On December 20, 2016, EPA Administrator Gina McCarthy signed a final rule that revised “National Emission Standards for Radon Emissions from Operating Mill Tailings,” Subpart W of 40 CFR part 61. The revised standard requires the use of generally available control technology (GACT) to limit radon emissions from uranium tailings impoundments built after 1989. Specific control technologies would be required at conventional tailings impoundments, evaporation ponds, and heap leach piles. The revised standard also contains record-keeping and construction requirements. Existing radon emissions standards and monitoring requirements for impoundments built before 1989 remain in force. The rule becomes effective 60 days… Read more