DRC-2022-000602 - 0901a06880ff7a74

DRC-2022-000602 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

Douglas J. Hansen
Director

January 18, 2022

Kathy Weinel, Quality Assurance Manager
Energy Fuels Resources (USA) Inc.
225 Union Blvd., Suite 600
Lakewood, CO 80228

RE: Energy Fuels Resources (USA) Inc. September 7, 2021, Source Assessment Report for
Uranium in Monitoring Well MW-29, White Mesa Uranium Mill
Utah Groundwater Discharge Permit No. UGW370004

Dear Ms. Weinel:

The Division of Waste Management and Radiation Control (DWMRC) has reviewed the Energy Fuels
Resources (USA) Inc. (EFRI), September 7, 2021, document titled “White Mesa Uranium Mill, State of
Utah Groundwater Discharge Permit No. UGW370004, Source Assessment Report Under Part I.G.4 for
Exceedances in MW-29 in the first Quarter of 2021” (SAR). The SAR includes an evaluation of “out of
compliance” (OOC) parameter (uranium) in Monitoring Well MW-29. Monitoring Well MW-29 is
located hydraulically downgradient from the central and eastern portions of cell 1, and Mill processing
areas.

Per Section 3.5 of the SAR, EFRI has concluded that current changes in groundwater chemistry and
uranium OOC at Monitoring Well MW-29 are due to groundwater background variation and not due to
Mill impacts. Section 3.5 discusses that the slight increasing uranium trend at MW-29 “is attributable to
mobilization of naturally occurring uranium from the formations hosting perched groundwater due to 1)
conditions that are increasingly oxidizing at MW-29 and 2) increases in bicarbonate concentrations at
MW-29.”

The SAR further supports that the source of uranium in MW-29 is not the tailings management system
with other information, including: 1. Findings discussed in the Mill groundwater background reports,
2. Mass balance calculations which demonstrate that MW-29 uranium concentrations are consistent with
background conditions and not with a tailings source, 3. Indicator parameter analysis, 4. Review of
increasing groundwater elevations due to infiltration and dissipation of water from the former wildlife
pond and associated evaluation of chloride concentrations, and, 6. Data review of uranium
concentrations in MW-29 with sitewide background comparison.
(Over)
Per DWMRC review of the SAR and historical data for MW-29, the OOC status for uranium in
Monitoring Well MW-29 does not appear to be associated with contamination from a tailings
wastewater source or other Mill activities. DWMRC findings are detailed in a separate SAR review
memorandum. Based on these findings it is appropriate to adjust the uranium Permit groundwater
compliance limit for uranium in MW-29, consistent with the currently DWMRC approved groundwater
data statistical process flow chart for the Mill and associated guidance.

Statistical Analysis

Based on DWMRC review of the SAR statistical analysis it was noted that analysis was conducted for
the complete historic data set for MW-29 and for a post 2011 data set. DWMRC notes that per the
MW-29 uranium historical data plot there is a slight shift starting in 2011 indicating rising
concentration. Per above the rising uranium concentrations is associated with natural background
(no corresponding changes indicate a Mill source). The complete data set and the post 2011 data set
both show normal uranium (The uranium trend is slightly increasing post 2011).

EFR Statistical methods used in the SAR included: 1. Descriptive statistics for the complete and
modified data sets; 2. Mean and Standard Deviation Calculation; 3. Shapiro-Wilk Test for normality;
and 4. Mann-Kendall Trend Analysis (non-normally distributed data sets). Proposed GWCL’s were
calculated based on Mean + 2σ of the complete and post 2011 data set, Highest Historical Value,
Fraction of the Groundwater Quality Standard, and Mean X 1.5. The calculations and findings are
summarized on a table in the SAR (Appendix B-1 of the SAR).

Per the SAR Section 4.2, EFR proposed that GWCL’s be adjusted according to 1.5 times the uranium
background (Mean X 1.5) for the post 2011 data set. The DWMRC approved statistical flow chart for
the White Mesa Mill groundwater monitoring wells clarifies that if an upward trend is apparent for a
constituent, then a modified approach should be considered. The modified approach should allow for a
GWCL which considers the increasing concentrations.

MW-29 Approved Modified GWCL

Per review of the SAR Section regarding proposed modifications to the GWCL and statistical analysis
of the data the GWCL will be modified in the White Mesa Uranium Mill Ground Water Permit for
Monitoring Well MW-29 uranium as summarized on the table below:

Well Number Parameter Current GWCL Modified GWCL Method of Analysis
MW-29 Uranium 15 µg/L 20.2 µg/L 1.5 X Background
*Based on 1.5 X background of the uranium background data mean of the post April 2011 data set for
MW-29

Note that the modified GWCL’s will not be effective until future issuance of a modified Permit, and that
the modifications will be subject to formal public notice and public participation requirements. These
Permit modifications are anticipated to be made during calendar year 2022.

If you have any questions, please call Tom Rushing at [phone].

Sincerely,

Phil Goble, Uranium Mills and Radioactive Materials Manager
Division of Waste Management and Radiation Control

PG/TR/wa

c: Grant Sunada, Health Director, San Juan Public Health Department
Ronnie Nieves, Environmental Health Director, San Juan Public Health Department
Russell Seeley, District Engineer, UDEQ