DRC-2022-018443 - 0901a068810b4f40

DRC-2022-018443 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

July 27, 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. March 7, 2022, Source Assessment Report for Manganese
and Sulfate in Monitoring Well MW-11, White Mesa Uranium Mill
Utah Groundwater Discharge Permit No. UGW370004

Dear Ms. Weinel:

The Division of Waste Management and Radiation Control (Division) has reviewed the Energy Fuels
Resources (USA) Inc. (EFRI), March 7, 2022, 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-11 in the Fourth Quarter of 2021 (SAR). The SAR includes an evaluation of “out
of compliance” (OOC) parameters (manganese and sulfate) in monitoring well MW-11. Monitoring
Well MW-11 is located hydraulically downgradient from cell 2, cell 3, and the Mill processing areas.

In Section 3.5.2 of the SAR, EFRI finds that based on assessment and factors demonstrating that MW-
11 has not been impacted by seepage from the tailings cell, that current changes in groundwater
chemistry and uranium and selenium OOC at monitoring well MW-11 are due to groundwater
background and impacts from the nitrate/chloride plume migration. The SAR includes discussion of the
assessment and Section 3.5.2 lists the 8 factors supporting that EFRI conclusion.

Specifically, the SAR states:

1. “Key indicator parameter fluoride is decreasing.
2. pH has been stable to increasing since 2016.
3. Iron (which is the constituent having the highest concentration in the TMS) has been decreasing
since the first quarter of 2012.

(Over)

4.Statistically significant increasing trends in sulfate and manganese were present in MW-11 at
the time of the Hurst and Solomon (2008) isotopic investigation report which included MW-11 in
its analysis and that concluded there were no impacts to groundwater from the TMS, indicating
that these trends are not the result of potential TMS seepage. Trends in both constituents are
attributable to oxidation of naturally occurring pyrite at the site. In addition, manganese may be
released from carbonate cement; and sulfate may be released by gypsum and anhydrite.
5.Although not within the plume, concurrently increasing chloride and nitrate at MW-11
since2018 results from the increasing influence of the nitrate/chloride plume. The increasing
influence of the nitrate/chloride plume, which originates approximately 1,000 feet upgradient of
the TMS, results from continued downgradient migration of the plume towards MW-11. One
consequence of the increasing nitrate is mobilization of naturally occurring uranium at MW-11.
6.Because uranium is substantially less mobile than nitrate or chloride at the near neutral pH
conditions at MW-11, concurrently increasing uranium, nitrate, and chloride indicate
geochemical changes in the immediate vicinity of MW-11 (caused in part by the increasing
influence of the nitrate/chloride plume) rather than transport from a remote source such as the
TMS.
7.Increasing water levels are expected to impact the MW-11 groundwater chemistry and
contribute to trends in dissolved constituents.
8.Mass balance analysis indicates that water level increases at MW-11 are unrelated to potential
TMS seepage.”
Per Division review of the SAR and historical data for MW-11, the out-of-compliance status for
manganese and sulfate in monitoring well MW-11 does not appear to be associated with contamination
from a tailing wastewater source or other Mill activities. Division findings are detailed in a separate
SAR review memorandum. Based on these findings it is appropriate to adjust the Permit groundwater
compliance limit for manganese and sulfate in MW-11, consistent with the currently approved
groundwater data statistical process flow chart for the Mill and associated guidance.
Statistical Analysis
Based on Division review of the SAR statistical analysis, it was noted that analysis was conducted for
the complete historic data set for MW-11 and for a post-January 1, 2016 data set. The Division notes in
the MW-11 pH concentration plot there is an apparent reversal in the pH trend from downward to
neutral/upward at around 2016. According to SAR discussion, the pH changes are reflective of a shift in
the data which warrants use of the modified data set as allowed by the U.S. Environmental Protection
Agency Statistical Guidance. Per Division review of a plot of historical data for pH in MW-11, the
2016 pH trend reversal is evident.
EFRI 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) and Linear Trend Analysis.
Proposed GWCL’s were calculated based on highest historical value (HHV) for manganese and Mean X
1.25 of the post-January 1, 2016 data set for sulfate. The calculations and findings are summarized on a
table in the SAR (Appendix A-1 of the SAR).
In the SAR Section 4.2, EFRI proposed that GWCL’s be adjusted according to HHV for manganese and
background (Mean X 1.25) for the post-January 1, 2016 data set for sulfate. The Division 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-11 Approved Modified GWCLs
In accordance with the review of the SAR Section regarding proposed modifications to the GWCL and
statistical analysis of the data, the GWCLs will be modified in the White Mesa Uranium Mill Ground
Water Permit for monitoring well MW-11 for manganese and sulfate as summarized on the table below:
Well
Number
Parameter Current GWCL Modified GWCL Method of Analysis
MW-11 Manganese 237 µg/L 376 µg/L HHV
MW-11 Sulfate 1309 mg/L 1493.6 mg/L* Mean X 1.25*
*Based on Mean X 1.25 of the Sulfate background data mean of the post-January 1, 2016 data set for
monitoring well MW-11
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
PRG/TR/kd
c: Grant Sunada, Health Director, San Juan Public Health Department
Ronnie Nieves, Environmental Health Director, San Juan Public Health Department
Russell Seeley, UDEQ District Engineer