Hanford workers have resumed digging up temporarily buried transuranic waste in central Hanford with improved technology that should take some of the surprises out of the work.
Retrieval of the transuranic waste -- typically debris contaminated with plutonium -- was stopped in February by CH2M Hill Plateau Remediation Co. when it ran into problems. Since then the Department of Energy contractor has been working on improvements to its processes.
In 1970 Congress ordered transuranic waste sent to a national repository. But until the Waste Isolation Pilot Plant in New Mexico opened, Hanford workers have been storing waste suspected of being transuranic, often by temporarily burying it.
Much of the waste that Hanford workers have dug up so far to ship to New Mexico was buried in tidy rows and information about what's underground has been available.
But within the last year CH2M Hill has been progressing to more difficult burial trenches, and that's contributed to problems.
In early February a backhoe unexpectedly hit a radioactively contaminated glove box buried close to the surface and in a second incident there was suspicion that a buried pressurized container had been hit and broken. However, CH2M Hill has since said it has found no evidence of a container in the dirt.
"Both constituted an indication we needed to go back and relook at how we were planning and conducting our waste retrieval," said Ty Blackford, CH2M Hill vice president of waste and fuels management.
Work was halted amidst concerns that hazards were not being adequately identified. The approximately 125 workers and supervisors assigned to transuranic waste retrieval were instead assigned to improving work plans and processes and assessing retrieval activities, including conducting drills and exercises.
A key change has been a new configuration of ground penetrating radar linked to global positioning systems that has given CH2M Hill better pictures and maps of what's buried in the dirt before digging begins, the contractor said. The technology and software both have been improved, Blackford said.
"We actually get a fair indication of what is down there," Blackford said. "It gives us a leg up on planning."
The technology provides enough clarity that items such as wooden boxes, metal boxes, pieces of pipe and culvert can be distinguished and identified, he said.
Work has resumed at Trench 17, which Blackford described as one of the last remaining trenches that is orderly and has a better known configuration. The revamped ground penetrating radar and GPS technology was used there to test its accuracy and help improve it.
"We're glad they've resumed retrieving (waste)," said Dieter Bohrmann, spokesman for the Washington State Department of Ecology, the regulator on the project.
Among work also under way is mapping of what's buried at Trench 8, which is believed to contain mostly large metal, wood and concrete boxes of waste.
In the next few weeks the improved technology will be used at Trench 17 -- the trench being excavated in February -- for "a more aggressive interrogation," Blackford said. It could solve the mystery of what caused two jets of gas and soil leading to suspicions that a pressurized container had been broken during excavation in February.
CH2M Hill was undergoing a verification review in February of its Integrated Safety Management System, a comprehensive safety system Hanford cleanup contractors are required to have in place. The system has been approved for the contractor's work at the company level but CH2M Hill continues to work toward getting the system approved for its transuranic waste retrieval work.