Hanford workers have torn down most of the massive water treatment system that served the K West Reactor.
It was a major project both because of its size -- the concrete structures removed covered more square feet than six football fields -- and because of the sturdy construction of the system.
Work to build the system started during the Korean War amidst fears of bombing, so thick concrete heavily threaded with rebar was used.
"Recovery Act funding put this project years ahead of the original schedule for demolition," Kurt Kehler, decommissioning and demolition project vice president for CH2M Hill Plateau Remediation Co., said in a statement.
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The work was done by CH2M Hill using $17.6 million in federal economic stimulus money.
"Removing the water treatment facilities is an important step towards protecting the Columbia River," Tom Teynor, Department of Energy project director for the K Basins Closure Project, said in a statement.
Removing the system will allow further cleanup of the chromium-contaminated soil beneath the K Reactors complex just 400 yards from the river. It also will help DOE meet its goal of cleaning up most of the 210 square miles at Hanford along the river by 2015.
The largest structures demolished were the 20-foot-deep sedimentation basins, which covered 292,344 square feet. Though they were prepared for robust construction, workers still found more substantial footings on the basins than expected.
In addition, the chlorine car protection facility, headhouse, sand filters, lime addition buildings and a pipe tunnel that held thousands of feet of underground piping that brought water from the river, have been turned to rubble.
The structures, including the basins, covered 380,000 square feet, or almost 8.75 acres.
Still left are the clear wells, or underground water storage tanks, covering 119,299 square feet. They will be torn out next spring.
The water treatment system was used to support the cooling of the K West Reactor, one of nine Hanford reactors that produced plutonium for the nation's nuclear weapons reactor. The system handled water before it entered the reactor and had no radioactive contamination.
During operations, water was pumped from the Columbia River at a rate of 140,000 gallons each minute and treated with chemicals to minimize corrosion when the water was sent to the reactor. After the water was used it was discharged to the river.
The K East Reactor had a twin water system linked to the K West Reactor's system by underground pipes so that either could be used by each reactor in an emergency. The complexes were built 2,000 feet apart because of wartime worries of bombings.
The K East Reactor Water Treatment Facilities will be demolished next. Although the K West water system has not been used for years, the K East system has been used to support environmental cleanup operations and to keep radioactive sludge held in containers in theK West basin covered with water to shield it.
When a backup system is in place, the K East system also will be demolished. Work is under way to address concerns that a new fire protection water supply system meets all code requirements.
However, DOE expects demolition of the old K East water treatment facilities to begin before the end of the year. It's expected to be completed in October 2011.
About 20,000 cubic yards of uncontaminated concrete rubble from the sedimentation basins of the K West system will be recycled as fill for a cap that will be built over U Canyon after it is demolished. U Canyon, which is in central Hanford, was used to reprocess uranium during the Cold War.
The rest of the debris will be taken to the Environmental Restoration Disposal Facility, a waste landfill in central Hanford.