Cleanup under way at old mill site
FORD, Wash. – Cleanup of contaminated soil began this summer at Dawn Mining Co.’s uranium mill – a relic from Eastern Washington’s role in the Cold War.
For more than two decades, Dawn processed uranium mined on the Spokane Indian Reservation at this remote site in Stevens County.
Ore was crushed, and the natural uranium – called “yellow cake” – was extracted. It was sold to the federal government, and later to nuclear power plants.
“I’m always amazed at how few people in Spokane understand there was this major mining industry here,” said Dorothy Stoffel, a state Department of Health project manager overseeing cleanup of the mill.
“It’s quite historic. It’s part of the Cold War.”
About 50 people worked at Dawn’s mill during its 22-year run. The company ceased operations in 1981, and the mill was torn down last year. Now, activity at the 125-acre site comes from excavators moving topsoil.
About 80,000 cubic feet of soil will be scraped off the site and disposed of in the mill’s tailings facility. Bob Nelson, Dawn’s vice president and general manager, describes the soil as “slightly contaminated” with dust from former ore stockpiles.
The cleanup will take several months. Dawn, a subsidiary of Newmont Mining Co., will pay for the work out of $14 million it has agreed to dedicate to the mill’s cleanup.
The work will reduce the risk of radon gas, a potential health hazard from uranium ore.
Uranium 238, in its natural state, is a “rather harmless isotope, as long as you don’t eat it or inhale it,” Stoffel said. As uranium decays, however, it produces radium, which gives off radon gas. Long-term exposure to radon is a cause of lung cancer.
“We typically don’t think of outdoor radon as a health hazard,” Stoffel said. “At this facility, we’re taking further steps to ensure that it won’t become a hazard.”
Monitors track the levels of radon gas on Dawn’s property, and at the property’s boundary line. The radon levels are low, Stoffel said. Several years ago, her home on the South Hill gave off higher readings than the on-site monitors.
“The radon in my kitchen was three times higher, at that moment, than what I had seen at Dawn Mining’s tailings facility,” she said.
Eastern Washington has high background levels of radon, due to the area’s uranium deposits. Geologically, the uranium is associated with the Loon Lake batholith, a granite body covering hundreds of miles in the eastern part of the state, Stoffel said. World-class uranium crystals, found at Mount Spokane, are part of the Smithsonian’s collection.
The ore milled at Dawn’s Ford facility was later sent to “enrichment facilities” in Canada, where the uranium used in nuclear weapons and power generation was extracted and concentrated, Nelson said. “Ninety-nine point seven percent is an unusable form of uranium,” he said.
Dawn has until 2013 to finish remediation work at the mill site, Stoffel said. In addition to the soil cleanup, the company is using settling ponds to evaporate 140 million gallons of an acidic solution, which once stripped uranium from the crushed rocks. That work could be completed in four years.
The leftover residue will end up in the tailings facility, which will be capped with a liner designed to last 1,000 years, Stoffel said. The liner consists of a polyethylene membrane, similar to those used at landfills, and 15 feet of dirt, covered by trees and brush, she said.
“Anyone walking through here will encounter a gentle slope, tree and huckleberry bushes,” Nelson said. “They won’t be exposed to anything because of the thickness of the cover.”
The federal government will take control of the mill site when the remediation is complete, Stoffel said.
“They get transferred to the Department of Energy for perpetuity,” she said. “There will never be subdivisions here.”