The Defense Waste Processing Facility at the Savannah River Site, a plant that is involved in the liquid-waste mission.

The final request for proposals for the upcoming Integrated Mission Completion Contract at the Savannah River Site is expected no sooner than September, according to the U.S. Department of Energy, which oversees the south-of-Aiken nuclear reserve.

The Energy Department in February announced it would forgo the typical draft request for proposals process and would, instead, field and utilize comments made on a cleanup contract in Idaho. At the time, the approach was described as streamlined.

More contract details were released earlier this month at the nuclear industry's request.

The Integrated Mission Completion Contract, meshing liquid-waste work with the management of some nuclear materials, is worth up to $21 billion over a 10-year period. The IMCC would assign the work of two current contractors – including Savannah River Remediation, the liquid-waste team whose contract the DOE intends to again extend – to a future one. A 90-day transition period is planned.

A single contractor, an Energy Department spokesperson has said, is "in the best interest of the government" and will ensure "maximum reductions" in environmental risk and financial liability at the Savannah River Site. At this time last year, the same spokesperson described the Integrated Mission Completion Contract as "in the very early stages."

The Savannah River Site – neighboring New Ellenton and Jackson and abutting Georgia – is home to millions of gallons of nuclear waste, a legacy of Cold War-era endeavors. Some have called the waste South Carolina's single largest environmental threat.

A draft statement of work for the Integrated Mission Completion Contract published earlier this year includes operations at the SRS tank farms, where radioactive waste is kept and monitored; the Defense Waste Processing Facility, where waste is encased in glass for safer long-term storage; the Salt Waste Processing Facility, a Parsons project not yet finished; the Saltstone Disposal Units, permanent disposal tanks for certain processed waste; and the Glass Waste Storage Buildings.

Colin Demarest covers the Savannah River Site, the U.S. Department of Energy, the National Nuclear Security Administration and government in general. Follow him on Twitter: @demarest_colin