphate solution and rinse Ge Iogiol Audi[S—i—,Inc. 2 Don'.Buggie WP/2-94/W.1-5