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L <br /> L Mr. Lloyd Gums A91701.01B <br /> January 15, 1996 Page 5 <br /> data. The work scope outlined in the following section was performed to collect the data <br /> necessary to satisfy the requests of the SJCPHS. <br /> L <br /> 4.0 INVESTIGATIVE PROCEDURES <br /> L This site characterization consisted ofre aration of a work plan and appropriate permit <br /> P P <br /> applications, a field investigation, a laboratory testing program, and preparation of a <br /> Lsummary report. Standard operating procedures(SOPs),relevant to the field and laboratory <br /> activities, are described in Appendix A. Any specific deviations from the SOPs are stated <br /> Lin the following sections. <br /> 4.1 Work Plan and Permit AouliOUM Approval: The work scope herein described was <br /> presented in Twining's work plan ('Twining, 1995). The work plan was approved by the <br /> L SJCPHS in a letter dated May 3, 1995. A drilling permit application was submitted to the <br /> SJCPHS and approved on December 5, 1995. Copies of the SJCPHS approval letter and <br /> Lthe approved drilling permit are attached in Appendix B. <br /> 4.2 Field Investigation: The field investigation consisted of drilling soil borings and <br /> collecting soil samples for chemical analysis. <br /> 4.2.1 Soil Boring Locations and Soil Sampling: A total of twelve soil borings (B-1 <br /> through 13-9 and HA-7, HA-8, and HA-10)were drilled to assess the presence (or absence) <br /> L of PPC concentrations in sub-surface soil. Approximate soil boring locations are shown on <br /> Drawing 3. Soil samples collected from each of the soil borings were field screened <br /> consistent with our SOPs. Field screening procedures include observation of the soil for <br /> lithologic data, odor, and unusual stains, and head-space analysis with a photoionization <br /> detector (PID) to detect the presence of organic vapors. The results of the field screening <br /> and lithologic descriptions of the subsurface soils are recorded in the soil boring logs <br /> presented in Appendix C. The soil samples collected in the field were preserved for <br /> laboratory analysis consistent with our SOPS. The soil borings were drilled as summarized <br /> Lbelow; <br /> Soil borings B-1, B-2, and B-8 were drilled to approximately 35 feet below site grade (BSG) <br /> L adjacent to the northwestern dispenser island. Soil boring B-1 was drilled on an angle to <br /> explore soil directly beneath the dispenser island to collect data for the assessment of the <br /> vertical extent of PPC migration. Drawing 4 presents a cross-section representation of soil <br /> L boring B-1. Soil borings B-2 and B-8 were drilled to collect data for the assessment of the <br /> lateral extent of PPC migration. These soil borings were drilled using the CME-75, truck <br /> mounted, hollow-stem auger drill rig. Soil samples were collected from these soil borings <br /> Lat five-foot intervals starting at 5 feet BSG. <br /> L <br /> L <br />