DRC-2024-006481

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

MEMORANDUM

TO: File

THROUGH: Dean Henderson, P.G.
Adam Wingate, Manager

FROM: Christopher Leahy, P.G.

DATE: August 7, 2024

SUBJECT: Review of the Energy Fuels Resources (USA) Inc. 1st Quarter 2024 Groundwater
Monitoring Report for the White Mesa Uranium Mill

Review Summary:

The Utah Division of Waste Management and Radiation Control (Division) has reviewed the
following documents submitted by Energy Fuels Resources (USA) Inc. (EFR):

1. EFR, April 24, 2024, Transmittal of 1st Quarter 2024 Groundwater Monitoring Report
Groundwater Quality Discharge Permit UGW370004 White Mesa Uranium Mill.
(Received by the Division on April 29, 2024) (DRC-2024-005465)
2. EFR, April 19, 2024, State of Utah Ground Water Discharge Permit No. UGW370004
White Mesa Uranium Mill – Notice Pursuant to Part I.G.1(a) (DRC-2024-005392)

The review was conducted to ensure compliance with all applicable parts of Utah Groundwater
Discharge Permit No. UGW370004 (Permit) issued for the White Mesa Uranium Mill located in
Blanding, Utah (Mill).

Significant Findings of the 1st Quarter 2024 Report and Related Actions at the White Mesa
Uranium Mill:

When a monitoring well has a pollutant that exceeds a Ground Water Compliance Limit (GWCL)
set forth in Table 2 of the Permit, it is in Probable Out-of-Compliance (POOC) status. According
to the Permit, EFR is then required to immediately initiate accelerated sampling of that pollutant
# - $ . / * + # - # 4 — 0 " F v A ? A C @ D w @ B ˜
Adam Wingate (Aug 8, 2024 13:49 MDT)
EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 2

(see the Permit, Part I.G.1). One new compliance parameter, Tetrahydrofuran in MW-26, went
into POOC and accelerated monitoring frequency based on sampling during the 1st Quarter 2024.

When monitoring wells have parameters that have exceeded the GWCL two or more consecutive
times they are in Out-of-Compliance (OOC) status (see the Permit, Part I.G.2). No new
compliance parameters went into OOC status based on their first consecutive non-exceedances
occurring during the quarter and/or previous quarter.

In the event a constituent is in OOC status, EFR is required to prepare and submit a report to the
Director within 30 calendar days. The report must contain a plan and time schedule for
assessment of the sources, the extent and potential dispersion of the contamination, and an
evaluation of potential remedial action to restore and maintain groundwater quality to ensure that
Permit limits will not be exceeded at the compliance monitoring point and that DMT or BAT will
be re-established, in accordance with Part I.G.4(c) of the Permit.

Table 1 and Table 2 below list monitoring wells with parameters currently in OOC or POOC
status as of the 1st Quarter of 2024. The following wells therefore are required to be sampled
under the accelerated monitoring requirements. EFR is required to notify the Division on a
quarterly basis regarding wells and parameters which went into accelerated monitoring during the
period [Part I.G.1(a), Accelerated Monitoring Status Reports (AMSR)].

Table 1 - Wells Monitored Quarterly Accelerated to Monthly Monitoring
Well Class Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-11 Class II
water
Downgradient of
Cell 3
Chloride
Sulfate
Manganese
Nitrate + Nitrite (as N)
Selenium
3rd Quarter 2019
3rd Quarter 2019
3rd Quarter 2021
1st Quarter 2022
4th Quarter 2022
November 2019
November 2019
November 2021
June 2022
March 2023
MW-25 Class III
water
Downgradient of
Cell 3 Chloride 4th Quarter 2022 March 2023
MW-26(a) Class III
water
Cross Gradient of
Cell 2
Nitrate + Nitrite (as N)
Chloroform
Chloride
Tetrahydrofuran
February 2010
February 2010
February 2010
1st Quarter 2024
May 2010
May 2010
May 2010
2nd Quarter 2024
MW-30 Class II
water
Downgradient of
Cell 2
Nitrate + Nitrite (as N)
Chloride
Uranium
Selenium
February 2010
1st Quarter 2011
1st Quarter 2021
1st Quarter 2019
May 2010
May 2011
April 2021
May 2019
MW-31 Class III
water
Downgradient of
Cell 2
Nitrate + Nitrite (as N)
Chloride
Total Dissolved Solids
Sulfate
Uranium
1st Quarter 2010
1st Quarter 2011
3rd Quarter 2019
3rd Quarter 2019
2nd Quarter 2020
May 2010
May 2011
November 2019
November 2019
August 2020
EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 3

a = Monitoring well MW-26 is a pumping well for the Chloroform investigation

Table 2 - Wells Monitored Semi-Annually Accelerated to Quarterly Monitoring

Well Class Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-03A Class III
water
Downgradient of
Cell 4B
Selenium 2nd Quarter 2023 4th Quarter 2023
MW-05 Class II
water
Downgradient of
Cell 3
Uranium 2nd Quarter 2023 4th Quarter 2023
MW-17 Class III
water
Downgradient of
Cell 4A
Chloride 4th Quarter 2022 2nd Quarter 2023
MW-24 Class III
water
Downgradient of
Cell 1
Beryllium
Cadmium
Thallium
Field pH
Fluoride
Nickel
Manganese
Sulfate
Gross Alpha
Total Dissolved Solids
4th Quarter 2017
2nd Quarter 2018
2nd Quarter 2018
2nd Quarter 2018
4th Quarter 2018
4th Quarter 2018
4th Quarter 2019
1st Quarter 2020
4th Quarter 2023
2nd Quarter 2021
1st Quarter 2018
3rd Quarter 2018
3rd Quarter 2018
3rd Quarter 2018
3rd Quarter 2019
3rd Quarter 2019
1st Quarter 2020
3rd Quarter 2020
2nd Quarter 2024
3rd Quarter 2021
MW-27 Class III
water
Upgradient of Cell
1
Nitrate + Nitrite (as N)
Fluoride
2nd Quarter 2010
2nd Quarter 2022
3rd Quarter 2010
3rd Quarter 2022
MW-28 Class III
water
Downgradient of
Cell 1
Chloride
Uranium
Selenium
Nitrate + Nitrite (as N)
Total Dissolved Solids
2nd Quarter 2010
2nd Quarter 2014
2nd Quarter 2019
1st Quarter 2019
2nd Quarter 2023
3rd Quarter 2010
2nd Quarter 2014
3rd Quarter 2019
3rd Quarter 2020
3rd Quarter 2023
MW-29 Class III
water
Downgradient of
Cell 2 Uranium 1st Quarter 2021 3rd Quarter 2021
MW-32 Class III
water
Cross gradient of
Cell 2
Chloride 2nd Quarter 2014 4th Quarter 2014
MW-37 Class III
water
Downgradient of
Cell 4B
Field pH 4th Quarter 2022 2nd Quarter 2023

Each well with a parameter in accelerated status is described in detail below:

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 4

Wells Monitored Quarterly - Accelerated to Monthly Monitoring

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-11 Class II Downgradient
of Cell 3
Chloride
Sulfate
Manganese
Nitrate + Nitrite (as N)
Selenium
3rd Quarter 2019
3rd Quarter 2019
3rd Quarter 2021
1st Quarter 2022
4th Quarter 2022
November 2019
November 2019
November 2021
June 2022
March 2023

Chloride and Nitrate + Nitrite (as N) - MW-11 is downgradient of the Nitrate plume and actions
currently being implemented from an approved CAP for Nitrate + Nitrite are expected to address
chloride also. A 30-day plan and time schedule (P&TS) for assessment to address consecutive
exceedances is not necessary. Additional actions are not required at this time and the
concentration of these constituents in groundwater will be monitored closely.

Sulfate - Under the current GWDP, the first consecutive exceedances of the 1,309 mg/L GWCL
occurred during the accelerated monthly July and August 2021 sample events. A Source
Assessment Report (SAR) was approved by the Division on July 27, 2022, which proposed the
GWCL be modified to 1,493.6 mg/L. The new GWCL will become effective on the next revision
of the GWDP. Sulfate did not exceed the current 1,309 mg/L GWCL during any of the 1st Quarter
monthly sample events.

Manganese – Under the current GWDP, consecutive exceedances of the 237 ug/L GWCL for
Manganese first occurred during the 3rd and 4th Quarter 2021 sampling events. A SAR was
approved by the Division on July 27, 2022 which proposed the GWCL be modified to 376 ug/L.
The new GWCL will become effective on the next revision of the GWDP. In the 1st Quarter
2024, Manganese exceeded the current 237 ug/L GWCL during the February and March monthly
sample events (269 ug/L and 265 ug/L).

Selenium – Consecutive exceedances of the current 12.5 ug/L GWCL for Selenium first occurred
during the 3rd Quarter and 4th Quarter 2022 sampling events. Accelerated monthly sampling
began in February 2023. A SAR was approved by the Division on November 6, 2023 which
proposed the GWCL be modified to 20.49 ug/L. Two of the three sampling events conducted
during the 4th Quarter 2023 exceeded the proposed 20.49 ug/L GWCL (20.9 ug/L, 20.1 ug/L, and
19.5 ug/L). However, all three sampling events conducted during the 1st Quarter 2024 were below
the 20.49 ug/L proposed GWCL 19.4 ug/L, 16.8 ug/L, and 17.9 ug/L). Due to these variations,
the new GWCL may be re-considered before the next revision of the GWDP.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 5

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-25 Class III
water
Downgradient
of Cell 3 Chloride 4th Quarter 2022 March 2023

Chloride – Since the onset for sampling Chloride in groundwater at MW-25 in 2005, the
concentration has remained from approximately 30-35 mg/L. Single exceedances of the 35 mg/L
GWCL occurred during the 3rd Quarter 2015 sampling event then did not occur until the
4th Quarter 2022 sampling event when the concentration was 35.8 mg/L. Accelerated monthly
sampling began in the 1st Quarter 2023. Since then, Chloride exceeded the GWCL in 6 of the 15
monthly sampling events including on consecutive occasions. An approved CAP addressing
nitrate + nitrite contamination in groundwater is expected to address the concentration of chloride
at nearby wells also. The actions specified in the CAP are currently being implemented, therefore
a P&TS for assessment to address consecutive exceedances is not necessary.

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-26 Class III
water
Cross
Gradient of
Cell 2
Nitrate + Nitrite (as N)
Chloroform
Chloride
Tetrahydrofuran
February 2010
February 2010
February 2010
January 2024
May 2010
May 2010
May 2010
2nd Quarter 2024

Note: MW-26 is used as a pumping well for the ongoing chloroform capture program and is
expected to yield an increased concentration of chloroform in groundwater. MW-26 is also
located within the nitrate plume which also contains an elevated concentration of chloride. CAPs
have been approved by DWMRC addressing chloroform in 2011 and Nitrate + Nitrite/Chloride in
2012. Activities associated with the CAPs are on-going and consecutive exceedances of the
GWCLs for these constituents is expected to occur. A P&TS for assessment of consecutive
exceedances is not necessary.

During the 1st Quarter 2024 sampling event in January, Tetrahydrofuran (THF) tested above the
GWCL of 23 ug/L. Accelerated monthly sampling was initiated for the 2nd Quarter 2024. While
these sampling events have not been officially transmitted in a quarterly Groundwater Monitoring
Report, preliminary reports indicate that all three sample events tested non-detect for THF. The
concentration of THF at MW-26 and surrounding wells will continue to be monitored closely.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 6

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-30 Class II
water
Downgradient
of Cell 2
Nitrate + Nitrite (as N)
Chloride
Uranium
Selenium
Field pH
February 2010
1st Quarter 2011
1st Quarter 2021
1st Quarter 2019
4th Quarter 2022
May 2010
May 2011
April 2021
May 2019
March 2023

Nitrate + Nitrite (as N) and Chloride – MW-30 is downgradient from and within the Nitrate
plume and actions currently being implemented from an approved CAP for Nitrate + nitrite are
expected to address chloride also. A P&TS for assessment to address consecutive exceedances is
not necessary, the concentration of these constituents in groundwater will be monitored closely.

Uranium and Selenium – The concentration of both these constituents in groundwater has
increased gradually at similar rates since 2005. Under the current GWDP, consecutive
exceedances of the 9.82 ug/L GWCL for Uranium occurred in 2021 and the 47.2 ug/L GWCL for
selenium, established during the 2018 GWDP revision, was exceeded on consecutive occasions in
2019. A SAR was approved by DWMRC on April 5, 2022, which proposed modifications of the
GWCLs for Uranium to 13.11 ug/L and for Selenium to 72.52 ug/L. The new GWCLs will
become effective in the next revision of the GWDP.

Uranium exceeded the current GWCL in all three of the accelerated monthly sampling events in
the 1st Quarter 2024 (11.2 ug/L, 10.0 ug/L 10.9 ug/L). Selenium exceeded the current GWCL in
all of the three accelerated monthly sampling events in the 1st Quarter 2024 (73.2 ug/L, 66.7 ug/L,
67.5 ug/L). Selenium also exceeded the proposed GWCL of 72.52 ug/L during 4 out of the last 9
monthly accelerated sample events including the 1st Quarter of 2024. As such, the Division may
re-consider the proposed GWCL for Selenium before the next revision of the GWDP.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 7

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-31 Class III
water
Downgradient
of Cell 2
Nitrate + Nitrite (as N)
Chloride
Total Dissolved Solids
Sulfate
Uranium
1st Quarter 2010
1st Quarter 2011
3rd Quarter 2019
3rd Quarter 2019
2nd Quarter 2020
May 2010
May 2011
November 2019
November 2019
August 2020

Nitrate + Nitrite (as N) and Chloride – MW-31 is downgradient from and within the
Nitrate/Chloride plume and actions currently being implemented from an approved CAP for
Nitrate + nitrite are expected to address chloride also. A P&TS for assessment to address
consecutive exceedances is not necessary, the concentration of these constituents in groundwater
will continue to be monitored closely.

Total Dissolved Solids (TDS) and Sulfate – Consecutive exceedances under the current GWCLs
for TDS (2,132 mg/L) and Sulfate (993 mg/L), established during the 2019 GWDP revision,
occurred in the 3rd and 4th Quarter 2019 sampling events for both constituents. A SAR was
approved by DWMRC on August 6, 2020, which proposed modifications of the GWCL for TDS
to 2,664 mg/L and Sulfate to 1,170.5 mg/L. The new GWCLs will become effective in the next
revision of the GWDP. Both constituents have experienced increases in concentration at MW-31
since 2005, however, per DWMRC review, from 2021 until the 1st Quarter 2024, a linear trend
analysis shows a flattening trend for TDS and Sulfate. TDS and Sulfate exceeded their current
GWCLs during all three of the 1st Quarter 2024 monthly accelerated sampling events.

Uranium - The current GWCL for Uranium of 15 ug/L was established during the 2019 GWDP
revision. Consecutive exceedances of the current GWCL occurred in the 2nd and 3rd Quarter 2020
sampling events and accelerated monthly sampling began in August 2020. A SAR was approved
by the Division on July 7, 2021, which proposed modifications of the of the GWCL to 29.03 ug/L.
The new GWCL will become effective in the next revision of the GWDP. Uranium exceeded the
current GWCL during all three of the 1st Quarter 2024 monthly accelerated sampling events at
concentrations of 25.0 ug/L, 24.9 ug/L, and 27.6 ug/L.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 8

Wells Monitored Semi-annually Accelerated to Quarterly Monitoring

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-03A Class III Downgradient
of Cell 4B
Selenium 2nd Quarter 2023 4th Quarter 2023

Selenium – Selenium exceeded the current GWCL of 109.58 ug/L in the 1st Semi-annual
sampling event of 2023 in April, testing at 112 ug/L. Accelerated quarterly sampling was initiated
in the 3rd Quarter 2023 sampling event and a second consecutive exceedance was recorded. A
P&TS for assessment was submitted and approved by the Division on December 5, 2023. A SAR
was submitted on March 4, 2024, and approved by the Division on May 7, 2024. The SAR
proposed a revision of the GWCL to 171 ug/L. Per Division review, a linear trend analysis of
Selenium concentration in groundwater since 2005 appears to show a slight upward trend,
however the concentration has been variable over that time, fluctuating between 70 ug/L and 110
ug/L during the majority of sample events.

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-05 Class II Downgradient
of Cell 3
Uranium 2nd Quarter 2023 4th Quarter 2023

Uranium – Under the current GWDP, Uranium first exceeded the GWCL of 7.5 ug/L in the 1st
Semi-annual sampling event of 2023 in April. Accelerated quarterly sampling was initiated for
the 3rd Quarter 2023 sampling event and results were below the GWCL. In both the 4th Quarter
2023 and 1st Quarter 2024 sample events, the concentration of Uranium in MW-05 was below the
GWCL. Per Division review, since 2005, the Uranium concentration in groundwater at MW-05
has been below the GWCL for the majority of the sample events (49 out of 58).

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-17 Class III
water
Downgradient
of 4A
Chloride 4th Quarter 2022 2nd Quarter 2023

Chloride – Chloride exceeded the 46.8 mg/L GWCL during the 2nd Semi-Annual sampling event
of 2022 in October, testing at 54.0 mg/L. This is the first and only exceedance since sampling
was initiated in 2005. Accelerated quarterly sampling was initiated during the 1st Quarter 2023
and results did not exceed the GWCL. In the four sample events since, including 1st Quarter 2024,
Chloride has not exceeded the GWCL. Per Division review, since 2007, the Chloride
concentration in groundwater at MW-17 has been consistently between 30 mg/L and 40 mg/L
with the only exceedance being during the 4th Quarter 2022 sample event.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 9

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-24 Class III
water
Downgradient
of Cell 1
Beryllium
Cadmium
Thallium
Field pH
Fluoride
Nickel
Manganese
Sulfate
Gross Alpha
Total Dissolved Solids
4th Quarter 2017
2nd Quarter 2018
2nd Quarter 2018
2nd Quarter 2018
4th Quarter 2018
4th Quarter 2018
4th Quarter 2019
1st Quarter 2020
4th Quarter 2023
2nd Quarter 2021
1st Quarter 2018
3rd Quarter 2018
3rd Quarter 2018
3rd Quarter 2018
3rd Quarter 2019
3rd Quarter 2019
1st Quarter 2020
3rd Quarter 2020
2nd Quarter 2024
3rd Quarter 2021

Note: After multiple constituents reached OOC status, a SAR was approved by the Division in
2019 to study groundwater trends near MW-24. The source assessment is nearing completion as
Phase 2 included installation of a downgradient/co-located well (MW-41B) in April 2023. An
additional P&TS for consecutive exceedances is not required. The concentration of all
constituents in groundwater at MW-24 will continue to be monitored closely and exceedances will
continue to be tracked until conclusion of the source investigation. Three rounds of groundwater
sampling at co-located well MW-41B have been completed through the 1st Quarter 2024.

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-27 Class III
water
Upgradient of
Cell 1
Nitrate + Nitrite (as N)
Fluoride
2nd Quarter 2010
2nd Quarter 2022
3rd Quarter 2010
3rd Quarter 2022

Nitrate + Nitrite (as N) - MW-27 is downgradient/cross-gradient from the Nitrate plume and a
CAP addressing Nitrate + Nitrite in groundwater was approved in 2012. Activities associated
with the CAP are on-going and a P&TS for assessment of consecutive exceedances is not required
for Nitrate + Nitrite and Chloride. In the previous 7 quarterly sampling events including the 1st
Quarter 2024, Nitrate + Nitrite (as N) has been below the GWCL of 5.6 mg/L.

Fluoride –Since 2010, Fluoride only exceeded the 0.85 mg/L GWCL one time during the 1st
Semi-Annual sampling event of 2022. Accelerated quarterly sampling was initiated during the 3rd
Quarter 2022. No exceedances have occurred since.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 10

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-28 Class III
water
Downgradient
of Cell 1
Chloride
Uranium
Selenium
Nitrate + Nitrite (as N)
Total Dissolved Solids
2nd Quarter 2010
2nd Quarter 2014
2nd Quarter 2019
1st Quarter 2019
2nd Quarter 2023
3rd Quarter 2010
2nd Quarter 2014
3rd Quarter 2019
3rd Quarter 2020
3rd Quarter 2023

Chloride and Nitrate + Nitrite (as N) – It appears that MW-28 is impacted by the western
margin of the Nitrate and Chloride plume and a CAP addressing Nitrate + Nitrite and Chloride in
groundwater was approved in 2012. Activities associated with the CAP are on-going and a P&TS
for assessment of consecutive exceedances is not required for Nitrate + Nitrite and Chloride. Per
Division review, after increases in the concentration of both constituents since sampling of MW-
28 began in 2005, the concentration of Nitrate + Nitrite from 2022-2024 has remained near the
GWCL of 5 mg/L and the concentration of Chloride has remained near 150 mg/L.

Uranium and Selenium - Consecutive exceedances of the GWCLs for Uranium (4.9 ug/L) and
Selenium (11.1 ug/L) have occurred and a SAR was approved by the Division on January 21,
2021. The SAR proposed modifications of the GWCLs for Uranium to 12.29 ug/L and for
Selenium to 17.9 ug/L. The new GWCL will become effective in the next revision of the GWDP.
Per Division review, the concentration of Uranium and Selenium in groundwater at MW-28 has
increased since 2017 but appears to show a flattening trend recently. Uranium and Selenium
exceeded their current respective GWCLs during the 1st Quarter 2024 sample event. Selenium has
exceeded the proposed GWCL of 17.9 ug/L during 6 out of the last 9 accelerated sample events up
to and including the 1st Quarter of 2024. Uranium has exceeded the proposed GWCL of 12.29
ug/L during 4 out of the last 9 accelerated sample events up to and including the 1st Quarter of
2024. As such, the Division may re-consider the proposed GWCLs for Selenium and Uranium
before the next revision of the GWDP. The concentration of Uranium and Selenium in
groundwater at MW-28 will continue to be monitored closely.

Total Dissolved Solids (TDS) – TDS first exceeded the GWCL of 3,852 mg/L in the 1st Semi-
annual sampling event of 2023 in April. Accelerated quarterly sampling was initiated for the 3rd
Quarter 2023 sampling event and results were below the GWCL. In the 4th Quarter 2023 and 1st
Quarter 2024 accelerated sample events, the concentration of TDS in MW-28 was once again
below the GWCL. Per Division review, since 2005, a linear trend analysis of the TDS
concentration in MW-28 shows a stable to decreasing trend with the only exceedance of the
GWCL occurring in the 1st Semi-annual sampling event of 2023 in April.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 11

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-29 Class III
water
Downgradient
of Cell 2 Uranium 1st Quarter 2021 3rd Quarter 2021

Uranium – The first exceedance of the current 15 ug/L GWCL was during the 2nd semi-annual
sampling event of 2020. Accelerated quarterly sampling and a consecutive exceedance occurred
in the 1st Quarter of 2021. A P&TS was submitted and a SAR was approved by the Division on
January 18, 2022. A modified GWCL of 20.2 ug/L will become effective in the next revision of
the GWDP. Per Division review, the concentration of Uranium in MW-29 from 2021-2024 has
remained steady and near the GWCL of 15 ug/L. Uranium exceeded the current GWCL in the 1st
Quarter 2024 sampling event (16.4 ug/L).

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-32 Class III
water
Cross-
Gradient of
Cell 2
Chloride 2nd Quarter 2014 4th Quarter 2014

Chloride – MW-32 (also known as TW4-17) has been sampled for Chloride since 2005. The
GWCL has been established as 35.39 mg/L. Per Division review, a linear trend analysis of
Chloride in MW-32 since 2005 appears to show a slight increasing trend, however, the
concentration in groundwater has generally remained from 30-40 mg/L with a handful of
exceptions over that same time. MW-32 is nearby the Nitrate plume and a CAP addressing
Nitrate + Nitrite and Chloride in groundwater was approved in 2012. Activities associated with
the CAP are on-going and a P&TS for assessment of consecutive exceedances is not required for
Chloride. Chloride exceeded the GWCL in the 1st Quarter 2024 sampling event (38.5 mg/L).

Well Water
Class
Location Parameter Date of First
Exceedance of
GWCL
Date Accelerated
Monitoring First
Required
MW-37 Class III
water
Downgradient
of Cell 4B
Field pH 4th Quarter 2022 2nd Quarter 2023

Field pH – During quarterly sampling from 2011 – 2017, Field pH exceeded the current GWCL
limits of 6.61 - 8.5 in 8 of the 26 sampling events including consecutive exceedances in 2016-
2017. Under the current GWDP, semi-annual sampling was performed from 2018 until an
exceedance occurred during the 2nd Semi-Annual sampling event of 2022 in November (pH =
6.60). A second consecutive exceedance of the GWCL limits occurred during accelerated
quarterly sampling initiated during the 1st Quarter 2023 (pH = 6.55) and Field pH at MW-37 went
into OOC status. A P&TS was submitted, and a SAR was approved by the Division on November
6, 2023. Per the SAR, the Field pH GWCL limits were modified to 6.05-8.5, based on the lowest
historical value, and will become effective in the next revision of the GWDP. Per Division
EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 12

review, a linear trend analysis since 2016 appears to show Field pH with an increasing trend
towards neutral. Field pH tested at 6.93 during the 1st Quarter 2024 sample event.

Division Review Checklist:

1. Monitoring Wells Purged for Two Casing Volumes Before Sample Collection:

As stated in Section 6.2.7 of the EFR Quality Assurance Plan (QAP), Rev. 7.7, EFR has a choice
regarding purge volumes as follows:

“1. Purging three well casing volumes with a single measurement of field parameters
2. Purging two casing volumes with stable field parameters (within 10% RPD)
3. Purging a well to dryness and stability of a limited list of field parameters after recovery”

Per Division review of the Report, the following purge methods were used during the 1st Quarter
2024 (including monthly accelerated samples). Purge methods and volumes are summarized in
Tab G, on Table G-1A and G-1B of the Report:

Quarter # Purged 2 Casing
Volumes
# Purged to Dryness # Purged 3 Casing Volumes
1st Qtr. 2024 25 4 2 (continuous pumping)

When purging two casing volumes, the QAP directs EFR to first calculate the amount of time to
evacuate two casing volumes and then to pump for that length of time. Per Division cross-check
of the field data sheets for each of the reports reviewed, it appears EFR correctly calculated the
well casing volumes and evacuated the required two volumes (when 2 casing volume method
selected) in monitoring wells prior to sample collection during the 1st Quarter 2024 monitoring
period. Volumes are calculated according to measured pump rates and can be verified by
calibration marks on the collection containers.

During the 1st Quarter 2024 monitoring period, four monitoring wells were pumped or bailed to
dryness (MW-03a, MW-37, MW-38, and MW-41B). In cases where wells are evacuated to
dryness the QAP Rev. 7.7 (Attachment 2-3) requires that:

“(vii) If the well is purged to dryness:

Record the number of gallons purged on the Field Data Worksheet.

The well should be sampled as soon as a sufficient volume of groundwater is available to fill
sample containers.

Upon arrival at the well after recovery or when sufficient water is available for sampling measure
depth to water and record on the Field Data Worksheet.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 13

Take one set of measurements of field parameters for pH, specific conductance, and temperature
only.

Collect the samples into the appropriate sample containers.

Take an additional set of measurements of field parameters for pH, specific conductance and
temperature after the samples have been collected.

If the field parameters of pH, specific conductance and temperature are within 10% RPD the
samples can be shipped for analysis.

If the field parameters of pH, specific conductance and temperature are not within 10% RPD,
dispose of the sample aliquots, and purge the well again as described above.

Repeat this process, if necessary, for three complete purging events. If after the third purging the
event, the parameters of pH, specific conductance and temperature do not stabilize to within 10%
RPD, the well is considered sufficiently purged and collected samples can be submitted for
analysis.”

Division staff verified that in cases where the monitoring well was evacuated to dryness and
samples were collected, the number of gallons evacuated was recorded in compliance with the
QAP. Additionally, depth to water before sample collection was recorded on all applicable field
data worksheets which resolved past Division comments.

2. Analytical Laboratories Used by EFR Certified by State of Utah to Perform Analysis
for all Analytes:

The analytical laboratories (GEL Laboratories LLC, Charleston, SC; Chemtech Ford Laboratory,
Sandy, UT) were contracted by EFR to perform analysis on the samples collected during the 1st
Quarter 2024. Per Division review of the National Environmental Laboratory Accreditation
Management System Website, both laboratories have an active certification within the State of
Utah. Screen prints from the website showing certification status are included in Appendix A.
Upon further cross checking of laboratory certification for specific parameters, it appears that the
EFR contract laboratories were certified to perform analysis for the specified parameters.

3. Laboratory Report Turn Around Times:

Per Division review of Laboratory reports contained in Tab E and Tab F, it was noted that
laboratory report turnaround times for both quarterly and accelerated monitoring was
approximately 28 days for radiological analysis performed by GEL and approximately 13 days for
all other analyses performed by Chemtech Ford (not including re-submission/corrected reports, if
any). The turn-around times and EFR data review timelines appear to be reasonable/appropriate.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 14

4. Sample Holding Times:

Per review of the 1st Quarter 2024 Report (Section 3.4.2, Tab E, Tab F, and Tables G-2A and G-
2B in Tab G of the Report, all method holding times were met for each analyte submitted for
laboratory analysis (for quarterly and accelerated samples). Division staff cross checked all
holding time requirements and verified that all samples/analytes appeared to be analyzed within
holding times during the reporting period.

5. Sample Preservation:

Per review of the 1st Quarter 2024 Report (Section 3.4.3, Tab E, Tab F, Tab G), it appears that all
samples required to be chilled (≤6° C) met the temperature preservation requirements. Per review
of the laboratory check-in sheets and laboratory QA/QC, no issues related to sample preservation
were noted. Per EFR information and method requirements, samples for gross alpha analysis do
not have a sample temperature requirement.

6. Analytical Reporting Limits:

Per Division review of the quarterly and accelerated electronic laboratory analytical reports as
well as Tables G-5A and G-5B in the 1st Quarter 2024 Report, it appears that laboratory reporting
limits met the required reporting limits set forth in Table 1 of the QAP.

7. Sample Trip Blank Evaluation:

Per review of the 1st Quarter 2024 Report, it appears that all trip blank samples met the following
criteria:
- Per Section 3.4.6, Tabs E and F, Table G-6A, and Table G-6B of the Report, all trip
blank results were non detect for VOCs.
- Per Table G-2A and Table G-2B in Tab G of the Report, all trip blank samples were
analyzed within the allowed holding time.
- Per Table G-3A and Table G-3B in Tab G of the Report, all trip blank samples were
received by the Laboratory within an acceptable temperature range.
- Per Table G-5A and Table G-5B in Tab G of the Report, the laboratory reporting limit
for all trip blank samples associated with the quarterly and accelerated samples met the
required reporting limits.

8. Review of Time-Concentration Plots

The Permit Part I.F.1.g requires EFR to submit Time-Concentration Plots for each monitoring
well for primary indicators of cell leakage; chloride, fluoride, sulfate, and uranium. The Division
notes that per the discussions with EFR, it was agreed that EFR need not plot trend lines on the
Time Concentration Plots and that all data is included on the plots (no data culled from the set).
Per Division review of the 1st Quarter 2024 Report, the reviewed plots appear to be in
conformance with the agreed upon changes.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 15

9. Review of Depth to Groundwater Measurements and Water Table Contour Maps

Per Division cross checks of groundwater elevation measurement calculations used for the 1st
Quarter 2024, approximately 5% of wells cross checked, comparing surface casing measured
elevations minus measured static levels with plotted elevations, no errors were noted.

The upper wildlife ponds at the White Mesa Mill were taken offline (pond recharge from
Recapture Reservoir discontinued) during the 2nd Quarter 2011 to re-establish groundwater
contours. Hydrographs of the upper wildlife pond ground water piezometers (Water Level
Elevation vs. Time) are included in Appendix B (Northern piezometers and southern
piezometers). It was also noted that the static water levels in several monitoring wells close to the
upper wildlife ponds showed significant decrease in water levels since the ponds were taken
offline. These declines can be attributed to natural dissipation of the area ground water mound
and/or ground water pumping activities related to corrective action of nitrate and chloroform
contamination plumes (development of cone of depressions around pumping wells).

Nitrate and Chloroform Corrective Action Plan Pumping Wells:

Ground water elevations are being impacted by effects from ground water pumping for the nitrate
and chloroform contamination plume remediation. The following monitoring wells have been
converted to active pumping wells:

Nitrate Pumping Wells – TW4-22, TW4-24, TW4-25, TWN-2 (The nitrate pumping project was
initiated during January 2013).

Chloroform Pumping Wells – MW-4, MW-26, TW4-1, TW4-2, TW4-4, TW4-11, TW4-19, TW4-
21, TW4-22, TW4-24, TW4-25, TW4-37, TW4-39.

The pumping wells for both the nitrate and chloroform projects are set up with a delay device
wherein the wells purge for a set amount of time then shut off to let the well recharge. All
pumping wells include a flow meter which records the volume of water pumped from the well in
gallons. Quarterly nitrate and chloroform reports are prepared by EFR and include pump volumes
and delineation of pump capture zones based on kriged water contours. The Division expects that
ground water elevation contours will continue to adjust in response to the pumping activities and
discontinuance of recharge to the upper wildlife ponds.

12. Conclusions and Recommendations

Per the Division review it appears that the Report complies with Permit and QAP. Therefore, a
letter will be drafted notifying EFR of the review and closing out of the April 24, 2024, 1st
Quarter, 2024 Groundwater Report.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 16

13. References

1 Energy Fuels Resources (USA) Inc., April 24, 2024, 1st Quarter 2024 Groundwater Monitoring
Report, Groundwater Discharge Permit UGW370004, White Mesa Uranium Mill.

2 Energy Fuels Resources (USA) Inc., April 19, 2024, State of Utah Ground Water Discharge
Permit No. UGW370004 White Mesa Uranium Mill – Notice Pursuant to Part I.G.1(a).

3 Energy Fuels Resources (USA) Inc., February 15, 2022, White Mesa Uranium Mill Ground
Water Monitoring Quality Assurance Plan (QAP), Revision 7.7.

4 INTERA Incorporated, 2007, Revised Background Groundwater Quality Report: Existing Wells
for Dension Mines (USA) Corp.’s White Mesa Uranium Mill Site, San Juan County, Utah.

5 INTERA Incorporated, 2007, Background Groundwater Quality Report: New Wells for Denison
Mines (USA) Corp.’s White Mesa Uranium Mill Site, San Juan County, Utah.

6 Utah Department of Environmental Quality, March 8, 2021, Modified Utah Ground Water
Discharge Permit No. UGW370004 issued for the Energy Fuels Resources (USA) Inc. White Mesa
Uranium Mill.

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 17

Appendix A – State of Utah Laboratory Certifications

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 18

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 19

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 20

Appendix B – Hydrographs of the Upper Wildlife Pond
Groundwater Piezometers

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 21

EFR 1st Quarter 2024 Groundwater Monitoring Report
DWMRC Review Memo
Page 22