K East Basin turns into Hanford history

The below-ground walls of Hanford's notorious K East Basin are being turned to rubble with a hammer and concrete processor mounted on excavators.

"It was built to last forever," said Mike Swartz, deputy vice president at CH2M Hill Plateau Remediation Co. "It's hard to beat up."

Tearing out the walls of the pool is one of the final steps in cleanup of the leak-prone basin to allow removal of radioactively contaminated soil beneath the concrete pool.

The basin was built to cool fuel irradiated at the attached K East Basin to produce plutonium for the nation's nuclear weapons program. But as processing of fuel ended with the Cold War, 1,100 tons of highly radioactive fuel rods were left stranded in the basin.

As the fuel corroded, it contributed to a thick layer of radioactive sludge that built up on the bottom of the water-filled pool.

For eight years workers have removed the fuel, vacuumed up the underwater sludge and drained 1 million gallons of water from it. The structures covering the basin have been torn down, and the basin filled first with a layer of grout and then a sandlike layer to give heavy equipment a base to work on during demolition.

"Fifty years of life and we're seeing the end of it," said Larry Gadbois, environmental scientist for the Environmental Protection Agency. "It's served its purpose."

Tuesday the excavator with the hammer pounded away at one of the concrete walls that divided the basin into sections. Then the clawlike processor took over to pulverize the concrete.

The two machines left a pile of the sandlike material, concrete and rebar waiting to be loaded into containers and hauled to the Environmental Restoration Disposal Facility in central Hanford, a lined landfill for low-level radioactive waste.

Each container holds about 20 tons of debris, and CH2M Hill expects to fill 1,500 of them.

The upper seven feet of the sides and dividing walls within the basin have been demolished and CH2M Hill expects to go just a little deeper before halting for a review. The basin is about 20 feet deep, and also has a leachate collection system beneath its concrete floor.

"So far it's gone very well," said Tom Teynor, Department of Energy federal project director. Several controls are being used to prevent the release of contaminated material into the air or exposure of workers.

Water is sprayed on the site when work is under way to control dust, and a soil cement also is used as a fixative. The heavy equipment operators are protected by extensive radiation monitoring and wear full radiation protection gear, including respirators. Airborne monitors are used at the perimeter of the work site.

DOE and contractors knew that radioactive cesium and strontium leached into the walls of the basin, but radiation levels have been lower than expected, Teynor said.

However, DOE expects the bottom 10 feet of the basin to be more contaminated. Before CH2M Hill goes much deeper, DOE will require a review to take a careful second look at the project, including planned procedures and worker training.

The bottom 14 inches of the basin is covered with grout that secures any residual radioactive sludge in place. There also was some equipment left on the bottom of the basin that will have to be cut up with shears.

Workers have a grid prepared by radiation monitoring to show what might be left in each area of the basin.

CH2M Hill also will have to remove the sand filter and ion exchange column which are grouted in place at the end of the basin as part of the water filtration system.

Plans call for using diamond wire to cut them out of their bases, then placing steel skeletons around them to hoist them up and set them on a trailer to be taken to the Environmental Restoration Disposal Facility for disposal, said David Del Vecchio, CH2M Hill vice president.

The two structures, each with a footprint of about 75 square feet, need to be removed to get to the soil beneath them.

The basin is 400 yards from the Columbia River and the Department of Energy wants to "get to the contaminated soil under the basin as soon as possible and keep the contamination from moving toward the river," Dave Brockman, manager of the DOE Hanford Richland Operation Office, said in a statement.

DOE faces a Sept. 30 deadline under the Tri-Party Agreement to finish the demolition of the basin. But it has made a commitment to have the basin gone by July 31 and start cleaning up the soil within the next 30 days.

"We're going to meet that," Teynor said.

w Annette Cary: 582-1533; acary@tricityherald.com