DRC-2018-002770 - 0901a068807d2758

State of Utah
GARYR. HERBERT
Governor
SPENCERJ. COX
Lieutenant Goyernor
TO:
THROUGH:
FROM:
DATE:
Department of
Environmental Quality
Alan Matheson
Execative Direclor
DTVISION OF WASTE MANAGEMENT
AND RADIATION CONTROL
Scott T. Anderson
Director
MEMORANDUM
File
PhirGobre,Manager PfZ C '/'/f
romRushins,P.c. Xd 3' h - ts
March 14,2018
SUBJECT: Review of the Energy Fuels Resources (USA) Inc. (EFR), White Mesa Uranium Mill,
Blanding, Utah August2l,2017 Source Assessment Report for Selenium, Sulfate, Total
Dissolved Solids (TDS) and Uranium in Monitoring Well MW-31, Ground Water
Discharge Permit UGW3 70004
Summarv
An August 21,2017 Source Assessment Report ('SAR') for Selenium, Sulfate, TDS and Uranium in
Monitoring Well MW-31 at the White Mesa Uranium Mill (MilD was submitted to the Director by Energy
Fuels Resources (USA) Inc. ("EFR"), and received on August23,2017 for review and approval of
proposed revised Ground Water Compliance Limits (GWCLs).
Monitoring well MW-31 is located on the southeast berm of the Mill tailings cell 2 and is hydraulically
downgradient from eastern portions of cell 2 and from the Mill processing areas. MW-31 is within the
defined nitrate/chloride plume, and non-compliance for nitrate and chloride are regulated through a
separate consent order (UGW|2-04) issued by the Director.
The SAR is broken up into four primary sections, 1. The approach for analysis of potential sources of the
contamination, 2. Results of the analysis (e.g. changes in groundwater in MW-31, indicator parameter
analysis, pH analysis, sorption analysis and mass balance analysis), 3. Statistical evaluation and calculation
of revised GWCL's for trending parameters, and,4. Conclusions and recommendations.
The SAR notes that though uranium is the only parameter required for assessment (in out-of-compliance
status) by Part I.G.2 of the White Mesa Mill Groundwater Discharge Permit (Permit), the EFR SAR is
additionally addressing exceedances of the recalculated GWCL's, noting that increasing trends are also
observed for these parameters (Se, SO4, TDS).
Figures below depict the rising concentration trends in monitoring well MW-31 for Se, SO4, TDS and U
using all available historical data. An additional Figure depicts the pH plot for all historical data available
for monitoring well MW-31 which shows a slight decreasing trend.
EFR August21,20l7 MW-31 Source Assessment Report
DWMRC Review Memo
Page2
Figure - Selenium Data Plot of Historical Data at MW-31 - lncreasing Trend
100
J80
h0Eoo
E
='E 40g
ot^ 20
0
Jan-04 Oct-06 Jul{9 Apr-12 Dec-14 Sep-17 Jun-20
Date
- Sulfate Data Plot of Historical Data at MW-31 - lncreasing Trend
MW-31SO4
u0
Eo
t!
=Jlrl
1000
800
600
400
200
0
Jan-04 Oct-06 Jul{9 Apr-12 Dec-14 Sep-17 Jun-20
Figuqe,'''JD_IS Data Plot of Historical Data at MW-31 - lncreasing Trend
MW-31TDS
b rsooE
E roooo(JI soo
Oct-06 Jul-09 Apr-12 Dec-14 Sep-17 Jun-20
Sample Date
EFR August2l,Z}l7 MW-31 Source Assessment Report
DWMRC Review Memo
Page 3
10
9
ing Trend
Data Plot of Historical Data at MW-3l-Sli Decreasing Trend
8-
=d-
s-
=-zf-t-fo.2-
t-
0-
Jan -04 Oct-06 Jul-09 Apr-72 Dec-14 Sep-17 Jun-20
Date
Based on the increasing trends, EFR is proposing that the use of higher GWCL's allowed by the Utah
Administrative Code R-317-6 should be considered and are in conformance with the Director approved
statistical flow chart for GWCL's. Conclusions of the SAR find that the GWCL exceedances and
increasing trends are not caused by releases from the Mill as discussed below.
EFR Investieations of Potential Sources of Report Increasine Trends at Monitorins Well IVIW-31
1. Changes in Mill Groundwater Operations
Section 3.1 and time series plots included as Appendix C-10 of the SAR discuss several Mill operational
and environmental changes that appear to be consistent with data inflections seen on the time series plots.
Specifically these changes are; 1. The initiation of monthly groundwater sampling in 2010; 2. A well
redevelopment project in 201l; 3. A change in environmental laboratory used in2012;4. A peak
groundwater elevation at MW-31 in20l3; and, 5. Five new chloroform wells brought online on the east
side of Cell 2in20l4- Per DWMRC review of the time series plot it is observable that the trends in MW-
31 and at other sitewide monitoring wells appear to begin in late 2010 and 2011, during the time of
initiation of increased frequency (monthly monitoring) and the well redevelopment project, which included
Fisure - U Data Plot of Historical Data at MW-31 - Slieht Increas
MW-3l Uranium
uo
E
E
Et!Lf
12.o0
10.00
8.00
6.00
4.00
2.00
0.00
Jan-04 Oct-06 Jul-09 Apr-12 Dec-14 Sep-17 Jun-20
EFR August2l,2}l7 MW-31 Source Assessment Report
DWMRC Review Memo
Page 4
overpumping all monitoring wells at the Mill. These actions may have introduced/allowed oxygen to enter
pores within the sandstone and shales of formations in the well screened intervals and caused geochemical
reactions within the minerals of those zones. Also, an inflection in certain monitoring analytes and wider
scattering of data is clearly seen in 2012 whenthe analytical laboratory was changed.
Per DWMRC findings regarding time series plots of data, the data inflection seen late 2012,for certain
parameters indicates a shift in background concentrations due to the laboratory change. For parameters
where this is observed in MW-31, and consistent with the EPA 2009 Unified Statistical Guidance, it is
appropriate to use the data after this inflection to evaluate the background data.
2. Discussion of Tailings Solution Groundwater Indicator Parameters at Monitoring WeA MIV-31
The SAR Section 3.2 discusses four primary indicator parameters (Chloride, Fluoride, Sulfate and
Uranium) which would be detected in ground water in the event of discharge from the Mill tailings cells.
Mass balance evaluation comparisons at MW-31 included Fluoride and Sodium, as representative mobile
contaminants for comparison with the study parameters (CL, Sulfate and Uranium).
Piper diagrams evaluating chemical relationships of Cell I wastewater and observed groundwater
concentrations are included in the SAR. Additionally, the SAR includes an evaluation of upgradient well
data and downgradient well data in comparison with current data from MW-31. Based on this review,
fluoride, sulfate and uranium concentrations in MW-31 are within the same background range of
monitoring wells upgradient and far downgradient from the Mill. The evaluation confirms that chloride
concentrations in MW-31 are well above background range, as expected, based on the MW-31 location
within the nitrate/chloride plume.
Chloride
Per the SAR, the use of chloride as an indicator parameter in the case of monitoring well MW-3lis
complicated by the fact that MW-31 is screened within a nitrate/chloride plume, and chloride is therefore
above background and is not a reliable primary indicator of cell leakage for MW-31. Chloride at
monitoring well MW-31 is showing a significant increasing trend. Findings related to comparisons of
MW-31 chloride and background wells outside of the nitrate/chloride plume show chloride well outside of
background range. The chloride plume has been delineated based on concentrations and plots clearly show
that the plume leading edge is hydraulically upgradient from the mill tailings cells and is not attributed to
tailings cell leakage based on groundwater flow data and mass balance calculations.
Fluoride
Fluoride is highly concentrated in tailings wastewater and per literature and mill groundwater transport
modeling has been shown to be highly mobile in the vadose zofle and groundwater beneath the tailings
cells. Per the figure below, fluoride is showing a decreasing concentration trend in MW-31.
EFR August2l,2}l7 MW-31 Source Assessment Report
DWMRC Review Memo
Page 5
Fizure - Fluoride Plot of Historical Data at MW-31 - Decreasins Trend
MW-3l Fluoride
L.4
L.2
t
(. o.sho
Eu 0.6
o.4
o.2
0
Jan-04 Oct-06 Jul-09 Apr-t2 Dec-14 Sep-17 Jun-20
Mass balance calculations for fluoride are included in the SAR. Per presented findings the concentration of
fluoride in groundwater when compared with less mobile constituents in tailings wastewater are much
lower that less mobile constituents and additionally as per the figure above are declining. The SAR uses a
comparison of selenium and fluoride in Cell 1 tailings wastewater and MW-31 groundwater and notes that
selenium is found at much higher percentages in groundwater than fluoride. Fluoride concentrations
should be over 20 times higher to indicate a relationship with tailings wastewater.
SuAatu
Sulfate concentrations in MW-31 are very low in comparison with other wells at the site. The highest
historic value of sulfate is 916 mglL (2"d Quarter 2Ol7). This concentration is compared with highest
historical values of other site monitoring wells (nearby MW-31) on the table below:
The SAR additionally includes box plots comparing groundwater chemistry and concentration in all wells
with MW-31. Per DWMRC review, the sulfate concentrations in MW-31 are low by comparison site wide.
Sulfate concenfrations are rising at several of the monitoring wells at the mill including upgradient and far
downgradient monitoring wells. EFR notes that the increasing sulfate in many wells and corresponds to
Monitoring Well No.Location Relative to Tailings Cells Highest Historic
Measured
Sulfate Value
(ms/L)
Average Sulfate
Concentration
(Complete Data
Set) (msll)
Iv[$r€1 Bofimffidi&n*ti&ll'z 1;,;go.1f ;,;;$r*,t
MW-l Uosradient 1.990 837
MW-l8 Upsradient 2.020 r.828
MW-19 Uperadient 1.320 669
MW-20 Far Downsradient 4,090 3,526
MW-03A Far Downmadient 5,940 3,568
MW-29 Downsradient Cells I and2 2.980 2704
MW-ll Downpradient Cells 2 and3 1.360 1.105
EFR August2l,2Al7 MW-31 Source Assessment Report
DWMRC Review Memo
Page 6
decreases in pH. Additionally, EFR offers this as a possible explanation for increases in some metals in
solution at those corresponding wells, including uranium.
In the case of MW-3 1, the relatively low concentration of sulfate indicates a source other than tailings
solution. Additionally, a clear data shift is observed to have started in2012 in association with the change
of laboratory.
Uranium
Uranium concentrations in monitoring well MW-31 are similar to sulfate concentrations in that site-wide
they are low, as demonstrated by box plot evaluation comparing uranium concentration in MW-31 to all
monitoring wells site wide. Box plot evaluation finds that the uranium concentrations in MW-31 are
within background concentration range and are low for the mill site. The SAR discusses that rising
uranium concentrations are likely associated with lower pH in the groundwater.
Indicator parameters, other than chloride, are seen to have low site wide concentrations regardless of
trends. Per SAR evaluations of ratios of the mobile contaminants in groundwater with the tailings
wastewater concentrations, it appears that the source of the mobile contaminants is due to causes other than
tailings wastewater.
3. pH Analysis
Section 3.3 and Appendix D of the SAR include an evaluation of pH in MW-31. The analysis includes
statistical evaluation (identification of outliers and trend analysis) which confirmed a significantly
decreasing trend in pH in MW-31. EFR then conducted a site wide analysis for selenium trends (included
as Appendix F of the SAR) and noted that 13 mill monitoring wells appear to have significantly increasing
selenium trends. Of the 13 monitoring wells with increasing selenium trends, 10 have significantly
decreasing pH trends. The SAR argues that the site wide distribution of pH declines and selenium
increases links the reaction as related but not associated with mill activities or tailings wastewater.
DWMRC review of upgradient wells (MW-l, MW-18 and MW-19) does confirm decreasing pH trends in
all three monitoring wells, however, an increasing selenium trend is only observed in monitoring well
MW-l9 and is probably due to the formation of a groundwater mound from infiltration from the wildlife
ponds.
Per review, it is agreed that in general, decreasing pH trends appear in select monitoring wells site wide,
including far upgradient and far downgradient wells. The rising selenium and uranium concentrations in
MW-31 may be related to decreases in pH. However, based on review of the SA& there does not appear
to be a consistent site-wide correlation sufficient to generalize the sorption reactions for a group of
monitoring wells. The Dakota/Buro canyon aquifer material is heterogeneous, as evidenced by drill logs
and area geological investigation. Geochemical reactions will be dependent on minerology of discreet
geological zones; this is recognized and is the basis of intrawell background and statistics at the White
Mesa Mill.
4. Sorption Analysis
Section 3.4 of the SAR provides a simple model, using Geochemist's Workbench (v. 11), of potential
mineral sorption for MW-31. The SAR notes that iron oxides have been identified in most of the boring
EFR Augustzl,2}l7 MW-31 Source Assessment Report
DWMRC Review Memo
Page 7
logs at White Mesa, and that per confirmation through X-Ray diffraction analysis of drill cuttings, "more
iron is available than can be accountedfor by common crystalline iron phases such as goethite."
The SAR questions some assumptions made in past geochemical modeling. Based on field readings of
redox at MW-31, the groundwater is oxidized and pH has historically been in a neutral range. Based on
these conditions it has been assumed that uranium and selenium are complexed with carbonate or oxygen
and that uranium and selenium concentrations should decrease with decreasing pH.
However, the SAR states"these early models, however, sufferedfrom convergence issues such as charge
inbalance." The SAR discusses that calcite is present in the bedrockat l%oto l4%o by weight and that the
addition of calcium in modeling would allow for charge balance by calcium ions. The SAR geochemical
model included calcium as an input.
Uranium and selenium sorption curves (SAR Figure 3) generated by the Geochemist's Workbench model
(Appendix I), indicates decreasing uranium and selenium sorption with decreasing pH, supporting the EFR
view that increasing concentrations of Se and U in solution are associated with the decreasing pH in MW-
31. Per summary of the SAR findings, the decreased sorption of selenium and uranium is due to other
prevalent anions (HCOj and SOa2-) occupying sorption sites blocking sorption of selenium and uranium.
The SAR discusses that several assumptions were made when using input values into *re model and that
the Geochemist's Workbench is a simplistic model.
Per review, the modeling demonstrates that calcite has a potential effect of inhibiting selenium and
uranium sorption. However, additional analysis would need to be conducted to confirm that this is the case
at specific locations including batch testing to determine the impact of specific variables for more
representative geochemical modeling (e.g. pH, time, presence and absence of oxygen, presence of
additional minerals, etc.).
5. Mass Balance
The SAR includes a mass balance evaluation of current concentrations (5/2017) of fluoride, uranium,
chloride, sulfate, selenium and sodium in MW-31, and average concentrations of the same paftrmeters in
cell I wastewater (based on averages of data collected between 2003 and 2016). The SAR clarifies that the
mass balance calculations evaluate the data only for comparisons due to dilution and do not consider
relative mobility of contaminants.
Based on large inconsistencies between the tailings wastewater concentrations and the expected diluted
concentrations, the SAR concludes that "modeled parameter concentrations in MW-31 differ greatlyfrom
observed concentrations ofJluoride in MW-31." Per review, the analysis indicates that the groundwater
concentrations of these parameters in MW-31 are not consistent with a tailings source.
DWMRC review conducted an additional dilution based evaluation using slimes drain concentrations of
Cell2. DWMRC calculations regarding the same method to calculate mean Cell 2 concentrations (data
from the Cell2 slimes drpin) from20A7 1.o2016 are included on the table below:
EFR AugustZl,2Al7 MW-31 Source Assessment Report
DWMRC Review Memo
Page 8
Units Fluoride Uranium Chloride Sulfate Selenium Sodium
MW-31
Concentration
5DA17
pg/L 690 9.62 2.658+05 7.418+05 85.2 1.05E+05
Cell2 Concentration
Slimes Drain
Average (2007-
2016)
pelL 74"000 27,773 3.5E+06 6.78+07 699 4.38+06
Dilution Factor ILs./L 0.00932432 .0003463795 .0757142857 .0110s9701s .1218884t2 .0239726027
Predicted Diluted
Fluoride
$slL 2s6 5,603 8r8 9,020 3.088+06
It was noted that a similar result of the SAR analysis using Cell I was obtained. Chloride, sulfate and
selenium were underestimated and uranium was overestimated. Per evaluation it was noted that sulfate
concentrations are in line with fluoride based on Cell2 slimes drain concentrations and concentrations seen
in MW-31, however, the fact that fluoride concentrations are decreasing while sulfate is increasing negates
this relationship as due to a tailings source. If tailings wastewater were the source, uranium concentrations
would be expected to be considerably higher and selenium concentrations considerably higher.
The table below summarizes the evaluation and includes lines indicating current May 2017 concenfations
of fluoride, uranium, chloride, sulfate and selenium, and expected concentrations of uranium, chloride,
sulfate, and selenium compared to fluoride if there was a release using the fluoride dilution factor for each
parameter:
The mass balance (dilution) evaluation results indicate that the source of the increasing trends is not the
result of tailings wastewater release.
6. University of Utah Study
Monitoring well MW-31 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-31 [chlorofluorocarbon ("CFC') analysis], the groundwater was found to exhibit
CFC recharge dates which predate the construction of the Mill in 1980.
Additionally, tritium concentrations in monitoring well MW-31 were found to be non-detect. If ground
water in monitoring well MW-31 had a surface infiltration source post 1950's (time period of atrnospheric
injection of tritium during above-ground thermonuclear weapons testing) then tritium concentrations would
be expected in ground water samples in monitoring well MW-31. Figure 5 below is taken from the
Units Fluoride Uranium Chloride Sulfate Selenium Sodium
MW-31 Mav 2017 Concentrations uslL 690 9.62 2.65F+05 7.41E+05 85.2 1.05E+05
Mass balance concentrations
expected in the event ofa release
from Cell 1
pe/L 690 191 9.65E+3 6.668+04 3.2 42.9
Mass balance concentrations
expected in the event ofa release
from the Cell2 Slimes Drain
ttdL 690 258 3.2E+4 6.248+05 6.5 979
EFR August2l,2}l7 MW-31 Source Assessment Report
DWMRC Review Memo
Page 9
University of Utah ("U of U") Report (Hurst and Solomon 2008) and depicts atmospheric concentrations of
tritium in the southwest by year.
Based on review of the U of U Report and specific data results for monitoring well MW-31 age dating of
groundwater at the well indicates that the MW-31 groundwater predates Mill construction.
7. Source Assessment Conclusions
Section 3.6 of the SAR discusses the summary of results for evaluation of each of the SAR parameters at
MW-31 (Se, SO4, TDS andU).
Based on EFR evaluations and studies performed and discussed in the SA& and DWMRC review as
discussed above, it appears that the Out of Compliance status (U) and rising trends (Se, SO4, TDS and U)
are not due to wastewater release from the mill.
EFRPronosed Modified GWCL Statistical Evaluation of Data:
Based on DWMRC review of the SAR statistical analysis it was noted that analysis was conducted for the
complete historic data set for MW-31 and for a post October 2012 data set. The complete data set showed
normal or log normal distribution for uranium but not for selenium, sulfate or TDS. The modified data set
did show normality for selenium, sulfate, TDS and uranium. Statistical methods used included; 1.
Descriptive statistics for the complete and modified data sets; 2. Mean and Standard Deviation Calculation;
3. Shapiro-Wilk Test for normality; and,4. Mann-Kendall Trend Analysis (non-normally distributed data
sets). Proposed GWCL'S were calculated based on Mean * 2 Standard Deviation, Highest Historical
Value, Fraction of Groundwater Standard, and Background Mean Concentration times 1.5. The
calculations and findings are summarized on a table in the SAR (Appendix B-1 of the SAR).
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 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 GWCL's according to the Utah Groundwater Rules (Utah
Figure 5 - Concentrations of Atmospheric Tritium in the Southwestern United States
glr, tlll
l^h* lrcrtq+F.oddt,tlan
. . i'"8rfr ti.)ctl(y {i8rbd,
" *..&rroilq$(atud)**-"FilSn{ar*r{eq
EFR August2l,2017 MW-31 Source Assessment Report
DWMRC Review Memo
Page 10
Administrative Code R317-6) which allow maximums to be set according to Mean + 2 Standard
Deviations, 0.5 times the GWQS (Class III Water), or 1.5 times the background concentration. DWMRC
findings note that setting the GWCL at a maximum value for these parameters is reasonable, given that the
wells will likely exceed a more conservative GWCL in a short period of time when considering the
increasing trends. This is particularly the case for selenium and sulfate in MW-3lwhich have relatively
stronger trends are present at higher concenhations.
Selenium and sulfate additionally show a defined change in background data pre October 2012. Per the
EPA 2009 Unified Statistical Guidance Section 5.3, and based on verification that the increases are due to
background influences, it is appropriate to use the data collected after the point of inflection and therefore,
GWCL's for selenium and sulfate will use the post 2012 data set. It should be noted that the difference
between the post 2012 data set mean and the complete data set mean are not significantly different. The
TDS time series plot does not show a clear point of inflection and the complete data set will be used. Since
uranium GWCL is being reset based on the fraction of the GWQS, the specific data sets are not used
except for comparisons.
Therefore, when comparing the various calculated GWCL's it is found appropriate to set GWCL's for
selenium and sulfate and TDS according to 1.5 times background for post 2012 data sets (Se and SO4) or
the complete data set (TDS). Uranium will be set according to 0.5 times the GWQS. These values are in
conformance with the approved statistical flow chart, the Utah Groundwater Rules, EPA Statistical
Guidance and consider the increasing data trends.
A cross review of EFR calculated mean concentrations for parameters using 1.5 X background was
conducted as shown on the table below. Per evaluation, the EFR mean calculations are correct and are
representative ofthe data set used for evaluation.
Table - Comparison of EFR Background Data Set Mean Values in SAR with DWMRC Calculated Mean
fbr Se. SO4 and'l'DS in MW
Parameter EFR Calculated Mean DWMRC Calculated Mean
MW-3l Selenium
(Post Oct. 2012\
79.6 pglL 80.0 pgll,
MW-31 Sulfate (Post
Oct.2012)
662mglL 665.1mgtL
MW-3I TDS
(Comolete Data Set)
l42l mglL 1434 mglL
The table below summarizes the EFR calculations and background rationale for the proposed modified
GWCL's.
EFR August2l,2Al7 MW-31 Source Assessment Report
DWMRC Review Memo
Page I 1
,-3'able of EFR Proposed Revised GWCL for Selenium at Monitorins lTell MW-31:
Well
Number
Parameter Current
GV/CL
EFR
Proposed
GWCL
Revision
Method to
Determine
GWCL
DWMRC Finding-Is
Proposed GWCL in
Conformance with the
Statistical Flow Chart?
DWMRC
Recommended
Modified
GWCL Based
on SAR
Review
MW-31 Selenium 86.81 pgll,119.4 pglL 1.5 x
Background
of Post Oct.
2012Data
Set
Increasing Trend allows for
modified approach on Flow
Chart. Per UAC 317-6, Class
III water is allowed to be
calculated by 1.5 X
Background. Per DWMRC
Review of the Selenium Data
the modified approach appears
appropriate since an
increasing trend is apparent.
Use of the post Oct. 2012 data
set is appropriate and in
conformance with EPA
guidance since a data shift is
noted corresponding to
laboratorv chanse.
l19.a pgL
MW-31 Sulfate 697.6mgtL 993 mgtL 1.5 X
Background
of Post Oct.
2072Data
Set
lncreasing Trend allows for
modified approach on Flow
Chart. Per UAC 317-6, Class
III water is allowed to be
calculated by 1.5 X
Background. Per DWMRC
Review of the Sulfate Data the
modifi ed approach appeaxs
appropriate. Use of the post
Oct.2012 data set is
appropriate and in
conformance with EPA
guidance since a data shift is
noted corresponding to
laboratorv chanse.
993 mglL
MW-31 TDS 1700 mglL 2228mgtL 1.5 X
Background
of Complete
Data Set
lncreasing Trend allows for
modified approach on Flow
Chart. Per UAC 317-6, Class
III water is allowed to be
calculated by 1.5 X
Background. Per DWMRC
Review of the TDS Data the
modified apDroach appears
2132mgll-
EFR August2l,2}l7 MW-31 Source Assessment Report
DWMRC Review Memo
Page 12
Conclusions:
Based on DWMRC review of the background statistics and confirmation that the proposed parameters for
GWCL modifications are showing increasing trends not associated with contamination from the mill, it is
appropriate to set GWCL's for these parameters at the maximum concenfrations per Utah Administrative
Code (UAC) R317-6 for Class III groundwater. This review is consistent with the Director approved
statistical flowchart which appreciates that a modified approach is appropriate for parameters showing
statistically significant increasing trends.
Based on review a letter will be sent to EFR of initial approval of the modified GWCL's on the table
above. The letter will include notification that the modifications are subject to public notice and public
participation requirements, and that the modifications will not be effective until formal issuance of a
modified Permit.
References
' Energy Fuels Resources (USA) Inc., August 20,2017, Transmittal of Source Assessment Report for
Sulfate, Selenium, Total Dissolved Solids, and Uranium in MW-31 ll'hite Mesa Mill Groundwater
D is char ge P ermit UGW3 7 0 0 0 4
'Energy Fuels Resources (USA) lnc., August 15,2017, White Mesa (Jrqnium Mill Ground Water
Monitoring Quality Assurance Plan (QAP), Revision 7.3
3 Er"rgy Fuels Resources (USA) Inc., October 12,2012, Source Assessment Reporr, Prepared by Intera
o Energy Fuels Resources (USA) Inc., November 9,2012, pH Report, Prepared by Intera
Well
Number
Parameter Current
GWCL
EFR
Proposed
GWCL
Revision
Method to
Determine
GWCL
DWMRC Finding- Is
Proposed GWCL in
Conformance with the
Statistical Flow Chart?
DWMRC
Recommended
Modified
GWCL Based
on SAR
Review
appropriate; however, there
does not appear to be a well-
defined data shift in Oct.
2012. Recalculated GWCL
uses background of complete
data set.
MW-31 Uranium 9.1pelL 15 pe/L 0.5 x
GWQS
Increasing Trend allows for
modified approach on Flow
Chart. PeTUAC 317-6, Class
III water is allowed to be
calculated by 0.5 X the
GWOS.
ts pdL
0.5 x GWQS
EFR August2l,2Al7 MW-31 Source Assessment Report
DWMRC Review Memo
Page l3
5 Hurst, T.G., and Solomon, D.K. University of Utah,2OO8, Summary of Work Completed, data Results,
Interpretations and Recommendationsfor the July 2007 Sampling Event at the Denison Mines, USA White
Mesa Uranium Mill Near Blanding, Utah, Prepared by Department of Geology and Geophysics
uHydro Geo Chem, December 7,2012, Pyrite Investigation Report
' Inter4 2007, Groundwater Data Prepardtion and Statistical Process Flowfor Calculating Groundwater
Protection Standards, White Mesa Mill Sile, San Juan County, Uah
'Utah Departrnent of Environmental Quality, August 24,2012, Utah Division of Radiation Control,
Ground Water Dischorge Permit, Permit No. UGW37A004, Energt Fuels Resources (USA) Inc.