Radiation Protection

Subpart W Rulemaking Activity

Subpart W is a radon emission standard for operating uranium mill tailingsHelptailingsThe remaining portion of a metal-bearing ore after some or all of a metal, such as uranium, has been extracted.. In accordance with the Clean Air Act Amendments of 1990, EPA formed a workgroup to review the standard.

Final Rule Issued

On January 17, 2017 EPA officially issued a final rule that revised “National Emission Standards for Radon Emissions from Operating Mill Tailings,” Subpart W of 40 CFR Part 61, which was last issued in 1989. Based on a review and assessment of available, effective and affordable pollution control approaches, the updated Subpart W standards protect human health and the environment by limiting the amount of radon emitted by uranium byproduct material or tailings being managed at uranium recovery facilities.

The revised standard minimizes both radon emissions from operating units and the chances for groundwater contamination by:

  • Requiring the use of generally available control technology (GACT) to limit radon emissions from conventional impoundments built after 1989, non-conventional impoundments (i.e., evaporation or holding ponds) and heap leach piles.

  • Limiting the size and number of conventional impoundments that can exist at any time.

  • Prescribing requirements for design and construction of the impoundments (e.g., double liners, leak detection systems).

Existing radon emissions standards and monitoring requirements for conventional impoundments built before 1989 remain in force. The rule becomes effective on March 20, 2017.

View the official rule in the Federal Register (82 FR 5142, January 17, 2017)

View a fact sheet on the 2016 revisions to Subpart W (2 pp, 114 K, About PDF).

Supporting and Background Documents

View Subpart W Rulemaking Activity: Documents to view documents pertaining to the proposed rulemaking, public comment period and other support documents. View Subpart W Rulemaking History to view historical documents related to Subpart W. View Subpart W Rulemaking Activity: Meetings and Presentations to view and download presentations EPA has made related to Subpart W rulemaking activity.


View Section 114 Letters/Responses related to Subpart W rulemaking. These documents are EPA requests (with responses as they are received) for facility information from uranium recovery facilities.


View documents related to Pinon Ridge Mill and the application for approval of construction of a tailings facility.

EPA-hosted Quarterly Conference Calls

EPA hosted quarterly conference calls with interested stakeholders during the rulemaking process. The final stakeholder conference call was held January 5, 2017. Notes from that call will be posted here shortly.

View and download 2016 conference call minutes.

View and download 2015 conference call minutes.

View and download 2014 conference call minutes.

View and download 2013 conference call minutes.

View and download 2012 conference call minutes.

View and download 2011 conference call minutes.

View and download 2010 conference call minutes.

View and download 2009 conference call minutes.

Uranium Location Database

EPA worked with the multi-agency Colorado Plateau Data Coordination Group Steering Committee to create the Uranium Location Database. EPA coordinated this effort with federal, state, and tribal agencies in other parts of the western United States. The database identifies and shows the location of active, inactive and suspected uranium mine and mill locations in fourteen western states, as well as mines which principally produced other minerals, but were known to have uranium in the ore.