DRC-2024-006168

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

Kimberley 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: File

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

FROM: Chris Leahy, P.G.

DATE: July 2, 2024

SUBJECT: Review of the Rio Algom Mining, LLC. Lisbon Facility 2023 Annual
Groundwater Monitoring Report, Dated February 28, 2024 and October 25, 2023
Division Split Sampling Findings

This memorandum summarizes the Utah Division of Waste Management and Radiation Control
(Division) review of the Rio Algom Mining, LLC (RAML) 2023 Annual Groundwater
Monitoring Report dated February 28, 2024 (received by the Division on March 1, 2024) (2023
Report) for the former Lisbon Valley Uranium Mill Facility (Facility). The Report was prepared
for RAML by Arcadis U.S., Inc. (Arcadis). This memorandum also includes a summary of
findings related to a Division/RAML split sampling event which occurred on October 25, 2023.

The Report was reviewed to determine compliance with the Facility Radioactive Materials
License No. UT1900481, Amendment 7 (License), Condition 29 relating to Groundwater
Protection.

RAML Ground Water Monitoring Plan

The 2023 Report was also reviewed to determine accordance with the July 31, 2015
Groundwater Monitoring Plan (GWMP), approved by the Division by letter dated August 19,
2015 (DRC-2015-005043).

The GWMP incorporates additional requirements to ensure quality control and assurance of
ground water sample collection and data quality per several discussions between the Division
and RAML regarding these issues. Per these discussions it was agreed that the GWMP would
serve to replace the RAML application for a Utah Groundwater Quality Discharge Permit
# - $ . / * + # - # 4 — 0 ' A v A ? A C @ E w ? H ˜
Adam Wingate (Jul 3, 2024 10:03 MDT)
Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 2

(RAML Application dated October 3, 2013), since the GWMP provides the information and
requirements which were intended to be included in the Permit. This was also considered
appropriate since the Facility is no longer active and is in the process of final remediation,
groundwater corrective action, and eventual ACL amendment/approval to facilitate License
transfer to the U.S. Department of Energy. Additionally, in 2023, the Facility entered into a
stipulation and consent agreement for actions leading to a GCAP. Specific criteria regarding the
GCAP will likely prompt a revision/update of the GWMP.

The GWMP includes a Facility groundwater monitoring quality assurance plan (QAP) as
Appendix B.

Review of Groundwater Monitoring Results

Monitoring wells sampled for the 2023 sampling period are listed on the Table 2 of the 2023
Report. Groundwater samples for this period were collected from all required wells listed in the
current License as verified through review of laboratory reports and field collection sheets
contained in appendices of the 2023 Report. Table 1 in the 2023 Report summarizes the
frequency of well sampling for monitoring wells EF-8, OW-UT-9 and RL-1 currently in Out of
Compliance (OOC) quarterly monitoring, and RL-3 in OOC monthly monitoring.

Comprehensive data tables, including historical data are included in the Report (summarized on
Table 3 of the Report) as required by License Condition 29.F. Review of data for monitoring
wells EF-8, RL-1, RL-3 and OW-UT-9, revealed continuing OOC status for laboratory results
for uranium in EF-8, uranium in RL-1, and arsenic in OW-UT-9. RL-3 remains in OOC status
for uranium, however none of the monthly 2023 results exceeded the target action level (TAL) of
37.3 mg/L.

During the 4th quarter 2023 sampling event, molybdenum in OW-UT-9 tested at 59.8 mg/L (over
the alternate concentration limit (ACL) of 58.43), triggering Probable Out of Compliance
(POOC) status. The Division was notified within 30 days of receipt of laboratory data. Four
subsequent re-injections/re-testing of the 4th quarter 2023 sample by the laboratory showed
results under the ACL for molybdenum while still being within the laboratories 20% precision
rate. RAML completed accelerated sampling of OW-UT-9 in the first quarter of 2024, results of
which showed the concentration of molybdenum at 50.2 mg/L, under the ACL. Per Division
review, since 2015, the concentration of molybdenum in OW-UT-9 has remained relatively
constant, generally between 45-50 mg/L, with the absence of an increasing trend. The
concentration of molybdenum in groundwater at OW-UT-9 will continue be monitored closely

The Division’s corrective actions for these parameter exceedances includes the License
requirement for accelerated monitoring and the requirement for implementation of a site
assessment to evaluate the contaminant plume, conceptual modeling to characterize flow paths
and directions, and computer modeling to analyze the validity (public health and environmental
protections) of the current ACLs and TALs. Per recent Division reviews of the Hydrogeological
Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 3

Supplemental Site Investigations and the Corrective Action Assessment Work Plan (CAAWP),
the facility is moving to an active Groundwater Corrective Action Plan (GCAP) to address
ongoing and currently expanding contamination.

The following text and tables summarize the reported concentrations for the parameters listed in
the License and collected by RAML during calendar year 2023.

Table 1 -- Reported Concentrations Values for the ACL’s listed in the License – Point of
Compliance (POC) Wells

Well
No.
Sample
Date
Mo
ACL
(mg/L)
Mo
Measured
(mg/L)
Se
ACL
(mg/L)
Se
Measured
(mg/L)
As
ACL
(mg/L)
As
Measure
d(mg/L)
U
ACL
(mg/L)
U
Measured
(mg/L)
EF-
3A
4/21/20223
23.34
3.40
0.93
0.044
3.06
0.251
96.87
23.0
10/29/2023 2.67 0.038 0.166 23.2
OW-
UT-9
3/2/2023
58.43
50.0
0.10
0.022
2.63
3.09
101.58
83.0
4/19/2023 50.0 0.024 3.51 86.1
8/2/2023 48.2 0.021 3.01 84.4.
10/28/2023 59.8 0.028 3.57 88.3

Review of data for “point of exposure” wells RL-4, RL-5, and RL-6 for the 2023 sampling event
revealed that all reported concentrations of dissolved uranium are below the compliance limits
listed in Condition 29.B. of the License.

Table 2 -- Reported Concentrations for Uranium Compared with Compliance Limits in the
License -- Point of Exposure (POE) Wells

Well No. Sample Date License Uranium Compliance
Limit (mg/L)
Uranium Measured
(mg/L)
RL-4 4/20/2023 0.32 0.0030
10/30/2023 0.0029
RL-5 4/20/2023 0.32 0.0021
10/26/2023 0.0020
RL-6 4/19/2023 0.32 0.0260
10/25/2023 0.0272
Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 4

Review of data for trend wells EF-6, EF-8, ML-1, RL-1, RL-3 and H-63 revealed continuing
OOC status for dissolved uranium results at well RL-1 and EF-8.

Table 3 – Reported Concentrations for Uranium Compared with Uranium Target Action Levels
– Trend Wells

Well No. Sample Date License Uranium Target
Action Level (mg/L)
Uranium (mg/L)
EF-6 4/25/2023 3.9 2.58
10/29/2023 2.82
EF-8
3/2/2023
0.30

3.13
4/21/2023 3.00
8/1/2023 3.27
10/29/2023 3.71
ML-1 4/25/2023 0.26 0.0084
10/30/2023 0.0078
RL-1

3/2/2023
42.1

46.0
4/19/2023 40.4
8/1/2023 43.3
10/26/2023 41.6
RL-3
1/25/2023
37.3
33.0
2/27/2023 32.0
3/22/2023 31.0
4/19/2023 31.6
5/16/2023 31.5
6/13/2023 15.4
7/18/2023 33.9
8/2/2023 28.4
9/12/2023 33.0
10/26/2023 32.0
11/14/2023 35.7
Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 5

Well No. Sample Date License Uranium Target
Action Level (mg/L)
Uranium (mg/L)
12/12/2023 30.0
H-63 4/18/2023 0.06 0.0074
10/25/2023 0.0074
LW-1 4/25/2023 0.028 0.0031
10/27/2023 0.0031

As mentioned above, four well parameters are currently in out-of-compliance status per License
condition 29.C. These wells parameters are 1) arsenic in well OW-UT-9; 2) uranium in well EF-
8; 3) uranium in well RL-1, and; 4) uranium in monitoring well RL-3. These wells/parameters
are therefore in accelerated monitoring. Scatter plots and discussion is included for each of these
wells/parameters below:

1) Arsenic in well OW-UT-9: The arsenic concentration has been above the ACL of 2.63 mg/L
since 2014 and accelerated monthly or quarterly monitoring has been required since 2005. OW-
UT-9 is located downgradient from and immediately adjacent to the upper tailings impoundment.
Per Figure 1 below, it appears that a flattening trend in recent years can be observed.

Figure 1 – Time Series Plot of Historical Arsenic Concentration at OW-UT-9

Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 6

2) Uranium in well EF-8– The concentration of uranium in EF-8 shows a strong increasing trend.
It appears that the western side of the plume is flowing along the Lisbon Fault northward. Past
hydrogeological site assessments and groundwater modeling efforts have attempted to
characterize migration of the plume. An updated groundwater model will be provided as part of
the ongoing Corrective Action Assessment, as described in the Corrective Action Assessment
Work Plan (CAAWP) submitted to the Division in late 2022. After a corrective action is chosen,
a GCAP for the site will be developed.

Figure 2 – Time Series Plot of Historical Uranium Concentration at EF-8

3) Uranium in well RL-1: Per Figure 3 below, an apparent increasing trend in uranium exists in
monitoring well RL-1 prior to approximately 2013. RL-1 is located on the east side of the
anticline impermeable zone. It is likely that the plume is migrating northward along the
impermeable zone boundary. Per review of the plot, it appears that the uranium trend has been
flattening in recent years.
Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 7

Figure 3 – Time Series Plot of Historical Uranium Concentration at RL-1

4) Uranium at well RL-3: RL-3 shows increasing uranium concentration since 2012, however it
is noted that none of the 2023 uranium data exceeds the target action level of 37.3 mg/L.

Figure 4 – Time Series Plot of Historical Uranium Concentration at RL-3
Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 8

Division Review Summary:

The Division reviewed the 2023 Report for compliance with License Condition 29.F which states
the annual groundwater monitoring reports shall include the following data at a minimum:
- Sampling Methodology
- Field Parameter Measurements
- Laboratory information, the lower limit of detection shall be lower than the ACL
- Data Evaluation
- Figures (Groundwater Contour Map, Uranium Concentration versus the Predicted
Concentration for compliance wells, Isoconcentration Map for arsenic, molybdenum,
selenium and uranium.
- Data Tables summarizing recent and historic monitoring data
- Concentration vs. Time Plots for compliance wells
- Appendices including copies of field measurements laboratory analytical reports and
chain of custody documentation

QA/QC for the 2023 Annual Report was reviewed per the current conditions in the GWMP.
Current QA/QC reporting requirements are found in the approved RAML GWMP, Version 2.0
(July 31, 2015) Section 3.0 and Appendix B. The GWMP includes requirements for
groundwater sampling procedures, required analytical procedures, laboratory quality control, and
internal (RAML) quality control checks and performance audits.

Ground Water Sampling Methodology/ Field Parameter Measurements

The ground water sampling methodology is included in the RAML GWMP. Per review of the
2023 Report, it was noted that all wells were purged prior to sampling using the approved low
flow purging and sampling methods. Per requirements of this method, groundwater is required
to achieve stabilization of prescribed field parameters prior to sampling.

Per Division field reviews during split sampling activities, it appeared that Arcadis is performing
the sampling in conformance with the GWMP procedures and no comments regarding sample
collection validity were noted per review of the Report. Per discussion below, the Division split
samples with RAML at two monitoring wells during 2023.

Ground Water Sampling Field Parameter Measurements

Table 2 of the 2023 Report summarizes the sampling field results for compliance wells in 2023.
Depth to water (DTW), purge volume, and final parameter readings are tabulated for each well.
Details are supplied in Appendix C of the 2023 Report through equipment print-outs of the
sampling logs provided by the water quality meters (Aqua Troll 600). Included in the printouts
is all of the same information previously contained in the field sheets. The printouts, titled “low
flow test reports” include:
Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 9

Date and Time, Weather Conditions, Client/Project, Operator (Sampler) Name, Well
I.D., Well Diameter, Casing Type, Screen Length, Top of Screen Depth, Total Depth,
Depth to Water (initial and final), Pump used, pump intake depth, Purge Rate,
Volume removed, instrument used, Field Parameter Readings (Time, Temp., pH,
Cond., Turbidity, DO, ORP, DTW during purge, and, Notes), Sample time, and
Sample I.D including any qa/qc samples.

Per Division review it appears that all field sheets were filled out completely and that field
stabilization criteria were achieved for the compliance wells prior to sample collection in
conformance with the submitted procedures. Appendix C of the 2023 Report also included
forms for water level measurements, well maintenance inspections, and sampling equipment
calibration. Per all forms inspected, no issues were noted.

Review of RAML Data Evaluation and Historical Data Tables

As stated above in the Review of Groundwater Results section, a data evaluation was performed
by RAML, and comprehensive historical data tables were included in the Report as required by
License Condition 29.F.

Figures - Groundwater Maps and Plots Review

Groundwater maps were contained in the Figures section of the 2023 Report including a;
1. Site Map with compliance monitoring well locations
2. Groundwater Elevation Contour Map
3. Dissolved Uranium Concentration Contour Map
4. Dissolved Arsenic Concentration Contour Map
5. Dissolved Selenium Concentration Contour Map
6. Dissolved Molybdenum Concentration Contour Map

All maps were dated October 2023. Per Division review it appears that all contour maps required
by the License were submitted. Between October 2022 and October 2023, groundwater level
increases greater than 1 foot were observed at six locations: EF-3A (+2.87 ft), EF-6 (+2.85 ft),
EF-8 (+2.94 ft), H-63 (+ 3.03 ft), ML-1 (+ 7.28 ft) and RL-6 (+ 1.35 ft). Per the 2023 report,
precipitation during the 2022 to 2023 winter season was greater than the previous year and could
be a contributing factor to the overall groundwater level increases observed at the Site.

Time Concentration Plots Review

Appendix A of the 2023 Report includes analytical time-concentration plots (time series charts)
of data for each of the 14 compliance monitoring wells for arsenic, molybdenum, selenium,
uranium, sulfate, chloride, bicarbonate, pH, total dissolved solids and ground water level
elevation. The plots do not include a trend line. Per Division staff review of the plots, it appears
that the 2023 data is included on the plots and that the License requirement was met.
Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 10

Background Concentration Wells Review
Per License Condition 29.A background wells MW-5 (north aquifer) and MW-13 (south aquifer)
shall be monitored for arsenic, molybdenum, selenium, and uranium. Below are the results
compared to the established background concentrations.
Table 4 - Reported Concentrations for Background Wells Compared with Established
Background.
Well No. Sample
Date
U-Nat
Established
Background
(mg/L)
U-Nat
Measured
(mg/L)
As
Established
Background
(mg/L)
As
Measured
(mg/L)
Mo
Established
Background
(mg/L)
Mo
Measured
(mg/L)
Se
Established
Background
(mg/L)
Se
Measured
(mg/L)
MW-13 4/19/23 0.02 0.0086 0.066 0.028 0.05 0.010 0.01 0.007
MW-13 10/27/23 0.02 0.0089 0.066 0.027 0.05 0.009 0.01 0.008
MW-5 4/20/23 0.01 0.0083 0.05 <0.001 0.07 <0.001 0.01 0.064
MW-5 10/27/23 0.01 0.0079 0.05 <0.001 0.07 <0.001 0.01 0.056

The reported concentration values of Se at background well MW-5 continue to remain elevated
above the background concentration of 0.01 mg/l per the 2023 monitoring data. The measured
concentration has consistently averaged around 0.06/0.07 mg/L since the beginning of ground
water quality data collection at the well. The reported value for monitoring well MW-5 Se was
0.064 mg/L and 0.056 mg/L for the 2023 sampling events.

QA/QC Review

Laboratory Data

Per review of the laboratory chain of custody forms it appears that all paperwork and sample
preservation was conducted according to laboratory requirements. Per Division staff review of
the Energy Laboratories analysis reports, it was noted that for several parameters the reporting
levels were increased due to sample matrix interference. Division staff verified that in all such
cases the reported sample concentration was higher than the raised limit.

Based on Division staff review of the Energy Laboratories data packets, all data appears to be in
conformance with laboratory and License requirements. Additionally, no issues regarding
sample collection or laboratory receiving were noted in the Report.

Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
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Field and Laboratory QA/QC

Field QA/QC methods included blind code labeling and the collection of quality control samples,
such as blind duplicates, splits, and equipment rinsates. Multiple QA/QC samples were collected
during sampling events in 2023.

A relative percent difference (RPD) analysis was performed on the results of the blind
supplicates and split samples for each constituent. The QAP defines a RPD greater than 20% as
a non-conformance. One non-conformance in license well duplicates was identified in the
duplicate sample collected from EF-8 in October 2023. The non-conformance at EF-8 for
molybdenum is due to significant digits reported.

A total of five split samples were sent to ACZ Laboratories in 2023. RL-3 in February, H-63 and
EF-8 in April, RL-3 in August, and RL-4 in October. Five non-conformances were identified in
license well split samples collected from RL-3 and EF-8. In all cases, the samples either
required dilution due to elevated concentration of constituents within the sample or a significant
digit discrepancy was reported between the two laboratories and do not disqualify the results
from being used for the intended groundwater quality monitoring purposes,

In all instances, per the QAP, the lab was contacted first to review the analytical data for
transcription and/or calculation errors.

Per Division review, the submitted data appears to be reliable for compliance purposes.
Copies of all field sampling data sheets and laboratory reports (including QA/QC) were included
electronically in searchable format.

Laboratory Certification

Energy Laboratories and ACZ Laboratories hold active certifications per review of the TNI
LAMS website which documents accreditation status with the National Environmental
Laboratory Accreditation Management System (NELAC). A screenshot is included as Appendix
3 of this review memo.

It was verified that Energy Laboratories and ACZ Laboratories hold a current Utah certification
for all parameters and methods reported for all the 2023 submitted data. Specifically, Energy
Laboratories and ACZ Laboratories hold a current certification for; Arsenic, Molybdenum,
Selenium and Uranium by Method 200.8; Chloride and Sulfate by Method 300.0; Total
Dissolved Solids by Method A2540C, and Alkalinity by Method A2320 B.

2023 Report Review Conclusions

Per Division review, it appears that the 2023 Report is in compliance with the reporting
requirements of the License and that the data submitted is reliable for compliance purposes.
Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 12

Based on findings, a close out letter regarding review of the Report will be prepared.

Division/RAML Split Sample Review

Division staff met with representatives of RAML and Arcadis on October 25, 2023, to conduct a
split sampling inspection at the Lisbon Valley Site.

The Division split samples with RAML at two groundwater monitoring wells, RL-6 and H-63,
on October 25, 2023. Additionally, the Division collected a blind duplicate of well H-63 which
was labeled as EF-92. Data comparison charts are included as appendices of this memo.

Review of Field Sampling Methods:

RAML followed field methods as outlined in the July 31, 2015, Groundwater Monitoring Plan
Table 4.

RPD Calculations – Compliance Parameters:

The Division Split Sample Guidance Document for Uranium Mills, dated August 7, 2007,
includes a section for data comparison of non-radiological parameters. Per the Guidance, all data
other than radiological analyses will be compared and the relative percentage difference will be
calculated. The Guidance outlines the acceptance criteria for samples split between different
laboratories as a maximum 30% Relative Percent Difference (“RPD”).

Appendix 1 of this memo includes the RPD calculations (Excel Spreadsheet) for the data results
for the October 25, 2023, split sample trip. Calculation of RPD in samples which were reported
as non-detect (sample results below the MDL) were not included since the data is not
comparable.

Comparison of the 2023 RAML and Division split samples showed that all sample results were
within the 30% acceptance criteria.

Division Blind Duplicate:

Results of the Division 2023 Blind Duplicate sample submitted to the Eurofins Denver
laboratory showed all results within the 20% (same lab) RPD acceptance criteria with the
exception of molybdenum. The RPD for molybdenum was calculated at 24.1%. Molybdenum
was detected in both samples at a very low concentration (within 5 the laboratory reporting limit)
which does not qualify as a non-conformance of the acceptance criteria.

The results of the comparison are included in Appendix 2 of this memo.

Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 13

2023 Division/RAML Split Sampling Conclusions:

Per data comparisons, all split sample data conformed to the acceptance criteria and no
additional actions will be conducted.

Conclusions

Based on review of the RAML 2023 Report and 2023 Split Sampling Inspection, a close out
letter will be prepared for review and signature.

Rio Algom Mining LLC
2023 Annual Groundwater Monitoring Report, Lisbon Facility
DWMRC Review Memo
Page 14

References

1 Rio Algom Mining LLC, February 28, 2024, 2023 Annual Groundwater Monitoring Report
Lisbon Facility.
2 Rio Algom Mining LLC, July 31, 2015, Groundwater Monitoring Plan Lisbon Facility.
3 Utah Radioactive Materials License No. UT1900481, Amendment 7.
4 Utah Division of Waste Management and Radiation Control, August 7, 2007, Split Sample
Guidance Document for Uranium Mills

Appendix 1 – 2023 Division/RAML Split Sampling Comparison

Appendix 2 – 2023 Division Blind Duplicate Analysis

Appendix 3 –National Environmental Laboratory Accreditation Management
System (NELAC) Certifications for Energy Laboratories and ACZ
Laboratories