Wash. Closure Finishes 618-7 Burial Ground

This story was published January 19, 2009

Weapons Complex Monitor

Washington Closure Hanford has finished cleaning up the 618-7 Burial Ground, one of the most hazardous Hanford burial grounds near the Columbia River. Over the last year, workers have dug up and hauled away almost 179,000 tons of dirt and debris that included thorium, chips of zircaloy that can spontaneously ignite, as well as lead, beryllium and cadmium contamination. The burial ground was considered high risk both because of its contents and location near the river just a mile north of the city of Richland. Washington Closure Hanford researched historical records to try to figure out what might have been disposed of in the burial ground from 1960 to 1973, but with only sketchy records kept, it did a good job of preparing for and dealing with the unexpected, said DOE and the Environmental Protection Agency. "It was the epitome of a well-planned job," said Dave Brockman, manager of the DOE Richland Operations Office. "The non-routine became routine."

Some Surprises Found, But Little Plutonium

The burial ground was used to dispose of waste from fuel production and plutonium production research. But though workers prepared to find plutonium, they didn't find much. They also didn't find the depleted uranium rods that historical records indicated might have been buried there. There were some surprises in the 10-acre burial ground, however, including two compressed gas cylinders. Because the burial site was so close to Pacific Northwest National Laboratory, workers at the Hanford 300 Area and city limits, the cylinders were taken out to central Hanford to be opened on the weekend. Both contained nitrogen, which Washington Closure believes was added as a safety precaution after the chemicals were purged before burial. 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 thorium. At Hanford, thorium was used in a program to research a new type of nuclear weapon. Workers also found hundreds of empty buckets labeled "thorium oxide" left from the project.

Workers Prepared For Discoveries

In two other trenches in the burial ground, each measuring 650 feet long by 100 feet wide, workers uncovered 800 drums, most with aluminum turnings or vermiculite, a material used mid-century for insulation or packing. They also found 116 drums containing beryllium-contaminated zircaloy shavings, which may have been left from producing N Reactor fuel. 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. "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," EPA environmental engineer Dave Einan said. "They did a really good job of planning the work and working the plan."

WCH Shifts Focus to Other Burial Grounds

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, is still 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.