DRC-2017-003405 - 0901a068806f7852

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

May 11, 2017

Colin Larrick
Ute Mountain Ute Tribe
Environmental Programs Department
P.O. Box 448 Towaoc, CO 81334-0448

RE: Response to Ute Mountain Ute Tribe Letter dated April 11, 2017

Dear Mr. Larrick:
The Division of Waste Management and Radiation Control has completed its review of the Ute
Mountain Ute Tribe (UMUT) letter dated April 11, 2017 and received by the Division on April 13, 2017
(UMUT Letter). The UMUT Letter was concerning ground water monitoring at the Energy Fuels
Resources (USA) Inc. White Mesa Uranium Mill (Mill).
Several comments were noted in the UMUT Letter concerning the Division’s review findings of the
UMUT contracted report prepared by Geo-Logic Associates1 (Report). A copy of a Division
memorandum, dated September 23, 2015, regarding review of the Report was provided to you which
details these findings. The Geo-Logic conclusions are not supported by the data presented and do not consider established background concentrations, established ground water compliance limits (GWCLs)
in the Mill Groundwater Permit (Permit), pre-identified concentration trends documented in background
reports, hydraulic properties of the Burro Canyon aquifer or contaminant mobility.

Additionally, Geo-Logic failed to correctly characterize the objectives of the pyrite study; failed to recognize the validity of measured hydraulic parameters in the perched aquifer; and failed to recognize
or discuss assumptions and estimations which were used to analyze the data.

Contrary to statements made in the UMUT Letter, the Division is not being “counterproductive” by
providing and discussing the review of the Geo-Logic Report with the UMUT. In the interest of
1 Geo-Logic Associates, August 2015, Data Review and Evaluation of Groundwater Monitoring White Mesa Uranium Mill,
Prepared for the Ute Mountain Ute Tribe DRC-2017-003405 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.utah.gov Printed on 100% recycled paper

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communication, the Division requests that the UMUT provide justifications and expand on comments
regarding the Geologic Report when refuting Division findings. For example, the UMUT Letter states,
“The Geo-logic Report does in fact consider concentrations of specific metals in the tailings cells and the relative mobility of contaminants in contrast to UDWMRC statements that it does not.” However,
the Geo-Logic Report does not consider the relative mobility of contaminants but instead claims that the
release of tailings solution is evident based on average metal concentrations in the groundwater when
compared with average concentrations in tailings cell solution.
The Geo-Logic Report, Section 3.4, explains the method used to calculate the average concentrations
and provides a spreadsheet of the values used on Table 10 of the report. In some cases, and as explained
in the Geo-Logic Report, sets of wells have been used to display data. The selection of data is biased
and not representative of well-by-well analysis which considers background concentrations determined
for individual wells. Using this culled data and estimated solubility limits for individual metals (using a specified pH’s of 5 and 7), Geo-logic has combined average metals concentrations for selected sets of
wells and plotted these average concentrations in comparison with average tailings solution
concentrations (Figure 23 of the Geologic Report) on different logarithmic scales. According to Geo-
Logic, the diagram (Figure 23) depicts that “the patterns observed show a general similarity in the relative concentrations of the various heavy metals, particularly for Tailing Cell 1, suggesting that the tailings solution is a likely source for the observed heavy metals concentrations in groundwater below
the tailings cells.”

Based on the Division’s review, this data analysis is not representative of concentrations which would be
expected in the event of a tailings solution release. The Geo-Logic report does not consider relative mobility of contaminants, background concentrations of metals, comparisons with GWCLs or rising
trends. It is expected that in the case of metals, the same metals will be found in the shallow aquifer
Burro Canyon Rock as are found in the ore used to produce the tailings, and therefore the same metals
will be found in natural background concentrations as are found in the tailings solution. Geo-Logic has
simply compared a biased assessment of background concentrations in the Burro Canyon Aquifer with average tailings solution concentrations.

Page 3 Paragraph 3 of the UMUT Letter states that “The Tribe would like to clarify to UDWMRC that
we are not, as stated the February 16, 2017 letter, and have not ever been using gross average trace metals concentrations in groundwater to claim that a contaminant plume exists below the Mill.” Contrary to this statement by the UMUT, the August 2015 Geo-Logic Report makes these exact claims
as discussed below.

The Geo-Logic Report plots concentrations on a site map of gross metals concentrations (Figure 24 of
the Geo-Logic Report) in site wells and includes contour maps which claim to be indicative of tailings solution releases to groundwater based on the same reasoning as discussed for the Report Figure 23
discussed above. This is not representative of tailings solution discharge but again, is simply a
representation of gross total background metals concentrations in the shallow aquifer.

For example, in the case of the Mill monitoring wells MW-32 and MW-29 which have the highest average concentrations of gross metals of all of the wells plotted on figure 24 of the Report, none of the
metals exceeded GWCLs (based on statistical analysis of background concentrations) during quarterly
2016 monitoring, and very few GWCL exceedances have occurred since the initiation of sampling at
these wells in 2005. The 2004 Statement of Basis for the Permit recognized that background
concentrations of heavy metals had not been established and that background reports were required prior to the establishment of GWCLs in the Permit.

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The Permit requires that groundwater monitoring wells be sampled and analyzed for 38 compliance
parameters. Intrawell background statistics are performed at the Mill due to recognition of the
heterogeneous nature of the Burro Canyon Formation. It is acknowledged and observable that parameters (e.g. heavy metals, nutrients, other inorganic and organics) which are detected at the tailings
cell monitoring wells are also detected at wells located hydraulically upgradient from the Mill and
tailings cells and at wells far downgradient from the Mill.

The Division reviews the monitoring well data (submitted in quarterly reports) and compares those measured concentrations against their corresponding GWCLs. Again, the GWCLs have been
established with consideration of background monitoring concentrations on an intrawell basis. This is in
recognition of the anisotropic and heterogeneity of the Burro Canyon aquifer. The Division also notes
that several of the parameters, in respective wells, were identified as having pre-existing upward or
downward data trends. The GWCLs are based on statistical analysis using an evaluation of all historical groundwater monitoring data for each well.

If any of the monitoring concentrations exceeds the GWCL, then Energy Fuels is required to report the
exceedance and commence accelerated monitoring for that well and parameter. If the concentration of a
parameter exceeds the GWCL in two consecutive samples, then Energy Fuels is required to notify the Director of the “out of compliance” status, continue accelerated monitoring and submit a plan and time
schedule for assessment of the source of GWCL exceedances.

EFR submits the plan and time schedules and source assessment reports to the Director according to the
requirements of the Permit for review and approval. Source assessments generally include the following types of evaluation which serve as lines of evidence when determining whether the GWCL exceedance
was or was not due to Mill activities:

• Evaluation of Tailings Solution Discharge Indicator Parameters (Cl, Fl, SO4, U) concentration and trends. These indicators are used in comparison to other compliance parameters since, based on distribution coefficients, retardation factors and high concentrations in the tailings solution,
they would be expected to arrive at the groundwater earlier than other parameters.

• Mass Analysis – Volumes of tailings wastewater which would be required to cause the concentration increase.

• Contaminant transport time of arrival to the point of exposure with consideration of unsaturated
transport through the vadose zone and measured groundwater velocity.
• Pre-identified background concentrations and pre-identified concentration trends in accordance
with the groundwater background reports.

• Groundwater age dating and evaluation of isotopic fingerprint analysis per the University of
Utah Groundwater Study2 at the Mill.

The UMUT Letter notes on page 4 that “extensive investigations conducted to date related to the Burro Canyon geology/shallow aquifer we should all be working with the foundation that it is an anisotropic
2 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.

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and heterogeneous sandstone aquifer with a fluvial depositional history.” It should be evident to the
UMUT that this is recognized and is the basis for study of background concentrations at the individual
wells and development of well specific GWCLs in the Groundwater Permit. Additionally, in recognition of this variability, over 100 discrete monitoring wells have undergone slug testing and/or
pump testing to provide location specific permeability and groundwater velocities.

Numerous studies and field measurements have been conducted by Energy Fuels Resources for the Mill.
An overview of these studies can be found in the Energy Fuels Resources June 6, 2014 Hydrogeologic Report which is available on the Division website.

Indicator Parameters

As discussed above, the Groundwater Permit includes 38 compliance parameters, monitored at determined baseline frequency, for the tailings monitoring wells. Groundwater compliance limits were
set for each of these parameters after evaluation of background concentrations. The 38 parameters are
subject to compliance requirements as defined in the Permit.

When evaluating two consecutive exceedances of any of these parameter GWCLs, one tool is to look for concentration trends for parameters that would be expected show up at monitoring wells in a relatively
short time and at high concentrations. Energy Fuels Resources and the Division agreed to an evaluation
of chloride, fluoride, sulfate and uranium in source assessment reports as early warning indicator
parameters of tailings solution discharge based on high concentrations in the tailings solution and low
retardation in the vadose zone.
In accordance with the UMUT Letter, references were cited regarding a possible complication in using
chloride as an indicator parameter. The UMUT Letter cites a few references and notes that regarding
these references, the chloride ion may be retarded due to its large size and subsequent retention
(entrapment) in the small pore spaces of fine grained clay layers in the Burro Canyon Aquifer vadose zone or clay liners below the tailings cells.

Regarding clay layers in the cell liners, Cells 1, 2 and 3 do not include clay or compacted clay layers;
Cells 4A and 4B include a 0.2 inch Geosynthetic Clay Liner (GCL) of low permeability bentonite clay.
Regarding clay layers in the Burro Canyon Aquifer in the area of groundwater monitoring, the Division is not aware of fine grained or compacted clay layers. If tightly compacted clay layers were present,
they would be supported by evidence in drill logs or perched saturated zones. For the most part, the drill
logs show sandstone and conglomerate down to the screened interval. Some logs show a shallow zone
of mancos shale (erosional remnants of negligible thickness) and occasional deeper thin shale layers.
The Burro Canyon stratigraphy is discussed in the Energy Fuels June 6, 2014 Hydrogeologic Report Section 3.1.2.2. Even if tightly packed clay lenses were present, it is most likely that the amount of
retention of chloride ions in these layers would be minimal due to the high concentration of chloride in
the tailings solution. Likewise the GCL layer in cells 4A and 4B would likely have a minimal effect in
reducing chloride concentrations in the tailings solution in the event of a leak or tear.
The UMUT Letter also questions the use of uranium as an indicator parameter and points specifically to
uranium sensitivity to redox conditions. It is true that uranium is most mobile under acidic and oxidized
conditions. Uranium may be retarded in unsaturated zones of the Burro Canyon Aquifer where
neutralization (buffering of the solution) and complexation are favorable. If strong sorption of uranium
were favorable in the vadose zone, then the resulting retardation coefficient could be much higher than literature cited values and other metals may be more mobile under those conditions. As discussed
above, all parameters are analyzed when a monitoring well is OOC for a specific contaminant. The use
of indicator parameters is one line of evidence used to evaluate tailings solution as a source.
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Source Assessment for MW-24
The UMUT Letter states “UDWMRC 2017 details how UDWMRC sees MW-2 as a suitable water
chemistry surrogate for MW-24 while there is a distance of 200 meters (approximately 656 feet)
between the two locations.” This is an incorrect characterization of the Division statements in its
February 16, 2017 letter.
MW-2 was used by Energy Fuels Resources as one of the lines of evidence supporting the conclusion
that the tailings solution was not a cause of cadmium and thallium GWCL exceedances in monitoring
well MW-24. This line of evidence was based on the age dating and isotopic fingerprinting done by the
University of Utah at monitoring well MW-2, which concluded that groundwater at that well had not been impacted by tailings solution. The Division is not considering MW-2 as a “suitable water
chemistry surrogate for MW-24.” The Division does consider the use of the University of Utah study
findings at a downgradient and relatively nearby monitoring well to be a valid line of evidence in the
MW-24 Source Assessment Report.
UMUT/Duke University Proposed Project:

The Division has not been informed about the intent, design, or scope of the Duke University study as is
claimed in the UMUT Letter page 5. The Division was informed during a September 22, 2016 meeting
with Malcolm Siegel at the White Mesa Community Center that the Tribe had contacted Duke University, that a professor at Duke specialized in isotopic studies, and that Duke University was
prepared to conduct and fund a project at the Mill. However, no details of the project were
communicated at that meeting and to date, the Division has not received written correspondence
regarding the project.
In its February 16, 2017 letter to the UMUT regarding response to two previous letters from UMUT, the
Division requested a copy of the Duke University Project Plan and Scope as well as the results of Duke
University November 2016 sampling trip. The Division also expressed concerns regarding quality
controls that would need to be undertaken for the project. Please provide these items as previously
requested so that the Division can understand the scope and intention of the UMUT proposed project.
If you have any questions, please call Tom Rushing at [phone].

Sincerely,

Scott T. Anderson, Director
Division of Waste Management and Radiation Control
STA/TR/ka

c: Kirk Benge, Health Officer/Environmental Health Director, San Juan County Health Department
Rick Meyer, Environmental Health Director, San Juan County Health Department
Scott Hacking, P.E., DEQ District Engineer Treasure Bailley, USEPA Region 8