|Contaminants||Metals and radionuclides|
The Midnite Mine is an inactive uranium mine near the American state of Washington which was operated from 1955 until 1981. It is in the Selkirk Mountains; approximately eight miles from Wellpinit, Stevens County. The mine is within the reservation of the Native American Spokane tribe and was listed as a Superfund site under American law on May 11, 2000. High levels of radioactivity and heavy metals in acidic drainage are a threat to human health and the environment.
The Midnite Mine was built and run by the Dawn Mining Company (DMC), a subsidiary corporation 51 percent owned by the Newmont Mining Corporation and 49 percent owned by Midnite Mines Inc. (Midnite Mines Inc. is a public Delaware corporation and includes Spokane tribe members.) The site is leased by the United States Bureau of Indian Affairs from the Spokane Tribe.
Uranium ore was transported from the Midnite Mine to the DMC's mill 25 miles east of the mine (outside the reservation boundary). Mining produced approximately 2.9 million tons of ore averaging 0.2 percent uranium oxide. As of September 2006, 2.4 million tons of stockpiled ore (containing about 2 million pounds of uranium oxide) and 33 million tons of waste rock were left behind.
According to the United States Environmental Protection Agency, two exposed pits, back-filled pits, waste rock piles, and ore stockpiles remain on site. Contaminated water surfacing below waste rock and ore piles is collected for treatment on-site. Ore piles, waste rock piles, and forming pit walls generate acidic drainage in groundwater, seeps, and surface water. Surface water from the mine's drainage basin flows to three drainages which empty into Blue Creek, a fishery and spawning area. Blue Creek enters the Spokane Arm of the Franklin D. Roosevelt Lake.
In 2001, the State of Washington decided that the ground water pump-back system was no longer effective in reducing contamination. It directed the DMC to prepare a Corrective Action Assessment of remediation alternatives. The final cleanup plan for the site was issued September 29, 2006 and as of 2007, ground water tests have commenced.
- "Midnite Mine site narrative". Archived from the original on 2013-09-15. Retrieved 2009-12-21.
- Cornwall, Warren (2007-11-24). "Radioactive Remains: The forgotten story of the Northwest's only uranium mines". Seattle Times. Archived from the original on 2013-09-15. Retrieved February 24, 2008.
- "Midnite Mine Superfund Site, Spokane Indian Reservation, Washington, Record of Decision" (PDF). September 2006. Retrieved 2012-09-13.
- "Region 10 Cleanup: Midnite Mine". United States Environmental Protection Agency. 2007-11-21. Archived from the original on 2013-09-15. Retrieved February 24, 2008.
- "Dawn Mining Company". Washington State Department of Health. 2007-04-06. Retrieved February 24, 2008.[dead link]