A new $24 million plant has begun removing toxic chromium from ground water near the horn of the Columbia River on the Hanford nuclear reservation.
With a water treatment capacity of 800 gallons per minute, the new pump and treat system is the largest one operating at Hanford. It will boost the capacity for treating contaminated ground water along the Columbia River by 40 percent, according to Department of Energy contractor CH2M Hill Plateau Remediation Co.
"Together with other systems already in operation along the river corridor, Ecology believes the new facility will bring the total treatment capacity to about where it needs to be to prevent toxic chemicals from entering the Columbia River," said Dib Goswami, lead hydrogeologist for the Washington State Department of Ecology's nuclear waste program.
It's a key part of the strategy of DOE and its regulators -- the state of Washington and the Environmental Protection Agency -- to stop chromium from entering the Columbia River by the end of 2012, Goswami said.
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The form of chromium contaminating Hanford ground water can cause cancer in humans and is particularly toxic to fish and other aquatic life.
Sodium dichromate, a chemical used as a corrosion inhibitor, was added to river water used to cool Hanford's older nuclear reactors while they were operating to produce plutonium for the nation's nuclear weapons program. The ground water was contaminated with the bright yellow chemical by leaks in the chemical transfer systems and piping.
The new plant near Hanford's H Reactor will help tackle a plume that has spread between the D and DR reactors upstream and the H Reactor. At the first of the year, a similar plant began operating near the D and DR reactors.
The "pump and treat" technology used at the two plants has proved its worth in mopping up chromium near the river for more than a decade. But with major work done to dig up contaminated soil that can spread chromium to ground water, the treatment plants should be able to get ahead of the problem.
"The Department of Energy's goal is to restore ground water to its intended beneficial use, either drinking water standards or stricter aquatic standards," said John Morse, DOE senior technical adviser, in a statement.
The pump and treat technology pumps contaminated water out of the ground, uses a resin to treat the chromium and then returns cleaned water to the aquifer through injection wells.
The two new systems at the horn of the Columbia River are using a newer resin that will not require as much maintenance and monitoring as the resin used earlier in Hanford pump and treat plants, said Dyan Foss, CH2M Hill vice president of soil and ground water projects.
It does not need to be replaced as often, which saves money, and it has proven at the D and DR reactor treatment plant to retain 15 times more chromium.
Work on the newest plant near H Reactor was built and tested three months ahead of schedule, said Kent Dorr, CH2M Hill vice president of engineering, projects and construction.
The 17,500-square-foot plant uses 31 extraction wells and more than 61 miles of piping to bring ground water to the plant. It also has 15 injection wells. It has the capacity to treat up to 35 million gallons of contaminated water per month.
* More Hanford news at hanfordnews.com.