Fifth Mega-Size Disposal Unit at Savannah River Site Ready for Operations

The U.S. Department of Energy’s Office of Environmental Management has authorized the fifth mega-size Saltstone Disposal Unit, foreground, for operations at Savannah River Site.

AIKEN, S.C. — The U.S. Department of Energy’s (DOE) Office of Environmental Management (EM) has authorized the fifth mega-size disposal unit for operations at the Savannah River Site (SRS), marking another milestone in the site’s cleanup program.

The authorization marks the last step before the Saltstone Disposal Unit (SDU) 10 can begin to receive decontaminated material for disposal. Construction of the unit was completed in June 2024, nearly 10 months ahead of schedule and two years after completing construction on SDU 9. A leak tightness test was completed for SDU 10 in December 2025, verifying it is safe to store up to 33 million gallons of solidified, decontaminated salt solution produced at SRS.

From design to construction, the SDU projects are examples of innovation and efficiency, according to Chuck Comeau, DOE-Savannah River federal project director.

“All of the larger SDUs built at SRS have come in under budget and ahead of schedule, without sacrificing safety or effectiveness,” said Comeau. “Having the SDUs ready and available to provide safe, permanent storage for the decontaminated legacy waste supports the accelerated pace of the liquid waste program at SRS.”

The SDUs are the end of the salt waste processing path. The Salt Waste Processing Facility (SWPF) produces the decontaminated salt solution 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 and 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 previous 80 smaller SDUs.

EM’s liquid waste contractor at SRS, Savannah River Mission Completion (SRMC), manages construction and operation of the SDUs.

Completion of SDU 10 stands as another example of excellence delivered by the SRMC team, according to SRMC President and Program Manager Thomas Burns Jr.

“Delivering a project of this scale safely and successfully took remarkable dedication, teamwork and expertise from everyone involved,” Burns said. “I am truly proud of what the SRMC team accomplished with SDU 10. This milestone moves us even closer to completing our mission and demonstrates the critical importance of this project.”

SRMC is also in various stages of completing the final two SDUs needed at SRS. With the final roof section placed this spring, all structural concrete placements for SDU 11 are complete. The unit is being wrapped with over 340 miles of steel cable to ensure structural integrity and enhanced durability.

Construction began on SDU 12 in April, marking a historic milestone in the site’s radioactive waste tank cleanup mission as the last unit needed to support the mission.

-Contributor: Colleen Hart