DRC-2022-020091 - 0901a068810cecdd

DRC-2022-020091 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
M E M O R A N D U M

TO: Project File C-2022-37

THROUGH: Phil Goble, Section Manager

FROM: Heather Mickelson, PE, PG

DATE: September 8, 2022

SUBJECT: Engineering Module 75C, Review of the 2nd Quarter 2022 (April-June, 2022) DMT
Performance Standards Monitoring Report and Impoundment 4A and Impoundment
4BBAT Performance Standards Monitoring Report. Groundwater Discharge Permit
(GWDP) UGW370004 and Radioactive Materials License (RML), 1900479, Amendment
10, Energy Fuels Resources, Inc. (EFR), White Mesa Mill, Blanding, Utah

This is a summary of Utah Division of Waste Management and Radiation Control (DWMRC) staff
review of the DMT Performance Standards Monitoring Report and Cell 4A BAT Performance
Standards Monitoring Report for the 2nd Quarter 2022 dated July 29, 2022 (DRC-2022-019805).

The requirements are listed given in the Ground Water Discharge Permit (GWDP), No UGW370004,
Dated March 8, 2021, and Radioactive Materials License (RML), 1900479 Amendment 10, dated July
27, 2021. Compliance with these requirements is further discussed in the White Mesa Mill Discharge
Minimization Technology (DMT) Monitoring Plan, Revision 12.4 (DMT Plan), dated December 2016.

DWMRC received the Report on August 9, 2022 in both hard copy and CD formats. The due date for
receipt of this report was September 1, 2022 (GWDP Part II.D).

After review of this report, DWMRC staff findings and recommendations are as follows:

Summary of Findings

1. Weekly monitoring of Impoundment 1 solution pool elevations occurred, as required, and the solution
pool elevation remained below the specified limit.

2. Weekly monitoring of Impoundment 4A solution pool elevations occurred, as required, to calculate
acceptable leakage rates, and the leakage rate thus determined remained below the specified limit.
9/8/22
09/08/2022
Review Memorandum, Project C-2022-37, 2022 Second Quarter BAT/DMT Report
September 8, 2022
Page 2

3. Weekly monitoring of Impoundment 4B solution pool elevations occurred, as required, and the
solution pool elevation remained below the specified limit.

4. Data provided in Attachments C and D to the Report support a conclusion that EFR has generally met
the requirement to keep fluid levels in the Impoundment 2 slimes drain as low as reasonably achievable.
Fluid elevations continue to slowly decline.

5. Monitoring of the feedstock storage area occurred as required. The data support a conclusion that no
feedstock existed outside the designated feedstock storage areas.

6. EFR met the requirements for inspection of the liner systems.

7. EFR has met the requirements for inspecting and maintaining the New and Existing Decontamination
Pads.

8. EFR has met the requirements for inspection of the used oil and fuel storage tanks and associated
concrete pads.

9. EFR has met the requirements for inspection of the HCl tanks and containment structure.

10. EFR has met the monitoring requirements for Impoundment 4A and 4B BAT performance and
corrected all mechanical failures the same day as detected.

11. The leak detection systems in Impoundments 1, 2, and 3 appear to have operated properly, and no
fluids were detected during the reporting quarter.

12. EFR has met the requirements for inspection and crack/joint repair of the Ammonium Sulfate Pad.

13. The report was dated July 29, 2022, and arrived in the Division offices on August 9, 2022, which
prior to the September 1, 2022due date.

Summary of Recommendations

1. The DWMRC should issue a closeout letter for the review of this report.

2. Upon completion of the ET cover test regimen, the DWMRC should move rapidly to resolve final
cover design questions, extend appropriate cover design approvals, and encourage placement of the final
cover on Impoundment 2.

1.0 Impoundment Wastewater Pool Elevation Monitoring

RML Requirement
Part 11.3 requires a leak detection system for impoundments 4A and 4b and operation, maintenance, and
monitoring system for impoundments 1, 2, and 3.
GWDP Requirements
Review Memorandum, Project C-2022-37, 2022 Second Quarter BAT/DMT Report
September 8, 2022
Page 3

Part I.F.2 requires EFR to submit a DMT Performance Standards Monitoring Report for Parts I.D.3 and
I.E.7 of the GWDP.

Part I.E.7(a) requires EFR to monitor and record weekly the elevation of the wastewater pool in
Impoundments 1 and 3 to ensure compliance with Condition 10.3 of the License.

DMT Plan
Part 3.1(a) requires EFR to measure the solution pool elevation in Impoundments 4A and 4B weekly to
determine compliance with FML leakage rate limitations.

Results
Non-conventional Impoundment 1
Attachment A to the Report contains weekly pool elevations for Impoundment 1 show compliance with
the freeboard requirements.

Conventional Impoundment 3
Impoundment 3 is nearly filled with tailing solids, there is no room for liquids at the surface of the
tailings. Recognizing this, letters from the Director dated January 27, 2011 and March 14, 2011
formally eliminated the need for solution pool elevation measurement in Impoundment 3. The January
27, 2011 letter and a letter from the Director dated March 15, 2011 concluded a process ending the need
for freeboard-related solution pool elevation monitoring in Impoundment 3.

There is no requirement for weekly solution pool elevation measurement at Impoundment 3.
Attachment A to the report reflects no measurements for the reported quarter.

Conventional Impoundment 4A
Attachment A to the Report contains weekly solution pool elevations for Impoundment 4A in support of
calculating acceptable leak rates for the liner system.

Non-conventional Impoundment 4B
Attachment A to the Report includes solution pool elevation readings for Impoundment 4B indicating
compliance with the prescribed freeboard requirements.

Findings: The data presented in the report demonstrate that EFR is in compliance with the solution pool
operational requirements of the RML, GWDP, and DMT plan in force during the quarter.

2.0 Slimes Drain Fluid Level Monitoring

GWDP Requirements
Part I.F.2 requires EFR to submit a DMT Performance Standards Monitoring Report for Parts I.D.3 and
I.E.7 of the GWDP.

Part I.D.3.b requires EFR to always maintain the fluid level in the slimes drain of Impoundments 2 and 3
as low as reasonably achievable, and to demonstrate that performance through adherence to the current
DMT Monitoring Plan.
Part I.E.7(b) requires quarterly monitoring and recording of the depth to wastewater in impoundments ls
2 and 3 slimes drain access pipe as described in Part I.D.3 of the GWDP and the current DMT
Review Memorandum, Project C-2022-37, 2022 Second Quarter BAT/DMT Report
September 8, 2022
Page 4

Monitoring Plan. It also requires EFR to determine the recovery head with a slimes drain recovery head
assessment.

DMT Plan
Part 3.l(b) lists activities for the Slimes Drain Water Level Monitoring for Impoundment 2.
Impoundments 3, 4a, and 4b are currently active; therefore, no pumping is authorized.

Results
Much of this section repeats the corresponding section in previous report reviews in 2019 through 2022.
The discussion is repeated here for ease of reference for the reader.

Section 4.1 of the Report asserts that the above discussed monitoring requirements only pertain to
Impoundment 2 for the reporting period, as dewatering operations have not commenced in
Impoundments 3, 4A or 4B. I agree with this assessment.

Weekly water level monitoring of the Impoundment 2 slimes drain is not required as part of the DMT
plan but is required under Part I.D.3(b)(l) of the GWDP. EFR retains records of lmpoundment 2 slimes
drain monitoring at the mill.

Attachment D to the Report contains data from the quarterly recovery head measurements. The recovery
head monitoring data provides indirect evidence that EFR has maintained the fluid level in the
Impoundment 2 slimes drain as low as reasonably achievable, as required in GWDP, Part I.D.3(b)(l).
From the graph of slimes drain recovery head data in Attachment D, it is apparent that the downward
trend that occurred between May of 2011 and April of 2014 did not continue uninterrupted but
approached a horizontal asymptote at approximately 28.5 feet below the top of the standpipe; then,
commencing with construction of the Phase 1 Cover on the impoundment surface, the recovery head
abruptly rose. The abrupt rise in the recovery head measurement is attributable to pressures resulting
from the cover construction activity and will be discussed toward the end of this section. The trend again
reversed and declined to the previous lows at about the same level, 28.5 feet below the top of the
standpipe, appeared to stabilize for a time but has again begun trending lower.

As detailed in the previous paragraph, using recovery head measurements to demonstrate success in the
dewatering effort has limitations. The method assumes that the properties of the tailings mass are
homogeneous, and, except for the degree of consolidation, unchanging. Were this the case, the fluid
withdrawal rate would be predictable, and the recovery head tests would not have the variability shown
in the Attachment D graph with consistent fluid withdrawal. The methodology used to generate the
graph in Attachment D was used as an enforcement tool, and worked well, until late 2014, as discussed
above. Noting that EFR was making all reasonable efforts to keep the fluid head declining, and forces
beyond EFR's control were preventing full compliance with the directive to maintain declining fluid
head, the method was abandoned as an enforcement tool during the license renewal in 2018.

In reviews of previous Reports, prior to placement of the radon barrier material (the second and third
layers of the cover system), Russ Topham stated that more information is required to understand
whether hydraulic equilibrium has been reached with approximately 7.5 feet of hydraulic head
(approximately 22.5 feet from the surface of the temporary cover on the impoundment) at the pumping
point (Report for 4th Quarter, 2017, Appendix D). Table 2-1 on p. 7 of the Tailings Data Analysis Report
(TDAR, April 2015) presents a water table at a depth of between 0.2 feet and 12.3 feet of the surface of
the temporary cover. Likewise, Table 4-1 indicates the depth to top of saturated tailings varying from
Review Memorandum, Project C-2022-37, 2022 Second Quarter BAT/DMT Report
September 8, 2022
Page 5

3.92 feet to 11.58 feet below the temporary cover surface, with the greater depths occurring closer to the
slimes drain alignment (TDAR, p. 17). These data indicate a substantial volume of fluid yet to be
removed from the impoundment. Recent installation of additional cover material has surcharged the
tailings, resulting in increase of approximately 2,000 gallons per month yield from the slimes drain as
well as increased fluid level within the tailings mass due to consolidation. However, stabilizing of the
head at the slimes drain may indicate that the withdrawal rate is equal to the percolation rate, and that no
further improvements are possible without installing the final cover layers.

The TDAR postulates the presence of gypsum in the interstices within the tailings mass (p. 11 ). This
condition would reduce hydraulic conductivity within the tailings. The temporary cover is composed of
random 'fill, which on visual inspection appears to be a sandy gravel or gravelly sand with cobbles and
boulders. Sieve analysis reveals a fines fraction (material finer than the #200 sieve) of between 10% and
30%, with Atterberg Limits testing suggesting the presence of clay in the fines. However, the temporary
cover was placed without significant densification, which would offset to some degree the ability of any
clay present to resist percolation of water. The porosity of this cover would allow surface water to
penetrate the tailings below. Surcharge of the tailings with the additional cover material will induce
some consolidation of the random fill and tailings below. Furthermore, the compacted surface of the
cover material would shunt aside much of the precipitation falling on the impoundment, reducing the
amount available for percolation. With placement of the radon barrier, the temporary cover has
consolidated as discussed above. However, no additional information is currently available regarding the
postulated precipitation of gypsum in the interstices of the tailings mass below the phreatic surface.
Furthermore, if the withdrawal rate from the slimes drain has achieved equilibrium with the percolation
rate from above, the suggested conclusion is that the precipitation received is controlling the fluid
balance.

The licensee has placed piezometers at the settlement monitoring points and is now providing
information gathered from the piezometers with this Report, as Attachment C. I have received weekly
reports by email of fluid level measurements in the piezometers which showed a progressive rise in the
phreatic surface as crews placed and compacted the first two layers of the final cover system, followed
by a decline in, then a stabilization of the phreatic surface.

During the reporting quarter, EFR pumped available fluid from the slimes drain. Using fluid level
measurements in piezometers installed in the Impoundment 2 cover, EFR has constructed fluid level
surface contour maps for each month for Impoundment 2. These maps and the associated data appear in
Attachment C to the Report. Comparing these maps and the underlying data demonstrate that the fluid
level has declined, appeared to have stabilized, and recommenced declining, much like the slimes drain
data.

If percolation and fluid withdrawal occur on equilibrium with each other, fluid levels will stabilize in the
tailings mass. That condition appeared to have been achieved when the fluid levels paused in their
decline. It is unclear whether the resumption in decline is a function of drought conditions at the surface
or whether other factors are at work here. However, it is worth noting that reviews of the cover test cell
monitoring program indicate no percolation at present, with vegetative conditions on the test cell not a
great deal different than on the remainder if the currently installed cover.

It appears from the data that EFR is removing fluid from the tailings mass as rapidly as it becomes
available. Installation of final cover would provide more surcharge, squeezing out more fluid, and
should impede or eliminate percolation.
Review Memorandum, Project C-2022-37, 2022 Second Quarter BAT/DMT Report
September 8, 2022
Page 6

Installation of final cover is dependent upon approval of the evapotranspirative cover proposed for the
site (ET cover), pursuit of another approvable cover system, or a decision to install the currently
approved rock armor barrier. The ET cover is under study, and insufficient data exists currently to
extend approval. It should be noted here that if the currently approved rock armor barrier is to be
installed, a modified design to increase cover slope may be necessary to increase runoff rate and
decrease percolation. It should also be noted that Energy Fuels has installed an additional secondary test
section to evaluate an alternative seed mix to that originally proposed for the ET cover because the
performance goals were not likely to be met.

Findings: Data provided in Attachments C and D of the Report supports a conclusion that EFR has
generally met the requirement to keep water levels in the Impoundment 2 slimes drain as low as
reasonably achievable.

It appears that the slimes removal rate matched the percolation rate from the cover surface for a time,
but that the removal rate once again exceeds the percolation rate.

Recommendation: The DWMRC and EFR should continue to monitor the licensee's efforts to remove
slimes from the tailings mass.

Upon completion of the ET cover test regimen, the DWMRC should move rapidly to resolve final cover
design questions, extend appropriate cover design approval and encourage placement of the final cover.

3.0 Feedstock Storage Monitoring

This section addresses both bulk conventional feedstock (ore) and alternate feed stored onsite. Ore is
stored on the ore pad. Alternate feed is stored on the ore pad or a small quantity may be placed on a
concrete pad near the intake features of the alternate feed circuit when the material is being staged for
processing through the alternative feed circuit.

GWDP Requirements
Part I.D.3.E describes the physical area used for open-air or bulk storage of feedstock materials.
I.D.11 lists the BAT Requirements for Feedstock Material stored Outside of the Feedstock Storage Area
Part I.E.7.c describes the weekly feedstock storage area inspection.
Part I.E.7.d describes inspection and criteria for storing Feedstock Material Stored Outside the
Feedstock Storage Area.
Part I.F.2 requires EFR to submit a DMT Performance Standards Monitoring Report for Parts I.D.3 and
I.E.7 of the GWDP.

Results
Weekly inspection revealed no evidence of ore beyond the boundaries of the ore pad. Storage practices
for alternate feeds appear compliant with GWDP requirements. During the monitoring period, the only
location of alternate feed storage was on the ore pad.

The current report highlighted no example of significant standing water volume persisting on the ore pad
after storms.

Review Memorandum, Project C-2022-37, 2022 Second Quarter BAT/DMT Report
September 8, 2022
Page 7

Finding: Monitoring of the feedstock storage area occurred as required. The data support a conclusion
that no feedstock existed outside the designated feedstock storage areas. Standing water problems were
addressed during the quarter.

4.0 Tailings Impoundments Liner System Repairs

GWDP Requirements
Part I.E.7.e describes the inspections and repair of defect to liners Impoundments 1,2, and 3.
Part I.E.8.c describes the liner maintenance and repair for Impoundment 4a
Part I.E.12 .c describes the liner maintenance and repair for Impoundment 4b

Results
Inspection of all impoundments occurred weekly during the period covered in the report. No leaks or
liner breaches were identified.

Finding: EFR met the requirements for inspection and repair of the liners.

5.0 Decontamination Pads

Two decontamination pads exist at EFR and are called, appropriately: New Decontamination Pad and
Existing Decontamination Pad

GWDP Requirements
Part I.F.12 describes the annual inspection report for the new and existing decontamination pads that is
submitted on or before September 1 of each year. It further describes the inspection and repairs of the
pads.
Part I.D.14 lists maximum water level requirements and pad cleanliness requirements as part of the BAT
Performance Standards for the New Decontamination Pad.
Part I.E.7.f requires EFR to conduct a weekly inspection of the New decontamination Pad.

Annual inspection and repair of both decontamination pads as required under Part I.F.12 of the GWDP
and Section 4.2 of the DMT Plan occurred during May 2022. Repairs included sealing cracks greater
than 1/8 inch.

Results
The monitoring portals of the New Decontamination Pad were dry during all inspections, indicating no
leakage from primary containment. Cracks were repaired in May 2022. Surfaces have been repaired to
prevent seepage of contaminants through the New and Existing Decontamination Pads and into the
ground water.

Finding: EFR has met the routine and annual requirements for inspecting both the Existing and New
Decontamination Pads, finding no indication of leakage from secondary containment.

Review Memorandum, Project C-2022-37, 2022 Second Quarter BAT/DMT Report
September 8, 2022
Page 8

6.0 Used Oil and Fuel Storage Tanks

GWMP Requirement:
Part I.D.3.f lists the mill site chemical reagent storage requirements.
Part I.D.10 describes the Storm Management and Spill Control Requirements to manage all contact and
non-contact stormwater and control containment spills.

The Spill prevention, Control and Countermeasures Plan and the DMT Plan require annual inspection of
the used oil and fuel storage tanks. The associated concrete is inspected and sealed in the same manner
and on the same schedule as the decontamination pads.

DMT Plan
Section 4.4 describes the annual inspection of waste oil and fuel tanks.

Results
Plant personnel inspected the tanks and pads, noted no leakage from the tanks, and applied sealant to
joints and cracks in the pads and containment walls as required. The requirement is annual, was
completed during June 2022.

Finding: EFR has met the routine requirements for inspecting the used oil and fuel tanks and associated
secondary containment features and has sealed joints and cracks therein.

7.0 Ammonium Sulfate Pad

Requirement
Phase I of the Nitrate Corrective Action Plan required installation of a concrete pad to prevent water
penetrating to nitrate-containing soils near the ammonium sulfate crystal tank. The DWMRC approved
the construction by letter on June 26, 2015. Inspections and filling of cracks were required quarterly for
eight consecutive quarters following approval and have been conducted annually thereafter.

DMT Plan
Section 5 describes the inspection of the ammonium sulfate cover area.

Results
Plant personnel inspected the pad and applied sealant to joints and cracks as. Annual inspection and
maintenance activities were completed during May 2022.

Finding: EFR has met the routine requirements for inspecting the Ammonium Sulfate Pad and has
sealed joints and cracks therein.

8.0 HCl Tanks

GWMP Requirements
Part I.D.3.f lists the mill site chemical reagent storage requirements.
Part I.D.10 describes the Storm Management and Spill Control Requirements to manage all contact and
non-contact stormwater and control containment spills.
Review Memorandum, Project C-2022-37, 2022 Second Quarter BAT/DMT Report
September 8, 2022
Page 9

Results
Plant personnel inspected the HCl tanks and the secondary containment. No repairs or maintenance
activities were required.

Finding: EFR has met the routine requirements for inspecting and maintaining the HCL tank and
associated
secondary containment.

9.0 Impoundments 4A and 4B BAT Performance Standards Monitoring

Requirements
Part I.D.6a and Part I.E.12 lists the BAT performance standards for impoundments 4A and 4B. These
requirements include verifying that leak detection system equipment operates appropriately, verifying
that fluid head in the leak detection system sumps does not exceed 1 foot above the lowest point in the
secondary (lower) flexible membrane liner, and recording the volume of fluid pumped from the leak
detection systems for the two impoundments. EFR must also record the fluid head in Impoundment 4B
for compliance purposes, and in Impoundment 4A for computation of acceptable leakage rate in
Impoundment 4A.

DMT Plan
Section 2.1 describes the daily measurements and monitoring for the leak detection systems in
impoundments 1, 2, 3, 4A, and 4B.
Section 3.1 describes the weekly measurements and monitoring for Impoundments 1, 2, 3, 4A, and 4B.

Results
The data provided in the report and its attachments provide evidence of compliance with Impoundments
4A and 4B BAT performance monitoring standards in place during the monitoring period.

No failures were noted in the Impoundment 4A or Impoundment 4B leak detection systems during the
second quarter. During the quarter, the fluid extraction pump experienced irregularity in the power
supply. The faulty part was identified and replaced without missing any measurements.

Finding: EFR has met the monitoring requirements for Impoundment 4A and 4B BAT performance. No
mechanical failures were noted during the quarter.

10.0 Impoundments 1, 2 and 3 Leak Detection System Monitoring

RML Requirement
Part 11.3 requires a leak detection system for impoundments 4A and 4b and operation, maintenance, and
monitoring system for impoundments 1, 2, and 3.

DMT Plan
Section 2.1 describes the daily measurements and monitoring for the leak detection systems in
impoundments 1, 2, 3, 4A, and 4B.

Review Memorandum, Project C-2022-37, 2022 Second Quarter BAT/DMT Report
September 8, 2022
Page 10

Section 3.1 describes the weekly measurements and monitoring for Impoundments 1, 2, 3, 4A, and 4B.

Requirement
Leak detection system monitoring requirements for Impoundments 1, 2 and 3 appear in the Radioactive
Materials License rather than the GWDP. For consistency, the DWMRC requested that this monitoring
be included as part of the quarterly report and EFR has consented to do so.

Results
The report and its attachments contain weekly monitoring data for the operational status of the leak
detection system equipment, fluid levels detected in the leak detection systems, and volumes of fluid
pumped. From the data, EFR represents that no failures of the monitoring equipment occurred that were
not corrected within 24 hours. Leak detection systems for the three impoundments measured dry;
therefore, no fluids were pumped from them.

Finding: The leak detection systems in Impoundments 1, 2 and 3 appear to have operated properly, and
no fluids were detected therein during reporting period