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Janet Dunlap, P.E. 2 January 2008 Page 4 Geosyntec consultants landfill. Costs for the transport of the brush and trees are included in the proposal. Costs for the disposal of the brush and trees are the responsibility of IRC. The excavation work will be performed with standard excavation techniques and Occupational Safety and Health Administration (OSHA) trained personnel. Personnel will not be permitted to enter the excavation. The proposed excavation task costs are based upon a tiered excavation area (Figure 1), with an outer excavation area of 25 ft x 75 It x 7 ft deep and an inner tier excavation area of 15 ft x 50 ft x 4 ft deep (7 to 11 ft BLS). This excavation footprint and associated soil volume could increase based upon the results of the delineation sampling. Upon excavation, the soils will be hauled to the IRC landfill for disposal. Costs for the transport of the excavated soils are included in the proposal. Costs for the disposal of the excavated soils are the responsibility of IRC. Additionally, up to 7,000 gallons of groundwater will be extracted from the center of the excavation area by a vacuum truck. The volume of groundwater was calculated using the volume of the inner tier excavation area (3,000 cubic feet) and an assumed porosity of 0.3. The extracted groundwater will be hauled by the vacuum trucks for proper disposal at an approved industrial wastewater treatment facility (Jacksonville, FL). Costs for the transport and disposal of the extracted groundwater are included in the proposal. Upon completion of the groundwater extraction activities, the excavation area will be backfilled with clean backfill. To evaluate the impact of the saturated zone excavation and groundwater extraction, a confirmation groundwater sample will be collected from the center of the excavation area. It is anticipated that one of the previously installed shallow monitoring wells will be removed prior to excavation and will be reinstalled prior to backfilling activities. The groundwater sample will be collected from the re -installed monitoring well in accordance with FDEPs SOPS, February 2004, and analyzed by a fixed based laboratory for arsenic by EPA Method 6010. Task 4 Contingency Costs. An excavation expense contingency cost has been added to this proposal to provide funding for a larger excavation area should laboratory analysis demonstrate that arsenic concentrations above the SCTL extend beyond the proposed 25 ft x 75 ft excavation area. The contingency costs assume that the excavation volume increase will not exceed 150 cubic yards. The Task 4 contingency costs will not be utilized without prior IRC notification and approval. XR07084/CCR08003. DOC cilgiliculS I SCiellLiAS I ltilloViLOIS