FROM: Kim Morrison Date:

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# + rn') Energy Fuels Resources (USA) Inc. 225 Union Blvd. Suite 600 Lakewood, CO, US, 80228 303-97 4-2140 www.energyfuels.com
3 September 2014
COMMENTS- EPA SUBPART W PUBLIC HEARING My name is Kim Morrison, and I am a consulting geotechnical engineer representing Energy Fuels, and the Environmental Manager for the proposed Sheep Mountain Project in Wyoming. The Sheep Mountain Project, which includes a proposed uranium heap leach facility, was heavily referenced by the EPA in the background information for the proposed rules. However, there is a clear misunderstanding by the EPA on the concepts of heap leaching ; the reduced level of radi um in a uranium heap leach facility as compared to a uranium tailings impoundment; and a fundamental m isunderstanding of the differences between moisture saturation and moisture content.
• When uranium ore is being leached on a heap leach facility, it is actively recovering uranium and is neither "tailings" nor 11 e.(2) byproduct material as defined by the Atomic Energy Act. When uraniu m recovery is complete, the spent ore then becomes 11 e.(2) byproduct material. But, at that time, the facil ity is no longer "active," nor "operational." As such, a heap leach facility, by definition, is not applicable to the Subpart W rules that, by title, are applicable to m ill tailings in "operating" facilities.
• If the position that heap leach facilities are applicable to Subpart W is maintained, then the EPA needs to understand the various types of heap leach facilities proposed for uranium recovery. The revised rules focus merely on reg ulating in-place permanent conventional heap leach facilities, but make no mention of other facilities, such as an onoff heap leach facility where material is leached on an eng ineered pad after which the leached ore is removed and placed in a permanent disposal facil ity.
• The EPA has proposed that heap leach facilities maintain a m inimum moisture content of 30%. Based on a review of the background information, it appears that the EPA are refe rring to the moisture content as a percentage of the weight. The proposed 30% water content is neither practical nor achievable if the heap leach facility is operated as intended. To put the proposed 30% moisture content into perspective, this would correspond to 185% ore saturation for the proposed Sheep Mountain Project. As such, this proposed ru le wou ld require that the ore be not only fully saturated, but "submerged" at all times. We have reviewed the background information EPA used to support the 30% moisture content proposal, and found a number of invalid assumptions in their approach. For instance, moisture saturation as a percent of available void space and moisture content as a percent of we ight are not interchangeable parameters, nor is the relationship between the two parameters a constant.
• Low grade ore is typically processed by heap leach methods, and the low grade ore contained within a heap leach facility emits less radon than a conventional tailings impou ndment of a sim ilar size assuming similar physical conditions. For example, the proposed ore grade at the Sheep Mountain Project is approximately 0.1% uranium, while ore grades of about 0.2% to 0.7% uranium have been processed at the White Mesa Mill 

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over the past three years. As such, a one-size-fits-all approach to setting moisture content requirements is overly conservative, and should be determined instead based on data and analysis.

**~** Using liquid levels to control radon emissions from a heap leach facility conflicts with the overall operational concept of a heap leach facility; would significantly dilute the leaching solution; would have an adverse effect on the process; significantly increase driving head on the underlying liner system; would result in much greater construction and operating costs for the facilities; and, would result in the wasteful consumption of water.



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