DRC-2021-012922 - 0901a06880f4e5e1

-:e,;:RGYFUELS
Energy Fuels Resource (USA ) Inc.
225 nion Blvd. uite 600
Lakewood, CO, S, 80228
303 974 2140
DRC-201.l-Ol29lZ-, w .cncrgy lucls.com
September 7, 202 1
Sent VlA E-MAlL AND OVERNIGHT DELIVERY
Mr. Doug Han en
Director
Divi ion of Waste Management and Radialioo Control
Utah Department of Environmental Quality
195 North 1950 West
Salt Lake City, UT 84114-4880
Div of Waste Management
and Radiation Control
SEP O 9 2021
Re: Transmittal of Source Assessment Report for MW-29 White Me a Mill Groundwater Discharge
Permit UGW370004
Dear Mr. Hansen:
Enclo ed are two copies of Energy Fuel Re. ource (U A Inc.' s "EFRI' s") Source As e ment Report
("SAR") for MW-29 at the White Mesa Mill. Thi SAR addres es the constituent that were identified a
exceeding the GWCL in the 1st Quarter 2021 as described in the Division of Waste Management and Radiation
Control ("DWMRC")-approved QI 202 l Plan and Time Schedule. EFRI submitted the Plan and Time Schedule
for MW-29 on May l I, 202 1. DWMRC approval of the Plan and Tim Schedule wa received by EFRI on
June 9, 2021 . Pursuant to the Plan and Time Schedule EFRI has prepared this SAR.
Thj tran mittal also includes two CD each containing a word earchable electronic copy of the report.
lf you hou1d have any question regarding this report plea e contact me.
;;;;r;~
E ERGY FuELS RE OURCES (US ) INC.
Kathy Weinel
QuaLity A surance Manager
CC: David C. Frydcnlund
Garrin Palmer
Logan Shumway
Scotl Bakken
Stewart Smit.h (HGC).
Angie Per ico (lntera)
White Mesa Uranium Mill
State of Utah Groundwater Discharge Permit No. UGW370004
Source Assessment Report Under Part I.G.4
For Exceedances in MW-29 in the First Quarter of 2021
Prepared by:
Energy Fuels Resources (USA) Inc.
225 Union Boulevard, Suite 600
Lakewood, CO 80228
September 7, 2021
i
EXECUTIVE SUMMARY
This Source Assessment Report ("SAR") is an assessment of the sources, extent, and potential
dispersion of uranium in MW-29 at the White Mesa Mill ("the Mill") as required under State of
Utah Groundwater Discharge Permit UGW370004 (the "GWDP") Part I.G.4, resulting from out-
of-compliance status under Part I.G.2 of the GWDP of uranium in MW-29. Uranium occurs
naturally at the Mill (INTERA, 2008) and has exhibited exceedances of the applicable
Groundwater Compliance Limits ("GWCLs") in various other wells at the site over time and
from time-to-time. As will be demonstrated in this SAR, the increased concentrations of uranium
in MW-29 are the result of background influences and are not the result of any potential seepage
from the Mill's tailings management system ("TMS"). Background influences affecting site
wells potentially include (but are not limited to): a natural decreasing trend in pH across the site
[evident until approximately 2016, when pH in most wells began to stabilize or trend upward];
changing water levels due to past seepage from the wildlife ponds and pumping of nitrate and
chloroform plumes; changes resulting from enhanced oxygen transport to groundwater near
wells via the well casings or as a result of wildlife pond seepage; and/or the geochemical
influences of the existing chloroform and nitrate/chloride plumes.
Groundwater at the Mill site has been evaluated in multiple recent investigations and reports,
including the Revised Background Groundwater Quality Report (INTERA, 2007a) and the New
Wells Background Report (INTERA, 2008) (collectively with INTERA, 2007b, the "Background
Reports"), the pH Report (INTERA, 2012), an isotopic investigation (Hurst and Solomon, 2008), a
report discussing the occurrence and likely impact of naturally-occurring pyrite on perched
(shallow) groundwater (the Pyrite Report [HGC, 2012a]), and multiple SARs.
At the time of the Background Reports, MW-29 had a limited data set comprised of eight data
points per GWDP parameter. Significantly more data points are now available, providing a more
robust understanding of the water quality and behavior of MW-29. In addition, uranium
concentrations in MW-29 have been increasing since the well was installed in 2005. The trend
in uranium concentrations was noted in the 2008 New Wells Background Report, the pH Report
submitted to DWMRC on November 9, 2012, and the 2013 SAR for Total Dissolved Solids
("TDS") in MW-29. In addition, the increasing trend in uranium at MW-29 was already present
at the time that the isotopic study (Hurst and Solomon, 2008) determined there were no impacts
to groundwater from the TMS. Furthermore, the stable to decreasing behavior of the key
indicator parameters chloride, fluoride and sulfate in MW-29 is inconsistent with a TMS impact.
As demonstrated herein, water level behavior at MW-29 is also important when assessing
potential sources of contamination. The water level in MW-29 has increased since 2005 due to
perched water mounding associated with the northern wildlife ponds. Although use of the
northern ponds was discontinued in March 2012, and the central portion of the mound has
diminished, this mound is still evident as water levels have not returned to pre-pond conditions;
therefore, the mound is still expanding and causing increases in water levels at relatively distant
wells such as MW-29. Increasing constituent concentrations in many wells (such as MW-29) are
at least in part attributable to water level changes caused by the associated groundwater mound.
In sum, the increasing trend in uranium in MW-29 is from natural background influences, and
not the result of any potential seepage from the Mill's TMS or other activities at the Mill. As a
result, it is appropriate to adjust the GWCLs for uranium in MW-29 to account for these
influences. In accordance with the DWMRC-approved Flowsheet (from INTERA [2007a],
included as Appendix E), increasing trends of this nature (i.e., resulting from background
influences such as increased water levels in MW-29 associated with the northern wildlife ponds
and other factors) necessitate a modified approach for calculation of GWCLs. The modification
in this approach considers a more recent dataset and the greater of (1) mean + 2cr, (2) highest
historical value, (3) background x 1.5, or (4) the fractional approach (i.e., the prescribed fraction
of the Utah Groundwater Quality Standards applicable to the class of water in the well), to
determine representative and appropriate GWCLs for trending constituents. Regular revisions to
GWCLs for constituents in wells with significantly increasing trends over time due to
background is consistent with the United States Environmental Protection Agency's
("USEPA's") Unified Guidance (USEPA, 2009). Such revisions account for the trends and
minimize unwarranted out-of-compliance status in such wells in the future.
ii
TABLE OF CONTENTS
1.0 INTRODUCTION ............................................................................................................... 1
1.1 Source Assessment Report Organization ......................................................................... 2
2.0 CATEGORIES AND APPROACHES FOR ANALYSIS .................................................. 4
2.1 Approach for Analysis ..................................................................................................... 4
2.2 Approach for Setting Revised GWCLs ............................................................................ 5
2.3 University of Utah Study .................................................................................................. 5
3.0 RESULTS OF ANALYSIS ................................................................................................. 7
3 .1 Site-Wide pH Changes ..................................................................................................... 7
3.2 Changes in Groundwater in MW-29 ................................................................................ 8
3.3 Indicator Parameter Analysis ........................................................................................... 9
3.4 Mass Balance Analyses .................................................................................................. 10
3.5 Summary of Results ....................................................................................................... 12
3.5.1 Uranium .................................................................................................................. 12
4.0 CALCULATIONS OF GROUNDWATER COMPLIANCE LIMITS ............................. 13
4.1 Evaluation of Modified Approaches to Calculation of GWCLs for Trending
Constituents ............................................................................................................................... 13
4.2 Proposed Revised GWCLs ............................................................................................. 14
5.0 CONCLUSIONS AND RECOMMENDATIONS ............................................................ 16
6.0 REFERENCES .................................................................................................................. 17
Table 1
Figure lA
Figure lB
Figure lC
Figure 2
Figure 3
Figure 4
LIST OF TABLES
Proposed GWCLs
LIST OF FIGURES
White Mesa Site Plan Showing Locations of Perched Wells and Piezometers
Kriged 2nd Quarter, 2021 Water Levels and Plume Boundaries, White Mesa Site
Kriged 4th Quarter, 2011 Water Levels and Plume Boundaries, White Mesa Site
MW-29 Groundwater Elevations Over Time
MW-29 Uranium (µg/L) and Ammonia (mg/L)
MW-29 Uranium (µg/L) and Bicarbonate (mg/L)
I
LIST OF APPENDICES
Appendix A GWCL Exceedances for First Quarter 2021 under the March 8, 2021 GWDP
Appendix B Statistical Analysis for MW-29 SAR Constituents
B-1 Statistical Analysis Summary Table
B-2 Comparison of Calculated and Measured TDS
B-3 Charge Balance Calculations
B-4 Descriptive Statistics
B-5 Data Used for Statistical Analysis
B-6 Extreme Outliers Removed from Analysis
B-7 Box Plots
B-8 Box Plots for MW-29 and in Upgradient and Downgradient Wells
B-9 Box Plots for SAR Parameters in Groundwater Monitoring Wells
B-10 Histograms
B-11 Time Series Plots
B-12 Time Series Plots with Events
Appendix C Statistical Analysis for Indicator Parameters in MW-29
C-1 Indicator Parameter Analysis Summary Table
C-2 Descriptive Statistics of Indicator Parameters
C-3 Data Used for Statistical Analysis
C-4 Data Omitted from Statistical Analysis
C-5 Box Plots for Indicator Parameters
C-6 Histograms for Indicator Parameters
C-8 Time Series Plots and Linear Regressions for Indicator Parameters
C-9 Time Series with Events
Appendix D Mass Balance Calculations
Appendix E Flowsheet (Groundwater Data Preparation and Statistical Process Flow for
Calculating Groundwater Protection Standards, White Mesa Mill Site
[INTERA, 2007a])
Appendix F Input and Output Files (Electronic Only)
11
ACRONYM LIST
Background Reports
CAP
CFCs
CIR
DF
Director
DWMRC
EFRI
GWCL
GWDP
GWQS
µg/L
mg/L
Mill
ooc
Ql
Q2
SAR
TDS
TMS
USEPA
collectively refers to relevant background reports for this well and site:
the Existing Wells Background Report (INTERA, 2007a), the Regional
Background Report (INTERA, 2007b), and the New Wells Background
Report (INTERA, 2008)
Corrective Action Plan
chlorofluorocarbons
Contaminant Investigation Report
Dilution Factor
Director of the Division of Waste Management and Radiation Control
State of Utah Division of Waste Management and Radiation Control
Energy Fuels Resources (USA) Inc.
Groundwater Compliance Limit
State of Utah Ground Water Discharge Permit UGW370004
Groundwater Quality Standard
micrograms per liter
milligrams per liter
White Mesa Uranium Mill
out of compliance
first quarter
second quarter
Source Assessment Report
Total Dissolved Solids
Tailings Management System
United States Environmental Protection Agency
iii
1.0 INTRODUCTION
Energy Fuels Resources (USA) Inc. ("EFRI") operates the White Mesa Uranium Mill
(the "Mill"), located near Blanding, Utah (Figure lA). Groundwater is regulated under
the State of Utah Groundwater Discharge Permit UGW370004 (the "GWDP"). This is
the Source Assessment Report ("SAR") required under Part I.G.4 of the GWDP, relating
to Part I.G.2 of the GWDP with respect to uranium in groundwater compliance
monitoring well MW-29.
Pait I.G.2 of the GWDP provides that an out-of-compliance ("OOC") status exists when
the concentration of a constituent in two consecutive samples from a compliance
monitoring point exceeds a Groundwater Compliance Limit ("GWCL") in Table 2 of the
GWDP. The GWDP was originally issued in March 2005, at which time GWCLs were
set on an interim basis, based on fractions of State of Utah Ground Water Quality
Standards ("GWQSs") or the equivalent, without reference to natural background at the
Mill. The GWDP also required that EFRI prepare a background groundwater quality
report to evaluate all historical data for the purposes of establishing background
groundwater quality at the Mill site and developing GWCLs under the GWDP. As
required by then Part I.H.3 of the GWDP, EFRI submitted three "Background
Groundwater Quality Reports" (INTERA 2007a, 2007b, 2008) (collectively, the
"Background Reports") to the Director (the "Director") of the State of Utah Division of
Waste Management and Radiation Control ("DWMRC") (the Director was formerly the
Executive Secretary of the Utah Radiation Control Board and the Co-Executive Secretary
of the Utah Water Quality Board).
Based on a review of the Background Reports and other information and analyses, the
Director re-opened the GWDP and modified the GWCLs to be equal to the mean
concentration plus two standard deviations ("mean + 2o") or the equivalent for each
constituent in each well, based on an "intra-well" approach. That is, the compliance status
for each constituent in a well is determined based on current concentrations of that
constituent in that well compared to the historic concentrations for that constituent in that
well, rather than compared to the concentrations of the same constituent in other
monitoring wells. The modified GWCLs became effective on January 20, 2010. On
January 19, 2018, March 19, 2019, and March 8, 2021, revised GWDPs were issued,
which set revised GWCLs for certain constituents in certain monitoring wells as
approved by the Director through previously approved SARs relating to those
constituents in those wells. GWCLs apply to groundwater monitoring wells located in the
perched aquifer at the Mill.
Figure lB is a site map showing perched well and piezometer locations, second quarter
("Q2"), 2021 perched groundwater elevations, and other relevant site features, such as the
locations of formerly used (unlined) wildlife ponds, the historical pond, and the
boundaries of two shallow groundwater plumes (the nitrate/chloride plume and the
chloroform plume) which are under active remediation by pumping. Specifically, Figure
lB shows the commingled nitrate and chloride components of the nitrate/chloride plume.
1
Figure 1 C shows the same features as Figure lB, except that water levels and plume
boundaries are as they existed just prior to cessation of water delivery to the wildlife
ponds in the first quarter ("Ql") of 2012. As shown in Figures lB and lC, perched
groundwater flows generally to the southwest across the site, and the nitrate/chloride
plume extends more than 1,000 feet upgradient of the tailings management system
("TMS") indicating an upgradient source. As discussed in HGC (2018), the chloroform
plume originated from disposal of laboratory wastes to two former sanitary leach fields
that were used prior to Mill construction and operation.
Groundwater quality at individual wells is impacted by transient conditions at the site.
Currently the perched groundwater system that is monitored at the site does not approach
steady state over much of the monitored area. A large part of the site perched water
system is in a transient state and affected by long-term changes in water levels due to past
and current activities unrelated to the disposal of materials to the TMS. Changes in water
levels have historically been related to seepage from the unlined wildlife ponds; however
past impacts related to the historical pond, and to a lesser extent formerly used sanitary
leach fields, are also expected, as discussed in HGC (2018). Water levels have decreased
at some locations due to chloroform and nitrate pumping and reduced recharge from the
wildlife ponds.
Figure 2 is a plot of groundwater elevation over time at MW-29 since installation in 2005.
Groundwater levels have increased by approximately 4 V2 feet since the well was
installed. As discussed above, the increase is attributable to former wildlife pond recharge.
1.1 Source Assessment Report Organization
A description of the approach used for analysis is provided in Section 2.0; the results of
the analyses are presented in Section 3.0; the calculation of GWCLs is provided in
Section 4.0; and conclusions and recommendations are presented in Section 5.0. Section
6.0 lists references cited.
The analyses performed for this Report are organized in Appendices A through F.
Appendix A contains a table showing exceedances; Appendix B contains the statistical
analysis performed on uranium; Appendix C contains the indicator parameter analysis;
Appendix D contains the mass balance analysis; and Appendix E contains the
Groundwater Data Preparation and Statistical Process Flow for Calculating Groundwater
Protection Standards, White Mesa Mill Site, San Juan County, Utah ("Flowsheet") that
was developed based on the United States Environmental Protection Agency's
("USEPA") Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities,
Unified Guidance (USEPA, 1989, 1992). This Flowsheet was approved by DWMRC
prior to completion of the Background Reports. Appendix F is included on the compact
disc that accompanies this SAR and contains the electronic input and output files used for
statistical analysis.
2
Statistical analysis was performed using the software package "R." R is a free statistical
package that allows the analyst to perform statistical analysis and format and output
graphs more effectively than the Statistica software package used in the past. Input and
output files included in Appendix F can be imported into either R or Statistica to
replicate the results presented in this SAR.
3
2.0 CATEGORIES AND APPROACHES FOR ANALYSIS
Previously, EFRI has categorized wells and constituents in five categories as follows:
• Constituents Potentially Impacted by Decreasing pH Trends Across the Site
• Newly Installed Wells with Interim GWCLs
• Constituents in Wells with Previously Identified Rising Trends
• Pumping Wells
• Other Constituents
This SAR addresses one constituent (uranium) in one well (MW-29). Uranium in MW-29
falls within the third category: Constituents in Wells with Previously Identified Rising
Trends. Uranium concentrations in MW-29 have been increasing since the well was
installed in 2005. Trends in uranium concentrations in MW-29 were observed in the
2008 New Wells Background Report, the pH report submitted to DWMRC on November
9, 2012, and the 2013 SAR for Total Dissolved Solids ("TDS") in MW-29. This trend
was already present at the time of the University of Utah isotopic study (Hurst and
Solomon, 2008; described below) that determined there had been no impacts to
groundwater from the TMS.
It is important to note that the initial GWCL for uranium in MW-29 was set using the
minimum eight data points and does not accurately reflect the true natural variation that
would be evident with a larger data set. There are now 40 data points available, which
will undoubtedly affect the outcome of the analysis.
Additional factors that may have contributed to a change in behavior of groundwater
conditions in MW-29 are discussed in Section 3.2.
2.1 Approach for Analysis
The first step in the analysis is to perform an assessment of the potential sources for the
exceedances to determine whether they are due to background influences or Mill
activities. If the exceedances are determined to be caused by background influences, then
it is not necessary to perform any further evaluations on the extent and potential
dispersion of the contamination or to perform an evaluation of potential remedial actions.
Monitoring will continue; and, where appropriate, a revised GWCL is proposed to reflect
changes in background conditions at the Mill site.
The analysis performed in this SAR considers all available data to date to help determine
if there have been any changes in potential TMS seepage indicator parameters (e.g.,
chloride, sulfate, fluoride, and uranium) since the date of the New Wells Background
Report and any potential influences of the nitrate/chloride plume that may suggest a
change in the behavior of the groundwater in the well. Although MW-29 is located
immediately downgradient of the nitrate/chloride plume, geochemical influences related
to this plume are not yet expected to impact MW-29.
4
As discussed in the Background Reports (INTERA, 2007a, 2007b, 2008), indicator
parameters of potential TMS seepage include chloride, sulfate, fluoride, and uranium.
Chloride is the best indicator of potential TMS seepage for wells such as MW-29 located
outside the nitrate/chloride plume. Sulfate and fluoride are useful indicator parameters
under geochemical conditions allowing conservative (i.e., non-reactive) behavior.
Uranium behavior may range from conservative to non-conservative depending on the
geochemical conditions.
Groundwater impacted by any potential seepage from the TMS is expected to exhibit
increasing concentrations of chloride, sulfate, fluoride, and uranium, among other
constituents. While uranium can be the most mobile of trace metals under certain
conditions, it is typically retarded behind chloride, fluoride, and sulfate due to possible
sorption and precipitation and would likely not show increasing concentrations in
groundwater until sometime after chloride, fluoride, and sulfate concentrations had begun
to increase (INTERA, 2007a). Based on data provided in USEPA (2008), uranium is
generally expected to sorb and have comparatively poor mobility at the near-neutral pH
conditions encountered at MW-29. Regardless, although the absence of a rising trend in
chloride, fluoride and sulfate concentrations would indicate that there has been no impact
from the TMS, a rising trend in concentrations could also result from natural influences
(INTERA, 2007a, Section 12.0).
The evaluation of SAR parameters and indicator parameters in MW-29 was supported by
a statistical analysis that followed the process outlined in the Flowsheet (INTERA,
2007a) attached as Appendix E. As discussed in Section 1.2, the Flowsheet was designed
based on USEPA's Statistical Analysis of Groundwater Monitoring Data at RCRA
Facilities, Unified Guidance (USEPA, 1989, 1992, 2009), and was approved by
DWMRC prior to completion of the Background Reports (INTERA, 2007 a, 2007b,
2008).
2.2 Approach for Setting Revised GWCLs
If the preceding approach indicates that the previous analysis in the Background Reports
has not changed, or that the OOC status of uranium in MW-29 is due to natural or other
site-wide influences, then new GWCLs may be proposed for the constituents. The revised
GWCLs use the DWMRC-approved Flowsheet, including the last decision of the process
that directs the analyst to consider a modified approach to determining a GWCL if an
increasing trend is present.
2.3 University of Utah Study
At the request of the DWMRC, T. Grant Hurst and D. Kip Solomon of the Department of
Geology and Geophysics of the University of Utah performed a groundwater study (the
"University of Utah Study") at the Mill site in July 2007 (Hurst and Solomon, 2008). The
purpose of this study was to characterize groundwater flow, chemical composition, noble
gas composition, and water age to evaluate whether the increasing and elevated trace
5
metal concentrations in monitoring wells at the Mill, all of which were identified in the
Background Reports (INTERA, 2007a, 2007b, 2008), may indicate that potential seepage
from the TMS is occurring.
To evaluate sources of solute concentrations at the Mill, low-flow groundwater sampling
was used as a method for collecting groundwater quality samples from 15 monitoring
wells. In addition, surface water samples were collected from TMS Cells 1, 3, and 4A,
and two wildlife ponds. Passive diffusion samplers were also deployed and collected to
characterize the dissolved gas composition of groundwater at different depths within the
wells. Samples were collected and analyzed for the following constituents: tritium,
nitrate, sulfate, deuterium and oxygen-18 of water, sulfur-34 and oxygen-18 of sulfate,
trace metals (uranium, manganese, and selenium), and chlorofluorocarbons ("CFCs").
Hurst and Solomon (2008, page iii) concluded generally that,
[t]he data show that groundwater at the Mill is largely older than 50
years, based on apparent recharge dates from chlorofluorocarbons and
tritium concentrations. Wells exhibiting groundwater that has recharged
within the last 50 years appears to be a result of recharge from wildlife
ponds near the site. Stable isotope fingerprints do not suggest
contamination of groundwater by tailings cell leakage, evidence that is
corroborated by trace metal concentrations similar to historically-
observed observations.
Hurst and Solomon (2008) also concluded that,
[i]n general, the data collected in this study do not provide evidence that
tailings cell leakage is leading to contamination of groundwater in the
area around the White Mesa Mill. Evidence of old water in the majority of
wells, and significantly different isotopic fingerprints between wells with
the highest concentrations of trace metals and surface water sites,
supports this conclusion.
It should be further noted that subsequent to the University of Utah Study EFRI
submitted the Contaminant Investigation Report ["CIR"}, White Mesa Uranium Mill
Site, Blanding Utah, dated December 30, 2009 (INTERA, 2009), in connection with the
nitrate/chloride plume at the Mill site. However, as discussed above, although MW-29 is
located immediately downgradient of the nitrate/chloride plume, geochemical influences
related to this plume are not yet expected to impact MW-29.
6
3.0 RESULTS OF ANALYSIS
This section describes the potential geochemical influences on groundwater in MW-29
and results of the analysis, summaries of which are presented in Appendices B and C.
Supporting analyses are presented in Appendices D and F.
3.1 Site-Wide pH Changes
As has been documented in INTERA (2012), a decreasing trend in pH was observed in
almost every groundwater monitoring well across the site, including upgradient and far
downgradient monitoring wells; and decreasing pH is one of the most important
contributors to increasing concentrations of many naturally-occurring parameters.
Hydro Geo Chem, Inc. (["HGC"]), 2012a) ("The Pyrite Report") attributed the decline in
pH across the Mill site to the site-wide existence and oxidation of pyrite in the perched
groundwater monitored at the site. Based on HGC (2012a), pyrite has been noted in
approximately 2h of the lithologic logs for wells installed at the site since 1999 and
verified by laboratory analysis in core and cuttings from at least 25 monitoring wells,
including MW-29, as well as MW-28, which is located upgradient of MW-29 (Figure
lB).
Pyrite may oxidize according to the following reaction (Williamson and Rimstidt, 1994):
(reaction 1)
Reaction 1 will increase hydrogen ion (acid) concentrations, which results in decreasing
pH. Oxidation of pyrite and the resulting decrease in pH enables subsequent pH-
dependent reactions to occur, including the mobilization of naturally-occurring metals
and metalloids (such as uranium) in the formation (McClean and Bledsoe, 1992). In
addition, pyrite typically contains many contaminants including selenium (Deditius,
2011) that are expected to be released upon pyrite oxidation. Furthermore, naturally
occurring uranium may be reduced and sorb onto pyrite (Descotes et al 2010; Glizaud,
2006) making it available for release upon oxidation. As discussed in EFRI (2021 ),
bottle-roll tests using 'generic' pyrite resulted in bottle-roll solutions initially consisting
of laboratory-grade DI water picking up between 25 micrograms per liter ("µg/L") and
3,420 µg/L uranium. Bottle-roll tests using pyrite-bearing core from the formation
hosting perched groundwater at the site yielded bottle-roll solutions having as much as
6,700 µg/L uranium.
The likely causes for site-wide oxidation of pyrite include processes that increase oxygen
transport to groundwater. Monitoring well casings themselves provide direct conduits for
oxygen to impact groundwater in the immediate vicinities of the wells. Additional factors
expected to increase oxygen transport to groundwater include: (1) infiltration of oxidized
water from the wildlife ponds upgradient of the Mill site; (2) changing water levels and
incorporation of oxygen in air-filled pore spaces into groundwater; (3) the introduction of
oxygen during pumping related treatment of the nitrate/chloride plume; and (4) the
introduction of oxygen during increased sampling of monitoring wells (INTERA, 2012).
7
Many of these mechanisms, in particular changing water levels, are expected to impact
MW-29. Water levels at many site wells increased due to former seepage from the
northern wildlife ponds located upgradient of the TMS. As shown in Figure 2, as a result
of former wildlife pond seepage and expansion of the resulting perched groundwater
mound, water levels at MW-29 increased by approximately 4.5 feet between 2005 and
present.
As discussed in the pyrite report, between the time of installation and 2012, pH at MW-
29 was trending downward, presumably as a result of pyrite oxidation. However, between
2012 and late 2016, pH at MW-29 appears to have stabilized; and subsequently, between
late 2016 and the present time, pH at MW-29 appears to be on an upward trend, similar to
most other MW-series wells at the site. Although pH is no longer decreasing, suggesting
that pyrite oxidation has diminished, oxygen transport mechanisms are presumably still
active, and are expected to impact the geochemistry at MW-29; in particular,
groundwater in the vicinity of MW-29 is expected to become more oxidizing.
3.2 Changes in Groundwater in MW-29
At the time of the Background Reports, MW-29 had a limited data set composed of eight
data points per GWDP parameter. At the time of this SAR, 40 data points are available,
providing a more robust understanding of the water quality and behavior of MW-29.
Other factors that may also contribute to the behavior of constituents in this well are
discussed below.
As discussed in Section 1, Figure lB shows water levels and chloroform, nitrate and
chloride plume boundaries for Q2 of 2021. Figure 1 C shows the same features as Figure
lB, except that water levels and plume boundaries are as they existed just prior to
cessation of water delivery to the wildlife ponds. A comparison between Figure lB and
Figure 1 C shows the substantial changes in water levels that have occurred in less than 10
years due to pumping and cessation of water delivery to the wildlife ponds. Currently,
although water levels have declined substantially in the center of the perched
groundwater mound associated with the northern wildlife ponds, water levels have not
returned to pre-pond seepage conditions, and consequently the groundwater mound is still
expanding.
The transient status of a large portion of the perched water system, manifested in long-
term changes in saturated thicknesses and rates of groundwater flow, is expected to result
in trends in pH and in the concentrations of many dissolved constituents that are
unrelated to site operations. Changes in saturated thicknesses and rates of groundwater
flow can result in changes in concentrations of dissolved constituents ( or pH) for many
reasons. For example, as discussed in HGC (2012), groundwater rising into a vadose zone
having a different chemistry than the saturated zone can result in changes in pH and
groundwater constituent concentrations. If the rise in groundwater represents a long-term
trend, long-term changes in groundwater constituent concentrations (or pH) may result.
8
As noted in Section 3.1, as a result of enhanced transport of oxygen to groundwater in the
vicinity of site monitoring wells, groundwater in the vicinity of MW-29 is expected to
become more oxidizing. This expectation is consistent with decreasing ammonia
concentrations. As shown in Figure 3, uranium concentrations at MW-29 have increased
as the ammonia concentrations have generally decreased; and increasing uranium
accompanied by decreasing ammonia is consistent with the findings of Miao et al (2013).
Under geochemical conditions where groundwater becomes more oxidizing, naturally-
occurring uranium is expected to become more mobile, leading to increased
concentrations. In addition, as shown in Figure 4, both uranium and bicarbonate
concentrations at MW-29 have generally increased. The nearly simultaneous increase in
both uranium and bicarbonate is expected; as discussed in Desbarats et al (2017), and
Drage and Kennedy (2013), increased bicarbonate enhances the mobility of uranium; and
Jurgens et al (2010) note that high bicarbonate water leaches uranium from sediments.
(With regard to Figures 3 and 4: subsequent to the Q2 of 2012, bicarbonate data provided
in Figure 4 that were reported by the analytical laboratory as CaC03 have been converted
to HC03 to be compatible with previous data; and the fourth quarter, 2005 uranium value
of 49 µg/L is an extreme outlier and is not included in either Figure 3 or 4).
3.3 Indicator Parameter Analysis
As discussed in the Background Reports (INTERA, 2007a, 2007b, 2008), indicator
parameters of potential TMS seepage include chloride, sulfate, fluoride, and uranium.
Chloride is the best indicator of potential TMS seepage; however, chloride is problematic
as an indicator parameter for those groundwater monitoring wells (such as MW-28,
located upgradient of MW-29) impacted by the chloride component of the
nitrate/chloride plume (EFRI, 2020b ). Sulfate and fluoride are useful indicator parameters
under geochemical conditions allowing conservative (i.e., non-reactive) behavior.
Uranium behavior may range from conservative to non-conservative depending on the
geochemical conditions.
Groundwater impacted by any potential seepage from the TMS is expected to exhibit
increasing concentrations of chloride, sulfate, fluoride, and uranium, among other
constituents. While uranium can be the most mobile of trace metals under certain
conditions, it is typically retarded behind chloride, fluoride, and sulfate due to possible
sorption and precipitation and would likely not show increasing concentrations in
groundwater until sometime after chloride, fluoride, and sulfate concentrations had begun
to increase (INTERA, 2007a). Based on data provided in USEPA (2008), uranium is
generally expected to sorb and have comparatively poor mobility at the near-neutral to
slightly acidic pH conditions encountered at MW-29. Regardless, although the absence of
a rising trend in constituent concentrations would indicate that there has been no impact
from the TMS, a rising trend in concentrations could also result from natural influences
(INTERA, 2007a, Section 12.0).
In general, the behavior of the key indicator parameters, chloride, fluoride, and sulfate, in
MW-29 has not changed significantly since the time of the 2008 New Wells Background
Report or the 2013 SAR (INTERA 2013). A summary of statistical analysis of indicator
9
parameters is included in Appendix C-1. Appendix C-2 presents a comparison of
descriptive statistics for indicator parameters from the 2008 New Wells Background
Report, the 2013 SAR and this 2021 SAR. Data used in the analysis and data removed
prior to analysis are presented in Appendices C-3 and C-4, respectively. The distribution
and identification of outliers and extreme outliers in indicator parameter concentration
data sets are demonstrated in the box plots included in Appendix C-5. Histograms and
time series plots included in Appendices C-6 to C-8 can be used to further visualize the
distribution and behavior of indicator parameters over time.
Chloride concentrations in MW-29 have remained relatively stable between 35 and 40
milligrams per liter ("mg/L"). Fluoride and sulfate concentrations in MW-29 are
exhibiting gradual statistically significant decreasing trends. Uranium concentrations in
MW-29 are increasing significantly. An increasing trend in uranium was noted at the time
of the 2008 background report, although the trend was not significant at that time. A
statistically significant increasing trend in uranium concentrations was identified in the
2013 SAR. Despite the increasing trend, uranium concentrations in MW-29 remain
relatively low compared to other wells at the Mill (Appendix B-9).
Although uranium concentrations display a significantly increasing trend, the Q2 2021
uranium concentration at MW-29 is about average for the site MW-series monitoring
wells. In addition, the stable to decreasing concentrations of the most mobile indicator
parameters chloride, fluoride and sulfate; and increasing concentrations of relatively low
mobility uranium; constitutes behavior that is the opposite of expectation should
increasing uranium result from TMS seepage.
3.4 Mass Balance Analyses
Since installation in 2005, water levels at MW-29 have risen by approximately 4.5 feet,
and the saturated thickness has increased by about 25%. TMS solutions contain chloride,
a conservative solute, at an average concentration exceeding 23,000 mg/L. If the water
level changes at MW-29 were due to potential TMS seepage, and implied a mixture
containing 20% TMS solution, then chloride concentrations at MW-29 would exceed
4,500 mg/L, rather than the measured values of less than 40 mg/L. This demonstrates
that the observed increases in water levels at MW-29 could not result from potential TMS
seepage.
An additional mass balance calculation based on indicator parameters chloride, fluoride,
sulfate and uranium is provided in Appendix D. For this mass balance calculation,
indicator parameters are assumed to be conservative tracers (INTERA, 2007a) and not
subject to attenuation during transport. Therefore, if the TMS is a source of
contamination at MW-29, and all four indicator parameters behave conservatively, then
all four parameters should be increasing; however the most conservative parameters
chloride, fluoride and sulfate are stable to decreasing; and only uranium is increasing.
Model calculations are presented in Appendix D. The mass balance calculations are
based on dilution factors ("DFs") computed as the ratio of a particular constituent's
10
current (Q2 2021) concentration in MW-29 to its average concentration in TMS Cell 1
solutions since 2003 (EFRI, 2020a) The DPs calculated for all indicator parameters based
on the ratio of Cell 1 and MW-29 constituent concentrations vary by more than three
orders of magnitude.
Based on the computed DPs for uranium, chloride and sulfate, the predicted MW-29
fluoride concentrations are 0.091, 3.3 and 31.2 mg/L, respectively; yet the most recent
observed concentration of fluoride in MW-29 is 0.694 mg/L. The dissimilarity between
predicted and measured fluoride concentrations and the large range in calculated DPs for
the indicator parameters indicate that potential TMS seepage is not a contributor to the
groundwater chemistry of MW-29. Instead, fluoride concentrations in MW-29 are similar
to most natural waters ( < 1 mg/L; Hem 1985) and are more consistent with natural
processes.
Applying the same mass balance methodology to uranium, the predicted MW-29 uranium
concentrations range from 123 µg/L (based on the fluoride DF) to 5,530 µg/L (based on
the sulfate DF); yet the most recent observed concentration of uranium in MW-29 is 16.2
µg/L. All of the predicted concentrations of uranium substantially exceed the mo t recent
observed uranium concentration of approximately 16.2 µg/L, an even more compelling
indication that potential TMS seepage is not a contributor to the groundwater cheml try
atMW-29.
As discussed above, chloride, fluoride and sulfate concentrations at MW-29 are stable to
decreasing (Appendix C), which is inconsistent with potential TMS seepage. In addition,
as discussed above, if water level changes at MW-29 were the result of TMS seepage,
chloride concentrations would be orders of magnitude higher than measured in MW-29.
Furthermore, the ratios of indicator parameters in MW-29 differ substantially from ratios
of the same constituents in Cell 1 solutions. The average chloride to average fluoride
ratio in Cell 1 is approximately 11 while the Q2 2021 ratio in MW-29 is approximately
51; the average chloride to average sulfate ratio in Cell 1 is approximately 0.14 while the
Q2 2021 ratio in MW-29 is approximately 0.015; and the ratio of average chloride to
average uranium in Cell 1 is approximately 61 while the Q2 2021 ratio in MW-29 is
approximately 2,185. None of these ratios are reflective of a TMS impact.
Overall, the mass balance analyses and geochemical considerations indicate that potential
TMS seepage is not a contributor to the groundwater chemistry at MW-29. Increasing
uranium at MW-29 is attributable to 1) a change in geocbemi try to more oxidizing
conditions, consistent with enhanced oxygen transpmt to groundwater via the well casing
and as a result of rising water levels; and 2) increa ing bicarbonate concentrations. Both
are expected to enhance mobilization of naturally occurring uranium from the formations
hosting the perched groundwater and to result in increa. ed uranium concentration in
MW-29 groundwater.
11
3.5 Summary of Results
As discussed in the Background Reports (INTERA, 2007a, 2007b, 2008), indicator
parameters of potential tailings system seepage include chloride, sulfate, fluoride, and
uranium. Chloride is the best indicator of potential TMS eepage for wells such as MW-
29 that are outside the nitrate/chloride plume that originates up gradient of the TMS.
As discussed above, chloride at MW-29 is stable; and fluoride and sulfate at MW-29 are
decreasing. Only uranium displays an increasing trend. The behavior of chloride, fluoride
and sulfate are inconsistent with a TMS impact; as are mass balance analyses based on
chloride and other indicator parameters. Increasing uranium is attributable to
mobilization of naturally occurring uranium from the formations hosting perched
groundwater due to: 1) conditions that are increasingly oxidizing at MW-29 and 2)
increases in bicarbonate concentrations at MW-29.
3.5.1 Uranium
As noted in Section 3.3 above, uranium concentrations are about average for the site and,
as shown in Appendix B, are exhibiting a statistically significant increasing trend.
Apparent changes in uranium concentrations occur after April 2011 at the time of well
redevelopment that included surging and bailing. The subset of data post-2011 that were
analyzed alongside the complete data set and presented in Appendix B are normally
distributed and also exhibit a statistically significant increasing trend.
However, in addition to the behavior of indicator parameters discussed above in Section
3.5, which is inconsistent with a potential TMS impact, the ratio of average chloride to
average uranium in Cell 1 is approximately 61 while the Q2 2021 ratio in MW-29 is
approximately 2,185, also not reflective of a potential TMS impact. Furthermore, in
performing the mass balance analyses discussed in Section 3.4, the calculated DFs for
chloride, fluoride and sulfate over-predict the concentration of uranium at MW-29 by one
to three orders of magnitude; and chloride concentrations would exceed 4,500 µg/L rather
than the measured values of less than 40 µg/L if water level increases at MW-29 resulted
from TMS seepage; both of which are inconsistent with a potential TMS impact. Finally,
the stable to decreasing concentrations of the most mobile indicator parameters chloride,
fluoride and sulfate; and increasing concentrations of relatively low mobility uranium;
constitutes behavior that is the opposite of expectation should increasing uranium result
from TMS seepage.
As discussed above in Section 3.4, the most likely mechanisms for increased uranium at
MW -29 are 1) the change in geochemistry to more oxidizing conditions, consistent with
enhanced oxygen transport to groundwater via the well casing and as a result of rising
water levels; and 2) increasing bicarbonate concentrations. Both are expected to enhance
mobilization of naturally occurring uranium from the formations hosting the perched
groundwater and to result in increased uranium concentrations in MW-29 groundwater.
12
4.0 CALCULATIONS OF GROUNDWATER COMPLIANCE LIMITS
The findings of analyses discussed above support the conclusions that (1) MW-29 is not
being impacted by any potential TMS seepage, and (2) increasing concentrations of
uranium in MW-29 are the result of background influences. Although the nitrate/chloride
plume does not yet impact MW-29, the plume does affect MW-28, which is located
upgradient of MW-29. Furthermore, the existing GWCLs for MW-29 were developed at
the time of the Background Report using eight data points that are no longer
representative of current conditions at that location. Therefore, revision of the GWCL for
uranium in MW-29 is proposed.
4.1 Evaluation of Modified Approaches to Calculation of GWCLs for Trending
Constituents
According to the DWMRC-approved Flowsheet (Appendix E), if an increasing trend is
present, a modified approach should be considered for determining GWCLs. Uranium
concentrations in MW-29 are exhibiting a statistically significant increasing trend that
can be attributed to 1) a change in geochemistry to more oxidizing conditions, consistent
with enhanced oxygen transport to groundwater via the well casing and as a result of
rising water levels and 2) increases in bicarbonate concentrations at MW-29.
The Flow sheet contemplates GWCLs being set in various circumstances based on ( 1) the
fractional approach; (2) the highest historical value; and (3) the mean+ 2cr, and states that
for rising trends a modified approach can be considered. In proposing a modified
approach for the GWCL for uranium in MW-29, the following alternative approaches to
calculating a GWCL have been considered, in addition to the fractional approach, highest
historical value, and mean + 2cr:
1. 1.5 times background concentration as defined m Utah Administrative Code
("UAC") R317-6-4.3.
The UAC R317-6-4.3 recognizes that "contaminants" may be present as part of naturally
occurring background conditions:
When a contaminant is present in a detectable amount as a background
concentration, the concentration of the pollutant may not exceed the
greater of 1.5 times the background concentration or 0.5 times the ground
water quality standard or background plus two standard deviations ...
In this rule, background concentration is defined as the "concentration of a pollutant in
ground water upgradient or lateral hydraulically equivalent point from a facility, practice
or activity which has not been affected by that facility, practice or activity." Background
at the Mill has been determined on an intra-well basis, as defined in the Background
Reports. Therefore, to be conservative, the mean concentration is proposed to be used as
background for the purposes of this calculation. The mean concentration would assume
all data to date (or a data subset as described below), after following the data quality steps
13
of the Flowsheet.
2. Using a recent subset of data to calculate GWCLs.
This approach follows the DWMRC-approved Flowsheet (Appendix E) by taking into
account increasing trends and processing the data consistently with previously
determined GWCLs. In this approach, the complete data set, which exhibits an increasing
trend for uranium over the history of the well record, is divided into a subset of data
based on identification of a point of inflection where the results have shifted. This
approach is appropriate in wells, such as MW-29, that have been thoroughly investigated
and where the causes of increasing trends are not due to any potential TMS seepage or
other Mill-related impacts that are not already being addressed. For purposes of this
modified approach and to be consistent with previous SARs, a point of inflection was
identified in the uranium data sets and data from post-April 2011 were evaluated
(Appendix B) in addition to the full data set. Both the full and post-April 2011 uranium
data sets are normally distributed, and exhibit statistically significant increasing trends.
These two modified approaches have been considered for developing revised GWCLs for
uranium in MW-29, which is increasing in concentration for reasons other than any
potential TMS impact. Based on this analysis, the most appropriate GWCL for uranium
in MW-29, considering increasing trends, is proposed as the highest of the following: (1)
fractional approach; (2) highest historical value; (3) mean + 2cr, calculated using either
the full data set or the post-April 2011 data set; or (4) 1.5 times background, calculated
using either the full data set or the post-April 2011 data set. This modified approach of
choosing the highest of these values combines elements from the Flowsheet and from
previously approved GWCLs (DWMRC, 2016).
4.2 Proposed Revised GWCLs
In accordance with the Flowsheet, the increasing trend identified for uranium warrants a
modified approach to the calculation of GWCLs. Two data sets were evaluated for use in
calculating GWCLs. Both data sets exhibit statistically significant increasing trends and are
normally distributed. Considering the increasing trends, a modified approach of choosing
the highest of the following: (1) fractional approach; (2) highest historical value; (3)
mean+ 2cr, calculated using either the full data set or the post-April 2011 data set; or (4)
1.5 times background, calculated using either the full data set or the post-April 2011 data
set, would be appropriate. Flowsheet analysis has been performed for both data sets and
is summarized in Appendix B.
Proposed GWCLs determined according to the Flowsheet using all data to date and the
post-April 2011 data are presented in Table 1 and Appendix B-1. In both data sets, the
modified approach of 1.5 times background is the proposed GWCL because it is the
greater of: (1) the fractional approach; (2) the highest historical value, (3) the mean+ 2cr,
or (4) 1.5 times background, calculated using either the full data set or the post-April
2011 data set. In light of the findings of this SAR and the significant increasing trend in
uranium concentrations, the GWCL of 20.2 ug/L which was calculated using the post-
14
2011 data set is recommended.
Table 1 Proposed GWCL
Parameter GWCL" Revised GWCL Rationale
Uranium (ug/L) 15 18.4 Modified Approach-
(full data set) 1.5 x background
Uranium (ug/L) 15 20.2 Modified Approach-
(post-2011 data set) 1.5 x background
Notes:
a= 2021 GWDP No.UGW370004.
15
5.0 CONCLUSIONS AND RECOMMENDATIONS
Background groundwater quality at the Mill site was thoroughly studied as described in
the Background Reports (INTERA, 2007a, 2007b, 2008) and in the University of Utah
Study (Hurst and Solomon, 2008). The Background Reports and the University of Utah
Study concluded that groundwater at the Mill site has not been impacted by Mill
operations. These studies also acknowledged that there are natural influences operating at
the Mill site that have caused increasing trends and general variability in background
groundwater quality. Note that the increasing trend in uranium at MW-29 was already
present at the time that Hurst and Solomon (2008) determined that there were no impacts
to groundwater from the TMS.
Consistent with the conclusions of the Background Reports and the University of Utah
Study, the conclusion of this SAR is that groundwater in MW-29 is not impacted by
potential TMS seepage. Mass balance calculations have demonstrated that concentrations
of SAR parameters and indicator parameters are consistent with background conditions,
and not the result of potential TMS seepage. Increasing uranium at MW-29 is attributed
to mobilization of naturally occurring uranium from the formations hosting perched
groundwater due to: 1) conditions that are increasingly oxidizing at MW-29 due to
enhanced oxygen transport to groundwater via the well casing and as a result of rising
water levels; and 2) increases in bicarbonate concentrations at MW-29.
One goal of this SAR was to identify any changes in circumstances identified in previous
studies. Accordingly. the change in MW-29 uranium concentrations is attributed to the
ongoing changes in background conditions described above.
Furthermore, increases in water levels at MW-29 related to former wildlife pond
recharge, and increased sampling frequency, may influence constituent concentrations.
Both conditions could contribute to increasing uranium concentrations and both are
unrelated to the TMS.
In addition to the above factors, a site-wide comparison of constituent concentrations in
MW-29 shows that even though many constituents have significant increasing long-term
trends, their concentrations are less than or within the range of site-wide background
concentrations. This constitutes further evidence that uranium concentrations in MW-29
are likely due to background influences and the water level increases, and not to potential
TMS seepage.
16
6.0 REFERENCES
Deditius, Artur P; Satoshi Utsonomiya; Martin Reich; Stephen E Kesler; Rodney C
Ewing; Robert Hough; and John Walshe, 2011. Trace Metal Nanoparticles in
Pyrite. Ore Geology Reviews, Vol. 42, Issue 1, Nov. 2011, pp 32-46.
Descotes, M; ML Schlegel; N Eglizaud; F Descamps; F Miserque; and E Simoni, 2010.
Uptake of Uranium and Trace Elements in Pyrite (FeS2) Suspensions.
Geochimica et Cosmochimica Acta, Volume 74, Issue 5, March 2010, pp 1551-
1562.
Desbarats, Alexander J; Jeanne B Percival; and Katherine E Venance, 2017. Uranium
Mobility in Groundwater at Historical Minesites in the Bancroft Region of
Ontario, Canada. Paper No. 299-7, GSA Annual Meeting in Seattle, Washington,
USA-2017.
Drage, John and Gavin W Kennedy, 2013. Occurrrence and Mobilization of Uranium in
Groundwater in Nova Scotia. Geo Montreal, 2013.
Division of Waste Management and Radiation Control (DWMRC), 2016. Letter RE:
Energy Fuels Resources (USA) Inc. December 9, 2015, Transmittal of Source
Assessment Report for Monitoring Well MW-31, White Mesa Uranium Mill
Groundwater Discharge Permit No. UGW370004. February 19, 2016
Energy Fuels Resources (USA) Inc. (EFRI), 2020a. White Mesa Uranium Mill Annual
Tailings System Wastewater Monitoring Report.
---, 2020b. Source Assessment Report for Exceedances in MW-28.
---, 2021. White Mesa Uranium Mill MW-24A Report, State of Utah Groundwater
Discharge Permit No. UGW 370004, June 14, 2021.
Glizaud, N. 2006. Retention and Reduction of Uranium on Pyrite Surface. Thesis, Paris-
11, Univ, 91-Orsay (France).
Hem, J. D., 1985. Study and Interpretation of the Chemical Characteristics of Natural
Water. United States Geological Survey Water-Supply Paper, 2254.
HGC 2012a. Investigation of Pyrite in the Perched Zone. White Mesa Uranium Mill Site.
Blanding, Utah. December 7, 2012.
---, 2012b. Corrective Action Plan for Nitrate White Mesa Uranium Mill, Near
Blanding, Utah.
17
---, 2018. Hydrogeology of the White Mesa Uranium Mill and Recommended
Locations of New Perched Wells to Monitor Proposed Cells 5A and 5B. July 11,
2018.
Hurst, T.G., and Solomon, D.K., 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, University of Utah.
INTERA Incorporated (INTERA), 2007a. Revised Background Groundwater Quality
Report: Existing Wells for Denison Mines (USA) Corp.' s White Mesa Uranium
Mill Site, San Juan County, Utah.
___ , 2007b. Evaluation of Available Pre-Operational and Regional Background Data,
Background Groundwater Quality Report: Existing Wells for Denison Mines
(USA) Corp.'s Mill Site, San Juan County, Utah. November 16.
---, 2008. Revised Background Groundwater Quality Report: New Wells for
Denison Mines (USA) Corp.'s White Mesa Uranium Mill Site, San Juan County,
Utah.
---, 2009. Nitrate Groundwater Contamination Investigation Report White Mesa
Uranium Mill Site, Blanding, Utah.
---, 2012. PH Report White Mesa Uranium Mill, Blanding, Utah.
---, 2013. Source Assessment Report for Total Dissolved Solids in MW-29.
Jurgens, Bryant C.; Miranda S. Fram; Kenneth Belitz; Karen R. Burow; and Matthew K.
Landon, 2010. Effects of Groundwater Development on Uranium: Central Valley,
California, USA. GROUND WATER, Vol. 48, No. 6, November-December
2010, pp 913-928.
McClean, Joan E. and Bert E. Bledsoe, 1992. Behavior of Metals in Soils. USEP A
Groundwater Issue EP A/540/S-92/018, October 1992.
United States Environmental Protection Agency (USEPA) Office of Radiation and Indoor
Air Radiation Protection Division, 2008. Technical Report on Technologically
Enhanced Naturally-Occurring Radioactive Materials From Uranium Mining
Volume 2: Investigation of Potential Health, Geographic, and Environmental
Issues of Abandoned Uranium Mines. EPA-402-R-08-005, April 2008.
United States Environmental Protection Agency (USEPA), 1989. Statistical Analysis of
Groundwater Monitoring Data at RCRA Facilities: Interim Final Guidance, 530-
SW-89-026, Office of Solid Waste, Permits and State Programs Division, U.S.
Environmental Protection Agency, 401 M Street, S.W. Washington, D.C. 20460.
18
__ , 1992. Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities:
Addendum to Interim Final Guidance, Office of Solid Waste, Permits and State
Programs Division, U.S. Environmental Protection Agency, 401 M Street, S.W.
Washington, D.C. 20460.
__ , 2009. Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities,
Unified Guidance, EPA 530/R-09-007.
Williamson, M. A., Rimstidt, J. D., 1994. The Kinetics and Electrochemical Rate-
Determining Step of Aqueous Pyrite Oxidation. Geochimica et Cosmochimica
Acta, 58, 5443-5454.
Miao, Ziheng; Hakan Nihat; Andrew Lee McMillan; and Mark L Brusseu, 2013.
Transport and Fate of Ammonium and its Impact on Uranium and Other Trace
Elements at a Former Uranium Mill Tailing Site. Appl. Geochem., 38; 10-1016,
Nov 2013.
19
FIGURES
APPENDICES
APPENDIX A
Monitoring-
Well(Water Clo~tituentE1Cceedll1g GW L
CJass)
Chloride (rng/L)
MW-ll Sulfate (rng/L)
(Class II) TDS (mg/L)
Manganese (uJ!/L)
MW-25 Cadmium (ug/L) (Class III)
Nitrate + Nitrite (as N) (m!.!.IL)
Chloroform (u!.!/L)
MW-26 Chloride (m.!V"L)
(Class lll) TDS (m!l/L)
Carbon Tetrachloride
Melhylcnc Chloride (uldL)
Nitrate + Nitrite (:as N) (mit/1.)
MW-30 Chloride ( mg/L)
(Class II) Selenium (ug/L)
Uranium (uJ!/L)
Nitrnte + Nitrite (as N) (mll/L)
MW-31 Sulfate (m!.!/L)
(Class III) TDS (111g/L)
Uranium (uJ!/L)
Chloride (mll/L)
MW-12 Uranium (ug/L)
(Class Ill) Selenium (ug/L)
Bervllium (u\?/L)
Cadmium (u.11/L)
Fluoride (mg/L)
MW-24 Nickel (mg/L)
(Class lll) M:m.e.nnese (ug/L)
Thallium (ug/L)
Gross Alpha (pCi/L)
Sulfate (mg/L)
Field pH (S.U.)
MW-27
(Class Ill) Nitrate + Nitrite (as N) (mg/L)
Chloride (mg/L)
MW-28 Selenium (ug/L)
(Class III) Nitrate+ Nitrite (ns N) (nH?/L)
Gross Alpha /pCi/L)
Uranium (ug/L)
MW-29 Uranium (ug/L) (Class Ill)
MW-32 Chloride (mg/L) (Class lll)
Notes:
NS= Not Required and Not Sampled
NA= Not Applicable
Exceedances are shown in yellow
6WOLln
March 19,
201?
GWD'J>
39.16
1309
2528
164.67
1.5
0.62
70
58.31
3284.19
5
5
2.5
128
47.2
8.32
5
993
2132
15
143
23.5
39
2
6.43
0.47
50
7507
2.01
7.5
2903
5.03 -8.5
5.6
105
11.l
5
2.42
4.9
15
35.39
Ql :Z020 Results
February Fcbr11.lll1' March20ZO March QI 2-0Z!) QI2020 2020 202'0 Mopthly 2020 ample Result Monthly, Mootl,Jy ample Monthly ~te Sample Date Result Date Res1,1lt II
38.9 42.1 41.0
1/15/2020 1180 1260 1120
1/28/2020 2/4/2020 3/10/2020 1920 NA NA
169 227 183
1/15/2020 1.35 2/5/2020 1.52 3/11/2020 1.41
0.873 0.978 1.60
1260 1640 1720
1/15/2020 78.8 66.9 76.9
3010 2/4/2020 NA 3/10/2020 NA
<1.00 NA NA
2.79 2.76 4.44
16.4 17.8 19.0
l/15/2020 182 2/5/2020 187 3/11/2020 182
49.7 49.9 48.1
8.88 9.06 9.50
17.5 18.0 19.2
1120 1150 1080
1/14/2020 2220 2/4/2020 2140 3/10/2020 2380
14.8 NA NA
381 370 368
1/16/2020 21.9
NA NS NA NS NA
2.07 NA NA
7.30 NA NA
0.805 NA NA
68.1 NA NA
1/22/2020 7010 NS NA NS NA
1.92 NA NA
4.95 NA NA
2960 NA NA
6.01 NA NA
1/16/2020 6.18 NS NA NS NA
151 NA NA
13.4 NA NA
1/16/2020 NA NS NA NS NA
1.79 NA NA
7.56 NA NA
NS NA NS NA NS NA
1/14/2020 38.0 NS NA NS NA
Appendix A -GWCL Exceedances for First Quarter 2021 under the March 8, 2021 GWDP
Q2 2020 ~esults Q3 2020 Results Q42020 Resl,llts
Moy2020 Ju~e21)20 August t\ugu t eptembl!l" September November November Oe<tcmber December Q22020 Q2W20 l\'lonthly May2020 Monthly June2020 Q.32-0.ZO Q32020 20.ZO 2020 2020 2020 Q4 2-0ZI) e,4 2020 2020 20:Z,O 2QZO 202-0. 11mple Result ample Mo11Jhly ample Monthly Sample: Result Mo,11thly MonUJly Monthly Monthly SampliDa(e R~lt Monthly Monthly Monthly Monthly Date Date Result Date-Result Date ample Result ample Date Re.wit SampJ~Date Res,,Jt ~ample Oat~ {\~ult D11te
Required Quarterly Sampling Wells
38.3 39.0 40.1 42.1 43.9 40.6 44.8 33.7 37.4
4/8/2020 1180 5/5/2020 1180 6/2/2020 1310 7/7/2020 1260 8/11/2020 1220 9/2/2020 1170 10/12/2020 1300 11/16/2020 858 12/7/2020 1330
1920 NA NA 2590 NA NA 992 2040 1990
189 206 211 178 276 230 211 174 212
4/7/2020 l.46 5/6/2020 1.52 6/3/2020 l.46 7/7/2020 l.39 8/10/2020 1.54 9/2/2020 1.61 10/13/2020 1.43 lt/17/2020 1.23 12/8/2020 1.59
0.747 1.16 3.44 1.360 0.407 0.623 0.936 0.379 0.611
1420 1200 1530 4030 1940 1070 872 2800 1200
62.8 5/6/2020 73.8 6/3/2020 63.7 7/9/2020 67.6 8/11/2020 57.5 9/2/2020 59.8 10/15/2020 57.2 11/17/2020 36.4 12/8/2020 42.1 4/8/2020 2600 NA NA 3880 NA NA 4860 2980 3040
<1.00 NA NA <1.00 NA NA <l.00 NA NA
1.94 1.48 2.35 6.59 2.67 <l.00 <1.00 14.60 1.52
18.1 18.6 18.3 18.4 21.1 18.3 16.8 1.1.4 12.0
4/6/2020 195 5/6/2020 177 6/3/2020 180 7/6/2020 185 8/11/2020 183 9/1/2020 166 10/13/2020 183 11/17/2020 150 12/8/2020 166
54.4 51.5 50.5 51.8 56.0 55.3 53.5 54.9 51.8
9.24 8.94 9.28 9.76 10.6 9.90 9.92 9.95 9.56
18.8 20.1 18.7 19.2 21.6 18.4 18.6 16.5 18.8
1130 1080 1130 1150 1100 1110 1100 676 922
4/6/2020 2400 5/5/2020 2330 6/2/2020 2440 7/7/2020 2400 8/10/2020 2580 9/1/2020 2650 10/19/2020 2370 11/16/2020 2490 12/7/2020 2560
15.5 NA NA 18.1 19.7 18.5 19.3 17.8 19.5
376 361 377 370 368 367 345 251 311
Required Scmi-Aon11al S11mpliDg Wclls.
23.7 25.6 NS 10/20/2020 26.2 NA 4/9/2020 NS NA NS NA 7/8/2020 40.1 NA NS NA 52.7 NS NA NS 41.2
2.95 NA NA 2.59 NA NA 2.47 NA NA
8.46 NA NA 8.43 NA NA 8.12 NA NA
0.732 NA NA 1.08 NA NA 0.976 NA NA
72.6 NA NA 76.7 NA NA 77.3 NA NA
4/22/2020 7750 NS NA NS NA 7/10/2020 8010 NS NA NS NA 10/28/2020 7480 NS NA NS NA
2.81 NA NA 3.07 NA NA 2.92 NA NA
5.69 NA NA 3.72 NA NA 9.03 NA NA
2870 NA NA 2920 NA NA 3220 NA NA
5.60 NA NA 5.70 NA NA 5.19 NA NA
4/8/2020 6.43 NS NA NS NA 7/8/2020 6.62 NS NA NS NA 10/21/2020 6.52 NS NA NS NA
129 NA NA 140 NA NA 127 NA NA
10.2 NA NA 15.5 NA NA 9.90 NA NA
4/15/2020 2.6 NS NA NS NA 7/8/2020 4.58 NS NA NS NA 10/23/2020 2.39 NS NA NS NA
1.69 NA NA 1.60 NA NA 1.68 NA NA
5.91 NA NA 11.80 NA NA 5.88 NA NA
4/8/2020 14.8 NS NA NS NA NS NA NS NA NS NA 10/13/2020 15.3 NS NA NS NA
4/7/2020 36.4 NS NA NS NA 7/6/2020 33.0 NS NA NS NA 10/12/2020 36.3 NS NA NS NA
APPENDIXB
Appendix B-2: Comparison of Calculated and Measured TDS in MW-29
Alkalinity Calcium Date Sampled (mg/Las
HC03)
(mg/L)
6/21/2005 155 452
9/22/2005 152 514
12/14/2005 165 532
3/22/2006 152 515
6/23/2006 174 491
9/12/2006 95 521
10/24/2006 156 518
3/15/2007 139 519
6/20/2007 151 521
8/28/2007 161 530
10/23/2007 162 538
3/12/2008 159 490
6/3/2008 149 514
8/6/2008 160 546
11/5/2008 154 546
2/4/2009 154 479
5/12/2009 156 483
8/17/2009 153 526
10/12/2009 158 512
1/19/2010 165 517
4/19/2010 158 500
11/12/2010 157 492
4/11/2011 155 513
10/5/2011 146 505
5/8/2012 160 522
11/14/2012 151 507
5/15/2013 156 487
12/4/2013 176 475
6/18/2014 293 554
11/5/2014 176 478
4/21/2015 183 531
11/10/2015 161 531
4/20/2016 151 506
11/1/2016 153 487
4/19/2017 151 485
10/18/2017 174 484
4/19/2018 153 532
10/30/2018 159 580
4/24/2019 181 574
10/22/2019 285 569
4/15/2020 181 538
Appendix B
Source Assessment Report for MW-29
White Mesa Uranium Mill
Chloride Potassium Magnesium Sodium Sulfate
(mg/L) (mg/L) (mg/L) (mg/L) (mg/L)
80 11 .6 148 302 2010
96 10.6 166 286 2310
86 12.5 203 303 2380
83 11.8 188 294 2320
91 11.9 167 276 2190
73 12.2 190 299 2380
86 12.1 184 294 2520
97 14.3 192 332 2340
94 12.4 188 291 2360
95 11.1 180 266 2440
99 11 .4 184 282 2370
99 11.4 160 292 2310
103 11 .1 167 303 2360
99 11 .5 179 311 2340
99 12.0 176 312 2340
91 11.0 157 286 2340
81 10.2 162 289 2410
100 11.7 169 302 2360
104 11.4 168 308 2380
102 11.6 168 0.6 2340
108 11.4 163 303 2310
107 11 .7 162 288 2290
109 11.9 167 310 2090
143 11.1 167 270 2340
114 12.9 177 298 2290
115 13.7 175 309 1710
102 11 .4 163 338 2030
109 10.6 162 287 2270
114 12.5 180 313 2410
117 11.9 162 277 2250
125 12.0 186 329 2490
116 11 .0 181 308 2440
121 11 .2 175 296 2350
126 12.8 168 296 2280
120 12.6 168 308 1970
123 13.0 184 311 1960
138 12.9 180 313 2280
119 13.3 203 365 2040
165 12.9 198 380 2390
149 11.9 209 351 2420
129 12.9 190 344 2280
Measured Calculated Ratio TDS (mg/L) TDS (mg/L)
3720 3159 85%
3590 3535 98%
3770 3682 98%
3640 3564 98%
3540 3401 96%
3720 3570 96%
3600 3770 105%
3800 3633 96%
3770 3617 96%
3700 3683 100%
3600 3646 101%
3640 3521 97%
3580 3607 101%
3590 3647 102%
3650 3639 100%
3730 3518 94%
3620 3591 99%
3680 3622 98%
3710 3641 98%
3490 3304 95%
3670 3553 97%
3630 3508 97%
3690 3356 91%
3610 3582 99%
3820 3574 94%
3610 2981 83%
3480 3288 94%
3610 3489 97%
3680 3876 105%
3660 3472 95%
3370 3856 114%
3450 3748 109%
3540 3610 102%
3660 3522 96%
3450 3215 93%
3440 3249 94%
3460 3608 104%
3380 3479 103%
3500 3900 111%
3780 3995 106%
3520 3674 104%
...... $INTERA
Appendix 8-3: Charge Balance Calculations for Major Cations and Anions in MW-29
Well Date Calcium
(meq/L)
MW-29 6/22/2005 23.35
MW-29 9/22/2005 23.90
MW-29 12/14/2005 25.35
MW-29 3/21/2006 24.75
MW-29 6/21/2006 23.10
MW-29 9/12/2006 24.55
MW-29 10/24/2006 25.05
MW-29 3/15/2007 25.20
MW-29 8/22/2007 24.60
MW-29 10/24/2007 25.45
MW-29 3/19/2008 23.00
MW-29 6/3/2008 23.45
MW-29 8/5/2008 26.15
MW-29 11/5/2008 25.85
MW-29 2/3/2009 25.35
MW-29 5/13/2009 21.81
MW-29 8/24/2009 24.75
MW-29 10/26/2009 24.35
MW-29 4/27/2010 25.25
MW-29 11/9/2010 23.45
MW-29 4/5/2011 24.05
MW-29 10/5/2011 23.75
MW-29 5/8/2012 24.75
MW-29 11/14/2012 24.10
MW-29 5/23/2013 21 .91
MW-29 11/20/2013 23 .10
MW-29 6/3/2014 23.85
MW-29 11/10/2014 28.94
MW-29 4/30/2015 24 .65
MW-29 11/16/2015 24.45
MW-29 4/27/2016 24.85
MW-29 11/8/2016 23.75
MW-29 04/20/2017 22.70
MW-29 10/16/2017 24.00
MW-29 4/11/2018 25.45
MW-29 10/22/2018 26 .70
MW-29 4/24/2019 26.15
MW-29 10/22/2019 26.40
MW-29 4/8/2020 25.95
MW-29 10/13/2020 22.85
MW-29 4/14/2021 22.75 .. meq/L= m1lllequ1valent per liter
HC03 = Bicarbonate
S04 = Sulfate
Appendix B
Source Assessment Report for MW-29
White Mesa Uranium Mill
Sodium Magnesiu
(meq/L) m (meq/L)
19.23 18.26
19.23 18.92
19.53 19.58
18.79 19.42
18.83 18.68
19.05 18.92
19.83 19.25
18.83 19.42
19.14 19.25
18.49 19.74
20.27 16.95
21.14 17.94
21.49 19.58
22.10 19.00
16.40 18.76
19.10 16.54
21.79 18.10
19.79 17.77
22.44 18.51
19.75 17.36
21.57 17.52
18.92 17.52
21.18 18.68
21.18 18.02
20.57 17.28
19.83 17.03
20.49 18.18
24.84 21.97
21.57 18.10
21.31 18.10
21.14 17.77
19.36 17.44
20.31 17.19
20.18 18.10
20.23 19.00
23.27 19.58
23.62 19.00
21.49 19.83
21 .66 19.33
19.92 17.44
19.53 17.61
Total Total Charge Potassium Cation HC03 Chloride 504 Anion Balance (meq/L) Charge (meq/L) (meq/L) (meq/L) Charge Error (meq/L) (meq/L)
0.42 61.26 -4.87 -1.13 -56.21 -62.21 -0.77%
0.42 62.47 -5.15 -1.10 -59.13 -65.38 -2.27%
0.44 64.90 -5.20 -1.02 -57.67 -63.88 0.79%
0.42 63.38 -5.51 -1.16 -56.42 -63.09 0.23%
0.44 61.06 -5.20 -1.07 -57.67 -63.94 -2.31%
0.44 62.96 -5.11 -1.04 -56.63 -62.79 0.14%
0.44 64.58 -5.51 -1.10 -62.04 -68.65 -3.06%
0.44 63.89 -5.29 -1.10 -57.88 -64.27 -0.30%
0.42 63.41 -5.57 -1.04 -58.09 -64.70 -1.01%
0.44 64.12 -5.54 -1.04 -58.09 -64.67 -0.43%
0.44 60.66 -5.65 -1.10 -59.13 -65.88 -4.13%
0.43 62.96 -5.26 -1.07 -59.13 -65.46 -1.95%
0.45 67.66 -5.41 -0.99 -58.51 -64.90 2.08%
0.46 67.41 -5.38 -0.90 -60.80 -67.07 0.25%
0.35 60.86 -5.42 -0.87 -56.42 -62.72 -1.51%
0.39 57.83 -5.56 -0.85 -58.09 -64.49 -5.45%
0.45 65.09 -5.72 -0.96 -56.63 -63.31 1.39%
0.43 62.35 -5.77 -0.99 -61.63 -68.38 -4.62%
0.45 66.65 -5.87 -0.99 -57.67 -64.53 1.62%
0.45 61.00 -5.82 -1.10 -56.01 -62.92 -1.55%
0.44 63.59 -5.75 -1.07 -54.13 -60.96 2.12%
0.43 60.62 -5.36 -1.04 -59.34 -65.74 -4.05%
0.51 65.12 -5.69 -1.13 -57.26 -64.07 0.81%
0.44 63.74 -5.66 -1.04 -27.90 -34.60 29.64%
0.44 60.20 -6.28 -0.99 -51.01 -58.28 1.62%
0.46 60.43 -5.74 -0.98 -57.26 -63.98 -2.85%
0.43 62.96 -6.12 -1.05 -52.26 -59.43 2.88%
0.43 76.17 -6.20 -1.14 -57.46 -64.80 8.07%
0.45 64.77 -6.06 -1.13 -61.63 -68.82 -3.03%
0.42 64.29 -5.72 -1.03 -57.05 -63.79 0.39%
0.42 64.18 -6.02 -1.09 -56.84 -63.94 0.19%
0.46 61.01 -6.08 -1.08 -47.68 -54.84 5.32%
0.46 60.67 -6.06 -1.11 -51.84 -59.01 1.39%
0.48 62.77 -6.08 -1.05 -49.55 -56.68 5.09%
0.43 65.11 -6.12 -1.10 -49.97 -57.18 6.48%
0.48 70.03 -6.12 -0.98 -51.43 -58.52 8.95%
0.47 69.24 -6.28 -1.07 -45.18 -52.53 13.73%
0.43 68.15 -5.96 -1.07 -56.84 -63.87 3.24%
0.54 67.48 -4.80 -1.03 -54.97 -60.80 5.21%
0.42 60.64 -6.60 -1 .05 -61.21 -68.86 -6.34%
0.47 60.36 -4.84 -1.00 -49.14 -54.97 4.67%
BINTERA
Appendix B-4: Descriptive Statistics for Out of Compliance Constituents in MW-29
Data Set Analyte
2008 Background Report Uranium
2021 SAR ALL Uranium
Subset Post April 11, 2011 Uranium
ALL 2021 SAR Data= All data with extremes removed
GWCL Subset Post 2011 = All data post April 11, 2011
µg/L = micrograms per liter
N = number of valid data points
Appendix 89
Source Assessment Report for MW-29
White Mesa Uranium Mill
Units % Non-Detects N Distribution
µg/L 0 8 Non Parametric
µg/L 0 41 Normal
µg/L 0 21 Normal
Mean
11.2
12.3
13.50
Min. Cone. Max. Cone. Std. Dev. Range Geometric Skewness Q25 Median Q75 Mean
9.5 12.1 0.8 2.6 11.2 -1.60 11 .1 11 .3 11 .8
8.1 16.9 1.8 8.8 12.1 0.52 11 .1 11.9 13.3
11.2 16.9 1.5 5.7 13.4 0.62 12.2 13.3 14.2
.....-SelNTERA
Appendix 8-5: MW-29 Data Used for Analysis
Well Date Sampled
MW-29 6/22/2005
MW-29 9/22/2005
MW-29 3/21/2006
MW-29 6/21/2006
MW-29 9/12/2006
MW-29 10/24/2006
MW-29 3/15/2007
MW-29 8/22/2007
MW-29 10/24/2007
MW-29 3/19/2008
MW-29 6/3/2008
MW-29 8/5/2008
MW-29 11/5/2008
MW-29 2/3/2009
MW-29 5/13/2009
MW-29 8/24/2009
MW-29 10/26/2009
MW-29 4/27/2010
MW-29 11/9/2010
MW-29 4/5/2011
MW-29 10/5/2011
MW-29 5/8/2012
MW-29 11/14/2012
MW-29 5/23/2013
MW-29 11/20/2013
MW-29 6/3/2014
MW-29 11/10/2014
MW-29 4/30/2015
MW-29 11/16/2015
MW-29 4/27/2016
MW-29 11/8/2016
MW-29 4/20/2017
MW-29 10/16/2017
MW-29 4/11/2018
MW-29 10/22/2018
MW-29 4/24/2019
MW-29 10/22/2019
MW-29 4/8/2020
MW-29 10/13/2020
MW-29 1/15/2021
MW-29 4/14/2021
Appendix B
Source Assessment Report for MW-29
White Mesa Uranium Mill
Parameter Name
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Page 1 of 1
Report Report Units Qualifier Result
8.1 ug/1
11.4 ug/1
9.5 ug/1
11.6 ug/1
12.1 ug/1
11.1 ug/1
11 .2 ug/1
11 .9 ug/1
11 .1 ug/1
11 .1 ug/1
10.3 ug/1
10.4 ug/1
10.8 ug/1
10.7 ug/1
10.4 ug/1
11 .1 ug/1
11 .6 ug/1
10.8 ug/1
11.6 ug/1
12.7 ug/1
11.7 ug/1
12.2 ug/1
11 .2 ug/1
11.9 ug/1
13.8 ug/1
12.1 ug/1
11 .8 u9/I
12.7 ug/1
13.2 ug/1
13.0 ug/1
13.7 ug/1
12.9 ug/1
13.6 ug/1
13.9 ug/1
13.3 ug/1
15.0 ug/1
14.2 ug/1
14.8 ug/1
15.3 ug/1
16.9 ug/1
16.2 ug/1
BINTERA
Appendix 8-6: Extreme Outliers Removed from Analysis
-
Reason Location ID Date Sampled Parameter Name Report Result Report Units
Extreme (Hi h)
Appendix B
Source Assesment Report for MW-29
White Mesa Uranium Mill
MW-29 12/14/2005 Uranium 49.0 u /I
~INTERA
Appendix 8-7: Box Plots
Appendix B
50
-40
O> :, -E 30 :, ·2
~ :::, 20
10
Uranium in MW-29 for All Data
Uranium in MW-29
•
Percent nondetect: 0%
o Outlier
• Extreme
Min: 8.1, Mean: 13.14, Max: 49, Std Dev: 5.94
Upper extreme threshold (Q75 + 3xH): 20.8
Lower extreme threshold (Q25 -3xH): 3.825
Uranium in MW-29 Post April 11, 2011
-
17
16
=::: g> 15 -§ 14
·2
~ 13 :::,
12
Uranium in MW-29
o Outlier
• Extreme
11 ------------------------------------------'
Percent nondetect: 0%
Min: 11.2, Mean: 13.5, Max: 16.9, Std Dev: 1.51
Upper extreme threshold (075 + 3xH): 20.2
Lower extreme threshold (025 -3xH}: 6.2
Source Assessment Report for MW-29
White Mesa Uranium Mill Page 1 of 1 l!!!IINTERA
Appendix B-8: Box Plots for MW-29 and Upgradient and Downgradient Wells
Appendix B
--
Uranium in MW-29 for All Data
Uranium
50 @ i o Outlier 8 • • Extreme
40 -I z=:: C> ::::, -30 E ::::, ·2 20 cu ... :::::, I
I
I
10
0
Downgradient MW-29 Upgradient
Uranium in MW-29 Post April 11, 2011
Uranium
40 o Outlier
• Extreme
-30 ==::::
C> :::, -E
.:2 20 C: cu ... ::>
10
0
Downgradient MW-29
Notes
All available data used in box plots
Downgradient wells: MW-3A, MW-20, and MW-22.
Upgradient wells: MW-1, MW-18, and MW-19
Upgradient
Source Assessment Report for MW-29
White Mesa Uranium Mill Page 1 of 1 ~¥nlNTERA
~ (/) )> )> ::::,-0 "O -· C: "O )> z 'C --, Cl) Cl) (") ::, =o 'C :s: Cl) a. Q) .... Uranium (ug/1) C'D )> -· < m Cl) >< :::I ~ g: CD ~-C. Cl) ii> -· Cf/l -, (/) CT ...... ...... I\J >< ~ 3 co <Tl 0 <Tl 0 CD 0 0 0 0 0 -· Cl) a. C: ::, I
3 -Q) U) -:s: ~ Q) ..
C CD ="8 en MW-01 le* ;:::i CD 0
0 a. MW-02 ~-{J-1 ><
-, ::J t~• '1J :s: CT MW-03A • -~ 0 MW-05 ...... • 0 X -I tn I\J "C ,. (0 0 MW-11 ...... -•i'n-1 0 en MW-12 .,
MW-14 * •M<D»--[l}--10 o• en
MW-15 • a--{l]--1 0 )>
:::0 MW-17 0 ~m---0 '1J
MW-18 O'*---ffi-1 D) .,
MW-19 1~ D)
"O MW-20 (}-o• 3
QJ C'D (JQ MW-22 ~{I]-1 -m C'D .... MW-23 t{l}--1 .,
0 • C tn -ffl-1 .... MW-24 • • • iii -· :::, :::I
MW-25 .. c· G')
MW-26 ~----~ I 1-------1 3 ., 0 0
MW-27 •{)t C
:::I MW-28 I•• • C.
MW-29 + • ~ D)
MW-30 ., -C'D
MW-31 ift• .,
MW-32 ct-s:
0 II MW-34 I :::I
MW-35 «tp ~ 0 -MW-36 + :::!. 2 MW-37 to • 0 :::I cc
MW-38 I mo :E t, ~c MW-39 ci; =· C'D -MW-40 I 3 ~ 'ui' (I)
Appendix 8-12: Timeseries Plots with Events
16
-14 ::::::: C) :::::, -E :::::, 12 '2
<ti ... =>
10
8
Uranium in MW-29
-
-• •• • • -• • ·~ • • • • • • • • •• • •• • •• • -• -•
-•
I I I
2005 2010 2015
Sample Date
I 2021-04-15 Peak Groundwater Elevation
J 2012-10-01 Lab Change
•
0
• • • • • • • • •
I
2020
2014-06-01 five New Chloroform Pumping Wells Brought Online
I 2011-04-11 Surged and Bailed; Inflection point used for analysis
Appendix B
Source Assessment Report for MW-29
White Mesa Uranium Mill Page 1 of 1 l!!!INTERA
APPENDIXC
Appendix C-2: Descriptive Statistics of Indicator Parameters in MW-29
Data Set 2008 Background Report 2013 SAR
Analyte
Units
Chloride Fluoride Sulfate Uranium Chloride Fluoride Sulfate Uranium Chloride
mg/L mg/L mg/L ug/L mg/L mg/L mg/L ug/L mg/L
% Non-Detects
N
Normally or
Lognormallly
Distributed?
---------
Mean
Min. Cone.
Max. Cone.
Std. Dev.
Range
Geometric Mean
Skewness
251h Quartile
Median
751h Quartile
Appendix C
10
Normal or
Log normal
38.3
36.0
41 .0
1.6
5.0
38.3
0.2
37.0
38.5
39.0
10
Normal or
Log normal
0.9
0.7
1.1
0.1
0.4
0.8
1.2
0.8
0.8
0.9
Source Assesment Report for MW-29
White Mesa Uranium Mill
10 8
Normal or Not
Log normal Normal
2785 11.2
2700 9.5
2980 12.1
81 0.8
280 2.6
2784 11 .2
1.7 -1.6
2720 11.1
2775 11 .3
2790 11.8
24 23 23 23 41
Not Normal or Normal or Not Not
Normal Log normal Log normal Normal normal
37.0 0.79 2787 11 .0 37.0
30.0 0.68 2600 8.0 30.0
41.0 0.95 2980 13.0 41.0
3.0 0.06 89 1.0 2.5
11.0 0.27 380 5.0 11.0
37.0 0.79 2786 11 .0 37.0
-0.92 0.83 0.4 -1 .3 -1.0
35.0 0.76 2720 11.0 35.4
37.0 0.78 2780 11 .0 37.2
39.0 0.83 2840 12.0 39.0
2021 SAR
Fluoride Sulfate Uranium
mg/L mg/L ug/L --41 43
Not Not I Normal normal normal
0.75 2712 12.27
0.05 2290 8.1
1.1 2980 16.9
0.15 166.24 1.80
1.05 690 8.8
0.72 2707 12.14
-2.14 -0.84 0.52
0.699 2680 11.1
0.76 2750 11 .9
0.81 2790 13.3
a--:2¥elNTERA
Appendix C-3: Data Used for Statistical Analysis
-• LU] ,1 ""'11'1 •
MW-29 06/22/2005
MW-29 09/22/2005
MW-29 12/14/2005
MW-29 03/21/2006
MW-29 06/21/2006
MW-29 09/12/2006
MW-29 10/24/2006
MW-29 03/15/2007
MW-29 08/22/2007
MW-29 10/24/2007
MW-29 03/19/2008
MW-29. 06/03/2008
MW-29 08/05/2008
MW-29 11/05/2008
MW-29 02/03/2009
MW-29 05/13/2009
MW-29 08/24/2009
MW-29 10/26/2009
MW-29 04/27/2010
MW-29 11/09/2010
MW-29 04/05/2011
MW-29 10/05/2011
MW-29 05/08/2012
MW-29 11/14/2012
MW-29 05/23/2013
MW-29 11/20/2013
MW-29 06/03/2014
MW-29 11/10/2014
MW-29 04/30/2015
MW-29 11/16/2015
MW-29 04/27/2016
MW-29 11/08/2016
MW-29 04/20/2017
MW-29 10/16/2017
MW-29 04/11/2018
MW-29 10/22/2018
MW-29 04/24/2019
MW-29 10/22/2019
MW-29 04/08/2020
MW-29 10/13/2020
MW-29 04/14/2021
MW-29 06/22/2005
MW-29 09/22/2005
MW-29 12/14/2005
MW-29 03/21/2006
MW-29 06/21/2006
MW-29 09/12/2006
MW-29 10/24/2006
Appendix C
Source Assesment Report for MW-29
White Mesa Uranium Mill
--..
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Chloride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Page 1 of 4
. :• 1~111 ..
40 mg/L
39 mq/L
36 mg/L
41 mg/L
38 mq/L
37 mg/L
39 mg/L
39 mg/L
37 mg/L
37 mq/L
39 mg/L
38 mq/L
35 mg/L
32 mg/L
31 mq/L
30 mg/L
34 mg/L
35 mg/L
35 mg/L
39 mq/L
38 mg/L
37 mg/L
40 mq/L
37 mg/L
35 mq/L
35 mg/L
37 mg/L
40 mq/L
40 mg/L
36 mg/L
39 mg/L
38 mg/L
39 mg/L
37 mg/L
39 mg/L
35 mg/L
38 mq/L
38 mg/L
37 mq/L
37 mg/L
35 mg/L
1.10 mq/L
0.90 mg/L
0.80 mg/L
0.90 mg/L
0.80 mg/L
0.70 mg/L
0.80 mg/L
----¥.INTERA
Appendix C-3: Data Used for Statistical Analysis
. r:, • •1:1 •
MW-29 03/15/2007
MW-29 08/22/2007
MW-29 10/24/2007
MW-29 03/19/2008
MW-29 06/03/2008
MW-29 08/05/2008
MW-29 11/05/2008
MW-29 02/03/2009
MW-29 05/13/2009
MW-29 08/24/2009
MW-29 10/26/2009
MW-29 04/27/2010
MW-29 11/09/2010
MW-29 04/05/2011
MW-29 10/05/2011
MW-29 05/08/2012
MW-29 11/14/2012
MW-29 05/23/2013
MW-29 11/20/2013
MW-29 06/03/2014
MW-29 11/10/2014
MW-29 04/30/2015
MW-29 11/16/2015
MW-29 04/27/2016
MW-29 11/08/2016
MW-29 04/20/2017
MW-29 10/16/2017
MW-29 04/11/2018
MW-29 10/22/2018
MW-29 04/24/2019
MW-29 10/22/2019
MW-29 04/08/2020
MW-29 10/13/2020
MW-29 04/14/2021
MW-29 06/22/2005
MW-29 09/22/2005
MW-29 12/14/2005
MW-29 03/21/2006
MW-29 06/21/2006
MW-29 09/12/2006
MW-29 10/24/2006
MW-29 03/15/2007
MW-29 08/22/2007
MW-29 10/24/2007
MW-29 03/19/2008
MW-29 06/03/2008
MW-29 08/05/2008
MW-29 11/05/2008
Appendix C
Source Assesment Report for MW-29
White Mesa Uranium Mill
• • 11:.1 -
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Fluoride
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Page 2 of 4
. :1111t:111n·
0.90 mg/L
1.00 mq/L
0.80 mg/L
0.80 mg/L
0.80 mq/L
0.80 mg/L
0.80 mq/L
0.80 mg/L
0.80 mg/L
0.80 mq/L
0.80 mg/L
0.76 mq/L
0.74 mg/L
0.68 mq/L
0.79 mq/L
0.76 mg/L
0.72 mq/L
0.77 mg/L
0.75 mg/L
0.70 mq/L
0.62 mg/L
0.10 mq/L u
0.64 mg/L
0.68 mg/L
0.66 mg/L
0.74 mg/L
0.82 mq/L
1.00 mg/L
0.68 mg/L
0.76 mg/L
0.56 mg/L
0.60 mq/L
0.89 mg/L
0.69 mg/L
2700.00 mq/L
2840.00 mg/L D
2770.00 mg/L
2710.00 mg/L D
2770.00 mq/L
2720.00 mg/L D
2980.00 mg/L D
2780.00 mg/L D
2790.00 mg/L D
2790.00 mg/L D
2840.00 mg/L D
2840.00 mq/L D
2810.00 mg/L D
2920.00 mg/L D
--=i.lNTERA
Appendix C-3: Data Used for Statistical Analysis
. • lli ,1 '"'•r.t
MW-29 02/03/2009
MW-29 05/13/2009
MW-29 08/24/2009
MW-29 10/26/2009
MW-29 04/27/2010
MW-29 11/09/2010
MW-29 04/05/2011
MW-29 10/05/2011
MW-29 05/08/2012
MW-29 05/23/2013
MW-29 11/20/2013
MW-29 06/03/2014
MW-29 11/10/2014
MW-29 04/30/2015
MW-29 11/16/2015
MW-29 02/10/2016
MW-29 04/27/2016
MW-29 09/01/2016
MW-29 11/08/2016
MW-29 01/26/2017
MW-29 04/20/2017
MW-29 08/15/2017
MW-29 10/16/2017
MW-29 04/11/2018
MW-29 10/22/2018
MW-29 10/22/2019
MW-29 04/08/2020
-2 / 3/
MW-29 04/14/2021
MW-29 06/22/2005
MW-29 09/22/2005
MW-29 03/21/2006
-06/21/2006
MW-29 09/12/2006
-29 0/2 I
MW-29 03/15/2007
MW-29 08/22/2007
MW-29 10/24/2007
MW-29 03/19/2008
MW-29 06/03/2008
MW-29 08/05/2008
-1( I
MW-29 02/03/2009
MW-29 05/13/2009
MW-29 08/24/2009
MW-29 10/26/2009
MW-29 04/27/2010
MW-29 11/09/2010
Appendix C
Source Assesment Report for MW-29
White Mesa Uranium Mill
1-.1..-. 1;.&(;:I
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
>L If t
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Sulfate
Uranium
Uranium
Uranium
Uranium
Uranium
r n·u
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
r ni m
Uranium
Uranium
Uranium
Uranium
Uranium
Uranium
Page 3 of 4
. 11111-:11111:.1
2710.00 mq/L D
2790.00 mq/L D
2720.00 mg/L D
2960.00 mq/L D
2770.00 mg/L D
2690.00 mg/L
2600 mq/L D
2850 mg/L D
2750 mq/L D
2450 mq/L
2750 mg/L
2510 mq/L
_7 1g/L
2960 mq/L
2740 mq/L
2710 mg/L
2730 mq/L
_7 mg/L
2290 mq/L
2670 mq/L
2490 mg/L
2780 mq/L
2380 mg/L
2400 mg/L
2470 mq/L
2730 mg/L
2640 mq/L
0 mg/L
2360 mq/L
8 uq/L
11 ug/L
10 uq/L
12 ug/L
12 uq/L
1 ug/L
11 ug/L
12 uq/L
11 ug/L
11 uq/L
10 ug/
10 uq/L
ug/L
11 uq/L
10 ug/L
11 ug/L
12 uq/L
1 1g/L
11.60 uq/L
~«EINTERA
Appendix C-3: Data Used for Statistical Analysis
~, ..... ·-•,:11• .. 1.-;1111r•1,~ .
MW-29 04/05/2011 Uranium 12.70
MW-29 10/05/2011 Uranium 11.70
MW-29 05/08/2012 Uranium 12.20
MW-29 11/14/2012 Uranium 11.20
MW-29 05/23/2013 Uranium 11.90
MW-29 11/20/2013 Uranium 13.80
MW-29 06/03/2014 Uranium 12.10
MW-29 11/10/2014 Uranium 11 .80
MW-29 04/30/2015 Uranium 12.70
MW-29 11/16/2015 Uranium 13.20
MW-29 04/27/2016 Uranium 13.00
MW-29 11/08/2016 Uranium 13.70
MW-29 04/20/2017 Uranium 12.90
MW-29 10/16/2017 Uranium 13.60
MW-29 04/11/2018 Uranium 13.90
MW-29 10/22/2018 Uranium 13.30
MW-29 04/24/2019 Uranium 15.00
MW-29 10/22/2019 Uranium 14.20
MW-29 04/08/2020 Uranium 14.80
MW-29 10/13/2020 Uranium 15.30
MW-29 01/15/2021 Uranium 16.90
MW-29 04/14/2021 Uranium 16.20
Notes:
D = Analyte reporting limit increased due to same matrix interference
U = Analyte undetected
Appendix C
Source Assesment Report for MW-29
White Mesa Uranium Mill Page 4 of 4
-,.,, ....
ug/L
uq/L
ug/L
ug/L
uq/L
ug/L
uq/L
ug/L
ug/L
uq/L
ug/L
uq/L
ug/L
ug/L
uq/L
ug/L
uq/L
ug/L
ug/L
uq/L
ug/L
uq/L
~\slNTERA
Appendix C-4: Indicator Parameter Data Removed from Analysis
Reason Location ID
Extreme (High) MW-29
Extreme (Low) MW-29
Extreme ( Low) MW-29
Extreme (Low) MW-29
Appendix C
Source Assesment Report for MW-29
White Mesa Uranium Mill
-Date Sampled Parameter Name
Removed
12/14/2005 Uranium
11/14/2012 Sulfate
04/24/2019 Sulfate
Not Removed
04/30/2015 Fluoride
-
Report Resu lt Report Units
49.0 ug/1
1340.0 mg/I
2170.0 mg/I
0.05 mg/I
~¥slNTERA
Appendix C-5: Box Plots for Indicator Parameters in MW-29
40 -38 ::::: O> E -36 <l>
"C ·.:: 0 34 :E ()
32
30
1.0 -0 .8 ::::: O> E -<l> 0.6 "O ·.:: 0 0.4 =, u::
0.2
Appendix C
Chloride in MW-29
o Outlier
• Extreme
Percent nondetect: 0%
Min: 30, Mean: 37.04, Max: 41, Std Dev: 2.46
Upper extreme threshold (Q75 + 3xH): 49.8
Lower extreme threshold (Q25 -3xH): 24.6
Fluoride in MW-29
0
0 0 •
•
Percent nondetect: 2%
Outlier
Extreme
Min: 0.05, Mean: 0. 75, Max: 1.1, Std Dev: 0.15
Upper extreme threshold (Q75 + 3xH): 1.143
Lower extreme threshold (Q25 -3xH): 0.366
Source Assesment Report for MW-29
White Mesa Uranium Mill Page 1 of 2 --3.INTERA
Appendix C-5: Box Plots for Indicator Parameters in MW-29
3000
-2500 :::::::: C)
E -Q) -~ 2000 "3 en
1500
50
-40 :::::::: 0) :, -E 30
:, "i: cu .... 20 ::>
10
Appendix C
Sulfate in MW-29
•
Percent nondetect: 0%
o Outlier
• Extreme
Min: 1340, Mean: 2669.33, Max: 2980, Std Dev: 271.98
Upper extreme threshold (075 + 3xH): 3240
Lower extreme threshold (025 -3xH): 2190
Uranium in MW-29
•
Percent nondetect: 0%
o Outlier
• Extreme
Min: 8.1, Mean: 13.14, Max: 49, Std Dev: 5 .94
Upper extreme threshold (075 + 3xH): 20.8
Lower extreme threshold (025 -3xH): 3.825
Source Assesment Report for MW-29
White Mesa Uranium Mill Page 2 of 2 9'!!-¥elNTERA
Appendix C-8: Time Series with Events
-::::::: C)
E -Q)
"C ·;::
0
..c (.)
-::::::: C)
E -Q)
"C ·;::
0 :::J u:::
Appendix C
•
40 -•
• ••
38 -•
• -36 -•
34 -
32 -
30 -
I
2005
•
1.0 -• • •• 0.8 -•• • • •
Chloride in MW-29
• ••
• •
• I
• It 0
•
• •• • •
•
•
•
•
I I
2010 2015
"' ••• . "'•
Sample Date
Fluoride in MW-29
• • • • • •
• •
0 0 ••• • 0.6 -
0.4 -
0.2 -
•
I I I
2005 2010 2015
Sample Date
I 2021-04-15 Peak Groundwater Elevation
I 2012-10-01 Lab Change
• •
•• • • •
•
I
2020
•
• • • • • • •
I
2020
I 2014-06-01 five New Chloroform Pumping Wells Brought Online
I 2011-04-11 Surged and Bailed; Inflection point used for analysis
i•
0
Source Assesment Report for MW-29
White Mesa Uranium Mill Page 1 of 2 ~S.INTERA
Appendix C-8: Time Series with Events
3000 • •
2900 • -
• -2800 ---• •• • •• • ::::::: E 2100 -• •• • • -Q) ..... 2600 ~ -
:::::J en 2500 -
2400 -
2300 -
I I
2005 2010
16 -
--14 ::::::: C> -
:::::J -E :::::J 12 C: ro ..... ::>
-• • • • • •• •• • •• •
10 -• -•
8 -•
I I
Sulfate in MW-29
•
•
• • • •• • •
4
.4
•
I
2015
Sample Date
Uranium in MW-29
•
•• 0 • • 4 • • • • 19
I
•
• • •
• •
• •
• •
•
I
2020
• • • • • • • • •
I
2005 2010 2015 2020
Appendix C
Sample Date
I 2021-04-15 Peak Groundwater Elevation
I 2012-10-01 Lab Change
I 2014-06-01 five New Chloroform Pumping Wells Brought Online
I 2011-04-11 Surged and Bailed; Inflection point used for analysis
0
•
4
Source Assesment Report for MW-29
White Mesa Uranium Mill Page 2 of 2 .---2¥.INTERA
APPENDIX D
APPENDIXE
APPENDIXF
Input and Output Files (Electronic Only)