With 25 wall sections, 208 support columns, and seven roof sections, all concrete construction on another mega-size disposal unit has been finished at the U.S. Department of Energy’s Savannah River Site. June 9, 2026
Office of Environmental Management
June 9, 2026
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All structural concrete placements are complete for Saltstone Disposal Unit 11, center, at the Savannah River Site.
AIKEN, S.C. — With 25 wall sections, 208 support columns, and seven roof sections, all concrete construction on another mega-size disposal unit has been finished at the U.S. Department of Energy’s (DOE) Savannah River Site (SRS).
Saltstone Disposal Unit (SDU) 11 will hold over 33 million gallons of saltstone — a decontaminated, hardened material safe for long-term disposal onsite. After all the concrete work, the unit is wrapped with seven layers of steel cable, totaling over 340 miles, to ensure structural integrity and enhanced durability.
Chuck Comeau, DOE-Savannah River federal project director, said the SDUs are key components of the SRS liquid waste program and meeting DOE’s Office of Environmental Management cleanup responsibilities.
“The SDUs provide safe, permanent storage for the decontaminated salt solution from the Salt Waste Processing Facility (SWPF),” said Comeau. “With SWPF processing at an accelerated rate, it is important to have the SDUs ready for operation. Completing construction milestones ahead of schedule ensures that the SDUs will be ready when needed.”
It takes more than 20,000 cubic yards of concrete to build an SDU, which is the end of the salt waste processing path. The SWPF produces the decontaminated material that is sent to the Saltstone Production Facility, where it is mixed with dry materials to make a cement-like grout. The grout is pumped into the SDUs, where it solidifies into a monolithic, nonhazardous form.
The larger SDUs are designed to support the increased material production from SWPF. The new SDUs result in more than $500 million in cost savings over the life of the liquid waste program because they require less infrastructure and materials than the previous 80 smaller SDUs.
EM’s liquid waste contractor at SRS, Savannah River Mission Completion (SRMC), manages the construction and operation of the SDUs. Subcontractors Quality Plus Services, US FUSION & Specialty Construction, and DN Tanks completed the site preparation, interior and exterior liner systems, and unit construction.
Finishing all the concrete placements on SDU 11 is a noteworthy achievement on the journey to mission completion, according to SRMC President and Program Manager Thomas Burns Jr.
“Building all the SDUs onsite has been a tremendous work in progress,” Burns said. “We have reached another satisfying milestone that is positive encouragement for the team to keep up the diligence, the ownership and the excellence as we work to have all the SDUs done and dusted in the near future.”
The SDU project team earned the DOE 2025 Project Controls Excellence Award for demonstrating superior project controls, rigorous data integrity and continuous improvement in practices.
The remaining two SDUs are in various stages of construction. Concrete construction of SDU 10 was completed in 2024 and it was deemed leak-tight in 2025. SDU 12, the final SDU needed for the SRS liquid waste mission, is under construction now.
SRMC is accelerating the radioactive liquid waste cleanup mission at SRS through advanced engineering solutions and innovative approaches, making significant progress toward safely and efficiently closing all waste tanks at SRS.
-Contributor: Colleen Hart
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