DRC-2016-005893 - 0901a0688061fd9e

99
K9®
State of Utah
GARY R. HERBERT
Governor
SPENCER J. COX
Lieutenant Governor
Department of
Environmental Quality
Alan Matheson
Executive Director
DIVISION OF WASTE MANAGEMENT
AND RADIATION CONTROL
Scott T. Anderson
Director DftC-Z0V6,- 0036^3
MEMORANDUM
TO:
THROUGH:
FROM:
DATE:
SUBJECT:
I. Review Summary;
A December 9,2015 Source Assessment Report (‘SAR”) for Selenium, Sulfate, TDS and pH in
Monitoring Well MW-3 lwas submitted to the Director by Energy Fuels Resources (USA) Inc. (“EFR”),
received by the Utah Division of Waste Management and Radiation Control (“DWMRC”) on December
11,2015. The SAR was submitted for review and approval of proposed revised Ground Water Compliance
Limits (“GWCL’s”) in the White Mesa Uranium Mill Groundwater Discharge Permit, Permit No. UGW-
370004.
SAR’s for Selenium, Sulfate and TDS in monitoring well MW-31 were also submitted to DWMRC by
EFR in 2012 and 2013. Per DWMRC review of those SAR’s it was recognized that increasing
concentration trends were present for those analytes in monitoring well MW-31, of varying degrees.
Specifically, it was noted that increasing concentrations of sulfate and TDS could be attributed to the
location of monitoring well MW-31 within the nitrate/chloride contaminant plume. Per discussions
between DWMRC and EFR at that time it was recognized that GWCL’s for those parameters would likely
exceed any modified GWCL’s and that the parameters would need be reanalyzed to reflect continuing
monitoring concentrations (statistics would need to reflect continuing concentrations) in order to cross
check recent data. The basis of the DWMRC review of potential tailings solution release to the
groundwater is the same, however, it was agreed that continuing review was necessary to ensure that none
of the criteria had changed and that no additional information was generated to potentially refute the
original findings. DWMRC notes that pH is also included in the December 9,2015 Source Assessment,
this parameter was noted to have a slight decreasing trend in past source assessment reports, and has been
potentially associated with site wide decreases in pH measurements.
The SAR is broken up into two primary sections, 1. Analysis of potential sources of the contamination,
and, 2. Statistical evaluation and calculation of proposed modified GWCL’s. EFR states generally in the
195 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144880 • Salt Lake City, UT 84114-4880
Telephone [phone] • Fax [phone] • T.D.D. [phone]
www.deq.uiah.gov
Printed on 100% recycled paper
File
Phil Goble, Manager Pfl. b ^//Cb
Tom Rushing, P.G. jft 2-1/-//
February 16,2016
Review of the Energy Fuels Resources (USA) Inc. Source Assessment Report for
Monitoring Well MW-31, White Mesa Uranium Mill
Ground Water Permit No. UGW370004
SAR that “Sulfate, and by extension TDS, are expected at increased concentrations due to the proximity of
the nitrate/chloride plume. The pH is decreasing site -wide, likely due to oxidation of pyrite.”
EFR uses categories of potential source analysis as has been used in past reports as follows:
1. Constituents in wells with previously identified rising trends.
2. Constituents in pumping wells.
3. Constituents potentially impacted by decreasing trends in pH.
4. Newly installed wells with interim GWCL’s.
5. Other constituents and wells.
Per the SAR, current exceedances in monitoring well MW-31 fall into categories 3 and 5 and the approach
for analysis was guided by these criteria. Per the SAR, EFR has used the historical data to evaluate the
behavior of the constituents in the well.
n. Investigations of Potential Sources of Contamination at Monitoring Well MW-31
1. Discussion of Tailings Solution Groundwater Indicator Parameters at Monitoring Well MW-31
The SAR Section 2.1 discusses indicator parameters which would be detected in ground water in the event
of discharge from the Mill tailings Cell 1 and reliable indications which would be detected specifically at
monitoring well MW-31.
Per the SAR, the indicator parameters in the case of monitoring well MW-31 are complicated by the fact
that monitoring well MW-31 is screened within the recognized nitrate/chloride plume, and chloride is
therefore not a reliable indicator of cell leakage (would normally be the primary indicator parameter based
on high concentrations in Cell 1 and chloride contaminant mobility in groundwater). Sulfate is also not a
reliable indicator parameter at monitoring well MW-31 since the sulfate concentrations in the well are
among the lowest at the site and are highly variable due to natural background fluctuations site-wide.
Therefore, in the case of monitoring well MW-31, Fluoride and Uranium are considered the most reliable
indicators of potential tailings cell leakage.
The discussion and figures below depict the concentration trends of the primary indicator parameters used
for the evaluation of potential tailings solution contamination in monitoring well MW-31 (FI and U).
a. Fluoride is the fastest-moving available indicator parameter of tailings seepage at monitoring
well MW-31. Average concentrations of Fluoride in tailings cell 1 solution is approximately
457 mg/L. Therefore, as an indicator of tailings solution release EFR calculates that Fluoride
concentrations at monitoring well MW-31 should be at least 3.8 mg/L in conjunction with the
current selenium concentrations. However, per concentrations in monitoring well MW-31, as
depicted on the figure below, have been primarily at concentrations less than 1 mg/L.
Additionally, fluoride concentrations at the monitoring well are displaying a decreasing trend
in concentration.
EFR December 9,2015 Source Assessment Report for MW-31
DWMRC Review Memo
Page 2
EFR December 9,2015 Source Assessment Report for MW-31
DWMRC Review Memo
Page 3
1.2
l
^5 0.8
I 0.6
MW-B1 Fluoride
0.4
0.2
0
Jan
MW-31 Fluoride
----------♦-------
■Linear (MW-31 Fluoride)
-----------1------------1------------1------------1------------\
04 Oct-06 Jul-09 Apr-12 Dec-14 Sep-17
b. Uranium - Uranium concentrations in monitoring well MW-31 are low for the site, in the 6 pL
to 9 pL range and are not exhibiting a significant upward trend. It is noted that based on
contaminant distribution coefficients for Fluoride and Uranium, it would be expected that an
increasing trend in fluoride concentrations at monitoring well MW-31 would be expected
before an increasing trend in uranium. A plot including all available historical data available
for uranium at monitoring well MW-31 is included in the figure below.
MW-31 Uranium
*V®MW-31 Uranium :
1
E3
CIDwD
8.00
6.00
4.00
2.00
Linear (MW-31 Uranium)
♦ > ♦ 4 ♦
0.00 -1----------------1----------------1----------------1----------------r
Jan-04 Oct-06 Jul-09 Apr-12 Dec-14 Sep-17
2. 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). The current data trends were noted
prior to the University of Utah Study. 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, indicating that the identified data trend were due to factors
other than establishment of the White Mesa Mill.
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 atmospheric
injection of tritium during above-ground thermonuclear weapons testing) then tritium concentrations would
be expected in ground water samples in monitoring well MW-31.
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. These finding
are consistent with previous source assessment reviews conducted by DWMRC for monitoring well MW-
31.
EFR December 9,2015 Source Assessment Report for MW-31
DWMRC Review Memo
Page 4
3. Source Assessment Conclusions
The SAR contaminant investigation concludes that, “The mass balance and mixing calculations
demonstrate that neither the concentrations of SAR constituents and indicator parameters present in MW-
31, nor the ratios at which they are present in MW-31 and Cell 1, are consistent with potential tailings
system seepage impacts. This conclusion is consistent with the previous work by Hurst and Solomon
(2008) using results from MW-31 and other wells as part of the University of Utah study to evaluate
whether seepage from the tailings system was affecting groundwater conditions. As discussed in Section
2.3 of the report, Hurst and Solomon (2008) found that stable isotope fingerprints do not suggest
contamination of groundwater by tailings cell seepage, evidence that is corroborated by trace metal
concentrations similar to historically observed concentrations.”
Based on DWMRC review of the EFR SAR, there is no clear indication that tailings solution is causing the
parameter exceedances and increasing concentration trends. This is based on review of the indicator
parameters, review of site data, review of the University of Utah Report, and review of the EFR SAR.
DWMRC agrees that review of the monitoring well MW-31 data and modification of the GWCL’s is
appropriate in order to avoid additional compliance actions associated with the exceedances.
DI. EFR Proposed Modified Groundwater Compliance Limits
1. EFR Proposed Approach for Modified GWCL’s at Monitoring Well MW-31
EFR proposes a modified approach to setting GWCL’s for the affected parameters. Per the SAR, “In this
approach, the complete data set, which exhibits an increasing trend over the history of the well record, is
divided into subsets of data based on identification of a point of inflection where the results appear more
stable...The fact that sulfate, selenium, and uranium now exhibit significant long-term trends in MW-31 is
not a complete representation of conditions in this well; such long-term trends do not indicate current
trends. As a result it is more appropriate to focus on the recent stable results and to recalculate GWCL’s
for those constituents based on that data.”
Per DWMRC review of the SAR, EFR proposes to modify the data sets for the SAR parameters to reflect
current conditions at monitoring well MW-31 which has been variable in concentrations and appears to
reflect rises in concentration and an apparent stabilization. Note that GWCL’s are set site wide based on
intrawell statistics. In the SAR, EFR provides a scatter plot of data for each constituent in the SAR and
includes vertical lines indicating the date when certain activities occurred, specifically 1. Date that monthly
sampling was initiated, 2. Date when sitewide monitoring well redevelopment took place, 3. Date when the
analytical laboratory was changed, and, 4. Date reflecting the peak groundwater elevation at the monitoring
well. Per DWMRC review, recognizing changes in procedures, as included in the SAR, is discussed in the
United States Environmental Protection Agency, 2009, Statistical Analysis of Groundwater Monitoring
Data at RCRA Facilities, Unified Guidance, EPA 530/R-09-007 (“EPA Guidance”).
According to DWMRC review of the EPA guidance it was noted that a periodic review of background data
for facilities is recommended. In general the EPA guidance notes that in cases when site wide interwell
statistics are being used and where upgradient monitoring wells indicate a data shift, the facility is
recommended to change to intrawell statistics to ensure that the data sets used are reflective of all site
wells. In cases of intrawell review, the EPA guidance notes procedural changes, such as changes in sample
collection and analytical procedures, could create a difference (EPA, 2009 p. 4-2), including the types of
changes that were provided in the SAR. In this case the EPA guidance recommends that the data be
analyzed for shifts in concentrations and whether analysis indicates that the concentrations have stabilized
at a different concentration based on recent results.
The DWMRC reviewed the currently approved statistical flow chart, used to insure that data evaluation is
consistent, to determine if the EFR modified approach was in conformance with agreed upon procedures.
Based on DWMRC review of the Director approved statistical flow chart and the EPA guidance it was
noted that EFR did not appear to include comparative tests:
• The EPA guidance prescribes that when data are not normally or log normally distributed based on
routine statistical tests then other methods should be employed to normalize the data using a
system termed the “ladder of powers” (EPA 2009 p. 3.6 and 3.8 refers to Helsel and Hirsch, 2002).
Attempts to normalize the data by these methods were not included in the EFR Report.
• In cases where data sets cannot be represented to follow a normal distribution, the EPA guidance
specifies that non-parametric tests should be used to weight data points (EPA 2009 multiple
references). This process is also specified by the Director approved flow chart. Non-parametric
tests do not appear to have been included in the SAR for data sets with non-normal distribution.
• The EPA Guidance notes that when choosing a data set within historical data, tests should be
performed to ensure that the observed data sets are representative, “A significant t-test or Wilcoxon
rank-sum result should spur a closer investigation and review of the background sample, in order
to determine which observations are most representative of the current groundwater conditions.”
These issues were discussed with EFR during a telephone conference on February 11, 2016 and it was
discussed that the methods should be included with future requests for GWCL modifications. However,
per review of the EFR SAR, DWMRC notes that the SAR includes the following methods of calculating
proposed modifications to the GWCL’s; 1. Modified Approach; 2. Highest Historic Value; and 3. Mean +
2o. DWMRC notes that, although the data sets for Selenium and Sulfate were not normally distributed per
the evaluation, all proposed GWCL’s were relatively similar. Per DWMRC review of the historical data
for these parameters in monitoring well MW-31 it was noted that the reported values for highest historical
concentration were not outliers and appeared reasonable. DWMRC concluded that the modified approach
did not appear to be significantly different than those listed by the other methods, and in most cases the
modified approach calculated GWCL’s that were lower than the other methods. Per this, comparison
review, the modified approach results were valuable in order to verify the analysis of the non-normally
distributed historical data sets. The table below summarizes the EFR calculations and background rationale
for the MW-31 proposed modified GWCL’s.
EFR December 9,2015 Source Assessment Report for MW-31
DWMRC Review Memo
Page 5
EFR December 9,2015 Source Assessment Report for MW-31
DWMRC Review Memo
Page 6
Table of EFR Proposed Revised GWCL *s for Monitoring Well MW-31:
Well
Number
Parameter Location Current
GWCL
(mg/L)
EFR
Proposed
GWCL
Revision
Modified
Approach
Highest
Historic
Value
Calculated
Mean + 2o
DRC Finding - Is
Proposed GWCL
in Conformance
with the Statistical
Flow Chart?
MW-31
MW-31
Selenium
(Pg/L)___
Downgradient
Cells 1 and 2
79 84.00 85.4 86.81
Sulfate
(mg/L)
Downgradient
Cells 1 and 2
552 691.00 691.0 697.60
Not log normal,
Increasing Trend
See Discussion
MW-31
MW-31
pH (S.U.)Downgradient
Cells 1 and 2
6.57-8.5 6.19 6.23
(LHV)
6.40
TDS
(mg/L)
Downgradient
Cells 1 and 2
1410.57 1674.73 1700 1613.78
Log Normal
Increasing Trend
See Discussion
Per review and discussion with EFR regarding past source assessment reports and approvals, it has been
the DWMRC policy to use full data sets when calculating GWCL’s. DWMRC has generally not approved
use of partial data sets or rolling data assessments using control charts. DWMRC has advocated separate
reviews of source assessments and comprehensive reviews of all data when compliance issues with
GWCL’s arise, even when an increasing trend is apparent. This process ensures that data are consistently
re-assessed which is important when evaluating potential releases of contaminants to the environment.
DWMRC recognizes that groundwater in the vicinity of the White Mesa Uranium Mill is variable.
Per the February 11, 2016 telephone conference with EFR, it was discussed that in the case of the EFR
Source Assessment, the GWCL’s would be reset according to EFR calculations based on either mean + 2o
or the highest historical value. The calculations which were based on the modified approach, partial data
sets, are valuable as a comparative tool to validate the calculations. It was discussed that for future GWCL
calculations, DWMRC would like to see additional tests, as prescribed by the approved flow chart,
discussed above. If the data still do not show a normal distribution then parametric statistics should be
used in conformance with the EPA guidance. DWMRC also discussed that in some cases the EFR
modified approach may be used to reset GWCL’s or used as a comparison tool to validate other
calculations as reviewed on a case by case basis.
Based on review of the statistical calculations, telephone conference with EFR, and consistent with the
Director approved flow chart for the White Mesa Uranium Mill, DWMRC staff recommends that the
GWCL’s for monitoring well MW-31 be modified as summarized on the table below:
Recommended Changes to GWCL’s
Well Number Parameter/units Current GWCL Modified GWCL Method of Analysis
MW-31 Selenium (pg/L)79 86.81 Mean + 2o
MW-31 Sulfate (mg/L)552 697.60 Mean + 2o
MW-31 pH (standard units)6.57 - 8.5 6.23 - 8.5 Lowest Historic Value
MW-31 TDS (mg/L)1410.57 1700 Highest Historic Value
EFR December 9, 2015 Source Assessment Report for MW-31
DWMRC Review Memo
Page 7
4. References
1 Energy Fuels Resources (USA) Inc., December 9,2015, Source Assessment Report for MW-31, Prepared
by Intera
2 Energy Fuels Resources (USA) Inc., June 6, 2012, White Mesa Uranium Mill Ground Water Monitoring
Quality Assurance Plan (QAP), Revision 7.2.
3 United States Environmental Protection Agency (USEPA), 2009, Statistical Analysis of Groundwater
Monitoring Data at RCRA Facilities, Unified Guidance, EPA 530/R-09-007
4 INTERA Incorporated, 2007, Revised Background Groundwater Quality Report: Existing Wells
for Dension Mines (USA) Corp. ’s White Mesa Uranium Mill Site, San Juan County, Utah.
5 INTERA Incorporated, 2007, Background Groundwater Quality Report: New Wells for Denison Mines
(USA) Corp. 's White Mesa Uranium Mill Site, San Juan County, Utah.
6 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 located near Blanding Utah. Prepared by University of Utah
Department of Geology and Geophysics.
7 Utah Department of Environmental Quality, August 24, 2012, Utah Ground Water Discharge Permit,
Permit No. UGW370004 issuedfor the Energy Fuels Resources (USA) Inc. White Mesa Uranium Mill.
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