The units built by Savannah River Remediation are used to hold decontaminated salt solution taken from salt waste inside SRS underground waste storage tanks.
The new Saltstone Disposal Unit 2 has two cells that are circular in design. Each cell will hold about 2.9 million gallons of nonhazardous cement grout, which is a mixture of the decontaminated salt solution with Portland, fly ash and slag cement powders. The first cell put into service is nearly full.
The disposal unit cells have a watertight design and a cylindrical shape, unlike the site’s current disposal unit, which has a rectangular shape. The cylindrical design reduces wall stresses found in the rectangular units. It also includes an engineered concrete and steel shell, a wall-to-floor joint design, and high-density polyethylene and geosynthetic-clay barriers below the unit.
Unit 2 began accepting low-level, nonhazardous cement grout in one of its two cells in October 2012. Once filled, the second cell will continue accepting the cement mix.
Construction is continuing on two additional units, each with two individual disposal cells. Together, these four cells will hold about 11.6 million gallons of the cement grout, which will provide enough disposal capacity until mid-2015.