Tetra Tech was contracted by the DOE to remediate areas within the Savannah River Site, a former nuclear materials production and reactor site, located in Aiken, SC. Tetra Tech’s mission entailed the excavation of approximately 45,000 cubic yards of materials and 350,000 cubic yards of fill material from the reactor sediment basins. Following excavation, areas were backfilled with common fill after which earthen and geosynthetic closure caps were constructed. Each cap consisted of common fill, structural fill, geogrid, GCL, FML, GDL, 18 inches of common fill and six inches of topsoil. After capping, all areas were re-vegetated to blend with the natural environment.

All waste material was relocated to a waste burial ground area for consolidation and capping. Work associated with the waste burial ground involved the construction of a 74-acre geosynthetic cap. Initially, 2 feet of topsoil was removed and stored for reuse. After topsoil removal, 2 feet of interium soil was removed used to level the area. Protection of the “red zones” was critical where waste cover was at a minimum. Once the cap areas were leveled, geogrid was placed and a layer of structural fill ranging from 6 inches to 1 foot was installed to grade. Subsequently, other geosynthetics, including GCL, FML and GDL, were installed. Eighteen inches of common fill and 6 inches of topsoil were then placed over the entire area which was then re-vegetated. Grade control was very important during this project due to numerous rain days and the subsequent necessity to control storm water. Drainage work accompanied the installation of a geosynthetic cap resulting in a completed project involving 80 acres.

Project Highlights

• Excavated 350,000 cubic yards of soil
• Excavated and disposed of 45,000 cubic yards of contaminated soil
• Performed storm water controls and management of an 80 acre site
• Saved the client almost $3.2 million dollars through material value engineering