Experience with wasteform delisting at the Oak Ridge Gaseous Diffusion Plant

The Oak Ridge Gaseous Diffusion Plant has generated large quantities of mixed, chemically toxic, and radioactive wastes over the years. Most of these wastes were contained as sludges in two large treatment and settling ponds. The federal mandate requiring all surface impoundments to be closed by November 1988 made the need for remedial action for these ponds very apparent. Both ponds were statistically sampled, and the sludge and clay layers were characterized. Cement stabilization was chosen as the method to process these sludges into a form that would qualify for delisting. Grout formulation development studies were performed, and a process flow-sheet was developed indicating the process of stabilizing these sludges into a durable, good strength, nonleachable final concrete form. Special equipment requirements associated with handling, pumping, processing, and moving the raw sludge, wet concrete, and hardened concrete were identified. The sludge treatment facility has been in operation since April 1987. Problems and operating experiences to date are discussed