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National Emission Standards for Hazardous Air Pollutants (NESHAP) subpart W protects human health and the environment by setting radon emission standards and work practices for operating uranium mill tailings impoundments. The EPA is in the process of reviewing this standard. If necessary, the Agency will revise the NESHAP requirements for radon emissions from operating uranium mill tailings.

Statement of Need:

This radionuclide NESHAP promulgated in 1989 limits radon emissions from operating impoundments that manage uranium byproduct material. This review of the rule is prompted by a settlement agreement based on EPA's failure to review the rule within 10 years of the 1990 Clean Air Act Amendments.

Summary of the Legal Basis:

The authority for this action comes from Clean Air Act section 112(q)(1).

Alternatives:

The rule proposed to establish Generally Available Control Technologies (GACT) or management practices for conventional impoundments, non-conventional impoundments, and heap leach piles. EPA proposed to: eliminate the radon flux standard and monitoring at older conventional impoundments; to require non-conventional impoundments to retain one meter of liquid; to regulate heap leach piles from the initial application of leaching solution; and to require heap leach piles to maintain 30% moisture content. A specific alternative was discussed only in relation to regulating heap leach piles. The alternative was to not regulate the piles under subpart W until the leaching (extraction) process was completed and the heap leach pile contained only uranium byproduct material.

Anticipated Costs and Benefits:

Costs attributable to the proposed rule include the cost to maintain one meter of liquid in non-conventional impoundments and the cost to maintain 30% moisture content in heap leach piles. These costs represent less than 0.1% of baseline facility costs. The primary benefit is maintaining air quality in the vicinity of uranium recovery facilities to levels consistent with the 1989 rule.

Risks:

The proposed rule maintains the estimated individual lifetime risk of fatal cancer at approximately 1 x 10-4 or below, consistent with the 1989 rule. Population risk is estimated at between 0.0015 and 0.0026 fatal cancers per year, or approximately 1 case every 385 to 667 years for the 4 million persons living within 80 km of uranium recovery facilities.