DRC-2019-006502 - 0901a06880aa389d

GARY R. HERBERT
Governor
SPENCER J. COX
Lieutenant Governor
Department of
Environmental Quality
L. Scott Baird
Interim Executive Director
DIVISION OF WASTE MANAGEMENT
AND RADIATION CONTROL
Ty L. Howard
Director
-1)12C -20/ 9-00092_
MEMORANDUM
TO: File
THROUGH: G 7 g' Phil Goble, Manager pg
FROM: Tom Rushing, P.G. Jg 1 -r- 11
DATE: July 8, 2019
SUBJECT: Review of the Energy Fuels Resources (USA) Inc. (EFR), White Mesa Uranium Mill,
Blanding, Utah January 15, 2019 Source Assessment Report for Selenium, Uranium and
pH in Monitoring Well MW-30
Ground Water Discharge Permit No. UGW370004 (Permit)
Summary
A January 15, 2019 Source Assessment Report ("SAR") for Selenium, Uranium and pH in Monitoring
Well MW-30 at the White Mesa Uranium Mill (Mill) was submitted to the Director by Energy Fuels
Resources (USA) Inc. ("EFR"), and received by the Utah Division of Waste Management and Radiation
Control (DWMRC) on January 17, 2019 for review and approval of proposed revised Ground Water
Compliance Limits (GWCLs).
Additionally, based on a June 18, 2019 conference call between DWMRC and EFR regarding review of the
SAR, an updated "Reanalysis of uranium data for the calculation of a groundwater compliance limit in
MW-30" (Prepared by Intera), dated June 28, 2019 was submitted. This update is discussed in the last
section of this memo below.
Monitoring well MW-30 is located on the southern berm of the Mill Tailings Cell 2 and is hydraulically
downgradient from portions of Cell 2 and from the Mill processing areas. MW-30 is within the defined
nitrate/chloride plume, and non-compliance for nitrate and chloride are regulated through a separate
consent order (UGW12-04) issued by the Director.
The SAR is broken up into four primary sections, 1. Approach for analysis of potential sources of the
contamination, 2. Results of the analysis (e.g. changes in groundwater in MW-30, 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).
— Linear (MW.30 Ora urn)
4 00
0.00
1/14/2004 10/10/2006 7/6/2009 4/1/2012 12/27/2014 9/22/2017 6/18/2020
• • 4ks Oa,* 8 f, * — e
. • ****
• • • * 6
•
• MW-30 Uranium
EFR January 15, 2019 MW-30 Source Assessment Report
DWMRC Review Memo
Page 2
Figures below depict the rising concentration trends in monitoring well MW-30 for Se, U and decreasing
Field pH using all available historical data.
Figure - Selenium Data Plot of Historical Data at MW-30
MW-30 Selenium
60
50
44
0, 44•41%**44,.*-401°-:* • *
• l°14 --OW* 30 * • tt e+ • MW-30 Selenium
—Linear (MW-30 Selen
20
10
0
1/14/2004 10/10/2006 7/6/2009 4/1/2012 12/27/2014 9/22/2017 6/18/2020
Figure — Uranium Data Plot of Historical Data at MW-30
MW-30 Uranium
•
1 0 on
Figure — pH Data Plot of Historical Data at MW-30
A
MW-30 pH
1 4.5
I 4
1/14 2004 10/10/2006 7/6/2009 4/1/2012 12/27/2014 9/22/2017 6/18/2020
(3 5
• itott • • tit 44.0 4' • MW-30 pH
- Linear PL4W-30 pH)
EFR January 15, 2019 MW-30 Source Assessment Report
DWMRC Review Memo
Page 3
The SAR findings are that the GWCL exceedances and data trends are not caused by mill activities
(leakage from the tailings cells), and based on the increasing trends, EFR is proposing that highest
historical values be used as a basis for revised selenium and uranium GWCL' s. DWMRC review findings
regarding the SAR and proposed revised GWCL's is discussed below.
DWMRC Review of Compliance Data and Trends
Selenium — DWMRC notes that the Permit GWCL was modified/raised to 47.2 t(g/L (from 34 lig/L) in the
January 19, 2018 Permit renewal. Measured concentrations of selenium remained below the modified
GWCL until a first quarter 2019 exceedance. The well also exceeded the modified GWCL for the 2nd
quarter 2019 and MW-30 is in Out-of-Compliance (00C) Status for selenium. Per review of a
time/concentration plot of selenium and as noted in the EFR Existing Wells Background Report, a long
standing upward selenium trend is evident.
Uranium — Uranium in MW-30 went into Probable Out-of-Compliance (POOC) status per the 4th quarter
2011 sample result (9.83 vg/L) and accelerated monthly monitoring was started during the first quarter of
2012. Several stand-alone exceedances were noted since that time and subsequent consecutive
exceedances of the GWCL were noted during May and June of 2018 putting MW-30 into 00C status and
Permit requirements for an SAR. Per review of a time/concentration plot and as noted in the EFR Existing
Wells Background Report, a long standing upward trend is evident.
Field pH — DWMRC notes that the GWCL (pH range) was modified to 6.47 S.U. — 8.5 S.U. (from 6.5 S.U.
to 8.5 S.U.) in the January, 19, 2018 Permit renewal. Per review of the field pH monitoring data since the
permit renewal Jan. 2018 through the lst Quarter 2019 sampling (15 samples), the modified GWCL was
exceeded for three of the fifteen samples (1/23/18, 4/12/18 and 2/13/19). It was noted that the monitoring
results were within the modified GWCL's for nine consecutive samples prior to the most recent •
exceedance. DWMRC notes that two consecutive exceedances have not occurred and MW-30 is not in
00C for pH. Based on these findings, DWMRC does not see a current need to evaluate MW-30 for an
additional modification until consecutive exceedances occur in the well. Quarterly monitoring will be
required to continue to better evaluate the pH trend in the well.
EFR Investigations of Potential Sources of Report Increasing Trends at Monitoring Well MW-30
EFR January 15, 2019 MW-30 Source Assessment Report
DWMRC Review Memo
Page 4
1. Tailings Solution Groundwater Indicator Parameters at Monitoring Well MW-30
The SAR Section 3.5 discusses four primary indicator parameters (Chloride, Fluoride, Sulfate and
Uranium) which would be detected in ground water in the event of a discharge from the Mill tailings cells.
Per the SAR it was noted "chloride concentrations in MW-30 exhibit a statistically significant increasing
trend, MW-30 is located at the margins of the nitrate/chloride plume which is actively being remediated
according to the Corrective Action Plan. It is likely thcit groundwater in this well is being impacted by that
plume; therefore, chloride is not an appropriate indicator parameter for potential tailings seepage in MW-
30. Sulfate concentrations exhibit a statistically significant decreasing trend, fluoride concentrations also
exhibit a decreasing trend (although not statistically significant), and uranium concentrations are
relatively low for the Mill site but exhibit a statistically significant increasing trend." The SAR
additionally presents data plots of historical data and evaluation of the indicators per historical data and as
evaluated in the New Wells Background Report. Additional evaluation by DWMRC is included below:
Chloride
Per the SAR, the use of chloride as an indicator parameter in the case of monitoring well MW-30 is
complicated by the fact that MW-30 is screened within the margins of the nitrate/chloride plume, and
chloride is therefore above background and is not a reliable primary indicator of cell leakage for MW-30.
Chloride at monitoring well MW-30 is showing a significant increasing trend. The chloride plume has
been delineated based on concentrations and plots clearly show that the plume originates 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 zone and groundwater beneath the tailings
cells. Per the figure below, fluoride is showing a decreasing concentration trend in MW-30.
Figure — Fluoride Plot of Historical Data at MW-30 — Decreasing Trend
MW-30 Fluoride
*
• MW-30
-Linear (44W.30 Fluoride)
0
1/14/2004 10/10/2006 1/6/2009 4/1/2012 9/22/2011 6/19/3020
Sulfate
Sulfate is also abundant in the tailings wastewater and is a relatively mobile constituent in groundwater.
Per the figure below sulfate is showing a decreasing trend in MW-30.
EFR January 15, 2019 MW-30 Source Assessment Report
DWMRC Review Memo
Page 5
MW-30 Sulfate met
1200
•••
••• •• gor --4-•-- • • -•-•. • • + • •• ••• ••-iet*--4t!t-.11
• MW-30 Sulfate mE,A,
- Ore. IMW-10 SOW
400 -
00
! ! 1/14/4004 10/10/0006 7/02009 4/1/2012 12/27/2014 9/22/2017 6/18/2020
Additionally, sulfate concentrations in MW-30 are very low in comparison with other wells at the site. The
average value of sulfate using all historic data is 784 mg/L. This concentration is compared with highest
historical values of other site monitoring wells (nearby MW-31) on the table below:
Monitoring Well No. Location Relative to Tailings Cells Average Sulfate
Concentration
(Complete Data
Set) (mg/L)
MW-30 Downgradient Cell 2 784
MW-1 Upgradient 837
MW-18 Upgradient 1,828
MW-19 Upgradient 669
MW-20 Far Downgradient 3,526
MW-03A Far Downgradient 3,568
MW-29 Downgradient Cells 1 and 2 2704
MW-11 Downgradient Cells 2 and 3 1,105
In the case of MW-30, the relatively low concentration of sulfate and decreasing trends in sulfate and
fluoride indicates that tailings wastewater is not the source of the uranium exceedances.
Uranium
Uranium concentrations in monitoring well MW-30 are similar to sulfate concentrations in that site-wide
they are low. This is additionally evaluated by box plot evaluation comparing uranium concentration in
MW-30 to all monitoring wells site wide (Appendix B-8 of the SAR).
Indicator parameter analysis supports the SAR finding that selenium and uranium exceedances and upward
trends are not due to tailings cell leakage.
2. University of Utah Study
Monitoring well MW-30 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
EFR January 15, 2019 MW-30 Source Assessment Report
DWMRC Review Memo
Page 6
monitoring well MW-30 [chlorofluorocarbon ("CFC") analysis], the groundwater was found to exhibit
CFC recharge dates which predate the construction of the Mill in 1980.
3. Source Assessment Conclusions
In addition to those above, the SAR discussed several lines of evidence to support that mill activities are
not the source of the selenium and uranium GWCL exceedances in monitoring well MW-30, including; 1.
Decreasing pH effects on monitoring well geochemistry; 2. Evaluation of tailings solution indicator
parameters (chloride, sulfate, fluoride and uranium); 3. Previous findings in the EFR Existing Wells
Background Report that the SAR parameters showed long standing upward trends; 4. Potential effects of
pyrite oxidation releasing selenium and other trace metals into solution; 5. Location of MW-31 within the
nitrate/chloride plume, and, 6. Findings of the 2007/2008 University of Utah Groundwater Study.
Per DWMRC review, these findings are consistent with previous EFR SAR's and it does not appear that
the GWCL exceedances are being caused by mill activities. Based on the increasing trends, adjustment of
the GWCL's for selenium and uranium in the Permit is appropriate. Evaluation of the comprehensive list
of monitoring parameters and evaluation of data by EFR and DWMRC at monitoring well MW-30 is
ongoing.
EFR Proposed Modified GWCL Statistical Evaluation of Data:
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 highest historical value (HHV).
Based on DWMRC review of the proposed GWCL's it was noted that the HHV for uranium used was the
3rd quarter 2008 value of lljtg/L. DWMRC noted that at that time this value would have been a statistical
outlier in the data set and is likely not a valid result. Per more recent and representative data, the HHV was
9.09 jtg/L measured in February 2019. This value is included in the approval below.
The table below summarizes the EFR calculations and rationale for the proposed modified GWCL's.
Table 1 — Table of EFR Proposed Revised GWCL for Selenium and Uranium at Monitoring Well MW-
30:
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
MW-30 Selenium 47.2 jtg/L 53.6 jtg/L HHV Increasing Trend allows for
modified approach on Flow
Chart (HHV).
53.6 jtg/L
MW-30 Uranium 8.32 mg/L 11 jtg/L HHV Increasing Trend allows for
modified approach on Flow
Chart (HHV). Per DWMRC
findings the EFR proposed
9.09 jtg/L,
based on HHV
of last 50
sample results
EFR January 15, 2019 MW-30 Source Assessment Report
DWMRC Review Memo
Page 7
Well Parameter Current EFR Method to DWMRC Finding — Is DWMRC
Number GWCL Proposed Determine Proposed GWCL in Recommended
GWCL GWCL Conformance with the Modified
Revision Statistical Flow Chart? GWCL Based
on SAR
Review
HHV of 11 pg/L is based on a
2008 measurement and would
have been considered an
outlier at that time. DWMRC
review finds that a more
recent HHV, within the last 50
samples is more appropriate.
The recent data HHV is 9.09
1.tg/L.
Updated June 28, 2019 "Reanalysis of uranium data for the calculation of a groundwater compliance
limit in MW-30"
A telephone conference was held between DWMRC and EFR on June 18, 2019 to discuss the findings of
the SAR review above. It was discussed that per DWMRC findings, the proposed revised GWCL for
uranium was based on what appeared to be an outlier in the data set. The DWMRC proposed HHV value
based on the most recent 50 uranium data points was discussed. EFR noted that the most recent 50 data
points may not be flexible enough and representative of the increasing trend and may cause unwarranted
re-evaluation of the GWCL in the near future. It was also discussed that the data shows a point of
inflection in 2012 which coincides with the EFR change in laboratory and analytical methods. DWMRC
agreed that a re-evaluation based on data collected after the October 2012 laboratory change was
appropriate and in conformance with the 2009 Environmental Protection Agency Statistical Guidance. A
summary of the review and proposed HHV based on the revised data set is summarized on table 2 below:
Table 2 — Reanal zed Revised GWCL for Uranium at Monitorin Well MW-30:
Well Parameter Current EFR Method to DWMRC Finding — Is
Number GWCL Proposed Determine Proposed GWCL in
GWCL GWCL Conformance with the
Revision Statistical Flow Chart?
MW-30 Uranium 8.32 Rg/L 9.8211g/L HHV Increasing Trend allows for
modified approach on Flow
Chart (HHV). The revised
HHV value appears
appropriate based on review
of data since the EFR
laboratory change in 2012.
Conclusions:
Based on DWMRC review of the background statistics and confirmation that the proposed parameters for
GWCL modifications are showing increasing trends not apparently associated with contamination from the
EFR January 15, 2019 MW-30 Source Assessment Report
DWMRC Review Memo
Page 8
mill, it is appropriate to set GWCL's for these parameters at highest historical values. This review is
consistent with the Director approved statistical flowchart which appreciates that a modified approach is
appropriate for parameters showing upward trends.
Based on review a letter will be sent to EFR of initial approval of the modified GWCL's on the tables
above (Selenium from Table 1 and Uranium from Table 2). 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., January 15, 2019, Transmittal of Source Assessment Report for MW-
30 White Mesa Mill Groundwater Discharge Permit UGW370004
2 Energy Fuels Resources (USA) Inc., June 28, 2019, Reanalysis of uranium data for the calculation of a
groundwater compliance limit in MW-30
3 Energy Fuels Resources (USA) Inc., August 15, 2017, White Mesa Uranium Mill Ground Water
Monitoring Quality Assurance Plan (QAP), Revision 7.4
4 Energy Fuels Resources (USA) Inc., October 12, 2012, Source Assessment Report, Prepared by Intera
5 Energy Fuels Resources (USA) Inc., November 9, 2012, pH Report, Prepared by Intera
6 Hurst, T.G., and Solomon, D.K. University of Utah, 2008, Summary of Work Completed, data Results,
Interpretations and Recommendations for the July 2007 Sampling Event at the Denison Mines, USA White
Mesa Uranium Mill Near Blanding, Utah, Prepared by Department of Geology and Geophysics
7 Hydro Geo Chem, December 7, 2012, Pyrite Investigation Report
8 Intera, 2007, Groundwater Data Preparation and Statistical Process Flow for Calculating Groundwater
Protection Standards, White Mesa Mill Site, San Juan County, Utah
9 United States Environmental Protection Agency, 2009, Statistical Analysis of Groundwater Monitoring
Data at RCRA Facilities, Unified Guidance EPA530/R-09-007
113Utah Department of Environmental Quality, January 19, 2018, Modified on March 19, 2019, Utah
Division of Radiation Control, Ground Water Discharge Permit, Permit No. UGW370004, Energy Fuels
Resources (USA) Inc.