Hanford's largest and most sophisticated groundwater-treatment plant has begun work to remove an estimated 110,000 pounds of pollutants over the next 25 years.

Its treatment capacity each month is 108 million gallons, or the equivalent of 108 typical city water towers.

Like five other groundwater-treatment plants operating at Hanford, it will clean water pumped out of the ground, and then the cleaned water will be reinjected into the earth.

But the 200 West Groundwater Treatment Facility is designed with multiple technologies to remove not just one contaminant but as many as eight radioactive and chemical pollutants from groundwater.

"This facility is key to Hanford's groundwater strategy and in ensuring that the Columbia River is protected," said Matt McCormick, manager of the Richland Operations Office of the Department of Energy (DOE). He spoke to about 200 workers and officials gathered Thursday to celebrate the opening.

The plant is attacking one of Hanford's largest groundwater plumes, which stretches over the northern portion of the 200 West Area.

When Hanford was producing plutonium for the nation's nuclear-weapons program during World War II and the Cold War, more than 450 billion gallons of contaminated liquid was discharged into the soil in central Hanford. That's almost equivalent to Lake Coeur d'Alene in northern Idaho, McCormick said.

Initially, CH2M Hill Plateau Remediation Co. will use the plant to remove three key contaminants from groundwater.

The plume includes technetium 99 from the Hanford tank farms, where radioactive waste is stored in underground tanks. It has nitrates from the nitric acid used to chemically separate plutonium from irradiated fuel. And it has carbon tetrachloride, which was used at the Plutonium Finishing Plant.

Groundwater that is contaminated with radionuclides will be sent to the plant's 17,500-square-foot radiological process building to have technetium 99 removed with resins in an ion-exchange system. It starts operations this week.

As work expands at the plant to treat water contaminated from the southern portion of the 200 West Area, uranium also will be removed with a different resin.

After removal of radionuclides, the water will be sent to the 35,000-square-foot main process building for removal of remaining hazardous chemicals. It is already operating, treating water contaminated only with hazardous chemicals.

It uses microorganisms to consume nitrates. An air-stripping system removes carbon tetrachloride.

The cleaned water is reinjected into the ground around the contaminated plume, to help keep it from flowing underground toward the Columbia River.

Much of the waste from the contaminated water can be disposed of at the Environmental Restoration Disposal Facility, a lined landfill in central Hanford.

The resins used to remove radionuclides will be sent there, and also the biosludge after it is thickened, dried and then combined with lime to shut down the biological process and create waste as hard as concrete.

The activated carbon from the air-stripping system will be sent out of state to be cleaned, then returned.

"I'm in awe of the size and scope," said Tracy Mustin, DOE's principal deputy assistant secretary for environmental management, after touring the building.

It's also the only DOE industrial facility she knows of that has been awarded Leadership for Energy and Environmental Design gold certification. The internationally recognized green-building certification system rates buildings on criteria such as energy savings, water efficiency, carbon-dioxide emissions reduction and indoor air quality.

About 50 percent of the steel used in the plant was recycled, and 420 tons of recycled concrete were used. And its efficient design is expected to result in an energy cost savings of more than 70 percent over the life of the facility, Mustin said.

Construction was completed on schedule and under budget.