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closeTuesday, Jan. 13, 2009
High-risk Hanford burial ground cleaned up (w/ video)
By Annette Cary, Herald staff writer
Hanford workers have finished cleaning up a high risk burial ground a mile north of Richland and even closer to the Columbia River.
Over the last year they've dug up and hauled away almost 179,000 tons of dirt and debris, some of it contaminated with chemicals or radionuclides, from the 618-7 Burial Ground.
Washington Closure Hanford, the Department of Energy contractor assigned the work, researched historical records to try to figure out what might have been disposed of in the burial ground from 1960 to 1973.
But with records sketchy, Washington Closure had to be ready for the unexpected.
It did that well, said DOE and the Environmental Protection Agency, a Hanford regulator.
"It was the epitome of a well-planned job," said Dave Brockman, manager of the DOE Hanford Richland Operations Office. "The nonroutine became routine."
"They didn't know what they were going to find, but they had action plans ready to go to deal with the things they found," said Dave Einan, EPA environmental engineer. "They did a really good job of planning the work and working the plan."
The burial ground, which is near the banks of the Columbia River, was used to dispose of waste from making fuel for Hanford's reactors and for researching projects at the nuclear reservation, which produced plutonium for the nation's nuclear weapons program.
One thing workers prepared for that they didn't find was much plutonium. They also didn't find the depleted uranium rods that historical records had indicated might have been there. But they did find some surprises in the 10-acre burial ground.
That included two compressed gas cylinders. Because the burial site was so near Richland and Pacific Northwest National Laboratory workers at the 300 Area, the cylinders were taken out to central Hanford to be opened on the weekend.
Both turned out to contain nitrogen, which Washington Closure believes was added as a safety precaution after the chemicals were purged before burial. But they are believed to have once held phosgene and hydrogen chloride used in a research project to improve plutonium production. Phosgene was more commonly used as a chemical weapon during World War I.
Another surprise was 16 stainless steel tanks, each about 10 feet tall, plus piping and processing equipment. All the tanks were empty, except one, which contained some thoria, a white, powdery oxide of radioactive thorium. At Hanford, thorium was used in a program to research a new type of nuclear weapon.
Workers also found hundreds of empty buckets with "thorium oxide" on the label left from the project.
In two other trenches in the burial ground, workers uncovered 800 drums, most with aluminum turnings or vermiculite, a material used for insulation or packing mid-century. They also found 116 drums with zircaloy shavings, which may have been left from producing N Reactor fuel. Zircaloy is an alloy of zirconium and a small amount of beryllium, which can cause in incurable lung disease in people with an allergylike reaction to it.
Because Washington Closure expected to find the zircaloy shavings, which can ignite if fine particles are exposed to air, fire precautions were planned. Initially just one drum was excavated at a time and they were opened beneath a sand hopper to quickly extinguish any potential fire, said John Darby, Washington Closure project manager.
There was a brief flash of flames this summer, although not because of the zircaloy shavings. Workers were using heavy equipment to move chunks of concrete when a piece of metal that looked like magnesium in the soil caught fire. The flames and puff of smoke disappeared before the equipment operator could drop dirt on it.
With the 618-7 Burial Ground now refilled with clean dirt and replanted, Washington Closure is concentrating on two other burial sites. The 618-13 Burial Ground, which also is just outside Richland, is actually a mound of contaminated soil removed from around Hanford buildings, and so far appears to have little contamination.
"Which is good. We need a break," said John Ludowise, a Washington closure project engineer.
The other is the 618-1 Burial Ground, which was used for debris from research and uranium fuel production from 1945 to 1951 and could be as challenging as the burial ground just finished.
But work on what are expected to be the worst burial grounds, the 618-10 and 618-11 burial grounds containing research wastes with high radioactivity and chemical contamination still is in the planning stages.
The experience Washington Closure and its workers have gained at the burial ground just completed will be important when cleanup is done there by 2015, Brockman said. "This is the way we want to plan jobs and execute work," he said.
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