DRC-2021-002332 - 0901a06880e109df

DRC-2021-002332 195 North 1950 West • Salt Lake City, UT Mailing Address: P.O. Box 144880 • Salt Lake City, UT 84114-4880 Telephone [phone] • Fax [phone] • T.D.D. [phone] www.deq.utah.gov Printed on 100% recycled paper
State of Utah
SPENCER J. COX Governor DEIDRE HENDERSON Lieutenant Governor
Department of Environmental Quality
Kimberly D. Shelley Executive Director DIVISION OF WASTE MANAGEMENT AND RADIATION CONTROL Ty L. Howard Director

February 26, 2021

Kathy Weinel, Quality Assurance Manager Energy Fuels Resources (USA) Inc. (EFR) 225 Union Blvd, Suite 600
Lakewood, CO 80228
RE: Additional Test Section for Evapotranspirative Cover Test Program Utah Ground Water Discharge Permit Number UGW370004 (GWDP)
Dear Ms. Weinel:
On February 18, 2021 we received an advance copy of your letter of the same date detailing your desire to construct a second supplemental test section to evaluate an adjusted seed mix for the proposed evapotranspirative cover system (ET Cover) for the tailings impoundments at the White Mesa Mill near
Blanding, Utah. This letter details our understanding of the proposal and identifies our thoughts on
proceeding with the additional test section. We included in our deliberations the conference call we held with you and your consultants on February 22, 2021 to gain a better understanding of the proposal. We have also reviewed the language of the Stipulation and Consent Agreement (SCA) governing the construction, operation and monitoring of the existing primary and secondary test sections.

The following summarizes our understanding: 1. EFR believes, based on monitoring data, that the test sections are not on track to meet the plant diversity and density targets spelled out in the SCA. Early indications are that the Primary Test
Section may meet the hydrologic targets spelled out in the SCA. Item 7(a) of the SCA indicates
that the Director may consider the cover system verified if both the plant diversity and density criteria and the percolation criteria are met. 2. The Primary Test Section has an overabundance of Squirreltail and little else and is not tracking
to meet either the plant diversity or density targets. The existing Secondary Test Section
received no topsoil or amendment, has performed better from a plant diversity perspective, but has almost no Squirreltail, and still looks to fall short of the targets. (Over)

3. EFR and its consultants believe the ET Cover concept can still work at the mill site with adjustment to the seed mix. The proposed adjustments would reflect the experience to date specifically with the Squirreltail and generally with the seed mix employed. The Secondary Test Section would receive seeding with more drought-tolerant plant selections to increase the
probability of success.
4. The two-year Calibration Period and the first year of performance monitoring under the SCA have elapsed. That being the case, the newly proposed Secondary Supplemental Test Section will not see five years of performance monitoring as will be the case for the Primary and original
Supplemental Test Section. This circumstance may bear on the Director’s deliberations on the
use of the data gathered from the Secondary Supplemental Test Section. 5. Item 7(b)(i) of the SCA provides a mechanism whereby Energy Fuels can use modeling to demonstrate that the proposed cover system will likely perform adequately notwithstanding
failure to meet the plant and/or percolation requirements of the SCA. The SCA anticipated using
the results of monitoring at the Primary and Supplemental Test Sections as inputs to the new modeling effort should new modeling become necessary. Energy Fuels seeks to generate additional data that may lead to an improved cover system without subjecting the construction of final cover on Impoundment 2 to additional delays. EFR proposes to do this by completing the
additional proposed study in parallel with the remaining four years of the term of the SCA.
6. The Division will not take a position to approve or deny approval of the additional study. The Division takes this posture to preserve the SCA intact. However, the Division does see the potential for a useful outcome from this endeavor. To that end, the Division will not take
exception to the construction and monitoring of the proposed Secondary Supplemental Test
Section. Furthermore, the Division will take the same interest in the monitoring of the new section as it does in the old. 7. Energy Fuels has committed to keep the Division informed of dates of significant activity with
respect to the new test section, such as placing of topsoil, amendments, and seed. The Division
assumes future monitoring will occur on the same schedule and on the same dates as the existing test sections. If you have any questions, please call Russ Topham at [phone].

Sincerely,
Phil Goble, Uranium Mills and Radioactive Materials Manager
Division of Waste Management and Radiation Control PRG/RJT/as
c: Mike Moulton, Interim Health Officer, San Juan County Public Health Department
Ronnie Nieves, Environmental Director, San Juan County Public Health Department Russell Seeley, UDEQ District Engineer Logan Shumway, Mill Manager Steve Snyder, Mill Engineer