AIKEN, S.C. – The Savannah River Site (SRS) will begin a leak tightness test on the fifth mega-volume saltstone disposal unit (SDU) constructed at SRS.
This leak tightness test will qualify the newly constructed SDU for use, verifying it is safe to store up to 33 million gallons of solidified, decontaminated salt solution produced at SRS.
Beginning October 27, 2025, Savannah River Mission Completion (SRMC), the liquid waste contractor at SRS, will begin filling SDU 10 with water to check for any signs of leakage visible on the exterior. It will take three to four weeks to fill the unit with approximately 33 million gallons, equivalent to the amount of water that would fill approximately 55 Olympic-sized swimming pools.
After approximately four feet of water is added to the unit, about 400 gallons of a dye/tracer will be introduced. The fluorescent yellow/green dye is certified by NSF International, an independent public health and safety organization, for use in drinking water and is commonly used in dye/tracer tests. The dye is being added as an additional means to confirm leak tightness and will assist in leak detection.
The test is expected to take six to eight weeks. Once the test is complete, SDU 10 will be drained, and the dyed water will be discharged to onsite drainage basins for a controlled release to the environment. When discharged, the water will traverse over land and will empty into an onsite tributary to the Savannah River. Because this dye is safe for the environment, there are no health, safety, or environmental concerns with discharging this water in the SRS ecosystem or the Savannah River.
The SDUs are a critical part of the liquid waste system as they are permanent disposal units that will hold solidified decontaminated salt solution at SRS. SDU 10 is the fifth mega-volume SDU at SRS – SDUs 6 and 7 are in operation. SDUs 8 and 9 are approved for operation. Leak tightness tests were performed on SDUs 6, 7, 8 and 9 using the same method as the SDU 10 test.