DRC-2021-009861 - 0901a06880eebf03

State of Utah
Di2c.-- z(72- I- (01861
Department of
Environmental Quality
Kimberly D. Shelley
Executive Director
SPENCER J. Cox
Governor
DIEDRE HENDERSON
Lieutenant Governor
DIVISION OF WASTE MANAGEMENT
AND RADIATION CONTROL
Douglas J Hansen
Director
MEMORANDUM
TO: Project File C-2021-35
THROUGH: Phil Goble, Section Manager P/2--&
FROM: Russell J. Topham, PE
If -
DATE: June 17, 2021
SUBJECT: Engineering Module 75B, Review of the lst Quarter 2021 (January-March 2021) DMT
Performance Standards Monitoring Report and Impoundment 4A and Impoundment 4B
BAT Performance Standards Monitoring Report (Report). Groundwater Discharge
Permit (GWDP) UGW370004 — 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 EFR DMT Performance Monitoring Report and Impoundment 4A and Impoundment 4B
BAT Performance Standards Monitoring Report dated April 27, 2021, for the 1st Quarter 2021 (January-
March 2021) monitoring period (Report). DWMRC received the Report on April 30, 2021, in both hard
copy and CD formats. The due date for receipt of this report was May 1, 2021. Discussions in this
document reference the White Mesa Mill Discharge Minimization Technology (DMT) Monitoring Plan,
Revision 12.4 (DMT Plan), dated December 2016.
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.
DRC-20 195 North 1950 West • Salt Lake City, UT
Mailing Address: P 0 Box 144880 • Salt Lake City, UT 84114-4880
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Review Memorandum, Project C-2021-35, 2021 Quarter 1 BAT/DMT Report
June 17, 2021
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. The data further demonstrate that the piezometric surface within the
tailings mass has dropped in elevation as far as it is likely to drop prior to installing the final
layers of the cover system.
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 the New Decontamination Pad.
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 inspecting the Old Decontamination Pad.
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 therein during the reporting quarter.
12. EFR has met the requirements for inspection and crack/joint repair of the Ammonium Sulfate
Pad.
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
Requirements
Part I.E.7(a) of the GWDP 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.
Part 3.1(d) of the DMT/BAT Plan requires EFR to measure the solution pool elevation in Impoundments
4A and 4B weekly, and the tailings beach maximum elevation and area within Impoundments 4A and
4B monthly.
Review Memorandum, Project C-2021-35, 2021 Quarter 1 BAT/DMT Report
June 17, 2021
Page 3
Results
Non-conventional Impoundment 1
Attachment A to the Report contains weekly pool elevations for Impoundment 1 indicating compliance
with the prescribed freeboard requirements.
Conventional Impoundment 3
Tailings have nearly completely filled Impoundment 3. 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. However, Part 3.1(a) of the DMT/BAT Plan requires monitoring solution pool
elevations in Impoundments 4A and 4B to facilitate determination of compliance with FML leakage rate
limitations.
As noted, no requirement for weekly solution pool elevation measurement at Impoundment 3 existed
during the monitoring period. 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 EFR compliance with the solution pool
operational requirements of the DMT/BAT plan in force during the quarter.
2.0 Slimes Drain Fluid Level Monitoring
Requirements
Part I.F.2 of the GWDP requires EFR to include in the Report, all DMT performance standards
monitoring detailed in Parts I.D.3 and I.E.7 of the GWDP.
Part I.D.3(b)(1) of the GWDP requires EFR to maintain the fluid level in the slimes drain of
Impoundments 2 and 3 as low as reasonably achievable at all times, and to demonstrate that
performance through adherence to the current DMT Monitoring Plan.
Part I.E.7(b) of the GWDP requires monthly monitoring and recording of the depth to wastewater in the
slimes drain access pipe as described in Part I.D.3 of the GWDP and the current DMT Monitoring Plan.
Review Memorandum, Project C-2021-35, 2021 Quarter 1 BAT/DMT Report
June 17, 2021
Page 4
Part 3.1(b)(v) of the DMT Monitoring Plan requires EFR to monitor and record weekly the depth to
wastewater in the Impoundment 2 slimes drain access pipe to determine maximum and minimum head
before and after a pumping cycle, respectively.
Results
Much of this section repeats the corresponding section in previous report reviews in 2019 through 2021.
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 concur 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)(1) of the GWDP. EFR retains records of Impoundment 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)(1).
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, and now appears to have stabilized at about the same
level, 28.5 feet below the top of the standpipe.
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), I 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 3.92 feet to
11.58 feet below the temporary cover surface, with the greater depths occurring closer to the slimes
Review Memorandum, Project C-2021-35, 2021 Quarter 1 BAT/DMT Report
June 17, 2021
Page 5
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 and seems now to have stabilized in the tailings mass.
Equilibrium between percolation and fluid withdrawal appears to have been achieved. The phreatic
surface has ceased declining, and the slimes drain recovery head has also ceased declining. 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.
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
Review Memorandum, Project C-2021-35, 2021 Quarter 1 BAT/DMT Report
June 17, 2021
Page 6
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 to 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 is matching the percolation rate from the cover surface.
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, when staging to mill the material, a
small quantity may be placed on a concrete pad near the intake features of the alternate feed circuit.
Requirement
Part I.D.11 of the GWDP anticipates and governs storage of alternate feed outside the confines of the
ore pad.
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.
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
Requirement
Parts I.E.7(f) and I.G.3 specifies how the licensee must address leaks discovered in the impoundment
liner system. Part I.F.2 specifies reporting requirements for such liner breaches.
Review Memorandum, Project C-2021-35, 2021 Quarter 1 BAT/DMT Report
June 17, 2021
Page 7
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
Requirement
Weekly inspection of the New Decontamination Pad for leakage occurred as required under Part I.F.12
of the GWDP.
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 April 2020 (New Decontamination Pad) and June,
2020 (Old Decontamination Pad). Repairs included sealing cracks greater than 1/8 inch. The 2021
inspection is anticipated during the second quarter Of 2021.
Results
The monitoring portals were dry during all inspections, indicating no leakage from primary containment.
Cracks were repaired during the 2nd Quarter Report period. Surfaces have been repaired to prevent
seepage of contaminants through the pads and into the ground water.
Finding.. EFR has met the routine and annual requirements for inspecting both the Old and New
Decontamination Pads, finding no indication of leakage from secondary containment.
6.0 Used Oil and Fuel Storage Tanks
Requirement
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.
Results
Plant personnel inspected the tanks and pads during the 2nd quarter of 2020, 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 April and May 2020, and was reported in the 2nd Quarter
Report. The 2021 inspection is anticipated during the second quarter Of 2021.
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.
Review Memorandum, Project C-2021-35, 2021 Quarter 1 BAT/DMT Report
June 17, 2021
Page 8
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.
Results
Plant personnel inspected the pad and applied sealant to joints and cracks as required. Annual
inspection and maintenance activities were completed during May 2020, and reported in the 2" Quarter
Report. The 2021 inspection is anticipated during the second quarter Of 2021.
Finding: EFR has met the routine requirements for inspecting the Ammonium Sulfate Pad and has
sealed joints and cracks therein.
8.0 Impoundments 4A and 4B BAT Performance Standards Monitoring
Requirement
Requirements for measuring BAT performance for Impoundments 4A and 4B 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.
The data provided in the report and its attachments provide evidence of compliance with the
Impoundments 4A and 4B BAT performance monitoring standards in place during the monitoring
period.
Results
No failures were noted in the Impoundment 4A or Impoundment 4B leak detection systems during the
Report period. 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.
Review Memorandum, Project C-2021-35, 2021 Quarter 1 BAT/DMT Report
June 17, 2021
Page 9
9.0 Impoundments 1, 2 and 3 Leak Detection System Monitoring
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.