SPOKANE — The U.S. Department of Energy on Wednesday issued its final cleanup plan for the 300 Area of the Hanford Nuclear Reservation, which for decades made plutonium for nuclear weapons and is the nation's most polluted nuclear site.
It is the first of six plans that will cover more than 200 square miles of the sprawling Hanford Nuclear Reservation just north of Richland along the Columbia River.
The plan proposes digging up contaminated soil and waste sites, treating the waste as needed and disposing of most of it in a Hanford landfill. It also addresses a uranium groundwater plume beneath the area that allows contaminated water to flow into the Columbia River.
But the head of a watchdog group criticized the decision not to remove all the radioactive soil, which the Energy Department says would have cost more than $1 billion.
Cleanup of the 300 Area, which covers about 40 square miles, has been underway since the 1990s and is expected to be completed by fall 2015.
The plan is a step in the lengthy process of finding future uses for the Hanford site, which is about half the size of Rhode Island. A portion of the 300 Area traditionally used as an industrial complex is expected to be made available for industrial use down the road and the rest will be used for conservation purposes.
The 300 Area started operations in 1943, conducting research and turning uranium into fuel for Hanford reactors that produced plutonium, the document said. The plutonium was used for nuclear weapons. The Hanford site is now engaged in cleaning up the resulting radioactive wastes.
The Energy Department has said it plans to clean the 300 Area to standards needed for unrestricted surface use of the land.
One of the key parts of the cleanup is dealing with contaminated groundwater that's seeping into the Columbia River.
The plan calls for adding a binding solution to contaminated soil in the 300 Area to reduce the movement of contamination to the groundwater. Phosphate would be added, which combines with uranium to make a material that does not readily dissolve in water.
Tom Carpenter, director of the watchdog group Hanford Challenge, criticized that decision, saying the radioactive waste should instead be removed.
"With a half-life for uranium-238 at over 4 billion years, this hardly seems wise or desirable to abandon this waste next to the second-most powerful river in the nation," Carpenter said.
The Energy Department has said about 330 pounds of uranium per year is released to the Columbia River from the Hanford 300 Area. But that is dwarfed by the 3,500 pounds of uranium a year released into the river from fertilizer and from uranium that's naturally in the ground.