Contact Superfund, Pacific Southwest
Pacific Southwest, Region 9
Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations
Addressing Uranium Contamination
in the Navajo Nation
Abandoned Uranium Mines (AUMs)
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From 1994 to 2007 EPA used its Superfund authority to conduct a thorough screening-level investigation, identifying approximately 1,100 mine features (portals, prospects, rim strips, pits, vertical shafts or waste piles) at 520 discrete abandoned mines throughout the Navajo Nation. EPA developed a Comprehensive Database and Atlas and a desktop risk ranking for all 520 mines. Using this information, EPA initially targeted 250 high-risk sites for further evaluation.
Under the Five-Year Plan, EPA is working with Navajo Nation EPA to conduct a tiered assessment of abandoned mines and to identify mines for more detailed assessments. EPA then works with Navajo Nation EPA to determine appropriate courses of action for the highest priority mines. EPA has conducted screening-level review and site visits of an additional 452 AUM sites in the Northern and Western AUM regions.
EPA also completed a removal action to clean up mine waste at Skyline Mine and an interim removal action at Northeast Church Rock "Quivira" Mine.
EPA will continue to pursue enforcement under Superfund, focusing on owners or operators of multiple mines. In 2008 and 2009, EPA sent information request letters to viable companies who owned or operated multiple mines.
Related Information
Navajo Nation AUM Screening Assessment Report and Atlas with Geospatial Data
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