DRC-2019-010131 - 0901a06880afc3a5

Department of
Environmental Quality
L. Scott Baird
Interim Executive Director
GARY R. HERBERT
Governor
SPENCER J. COX
Lieutenant Governor
DIVISION OF WASTE MANAGEMENT
AND RADIATION CONTROL
Ty L. Howard
Director
MEMORANDUM DRC-2019-01013 1
TO: File
THROUGH: Phil Goble, Manager Kit 4A/2016k
FROM: Tom Rushing, P.G. 02 i/a61/1
DATE: September 4, 2019
SUBJECT: Review of the Energy Fuels Resources (USA) Inc., White Mesa Uranium Mill, Blanding,
Utah June 27, 2019 Source Assessment Report for MW-11 and MW-24
Ground Water Discharge Permit No. UGW370004 (Permit)
Summary
An Energy Fuels Resources (USA) Inc. ("EFR") Source Assessment Report ("SAR"), dated June 27, 2019,
for wells/parameters in out-of-compliance status ("00C") was received by the Director of the Division of
Waste Management and Radiation Control (DWMRC) on July 2, 2019. The SAR is for Manganese in
Monitoring Well MW-11 and Beryllium, Cadmium, Fluoride, Nickel, Thallium and pH in Monitoring Well
MW-24 at the White Mesa Uranium Mill (Mill). The SAR was submitted for review and approval of
proposed revised Ground Water Compliance Limits ("GWCLs") for the parameters listed.
Monitoring well MW-11 is located on the southern berm of the Mill Tailings Cell 3 and is hydraulically
downgradient from portions of Cells 2 and 3; and from the Mill processing areas. Monitoring well MW-24
is located on the southwest corner of Evaporation Cell 1 and is hydraulically downgradient from
Evaporation Cell 1.
The SAR is broken up into four primary sections, 1. Categories and Approach for Analysis, 2. Results of
the Analysis (e.g. site-wide decreasing pH, Sorption Analysis), 3. Statistical evaluation and calculation of
revised GWCL's, and, 4. Conclusions and recommendations.
Figures below depict the concentration trends in monitoring well MW-11 and MW-24 for the source
assessment parameters using all available historical data.
• WNW Cd
— wear 921W 24C*
//6/2209 12/27/2016 9/22/2012 6/11/2020
EFR June 27, 2019 MW-11 and MW-24 Source Assessment Report
DWMRC Review Memo
Page 2
Figure - Manganese Data Plot of Historical Data at MW-11
MW-11 Manganese
• •
*VV. • ••••._• • _ • ...•-•• • •• • 411 -e•.*L**,' • foW 11 112/1•11•3. • ilki,•• • • -
*
1/14/2001 10/10/2006 7/6/2072 9122/2017
Figure — pH Data Plot of Historical Data at MW-24
PAW-24 pH
••
las w 0101 20/ I/ lO1tO
Figure — Cadmium Data Plot of Historical Data at MW-24
MW-24 Cd
EFR June 27, 2019 MW-11 and MW-24 Source Assessment Report
DWMRC Review Memo
Page 3
Figure — Thallium Data Plot of Historical Data at MW-24
MW-24 Thallium
Figure — Beryllium Plot of Historical Data at MW-24
MW-24 Beryllium
•MW 74 Elwyn,.
+1.• •1444•40 • 11 4/7/T012 17/2//2010 9/22/7087 6/ 20
Figure — Nickel Plot of Historical Data at MW-24
MW-24 Nickel
• MW 201.101

•
•••••11.111••• ••• 10/10/2006 7/6/2029 4/1/2012 12/27/2014 9/22/2011 6/16/2020
EFR June 27, 2019 MW-11 and MW-24 Source Assessment Report
DWMRC Review Memo
Page 4
Figure — Fluoride Plot of Historical Data at MW-24
MW.24 Fluoride
.1, 4g2.1.1
Per review of the data plot for MW-11 manganese, it appears that an ongoing increasing trend has been
occurring since installation of the monitoring well and was identified at the time of the background report.
Per review of the data plots for MW-24, it was noted that recent increasing trends for certain parameters
has resulted in out-of-compliance status warrants further investigation. A proposed path forward is found
below in the Conclusion section of this memorandum.
DWMRC Review of Compliance Data and Trends for Manganese in MW-11
MW-11 (Manganese) — DWMRC notes that manganese concentrations in MW-11 have been indicating an
increasing trend since the beginning of monitoring for the parameter at the monitoring well. DWMRC
notes that the trend is more evident starting in 2012 when a new laboratory and more sensitive methods of
analysis were implemented. Per the SAR, the complete historical dataset for Mn shows a normal
distribution of data. A review of other indicator parameters does not indicate that the increasing Mn or
decreasing pH is being caused by the release of tailings solution. Monitoring well MW-11 was part of the
University of Utah Study and findings indicated that the monitoring well was unaffected by Mill activities.
The SAR discusses that the increasing trend is potentially related to dissolution of manganese in clays and
carbonate minerals in the aquifer in the region of MW-11.
DWMRC Review of Compliance Data and Trends for SAR Constituents in MW-24
MW-24 (Beryllium, Cadmium, Nickel, Thallium, Fluoride, pH) — DWMRC notes that beryllium,
cadmium, nickel, thallium and fluoride are showing increasing trends at MW-24 and that pH is showing a
significant decreasing trend. Recent pH values at MW-24 have been as low as 4.45. The SAR discusses
that the rising concentrations of metals is potentially due to desorption of minerals from hydrous ferric
oxides due to decreasing pH and/or the dissolution clay and sulfide minerals in the Brushy Basin and Burro
Canyon Formations. Based on review of the groundwater data, including tailings wastewater indicator
parameters the SAR discusses that the trends do not appear to be associated with Mill activities; however,
recent increasing trends for certain parameters has resulted in out-of-compliance status warrants further
investigation. A proposed path forward is found below in the Conclusion section of this memorandum.
MW-11 fluoride
0 1
• • • • *ft* •
4Lee
• MW O..<
- OW flunnal
0 411/2004 11111042014 7/0121104 IMM018 0111/1011 01 Pe
EFR June 27, 2019 MW-11 and MW-24 Source Assessment Report
DWMRC Review Memo
Page 5
EFR Investigations of Potential Sources of Report Increasing Trends at Monitoring Wells MW-11
and MW-24
1. Tailings Solution Groundwater Indicator Parameters at Monitoring Wells MW-11 and MW-24
The SAR Section 3.5 discusses four primary indicator parameters (Chloride, Fluoride, Sulfate and
Uranium) which would be detected in ground water in the event of a discharge from the Mill tailings cells.
DWMRC plots of these parameters are included below for monitoring well MW-11 and MW-24:
MW-11
IVIW-11 Chloride
• NW 1141441411
— n OM II (Mendel
1,1001100 1.011000 411/20l2 10/1100. 0121000
fV1W-11 Sulfate
• IOW II Viate
--kinear OW roaffatej
1422/2014 4/24/44•7
1. •
EFR June 27, 2019 MW-11 and MW-24 Source Assessment Report
DWMRC Review Memo
Page 6
MW-11 Uranium
1 2
• MW-11Uransum
—lour MOW wan.urn)
o 40.1004* 1/14/1004 10/10/2006 7/6/7000 3/1/2010 10/27/2013 9/22/2017 6/18/2020
MW-24
MW-24 Chloride
Apr I,rll AA 10i
MW-24 Sulfate
3100
EFR June 27, 2019 MW-11 and MW-24 Source Assessment Report
DWMRC Review Memo
Page 7
MW-24 Urarwium
• PAW Attlfanms
[yrs {WHAM..
Note that fluoride at MW-24 is one of the current SAR parameters and is not reviewed as an indicator
parameter.
MW-11 DWMRC Analysis: Chloride Flat, Fluoride Decreasing, Sulfate Flat, Uranium Increasing (Note
that if uranium is plotted starting in 2012 there is no trend. Per review of the indicator parameters for MW-
11 it does not appear that trends or concentrations are indicative of a tailings wastewater release to the
groundwater. Per review of other monitoring parameters at MW-11 it is noted that pH is showing a slight
decreasing trend, no other trends noted in the data.
MW-24 DWMRC Analysis: Chloride Flat, Sulfate Flat, Uranium Increasing (Early data appears unreliable
in the data set). Field pH is showing a strong decreasing trend, MW-24 has been noted to have higher
percentages of pyrite and other sulfuric minerals in core materials than other cores examined. Per review
of indicator parameters and other parameters in MW-24, it does not appear that groundwater is impacted by
the release of tailings wastewater.
2. University of Utah Study
Monitoring well MW-11 was included in a University of Utah study conducted at the White Mesa Uranium
Mill during 2007 (Final Report of Study Findings Dated May, 2008). Based on groundwater age dating at
monitoring well MW-11 [chlorofluorocarbon ("CFC") analysis], the groundwater was found to exhibit
CFC recharge dates which predate the construction of the Mill in 1980. Manganese concentrations in MW-
11 were showing an upward concentration trend at the time of the study.
3. Sorption/Desorption Modeling for MW-24
The SAR section 3.2, 3.4, and Appendix F (Electronic Only) provide a summary and input/output files for
a ferrihydrite sorption model for beryllium, cadmium, nickel, and thallium in MW-24. The model was
created in the Geochemist's Workbench software (v. 11.0.8) using the React module and the minteq and
Fe0H_minteq databases. Overall, the model showed that desorption of cadmium and nickel bound to
ferrihydrite would occur at pH values lower than 5.5 (lower pH would result in less sorption and higher
groundwater concentrations). Model findings for beryllium and thallium did not produce a definitive
conclusion regarding an effect of pH on desorption from ferrihydrite, and other potential causes of rising
concentrations for these metals is discussed in the SAR. Beryllium and thallium may be desorbed from
clay or sulfide minerals. In general the model helps to support EFR claims that the increasing trends are
caused by lowering pH in MW-24 but does not definitively determine this as a source for exceedances.
EFR June 27, 2019 MW-11 and MW-24 Source Assessment Report
DWMRC Review Memo
Page 8
4. Pyrite Oxidation
Section 3.1 of the SAR discusses findings and previous studies and findings regarding pyrite oxidation and
site-wide decreasing pH at multiple groundwater monitoring locations, including upgradient and far
downgradient monitoring wells. Per past studies and reports (Pyrite Report, 2012) it was determined that
monitoring well MW-24 contained the highest observable pyrite percentage among the samples analyzed.
It has been observed that the pH in monitoring well MW-24 is among the lowest at the site and it is
expected that the lowering pH will have a geochemical response in the aquifer mineralogy and
groundwater. Per the SAR this is proposed as a cause for the individual parameters studied. Probable
minerals noted in the onsite formations were identified in the SAR.
5. Source Assessment Conclusions
Based on DWMRC review of the SAR, it appears that Mill activities are not influencing SAR
concentrations at monitoring well MW-11. This is based on the findings of several lines of evidence in the
SAR including: 1. Decreasing pH effects on geochemistry in MW-11: 2. Evaluation of tailings solution
indicator parameters (chloride, sulfate, fluoride and uranium) for MW-11 and evaluation of the historical
data at MW-11: 3. Potential effects of pyrite oxidation releasing selenium and other trace metals into
solution, and: 4. Findings of the 2007/2008 University of Utah Groundwater Study Regarding MW-11.
Per DWMRC review, these findings are consistent with previous EFR SAR's and it does not appear that
the GWCL exceedances and/or manganese trends at monitoring well MW-11 are being caused by mill
activities. Based on the increasing trend, adjustment of the GWCL for manganese in the Permit is
appropriate.
In the case of SAR parameters at monitoring well MW-24 it was noted that recent increasing trends for
certain parameters has resulted in out-of-compliance status warrants further investigation. Based on
DWMRC review findings and a conference call discussion with EFR on September 3, 2019 it was decided
that additional source assessment needs to be conducted for monitoring well MW-24. EFR mentioned
during the call, that there is a potential that monitoring well construction could be the cause of the out of
compliance parameters and that additional evaluation to determine if this is the cause could include the
construction of a nearby monitoring well and subsequent tandem sampling of the two wells to determine if
well construction is an issue. Based on discussion this was determined to be a useful and reasonable
evaluation of the non-compliance. Consideration is given that based on a review of indicator parameters
and the comprehensive historical data record, the parameter trends and out-of compliance do not appear to
be caused by a tailings wastewater source.
EFR Proposed Modified GWCL Statistical Evaluation of Data:
Proposed Modified Approach GWCL's:
Appendix B-1 of the SAR summarizes the statistical evaluation and proposed GWCL's for the SAR wells
and parameters.
Per the DWMRC approved statistical flow chart for the White Mesa Mill groundwater monitoring wells, it
was noted that if an upward trend is apparent and is related to rising background concentrations for an
analyte then a modified approach should be considered. The modified approach should allow for a GWCL
which considers the increasing concentrations. Based on this, EFR calculated a proposed modified GWCL
EFR June 27, 2019 MW-11 and MW-24 Source Assessment Report
DWMRC Review Memo
Page 9
for manganese at monitoring well MW-11 according to the highest historical value (HHV). DWMRC
reviewed the proposed modified GWCL to ensure that it is reflective of the collected data and provides for
a continuing regulatory mechanism.
In the case of monitoring well MW-24 it was recognized that two of the data sets have significant early
time not detected values (83% non-detects for beryllium and 58% for nickel), and that cadmium and
thallium also have a high amount of non-detects in the early time (24% and 28% respectively). Fluoride
also shows a period of relative stabile readings in the early time followed by a rising trend. This
anomalous data does not clearly establish pre-identified trends and it appears that trends began at various
times after well construction. Per additional discussion above and below, it was agreed that the rising
trends will need more investigation prior to potential GWCL modification.
The table below summarizes the EFR calculations and rationale for the proposed modified manganese
GWCL for monitoring well MW-11.
Table o EFR Pro osed Revised GWCL for Selenium and Uranium at Monitorin Well MW-30:
Well Parameter Current EFR Proposed Method to DWMRC Finding — Is DWMRC Discussion
Number GWCL GWCL Determine Proposed GWCL in of EFR Modified
Revision GWCL Conformance with the Approach
Statistical Flow Chart?
MW-11 Manganese 164.67
1,t g/L
237 vg/L HHV Increasing trend and
non-normal data set,
120 data points. HHV
value appears to be
appropriate. HHV is an
October 2015 sample
analysis result. No non
detects in data set.
EFR modified
approach proposes a
limit based on fraction
of the GWQS,
however, the value is
high and out of range
with the measured
data regardless of the
increasing trend.
Conclusions:
Per review of the SAR Sections and tables regarding proposed modifications to the GWCL's and statistical
analysis of the data, and a telephone conference amongst DWMRC representatives and EFR
representatives on September 3, 2019, it was agreed that the MW-11 Manganese GWCL will be modified
in the White Mesa Uranium Mill Ground Water Permit as summarized on the table below:
Well Number Parameter Current GWCL Modified GWCL Method of Analysis
MW-11 Manganese 164.67 [tg/L 237 Rg/L Highest Historical Value
The modified GWCL will not be effective until future issuance of a revised Groundwater Discharge
Permit, and that the modifications will be subject to formal public notice and public participation
requirements. This is expected to take place in the winter of 2019. A letter will be sent to EFR, clarifying
the approval and future requirements of the MW-11 modified manganese GWCL.
During the September 3, 2019 telephone conference call with EFR, it was discussed that based on review
of the GWCL exceedances at MW-24 and well data, it does not appear that tailings wastewater is the
EFR June 27, 2019 MW-11 and MW-24 Source Assessment Report
DWMRC Review Memo
Page 10
source. However, beryllium was measured as non-detectable from July 2005 until April 2016, and
likewise nickel shows a significantly large amount of non-detect data until the recent rising trend. Based
on these data anomalies it was discussed that problems with the well (e.g. design and installation) may be
the cause of the out-of-compliance status for the SAR parameters. EFR suggested that in order to
determine whether the well is the cause, an additional well, screened at the same well interval will be
placed close-by the existing MW-24, and monitored in tandem. This is similar to the approach used at
other wells which showed similar anomalous data. Until conclusion of the tandem well monitoring the
GWCL's will remain the same in the Permit with recognition that the exceedances are being actively
investigated. This will allow more monitoring data to be collected at MW-24 for better evaluation of data
trends.
A letter will be sent to EFR requiring that a plan for the new monitoring well installation be submitted to
the Director for review and approval on or before 30 calendar days from receipt of the letter.
References *
'Energy Fuels Resources (USA) Inc., June 27, 2019, Transmittal of Source Assessment Report for MW-11
and MW-24, White Mesa Mill Groundwater Discharge Permit UGW370004
3 Energy Fuels Resources (USA) Inc., May 14, 2019, White Mesa Uranium Mill Ground Water Monitoring
Quality Assurance Plan (QAP), Revision 7.5
4 Energy Fuels Resources (USA) Inc., October 12, 2012, Source Assessment Report, Prepared by Intera
5 Energy Fuels Resources (USA) Inc., November 9, 2012, pH Report, Prepared by Intera
6 Hurst, T.G., and Solomon, D.K. University of Utah, 2008, Summary of Work Completed, data Results,
Interpretations and Recommendations for the July 2007 Sampling Event at the Denison Mines, USA White
Mesa Uranium Mill Near Blanding, Utah, Prepared by Department of Geology and Geophysics
7 Hydro Geo Chem, December 7, 2012, Pyrite Investigation Report
8 Intera, 2007, Groundwater Data Preparation and Statistical Process Flow for Calculating Groundwater
Protection Standards, White Mesa Mill Site, San Juan County, Utah
9 United States Environmental Protection Agency, 2009, Statistical Analysis of Groundwater Monitoring
Data at RCRA Facilities, Unified Guidance EPA530/R-09-007
m Utah Department of Environmental Quality, January 19, 2018, Modified on March 19, 2019, Utah
Division of Radiation Control, Ground Water Discharge Permit, Permit No. UGW370004, Energy Fuels
Resources (USA) Inc.