Molasses considered for uranium mine cleanup
Date posted: March 22, 2013
GOLDEN, Colo. (AP) — A uranium company wants to use molasses to clean up an abandoned mine west of Denver, hoping bacteria inside the mine will eat up the molasses and dissolved uranium, creating solid uranium particles that can be recovered.
Cotter Corp. is hoping the procedure will reduce a threat to city water supplies after years of trying other efforts that have failed.
The U.S. Environmental Protection Agency has approved Cotter’s project and state regulators are reviewing it.
The plan is to mix molasses and alcohol into a stream of water discharged down Ralston Creek and re-inject that mix into Cotter’s 2,000-foot-deep Schwartzwalder mine.
Cotter vice president John Hamrick said he believes the innovative plan will work.
“We believe we can get the water to such a state that it would be OK to let it come out,” Hamrick said.
The company hopes so-called “bioremediation” would save tens of millions of dollars instead of having to continually pump out and treat the mine water.
Nearly four years ago, The Denver Post reported that a state mining inspector had detected heavy uranium contamination in the mine along Ralston Creek. Cotter fought repeated state orders to clean up the mine and the creek, but finally agreed.
The contamination has reached concentrations as high as 24,000 parts per billion inside the mine shaft, well above the 30 parts per billion federal drinking water standard.
Uranium seeping from the mine has contaminated Ralston Creek, which flows into Denver Water’s Ralston Reservoir, a source of drinking water for more than 1 million metro residents. Utilities say additional treatment removes uranium before it reaches households.
Cotter says the experiment could hold promise for tens of thousands of abandoned mines across the western United States if it works.
The EPA says a similar experiment is being tried at Asarco’s smelter in Denver and it has high hopes for success.
Under a legal settlement last fall, Cotter agreed to lower the water level 150 feet below the mouth of the mine and pay $3.5 million into a fund to ensure cleanup.
The Schwartzwalder once was the nation’s largest underground uranium mine. Last year, Cotter crews rerouted Ralston Creek around the mine through an 18-inch pipeline to reduce uranium levels.
Cotter has also been ordered to irrigate the creek corridor so that trees and wildlife survive cleanup work during the diversion.