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SOIL VAPOR EXTRACTION PILOT STUDY WORK PLAN San Joaquin County Montgomery Ward Auto Service Center Public Health Services Department 5400 Pacific Avenue, Stockton CA Site Code 2163 ' 1.0 INTRODUCTION ' Environmental Audit, Inc (EAI) was retained by Montgomery Ward & Co , Incorporated (Montgomery Ward) to conduct a Soil Vapor Extraction (SVE) Pilot Study at the Montgomery I Ward Auto Service Center facility, 5400 Pacific Avenue, Stockton, California (Montgomery Ward site) (see Figure 1) EAI prepared this Work Plan to present the scope of work to be performed as part of the pilot study The objectives of the pilot study are as follows ' ■ Fill gaps in the soil plume delineation, ■ Obtain site specific data for the design and implementation of a full-scale vapor ' extraction system, ■ Evaluate the degree of intrinsic bioremediation in affected soils, and ■ Evaluate likely mass removal rate, and thus the anticipated length (time) of remediation efforts ' It is Montgomery Ward's intention to complete soil remediation measures prior to addressing ground water The source of ground water contamination beneath the Montgomery Ward site has not been clearly defined The ground water data available for the Unocal site located ' across the street from the Montgomery Ward site (see Figure 1) suggests that releases from the Unocal site have impacted the Montgomery Ward site Therefore, any ground water remediation efforts, should they be necessary, must, in EAI's opinion, be addressed jointly by Montgomery Ward and Unocal ' 2.0 BACKGROUND Several site assessments have been completed to date to attempt to define the extent of soil and ' ground water contamination beneath the Montgomery Ward site Appendix A provides a descriptive summary of each assessment, the results obtained and the conclusions made ' Tables 1 through 7 present the results of testing soil samples collected from the Montgomery Ward site Table 8 presents the results of testing ground water samples 2.1 SUMMARY OF PREVIOUS SOIL INVESTIGATIONS ' Figure 3 shows a summary of the contaminant concentrations detected in soil samples collected from the Montgomery Ward site These data suggest there are two separate plumes at the site ki-P Fronrp 4 1 The first plume is centered around soil borings B-6 and B-11 This plume extends in a northeast to southwest direction, covering a surface area of approximately 2,700 square feet The second plume is centered around monitoring well MW-2 and covers a surface area of approximately 2,800 square feet ' Project No 1232 - 1 - ENVIRONMENTAL AUDIT, INC