Washington Closure Hanford has begun removing waste from vertically buried pipes at Hanford for the first time. Just two Hanford burial grounds, 618-10 and 618-11, used the disposal method for the pipes, called vertical pipe units. The two were saved as the last burial grounds in the river corridor for remediation because they were expected to be the most complex and challenging. Work started first on the 618-10 Burial Ground, with overcasings driven into the ground around 80 of the 94 vertical pipe units. Most of the vertical pipe units were made of either corrugated piping or 55-gallon drums welded together after their tops and bottoms were cut off.
However, 14 were made of thick-walled steel and remediation work has not started on them. The 618-10 Burial Ground, which also has trenches where waste was deposited directly in the ground, was used from 1954 to 1963 for waste the Department of Energy did not want to be buried too close to Richland. Some of the high-hazard waste from research and from fuel fabrication at the 300 Area near Richland was hauled to the burial ground 6 miles north of Richland for disposal, sometimes in large, heavily shielded cask trucks that would back up to the vertical pipe units to release their cargo.
Washington Closure began using an auger in September to chew through the contents within the overcasings placed around 80 of the vertical pipe units, breaking up and mixing together the vertical pipe units themselves, the waste they hold, and the band of soil between the walls of vertical pipe units and the overcasings. With augering well underway this spring, Washington Closure began retrieving waste from one of the augered vertical pipe units last week, completing the retrieval this week. The waste was lifted out using a clamshell equipped with a camera and light lowered into the overcasing using heavy equipment. The clamshell can be maneuvered to circle 360 degrees within the overcasing, said Mark Buckmaster, Washington Closure project manager for the vertical pipe units. The waste was deposited into steel boxes beside the vertical pipe units, where it was mixed with grout for disposal at the Environmental Restoration Disposal Facility in central Hanford.
Late this week Washington Closure workers had augered 40 vertical pipe units, which is well ahead of schedule. “This is great,” said Mark French, DOE River Corridor Division director. The contractor had planned to auger the waste in 28 of the vertical pipe units before its contract expires at the end of September 2016. It is possible that Washington Closure could auger 80 of the vertical pipe units before work at the burial ground is turned over to CH2M Plateau Remediation Co. this fall, according to the Department of Energy. The remaining 14 steel pipes are expected to be left for CH2M. An auger is not expected to work well to break them up. A possible plan for those vertical pipe units calls for a hole to be dug around them into which liquid grout would be poured. The contents of hole would then be crushed and mixed together using heavy equipment before being loaded out to a waste disposal box.
To date all of the vertical pipe units augered have had low enough levels of transuranic waste that their contents can be disposed of at the Hanford landfill, rather than set aside to be shipped to the Waste Isolation Pilot Plant. Disposal at Hanford’s Environmental Restoration Disposal Facility can be done more quickly and at less expense. At most, just one of the vertical pipe units still to be augered could contain enough transuranic waste that it could be required to be sent to WIPP, French said.
Most work to retrieve waste from the 12 trenches in the 618-10 Burial Grounds has been completed. However, because some of the vertical pipe units are so close to certain trenches, a portion of the trenches cannot be dug up until work at those vertical pipe units is completed. There also is an area where waste is suspected of being buried deeper than originally thought, requiring more excavation to be done there. Most waste has been found buried 20 to 25 feet deep, with waste up to 35 feet in some places.
Much of the waste recovered from the trenches was disposed of in drums. Washington Closure workers have found about 1,700 drums, and about 1,500 drums have been processed for disposal. Just six of the drums so far are suspected of containing transuranic waste that would have to be be sent to WIPP. Those drums have been sent to central Hanford for storage. Drums that held uranium shavings in oil have been sent to Perma-Fix Northwest’s facility near Hanford for treatment. Others, which were lined in concrete to shield radioactive waste, are being crushed in boxes of liquid grout at the burial ground. The boxes of hardened grout will be taken to the Environmental Restoration Disposal Facility.
