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303 South Cherokee Lane TL A91701.01 <br /> March 10, 1995 Page 5 <br /> L <br /> L According to a letter dated February 15, 1995,PHS/EHD requires that soil sample location <br /> #s 7, 8, and 10 be resampled due to a discrepancy between field notes taken during the <br /> piping removal and subsequent analytical results. <br /> L <br /> 4.0 PROPOSED FIELD ACTIVITIES <br /> L <br /> Proposed field activities are summarized in the following subsections. Standard operating <br /> procedures (SOPs), relevant to the field activities, are described in Appendix A. <br /> L <br /> 4.1 Soil Borines <br /> L 'Twining proposes to drill one angle soil boring and two vertical soil borings around the <br /> northern dispenser island using a CME-75 truck-mounted drill rig equipped with 6-5/8-inch <br /> L diameter hollow-stem augers. Initially, the angle soil boring will be drilled from the south <br /> side of the dispenser island to assess the vertical extent of PPC-containing soils. The depth <br /> of this boring will be based on field screening of soils for petroleum hydrocarbons. It is <br /> L anticipated that the boreholes will extend a minimum of 10 feet below field detectable <br /> petroleum hydrocarbons or a maximum vertical depth of 50 feet BSG. The depth of the <br /> remaining two soil borings will be based on data generated from the angle boring. The <br /> L remaining two vertical soil borings will be located to the north and east to assess the lateral <br /> boundaries of PPC-containing soils (Drawing 2). If PPCs are detected in soil samples <br /> through the field screening process, then additional soil borings would be necessary to fully <br /> assess the lateral extent of PPC migration. Additional soil borings would be proposed <br /> approximately 20 feet beyond the nearest soil boring containing PPCs detected through field <br /> screening. Actual soil boring locations will be determined based on field data. <br /> Soil samples will be collected at five-foot intervals beginning at five feet BSG. A Twining <br /> geologist will log the soils in accordance with the Unified Soil Classification System and will <br /> L screen the samples for evidence of contaminants. The screening will consist of visual <br /> observation for staining or unusual fluids, unusual odors, and head space analysis with a <br /> photoionization detector (PID) for the presence of organic vapors. PID operation and <br /> Lprocedures for the performance of head space analysis are described in our SOPS presented <br /> in Appendix A. <br /> LSix vertical soil borings will be drilled in the vicinity of the three former product USTs. One <br /> soil boring will be drilled to a depth of approximately 20 feet BSG on each end of each <br /> former UST. One soil sample will be collected from native soil at the bottom of each soil <br /> Lboring. <br /> L <br /> L <br />