SRS Sign, SDU Construction

An entrance to the Savannah River Site, a federal nuclear complex near Aiken.

Construction of the next mega-volume waste storage tank at the Savannah River Site is on schedule to be finished in three years, according to information included in a new U.S. Department of Energy newsletter.

Saltstone Disposal Unit 7, the sister of Saltstone Disposal Unit 6, will likely be completed by spring 2022.

SDU 6 was completed in July 2017.

SDU 7 construction began last year, and work on what the DOE calls the "outer shell" is now underway.

The shell itself – reinforced concrete wrapped in 341 miles of steel cable – will take about seven months to finish, according to the DOE.

"We look forward to continued safe progress as we build this key structure," Federal Project Director Shayne Farrell said in a prepared statement.

SDUs are designed to permanently house SRS's processed waste.

Once finished, SDU 7 will be 43 feet tall, 375 feet in diameter and will be able to hold 32 million gallons of treated waste.

The larger SDUs – several more are planned, and the president's latest budget blueprint invests in them – are made with the Salt Waste Processing Facility in mind.

The SWPF, expected to come online at the end of this year, is designed to bolster the SRS liquid waste mission by processing millions of gallons of nuclear waste per year.

The SWPF is currently in a testing and commissioning phase.

Savannah River Remediation, led by AECOM, is the SRS liquid waste contractor.

Colin Demarest is the government and Savannah River Site reporter with the Aiken Standard. Follow him on Twitter: @demarest_colin