The Department of Energy and the Environmental Protection Agency are proposing a waiver of the Resource Conservation and Recovery Act requirement that waste be treated before it is placed for disposal in Hanford’s Environmental Restoration Disposal Facility. The waiver would reduce risk to workers, they said in their proposal. In the past some large, long, or heavy equipment with radioactive contamination was placed directly in ERDF, a central Hanford landfill for mixed low-level waste, or Hanford’s mixed waste trenches. An earthen berm or plywood frame was constructed to serve as a form that allowed the equipment, already placed for disposal, to be surrounded with grout to encapsulate it before burial in place.
DOE stopped that treatment practice about three years ago when visiting EPA inspectors noted that in-trench treatment violated RCRA requirements. Instead, large or other unwieldly equipment, such as slurry pumps used in Hanford waste storage tanks, now are unloaded into a staging area for treatment. Workers perform radiological inspections and then apply four or more polymer coatings to the equipment, which requires using a crane to lift it four to 10 times, according to DOE and EPA. An inspection with touch-ups of the coating is required before it is hauled to the bottom of ERDF for disposal. There it is inspected, and often the coating requires more touch-ups.
Both practices meet final treatment standards to contain the waste, according to the agencies. But allowing the treatment after the waste is placed in ERDF would reduce worker radiation exposure, they say. In-trench treatment under the waiver would reduce the number of workers required from 13 to four. They would be 8 to 12 feet from the contaminated equipment as it is prepared and grouted in the landfill, compared to 1 to 5 feet away from contaminated equipment being coated with a polymer, giving them 1/64th the exposure when closest to the equipment. The time they spend near contaminated equipment being treated would drop from 9.5 hours for the out-of-trench treatment to just 2.2 hours for in-trench treatment, DOE and EPA say. Just one crane lift would be needed for macroencapsulation with grout in the trench, compared to up to 10 lifts for polymer coating.
