Saltstone Disposal Unit 11, center, has had all of its concrete work completed at the Savannah River Site’s Saltstone Disposal Facility in Aiken, S.C. (Photo: SRS)
The Savannah River Site has completed all concrete construction on its “mega-size” Saltstone Disposal Unit (SDU) 11 at the Saltstone Disposal Facility in Aiken, S.C. The several SDUs at the site are designed to provide safe, permanent storage for decontaminated salt solution from the Salt Waste Processing Facility (SWPF) as production is ramped up. The SDUs are crucial components of SRS’s liquid waste program, allowing the site to meet the cleanup responsibilities of the Department of Energy’s Office of Environmental Management.
SDU 11 contains more than 20,000 cubic yards of concrete, including 25 wall sections, 208 support columns, and seven roof sections. With the concrete work finished, the SDU will get wrapped in 340 miles of steel cable arranged in seven layers to enhance its structural integrity and durability. The massive structure will be able to hold more than 33 million gallons of saltstone waste.
Chuck Comeau, DOE–Savannah River federal project director, said that concrete construction on SDU 11 was completed sooner than originally planned, which “ensures that the SDUs will be ready when needed.” The DOE honored the SDU project team last year with the Project Controls Excellence Award for demonstrating superior project controls, rigorous data integrity, and continuous improvement in practices.
Salt waste treatment process: SRS’s two tank farms still hold 43 operational waste tanks. The waste in those tanks is being processed and sent to one of two destinations: Sludge is treated at the Defense Waste Processing Facility using vitrification, where it is converted into a solid glass form; and the remaining salt waste is processed at the Salt Waste Processing Facility. The DOE treats the salt waste to remove highly radioactive radionuclides, and then processes the waste into saltstone grout for permanent disposal in the SDUs.
DOE-EM announced in 2024 that more than 10 million gallons of liquid radioactive waste had been processed at the SWPF.
SDU complex: The Saltstone Disposal Facility, located in SRS’s Z Area, currently has two rectangular SDUs, six small round SDUs, and four large round SDUs. Three larger round SDUs in various stages of construction are numbered 10, 11, and 12. Concrete construction on SDU 10 was completed in 2024, and it was rated as leak-tight in 2025. SDU 12 is the final SDU required to complete SRS’s radioactive liquid waste cleanup mission.
