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SRS Completes Construction Milestone on Next Mega-Size Disposal Unit

AIKEN, S.C. (June 13, 2024) – The U.S. Department of Energy (DOE) Office of Environmental Management (EM) has attained another milestone in the construction of mega-size disposal units necessary to complete the cleanup program at the Savannah River Site (SRS).

All major concrete placements have been completed on Saltstone Disposal Unit 10, the latest mega-size disposal unit being built at the Savannah River Site, bringing the U.S. Department of Energy Office of Environmental Management and contractor Savannah River Mission Completion a step closer to achieving the liquid waste mission. This aerial view shows the final roof section being installed on the unit.


With the placement of 25 wall sections, 208 support columns and seven roof sections, EM crews have completed all major concrete placements for Saltstone Disposal Unit (SDU) 10. When complete, SDU 10 will be the fifth mega-size unit built at SRS that can hold up to 33 million gallons of saltstone. More than 20,000 cubic yards of concrete is needed to build each SDU, using approximately 700,000 total labor hours.


Savannah River Mission Completion (SRMC), the SRS liquid waste contractor, manages the construction and operation of the SDUs. Constructing the large-scale disposal units is a priority for the cleanup program, and this milestone comes just weeks after SRMC received authorization to operate SDU 9.


Subcontractor DN Tanks completed the concrete construction, and Quality Plus Services completed the site preparation for the project.


Jim Folk, DOE-Savannah River assistant manager for waste disposition, said it has been affirming to witness the landscape change at SRS as the SDUs are built.


“Since the first mega-unit, SDU 6, was built in 2017, EM has not slowed down on construction of these critical structures,” Folk said. “These SDUs ensure that the decontaminated salt solution will have a place to be safely and permanently disposed of. Completion of the concrete placements for SDU 10 is another step forward on the mission to clean up the legacy radioactive waste at the Savannah River Site.”


The SDUs are the end of the salt waste processing path. The Salt Waste Processing Facility (SWPF) separates and concentrates the highly radioactive waste from the less radioactive salt waste, producing a decontaminated salt solution that is sent to the Saltstone Production Facility. There, the solution is mixed with dry materials to make a cement-like grout. The grout is pumped into the SDUs, where it solidifies into a monolithic, non-hazardous form.


The larger SDUs are designed to support the increased material from SWPF. The new SDUs result in more than $500 million in cost savings over the life of the SRS liquid waste program because they require less infrastructure and materials than the previously planned 80 smaller SDUs.


Next on the to-do list for SDU 10 is to wrap the unit with 341 miles of cable around the exterior walls. The cable in the unit walls ensures the structural integrity while grout is being added before it turns into hardened saltstone.


Work is also underway for the final pair of SDUs — 11 and 12 — adjacent to SDU 10. Mud mat installation for SDU 11 is scheduled to start later this summer, and the mud mat addition for SDU 12 is scheduled to begin in the fall. They provide a solid surface for the SDU concrete floor.


Dave Olson, SRMC president and program manager, said he is impressed and proud of the skilled work by the crews constructing SDU 10.


“Most importantly, this project is being completed safely, with no injuries that caused a missed day on the job,” Olson said. “The construction crews building the SDUs continuously prove themselves to be safety-focused and reliable, which are two important core values of Savannah River Mission Completion.”


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