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Geo(ogicaf7ec&tics Inc. • Page 2 Feasibility Study Work Plan ' Project No.425.2 August 17,2000 ' 2.0 REMEDIAL ALTERNATIVE 2.1 Contaminated Soil Excavation The highest concentrations of petroleum hydrocarbons in the soil at the site are generally in the upper 10 to 15 feet. The lateral extent of the heaviest soil contamination only covers an ' area approximately 30-feet by 40-feet in size. Due to the relatively small volume and shallow nature of highly contaminated soil, it is proposed that a limited excavation be considered to remove the heart of the source. Figure 2 is a site map showing the proposed boundary of the excavation. An estimated 500 to 600 cubic yards would be excavated. The volume of soil that would be disposed of is ' estimated to be 700 to 800 tons. The excavation would preserve the well cluster of MW-2, MW-102 & MW-202 so as not to damage these wells. The excavation would be limited as follows: • To the north by the underground fiber optic cable that runs along south side of Durham Ferry Road. ' . To the east by the well cluster MW-2, MW-102 &MW-202. • To the south by the building. To the west by low concentration of contaminants. A detailed plan for excavation is attached in Appendix D. This plan was prepared by Del- Tech under supervision by Ray Kablanow. A preliminary cost evaluation shows that for the soil excavation remediation activities as ' outlined below is approximately $115,000. Before this work could be implemented, detailed unit costs for this work would be developed and pre-approval by the Fund would be obtained. 1. Excavation ' 2. Transportation& Disposal 3. Backfill & Compaction 4. Confirmation Testing 5. Groundwater monitoring for one year 6. Supervision 7. Reporting ' 2.2 Air Sparging& Vapor Extraction Remediation Air sparging is the process of injecting air into the aquifer to volatilize contaminants from the groundwater. These contaminants are captured in the vadose zone and removed with the use