Hanford cleans record amount of groundwater

Tri-City Herald staff writerJuly 15, 2013 

Hanford workers have treated 1.4 billion gallons of contaminated groundwater so far this fiscal year, setting a new record.

That’s about enough water to fill 2,100 Olympic-size swimming pools or 500,000 water trucks, according to Hanford officials. Line the trucks up and they would stretch almost across the United States.

Last fiscal year, which ended Sept. 30, Hanford contractor CH2M Hill Plateau Remediation Co. treated 1.2 billion gallons of contaminated groundwater.

The increase this year, with more than three months remaining in the fiscal year, is the result of operating existing groundwater treatment plants with less down time and adding a sixth plant.

About a year ago, Hanford’s largest and most sophisticated groundwater treatment plant came on line, the 200 West Groundwater Treatment Facility. It’s now treating 1,400 to 1,900 gallons of contaminated water a minute and is expected to keep ramping up to treat more water.

All six of the groundwater treatment plants use wells to pump contaminated water out of the ground, treat it and then release the cleaned water back into the ground.

The five pump and treat plants along the Columbia River target hexavalent chromium, which was added to cooling water used in reactors to prevent corrosion. Hanford reactors produced plutonium through the Cold War for the nation’s nuclear weapons program.

In May, the Department of Energy announced that 500 pounds of hexavalent chromium had been removed from Hanford over six months because of efficiencies and new water treatment plants. Two of the plants along the Columbia River began operating in 2011.

“Now we are seeing the results,” said Briant Charboneau, DOE project director, in a statement. Some areas of contamination have been significantly reduced, he said.

A plume of contaminated groundwater stretched from the D and DR set of reactors to the H Reactor and extended along the river in 2009. But now it has been shrunk to two smaller plumes at each reactor area with little remaining connection with the river.

The new central Hanford plant is removing not just chromium, but also seven additional contaminants from the groundwater: nitrate, carbon tetrachloride, uranium, technetium 90, tritium, iodine 129 and trichloroethylene.

Since work began to treat contaminated groundwater in the ’90s, about 7.8 billion gallons of water have been treated and 55 tons of contaminants have been removed. More than half of that tonnage of contaminants has been removed so far this year, in part because of the large quantity of nitrates being removed by the new central Hanford treatment plant.

Hanford still has about 60 square miles of contaminated groundwater. That’s down from previous estimates of 80 square miles, in part because a large plume of tritium is shrinking as its radioactivity decays. About half of its radioactivity decays every 12 years.

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