EM has made substantial progress in Saltstone Disposal Unit (SDU) construction in the last year at the Savannah River Site (SRS). At top left is the SDU landscape at SRS in September 2020; immediately above is the SDU landscape at SRS in August 2021.
EM has made substantial progress in Saltstone Disposal Unit (SDU) construction in the last year at the Savannah River Site (SRS). At top left is the SDU landscape at SRS in September 2020; immediately above is the SDU landscape at SRS in August 2021.

AIKEN, S.C. – EM achieved unprecedented progress on the mega-sized Saltstone Disposal Units (SDU) at the Savannah River Site (SRS) in the past year. 

During that period, EM completed construction on SDU 7, the second mega-sized SDU built at SRS; finished the outer shell of SDU 8; started building the walls of SDU 9; and authorized the start of SDUs 10, 11, and 12.

Savannah River Remediation (SRR), EM’s liquid waste contractor at SRS, is building and operating the SDUs for EM. The SDUs will receive decontaminated salt solution (DSS) processed at the Salt Waste Processing Facility. The DSS is mixed with dry materials at the Saltstone Production Facility (SPF) to form a grout. The grout is pumped to the above-ground SDUs where it hardens to a form called saltstone.

Construction of the SDUs has occurred safely, with unprecedented speed, according to Shayne Farrell, DOE-Savannah River federal project director for SDU projects.

“The change of the Saltstone Disposal Unit landscape in one year is astounding,” Farrell said. “The Department of Energy, with Savannah River Remediation, has moved with great efficiency in the construction of these next-generation SDUs.”

Just over a year ago, the interior liner installation inside SDU 7 was underway. Crews hand-placed more than 7,000 pieces of rubber inside the 33-million-gallon-capacity unit.

Since then, SDU 7 passed its liquid tightness test and received authorization from EM to begin operations. The project was completed eight months ahead of schedule and $32 million under budget. SDU 7 is currently ready and available to receive grout.

A year ago, EM was just beginning the floor formwork for SDU 8. Now, the entire landscape has changed again. Crews have completed all major concrete placements, including 14 floor sections, 25 wall sections, 208 support columns, and seven roof sections.

Last year, mud mat installation for SDU 9 was wrapping up. The mud mats provide a solid surface for the concrete floor and support a leakage detection system comprising a clay liner and high-density plastic liner. Now, the floor is almost complete, and the walls are going up.

EM authorized construction to begin on SDUs 10, 11, and 12 — the last three SDUs needed to complete the SRS liquid waste mission.

SDU 6 was the first mega-sized SDU built at SRS. It has received more than 6.7 million gallons of grout since it went operational in August 2018.

The mega-sized SDUs support the increased DSS from SWPF. Salt waste at SRS is decontaminated through processes at SWPF that remove radioactive isotopes, including cesium, strontium, and actinides.