Staff Reports
WC Monitor
10/30/2015
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.
The Hanford Advisory Board sent a letter of advice to the agencies favoring the waiver a year ago as EPA officials were considering whether and how to authorize a change in the treatment protocol for certain contaminated equipment. The practice of coating equipment before it is placed in ERDF not only created a risk of industrial accidents and avoidable radiological exposure for workers, it also increased the potential for an airborne release of contaminants, the board said. “The board supports a common sense, streamlined approach to reducing both worker risk and the potential for airborne releases while achieving the goal of remediation,” the board said. However, it cautioned that the approach should be limited to well-defined wastes.
The proposed waiver would apply only to ERDF and would be limited to three categories of waste. One would be large hot cells, such as those taken from the Plutonium Finishing Plant, and the second would be large debris that has been in contact with tank waste. That could include cover blocks, tank lids, and equipment skids. The final category would be long-length tank equipment such as thermocouples, pumps, cone penetrometers, sluicers, solids level detectors, radiation hardened cameras, liquid observation wells, and other equipment inserted through risers into the underground tanks. Smaller debris would continue to be treated before it is placed in ERDF. Controls would be put in place to ensure environmental protection. They would include ensuring rain does not wash contaminants into ERDF before the equipment is treated and a tracking system to ensure disposed equipment is treated before being covered with soil, said Dave Einan of EPA’s Hanford project office. The waiver is expected to be finalized after public comments are considered.
EPA expects to move through the process to finalize the waiver promptly, although no timeline has been set. The three Tri-Party agencies – DOE, EPA and the state of Washington – are required to sign off on the waiver under the federal Comprehensive Environmental Response, Compensation, and Liability Act. It provides a process for waivers for "applicable or relevant and appropriate requirements," sometimes called ARARs, for regulations that would cause greater risk to human health and the environment than noncompliance. The state has not been a lead agency on work toward the waiver, but has concurred with the need for it.
