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r <br /> VED <br /> 1 GeologicafTechnics Inc. pUG 18 zo <br /> 111 <br /> 1 2741 River Road VIRowuj <br /> Modesto,califomw 95351 ENpERM1TISERVICES <br /> (209)538-6424IFaX,#538-5852 <br /> 1 <br /> Work Plan <br /> 1 Remedial Alternative -- Feasibility Study <br /> 1 George's Service <br /> 1600 Durham Ferry Road <br /> 1 Tracy, California <br /> Project No. 425.2 <br /> 1 August 17, 2000 <br /> 1 1.0 INTRODUCTION <br /> ' Per the directive of SJC-DPHEHD given on July 3, 2000, Geological Technics Inc. has <br /> prepared this work plan to evaluate soil excavation and air-sparging/vapor extraction <br /> remedial alternatives and provide determination as to which technology is appropriate to <br /> 1 mitigate the petroleum hydrocarbons present in the soil and groundwater beneath the site. <br /> This work plan provides details on both alternatives and outlines the limitations of the air- <br /> ' sparging/vapor extraction alternative. I have already discussed these limitations with Ms. <br /> Carol Oz, and after she has reviewed this plan, she may have further questions regarding <br /> these alternatives. <br /> 1 Of these two alternatives, soil excavation is the preferred choice for the following reasons: <br /> 1. The costs for sparging/vapor extraction & monitoring are approximately 1.5 times that of <br /> 1 soil excavation& monitoring. <br /> 2. Given the fact that most of the contamination occurs above the depth of 15 feet, <br /> excavation will remove the high concentration of soil around the former USTs, which <br /> 1 contain very high concentration of TPH-g and BTEX contamination. <br /> 3. Sparging/vapor extraction technologies are suited for course-grained soils, not fine- <br /> grained silts & clays as present in the upper 25 feet of this site. <br /> 1 1.1 Contamination Distribution <br /> 1 Boring logs are included as Appendix A. Summary tables listing a compilation of soil and <br /> groundwater testing results to date for the project are attached in Appendix B. Contaminant <br /> concentration contour maps and cross sections are attached in Figures 2, 3, &4. <br /> 1 <br />