DRC-2015-002582 - 0901a068805321e9

Department of
Environmental Quality
Alan Malheson
Ewe ituvi' Dun lot
State of Utah DIVISION OF RADIA1 ION CONTROL
GARY R HERBERT
Govi-mnr
Rusiy Lundberg
Dirct ror
SPENCERJ COX
Lit'ttrrntinr Govemar
DRC-2015-002582
May 28, 20I5
Kathy Weinel, Quality Assurance Manager
Energy Fuels Resources (USA) Inc.
225 Union Boulevard, Suite 600
Lakewood, Colorado 80228
RE: Geotechnical Final Review of Energy Fuels Resources (USA) Inc., White Mesa Mill,
Tailings Data Analysis Report dated April 2015, and Probabilistic Seismic Hazard Analysis
Report dated April 2015, RML# UT 1900479, San Juan County, Utah
Dear Ms. Weinel:
Please find enclosed the Utah Division of Radiation Control (DRC) Technical Memorandums on
the final geotechnical review of the revised MWH Americas, Inc. (MWH) Tailings Data Analysis
report (TDAR) dated April 2015, and the revised Probabilistic Seismic Hazard Analysis (PSHA)
report also dated April 2015. These Technical Memorandums will also serve to document DRC
concluding resolution of AECOM's (formerly URS) review comments dated March 31, 2015 and
January 21, 2015 on the TDAR and along with comments dated March 31, 2015 on the PSHA.
Prior versions of these reports by MWH were both dated March 2015 and October, 2014.
The Tailings Data Analysis Report was prepared pursuant to the MWH July 2013, White Mesa Mill
Tailings Characterization and Analysis Work Plan. The Probabilistic Seismic Hazard Analysis
report was prepared pursuant to DRC's February 2013 review comments on EFRI's August 2012
responses to DRC's Round I Interrogatories for the White Mesa Mill Reclamation Plan Revision
Each of the April 2015 reports include revisions addressing the review comments submitted to
EFRI by the DRC in letter dated March 31, 2015 (DRC 2015a). It is our expectation that the
information contained in the TDAR and PSHA will allow for continuation of preparation of the
proposed White Mesa Mill Reclamation Plan Revision 5.0 as well as the responses to the March
5.0.
195 Nonh 1950 West • Salt Lake City. UT
Mailing Address PO Box 144850 • Salt Lake City. UT 84114-4850
Telephone [phone] • Fa\ [phone] • T D D (801) 536-WI4
n it ti dcq ulult eft
Printed on (OCK* recycled paper
Page 2
May 28, 2015
2012 Round 1 Interrogatories and the subsequent February 2013 review comments.
If you have any questions or require clarification concerning the technical memorandum, please
contact Mr. Eric Boone at [phone].
Sincerely,
John Hultquist, Licensing Program Mgr.
Division of Radiation Control
Enclosures
cc: David C. Frydenlund, Energy Fuels Resources (USA) Inc.
Jon Luellen, AECOM (Formerly URS)

195 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144850 • Salt Lake City, UT 84114-4850
Telephone [phone] • Fax [phone] • T.D.D. [phone]
www.deq.utah.gov
Printed on 100% recycled paper
State of Utah

GARY R. HERBERT
Governor

SPENCER J. COX
Lieutenant Governor
Department of
Environmental Quality

Alan Matheson
Executive Director

DIVISION OF RADIATION CONTROL
Rusty Lundberg
Director

T E C H N I C A L M E M O R A N D U M on T D A R

Geotechnical Review of Energy Fuels Resources (USA) Inc., White
Mesa Mill Tailings Data Analysis Report dated April 2015, Prepared by
MWH Americas, Inc., RML# UT1900479, San Juan County, Utah.
May 28, 2015
Introduction
This Technical Memorandum prepared by Division of Radiation Control (DRC) staff presents
updated final geotechnical review comments on the subject Tailings Data Analysis report (TDAR)
prepared by MWH Americas, Inc. (MWH) for Energy Fuels Resources (USA) Inc., (EFRI). The
subject report dated April 2015 (MWH 2015a) is a revision to the report previously dated March
2015 (MWH 2015c) and presents the results of subsurface investigations performed in accordance
with a Work Plan dated July 2013 (Revision transmittal dated August 1, 2013) to collect site-
specific tailings geotechnical data on tailings Cells 2 and 3 at the White Mesa facility in San Juan
County, Utah. The objectives of the referenced Work Plan have been restated in Sections 1.3 and
1.4 of the TDAR.
While there are several concepts were consensus has been difficult to obtain the DRC finds that
the latest version of the TDAR (MWH 2015a) is at a place where future analyses using data
therein can account for the prevailing differences. The revisions captured in the latest TDAR
range from grammatical improvements to additions of clarifying text. Cross-sections and
analytical figures have been revised to depict three soil categories within tailings Cells 2 and 3,
and tabulated attributes of the soil categories have received additional qualifying narrative.
This Memorandum is intended to provide tangible closure to the remaining open issues identified
in the DRC March 31, 2015 review memo (DRC, 2015a) as well as to serve to document DRC
concluding resolution of AECOM ’s (formerly URS) review comments dated March 31, 2015 and
January 21, 2015 on the TDAR. Several items are being closed by the DRC with an
understanding that EFRI’s consultant has interpreted and presented the testing data before them as
reasonably as appropriate. It should be understood that in order for the DRC to make informed
decisions on future geotechnical analysis and modeling that the DRC will expect subsequent
geotechnical analyses to incorporate the spatial variability of the tailings constituents by
presenting models and results that have utilized the range of soil categories and parameters that
have been defined for these soil categories rather than single values or using the most conservative
value.
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Part 1: DRC March 31, 2015 TDAR comments
The following section of this Technical Memorandum list specific DRC review comments that
were contained in the DRC Technical Memorandum dated March 31, 2015 (DRC 2015a) and
narrative as to how or why DRC staff considered the review comments to be adequately addressed
and therefore closed.
Findings – DRC March 31, 2015 TDAR comments
1. Section 2.1 - CPT Soundings
For consistency with wording in DRC 2015a, see the following Part 1, Comments No. 4 and
No. 5 of this Technical Memorandum for closure of several review comments concerning the
interpretation the CPT plots with a simplified two category classification scheme and
interpretation of water level data that were apart of Section 2.1 of the TDAR.
Per a request in DRC 2015a, MWH has corrected several data gaps on Figure 2-1 – Location
Map, by adding depths penetrated with CPT soundings: CPT-2W3, CPT-2W4-C, and CPT-
2W6-S in Cell 2. The DRC considers this item adequately addressed.
2. Section 2.2 - Direct Push Sampling
In response to a request made in DRC 2015a, MWH clarified the depiction of push sample
symbols that were absent from the “Push Samples” column on the log for CPT-2W6-S(3).
The DRC considers this item adequately addressed.
As above with Comment No. 1, see Part 1, Comment No. 4 of this Technical Memorandum
for closure of the review comment concerning how material that would be identified by
typical soil behavior classification charts as sensitive fine grained material was going to be
classified, treated, and modeled.
3. Section 3.0 - Laboratory Investigation
In DRC 2015a the DRC requested that the non-standard results from the tailings consolidation
testing be noted and clearly described as such in the TDAR. DRC also requested that a
qualifying statement be added to indicate how the licensee anticipates these data will be
treated in downstream technical analyses/models. MWH expanded the narrative of Section
3.0 and Section 4.5 of the TDAR to adequately address these two DRC comments.
General Laboratory Investigation Review Comments
In DRC 2015a the DRC indicated that it assesses the particular portion of sample run “CPT-
2W6-S(2)@12.3 feet”, that was used within the consolidation test apparatus, as being
comprised of material representative of the sand-slime category, that the material collected
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within the sample run appears to have transitioned from one category to another along the
length of the sample run and that the representative gradation test was performed on a separate
portion of the sample run which classified as tailings slime. A gradation test on the actual
consolidation specimen was not provided so the review comment ends up being moot. In any
case, for the geotechnical properties associated with the subject consolidation test, MWH has
defended their position that the test results from this consolidation test are reasonably within
the range of previously published ranges for slime tailings (Keshian and Rager, 1988). The
DRC understands that the tailings have a high spatial variability and therefore it is
understandable that a particular result may fall within the representative ranges of two material
categories. For this reason the DRC can accept MWH’s explanation for their
interpretation of the data.
As stated in the introduction of this Technical Memorandum, the DRC will look closely at
future geotechnical analyses to determine that there have been sufficient parametric analyses
to identify the behaviors and parameters of most importance to the computed responses. The
licensee will need to evaluate if there is sensitivity to the range of cv rates, or to the relative
percentages of material categories. The licensee’s analyses will need to show that the
embankment settlement is consistent with on-going field measurements. And in order for the
DRC to make an informed decision, have the final evaluations clearly documented how the
licensee’s analyses have demonstrated that the key uncertainties have been accounted for and
that additional information (from exploration or analysis) could reasonably be expected to
change (or not) the outcome. On this basis the DRC considers this item adequately
addressed.
In response to a request made in DRC 2015a, MWH corrected the units for cv in Note g of
Table 3-2, Summary of Laboratory Testing. The DRC considers this item adequately
addressed.
4. Section 4.1 - Tailing Classification - Correlation
DRC 2015a included a lengthy discussion on the MWH-recommended material classification
scheme and the need to include a curve dividing sand from sand-slime. This MWH-
recommended classification scheme is an adaption of the L&M 1986 classification scheme
that has been revised for this project to account for data collected from site specific sampling.
As mentioned in the introduction to this Technical Memorandum, this latest TDAR has
revised the scheme to include a curve dividing sand from sand-slime. The DRC held strongly
about the need to include separate sand / sand-slime categories and appreciates this revision to
the classification scheme. The curve was placed in the same configuration as was done with
the L&M 1986 classification scheme without a lateral shift as was done for the curve
separating sand-slime from slime. On this basis the DRC considers this item adequately
addressed.
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DRC 2015a requested that the licensee re-evaluate the distribution of tailings sediments to
provide horizontal interpretation of the interlayered nature of the tailings beyond the CPT
plots and across each tailings cell. In response MWH confirmed their interpretation that the
tailings are significantly interbedded with minimal large-scale segregation. They state that
this vertical and lateral heterogeneity precludes the ability to develop a horizontal
interpretation of tailings characteristics between CPT locations. The DRC does recognize the
heterogeneity; however it also cannot overlook often thicker sequences of sand at the surface
of both Cells 2 and 3, the localized conditions of equipment refusal at the southwest portion of
Cell 3, as well as the localized condition of Sensitive Fine Grained soil observed within CPT
soundings SP2W3; SP3-3S; and SP3-6N. These conditions behave differently from one
another and therefore as stated above in Part 1, Comment No. 3 of this Technical
Memorandum, the DRC will look closely at future geotechnical analyses to determine that
there have been sufficient parametric analyses to identify the behaviors and parameters of
most importance to the computed responses. And then in a final assessment has the licensee
included a statement regarding what properties are most important to the performance of the
tailings impoundments on a long term basis, and is the basis for selecting the values for those
most important properties well documented and transparent. The licensee will need to
evaluate if there is sensitivity to the relative percentages of material categories. And in order
for the DRC to make an informed decision, have the final evaluations clearly documented how
the licensee’s analyses have demonstrated that the key uncertainties have been accounted for
and that additional information (from exploration or analysis) could reasonably be expected to
change (or not) the outcome. On this basis the DRC considers this item adequately
addressed.
Editorial comments on Updated Figures
MWH corrected several plotting errors in response to the DRC noting that the updated Figure
E.1-2, Friction Ratio vs. Cone Resistance, Adjusted Tailings Classification, had several
consolidation data points incorrectly shaded in the updated graph. The DRC considers this
item adequately addressed.
DRC 2015a found that the legend within Figures E.1-21 through E.1-37 with blue shading for
sand tailings was misleading because the previous two-soil category classification scheme
would not produce blue shading displayed on the CPT plots. With replacement of the sand
category, blue shading is now being displayed on the CPT plots and allowing for a better
understanding of the extent of tailings sand. The DRC considers this item adequately
addressed.
5. Section 4.2 - Pore Pressures
DRC 2015a questioned the methodology used by the licensee to estimate water levels within
tailings Cells 2 and 3 from the CPT data obtained during this study. In general the method
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was to interpret dynamic pore pressure readings during CPT advancement to establish water
surface levels.
To address DRC’s and AECOM’s concerns with the interpretation of water levels in the
tailings, MWH revised the interpretation of the estimated elevations of the top of saturated
tailings shown on Figures E.2-1 through E.2-16 to conservatively base these estimates solely
on pore pressure dissipation test measurements instead of using both pore pressure dissipation
test and generation of positive dynamic pore pressure measurements. Based on this revision
the DRC considers this item adequately addressed.
6. Section 4.3 - Tailings Density
DRC 2015a highlighted that in four places, figures called out in the second paragraph of
Section 4.3 appeared to be incorrectly directed to figures labeled “E2” in Appendix E instead
of “E3”. MWH corrected these editorial problems and the DRC considers this item
adequately addressed.
DRC also noted in DRC 2015a that the plots presented on Figure E.3-12 appeared to be
incorrectly plotting the interpretation of data. MWH reviewed the plotting and confirmed the
plotting is correct but has concluded the Lunne et al (1997) relationship does not provide a
good correlation with field data. The DRC considers this item adequately addressed.
In DRC 2015a the DRC remarked that Section 4.3-Tailings Density of MWH 2015c discussed
geotechnical test results associated independently within the sand tailings category. The
latest TDAR has revised the soil classification scheme to include a curve dividing sand
from sand-slime and therefore this comment is no longer a concern of the DRC.
7. Section 4.5 - Consolidation Properties
Above in Part 1, Comment No. 3 of this Technical Memorandum, the DRC has reviewed
MWH’s responses to our review comments on consolidation testing for the TDAR. As
described above in Comment No. 3 the DRC considers this item adequately addressed.
8. Section 5.0 - Summary
In DRC 2015a the DRC requested and MWH has provided the DRC with a copy of the
October 2013 work plan. The DRC considers this item adequately addressed.
DRC 2015a also inquired as to internal inconsistency with a conclusion made in the seventh
paragraph of Section 4.1 and the second paragraph of Section 5.0. In response MWH revised
the second paragraph of Section 5.0 to be consistent with Section 4.1. The DRC considers
this item adequately addressed.

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Part 2: AECOM March 31, 2015 TDAR comments
The following section (Part 2) of this Technical Memorandum considers the specific AECOM
review comments contained in the AECOM Technical Memorandum dated March 31, 2015, that
was included as a part of DRC 2015a (hereafter referred to as DRC 2015a-ATM). And a
subsequent section (Part 3) addresses AECOM review comments that were contained in the
AECOM Technical Memorandum dated January 21, 2015 that was included as a part of DRC
2015b (hereafter referred to as DRC 2015b-ATM).
The comments have been reduced to specific questions and narrative how or why DRC staff
considered the review comments to be adequately addressed and therefore closed.
Findings – AECOM March 31, 2015 TDAR comments
1. General Comment:
In DRC 2015a-ATM, AECOM made a general comment that a document containing specific
responses to the individual technical comments in its’ Technical Memorandum dated January
22, 2015, which would facilitate review and determination of whether and how each
individual comment has been addressed, was not provided. To improve transparency and
traceability the licensee provided a comment/response document documenting the response to
each review comment previously submitted, with their April 2015 submittal package. The
requested comment/response document is included in the reference section (see MWH
2015b) and therefore the DRC considers this item adequately addressed.
2. Section 3.0., 6th paragraph, page 12:
In DRC 2015a-ATM, AECOM referenced Comment No. 19 in the January 22, 2015 Technical
Memorandum, that noted according to ASTM D2435 the minimum specimen diameter or
inside diameter for testing consolidation properties shall be 2 inches. AECOM also noted that
the March 2015 redline version of the TDAR references two published papers that indicate
that a reduction in diameter from 2.4 to 1.2 or 1.4 inches for fine-grained soils has an
insignificant impact on measured consolidation. Both papers involved testing of clays (one
involving marine clays), rather than tailings having grain sizes/classifications ranging from
slimes to sands.
In response MWH expanded the narrative of Section 3.0 and Section 4.5 of the April 2015
TDAR to highlight the non-standard testing results and added a qualifying statement how the
licensee anticipates that these data will be treated in downstream technical analyses/models.
The DRC considers this item adequately addressed.
3. Section 4.1., Tailings Classification, paragraph 8, page 16:
In DRC 2015a-ATM, AECOM comments that cross sections have been provided but no
explanation is presented as to how slime and sand-slime zones will extend in plan view. Also
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sand zones have not been identified but grouped in with sand-slime zones, without sufficient
justification. Within the comment, AECOM recommended that the licensee re-evaluate the
proposed adjustments to the L&M classification scheme and revise the TDAR report
accordingly to reflect the licensee’s final proposed classification of the tailings materials, or,
alternatively, provide additional detailed rationale to support the proposed adjustments.
These issues were also a concern of DRC staff and the DRC has provided closing comments
to this issue in Part 1, Comment No. 4 of this memorandum. However, due to the importance
of this issue the DRC has repeated here the essential substance of DRC’s outlook on how
future modeling and analyses of the tailings profiles and tailings material classifications will
be reviewed. In essence, the DRC will look closely at future geotechnical analyses to
determine that there have been sufficient parametric analyses to identify the behaviors and
parameters of most importance to the computed responses. And then in a final assessment has
the licensee included a statement regarding what properties are most important to the
performance of the tailings impoundments on a long term basis, and is the basis for selecting
the values for those most important properties well documented and transparent. The licensee
will need to evaluate if there is sensitivity to the relative percentages of material categories.
And in order for the DRC to make an informed decision, have the final evaluations clearly
documented how the licensee’s analyses have demonstrated that the key uncertainties have
been accounted for and that additional information (from exploration or analysis) could
reasonably be expected to change (or not) the outcome. On this basis the DRC considers
this item adequately addressed.
4. Sections 4.1 and 4.2., and Figures 4-3 through 4-6:
In DRC 2015a-ATM, AECOM states that they do not agree with the established elevation of
saturated tailings as shown on Figures 4-3 through 4-5 and recommends piezometers be
installed to measure changing water levels with time and to establish the pore pressure regime
with the tailings for further geotechnical analysis. In MWH 2015b, MWH acknowledges that
installation of piezometers can provide measurements of water levels within the tailings
however they were not a part of the Work Plan (MWH 2013). In addition, MWH points out
that the estimates of the top of saturated tailings as now presented in the TDAR (April 2015)
should be sufficient to provide conservative estimates for use in technical analyses. The DRC
has assessed that the revisions included in the most recent TDAR have adequately
addressed this issue, see also Part 1, Comment No. 5 of this Technical Memorandum.
5. Section 4.4., Hydraulic Conductivity and Table 4-4:
In DRC 2015a-ATM, AECOM recommended that Table 4-4 show each laboratory test value
and what material type it is considered to be instead of showing a range of values.
Additionally AECOM points out that the sand-slime permeability is shown to be as less
permeable than slime. AECOM requested MWH clarify that the information is correct and
accurate and provide an explanation for this apparent discrepancy, or revise the information if
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necessary. MWH responded in MWH 2015b that Table D-1 in Appendix D provides
individual laboratory test results for all the laboratory tests conducted. MWH further states
that the results listed in Table 4-4 are correct and indicate that the laboratory vertical hydraulic
conductivity results for the sand-slime and slimes tailings are similar and potentially
controlled by the finer fraction of the tailings samples.
The DRC understands that the tailings have high spatial variability and acknowledges the
hydraulic conductivity testing indicates values lower than previously used for modeling. It is
also noted that the geometric mean value for sand-slime in Table 3.2 is outside and below the
range previously published for sand-slime tailings in Keshian and Rager, 1988 and as
previously assessed by the DRC (see Comment No. 4 of DRC 2015a) that MWH had
difficulty obtaining representative samples of the coarser tailings sand and therefore the
tailings sands appear to have been under represented in the laboratory data analysis contained
in the TDAR. Therefore, as stated in the introduction of this Technical Memorandum, the
DRC will look closely at future geotechnical analyses to determine that there have been
sufficient parametric analyses to identify the behaviors and parameters of most importance to
the computed responses. And then in a final assessment has the licensee included a statement
regarding what properties are most important to the performance of the tailings impoundments
on a long term basis, and is the basis for selecting the values for those most important
properties well documented and transparent. The licensee will need to evaluate if there is
sensitivity to the range of kv rates, or to the relative percentages of material categories. And in
order for the DRC to make an informed decision, have the final evaluations clearly
documented how the licensee’s analyses have demonstrated that the key uncertainties have
been accounted for and that additional information (from exploration or analysis) could
reasonably be expected to change (or not) the outcome. On this basis the DRC considers
this item adequately addressed.
6. Section 4.5., Consolidation Properties and Table 4-7:
In DRC 2015a-ATM, AECOM recommended that Table 4-7 show each laboratory test value
and what material type it is considered to be instead of showing a range of values. They note
in Table 4-7, the cv value is greater for slime than sand-slime, indicating more rapid
consolidation in slime than sand-slime, which is most likely not realistic. AECOM requested
MWH clarify whether there is a significant difference in behavior between slimes and sand-
slimes. These issues were also a concern of DRC staff and the DRC has provided closing
comments to these issues in Part 1, Comment No. 3 of this memorandum. The DRC
considers this item adequately addressed.
7. Section 4.4., Hydraulic Conductivity:
In DRC 2015a-ATM, AECOM recommended that this last sentence of Section 4.4 be deleted
or, alternatively, a comprehensive analysis and discussion, including an evaluation of
uncertainties associated with the use of values of hydraulic conductivities for all tailings types
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that may be present in different areas of cells 2 and 3, be provided. In response MWH deleted
the sentence to reduce the confusion. The DRC considers this item adequately addressed.
8. Section 4.5., Consolidation Properties and Table 4-8:
In DRC 2015a-ATM, AECOM comments on the estimated ch values in Table 4-8 and requests
that MWH provide additional explanation of other factors and possible uncertainties that could
affect the accuracy of the estimated ch values listed in the last column of Table 4-8. AECOM
also requested additional discussion on the reliability of use of cv values measured for slimes,
sand-slime mixtures, and sand tailings, given the small sample diameters that were used in the
laboratory consolidation testing. MWH responded in MWH 2015b that other factors that can
impact ch values estimated from CPT data were added to the 3rd paragraph of Section 4.5 of
the TDAR. The issues with regards to cv values and the diameter of tailings samples were also
a concern of DRC staff and the DRC has provided closing comments to these issues in Part 1,
Comment No. 3 of this memorandum. Additionally, the DRC has assessed that the revisions
included in Section 4.5 of the most recent TDAR have adequately addressed the concerns with
regards the ch concerns. The DRC considers these items adequately addressed.
9. Section 1.2., Historical Tailings Data:
In DRC 2015a-ATM, AECOM identified a reference “Denison 2009” that was not included in
Section 6.0, References of the TDAR. MWH revised Section 6.0 to include the reference.
The DRC considers this item adequately addressed.
10. Section 3.0., 11th paragraph page 13:
In DRC 2015a-ATM, AECOM requested MWH to clarify if a statement, as follows, is correct
and accurate that “It is not expected that natural moisture contents will not be used in any
future technical analyses for the Reclamation Plan and ICTM Report.” MWH revised the
sentence with removal of the second “not” from the sentence. The DRC considers this item
adequately addressed.
Part 3: AECOM January 21, 2015 TDAR comments
The following section (Part 3) of this Technical Memorandum considers the specific AECOM
review comments contained in the AECOM Technical Memorandum dated January 21, 2015, that
was included as a part of DRC 2015b (hereafter referred to as DRC 2015b-ATM). The comments
have been reduced to specific questions and narrative how or why DRC staff considered the
review comments to be adequately addressed and therefore closed.
Findings – AECOM January 21, 2015 TDAR comments
1. Section 1.2, Objectives, and Sections 4.0 and 5.0:
In DRC 2015b-ATM, AECOM requested that cross sections be provided that show inferred
distributions of sand, sand-slime and slime tailings types in the two cells investigated and
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indicating how the CPT characterization is used on sections. AECOM also requested a
summary of tailings data collected to date and their intended use(s), including how the current
data compare to previous information/data provided on tailings properties and indicate
whether data acquired to date are considered adequate for fulfilling the intended use(s). These
issues were also a concern of DRC staff and the DRC has provided closing comments to these
issues in Part 1, Comment No. 4 of this memorandum (restated also in Part 2, Comment No.
3). The DRC considers this item adequately addressed.
2. Figure 2-2:
In DRC 2015b-ATM, AECOM indicated that the depths shown on Figure 2-2 were unclear
and requested clarification. MWH responded in MWH 2015b that the depth of the CPT
soundings is shown on Figure 2-1 of the TDAR (see also DRC Comment No. 1 in Part 1).
The total thickness of interim cover and tailings at each CPT location are shown on Figure 2-2
of the TDAR and was intended to illustrate that CPT penetrations were above the cell liner.
The DRC considers this item adequately addressed.
3. CPT Soundings
In DRC 2015b-ATM, AECOM requested clarification of the distinction between interim cover
and tailings with respect to data obtained by the CPT soundings. Additionally AECOM
highlighted that all laboratory testing was performed on samples with lower tip resistance and
lower skin friction, i.e. tailings. AECOM requested information on test data that are currently
available for the interim cover/platform fill, and whether such data is considered adequate for
final cover design. AECOM’s comment is similar to a concern raised by DRC in Comment
No. 2 of DRC 2015b. MWH’s response was to revise Section 1.3 of the TDAR to include that
the interim fill was evaluated extensively in Denison, 2011 and EFRI, 2012 and therefore not
included as a part of the tailings investigation. The DRC considers this item adequately
addressed.
4. Section 3.0 (all):
In DRC 2015b-ATM, AECOM recommended that an explanation be added to the discussion
as to how the Specific Gravity values determined for the different tailings samples tested
might have been affected by gypsum concentrations in the tailings (owing to the low specific
gravity of gypsum) and how this might impact any analyses completed for the Reclamation
Plan or the Infiltration and Contaminant Transport Modeling. MWH’s responded by
providing additional discussion in Section 3.0 (paragraphs 9 and 10) of the TDAR in regards
to the potential impact of the presence on gypsum on specific gravity measurements of the
tailings samples. The DRC considers that these items have been adequately addressed.
5. Section 3.0: Tables 3-1 and 3-2:
In DRC 2015b-ATM, AECOM noted two matters relevant to the hydraulic conductivity
testing present in Section 3.0 of the TDAR, firstly that a total of 5 tailings samples were tested
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for hydraulic conductivity, compared to the 6 hydraulic conductivity tests specified in the
Tailings Characterization Work Plan, and secondly, that Table 3-2 indicated no sand tailings
were tested for hydraulic conductivity. AECOM requested the following information with
respect to the characterization of hydraulic conductivities in the tailings be provided:
i. A comparative analysis of the current hydraulic conductivity testing results (for sand-
slimes and slimes tailings only) relative to (higher) estimates of overall hydraulic
conductivity for the tailings previously developed based on White Mesa tailings testing
data collected in 1987 and 1999; and
ii. An assessment of the representativeness of the current tailings hydraulic conductivity
testing results with respect to the distribution of sand, sand-slime, and slime tailings types
in the various cells, with respect to the previously estimated tailings hydraulic conductivity
values, and with respect to dewatering and final cover design needs.
MWH responded in MWH 2015b that the specific hydraulic conductivity values used for
analyses will depend on the type of analyses and how the tailings will be modeled. MWH
indicated that it is expected that the hydraulic conductivities used for the tailings for future
analyses will be lower than the estimated hydraulic conductivities used in previous analyses.
Although the data presented in the TDAR will be used for these future technical analyses, it is
not the intent of this report to provide specific recommendations on how tailings properties
will be selected for each type of analysis.
As stated in Part 2, Comment No.5, the DRC understands that the tailings have high spatial
variability and acknowledges the hydraulic conductivity testing indicates values lower than
previously used for modeling. It is also noted that the geometric mean value for sand-slime in
Table 3.2 is outside and below the range previously published for sand-slime tailings in
Keshian and Rager, 1988 and as previously assessed by the DRC (see Comment No. 4 of DRC
2015a) that MWH had difficulty obtaining representative samples of the coarser tailings sand
and therefore the tailings sands appear to have been under represented in the laboratory data
analysis contained in the TDAR. Therefore, as stated in the introduction of this Technical
Memorandum, the DRC will look closely at future geotechnical analyses to determine that
there have been sufficient parametric analyses to identify the behaviors and parameters of
most importance to the computed responses. And then in a final assessment has the licensee
included a statement regarding what properties are most important to the performance of the
tailings impoundments on a long term basis, and is the basis for selecting the values for those
most important properties well documented and transparent. The licensee will need to
evaluate if there is sensitivity to the range of kv rates, or to the relative percentages of material
categories. And in order for the DRC to make an informed decision, have the final
evaluations clearly documented how the licensee’s analyses have demonstrated that the key
uncertainties have been accounted for and that additional information (from exploration or
analysis) could reasonably be expected to change (or not) the outcome. On this basis the
DRC considers this item adequately addressed.
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6. Water Levels:
In DRC 2015b-ATM, AECOM notes an inconsistency between CPT static pore pressure
measurements and laboratory data, with the CPT dynamic pore pressure measurements. The
latter of which were interpreted by MWH to establish the top of saturated tailings (listed in
Table 4-1). AECOM requested a discussion be provided on how the data will be used in
future analysis. The DRC has assessed that the revisions included in the most recent
TDAR have adequately addressed this issue, see Part 1, Comment No. 5 of this Technical
Memorandum.
7. Section 4.2:
In DRC 2015b-ATM, AECOM comments that vibrating wire piezometers should be installed
to evaluate pore pressures within the tailings and thus providing data over time and guidance if
drainage is occurring. In MWH 2015b, MWH acknowledges that installation of piezometers
can provide measurements of water levels within the tailings however they were not a part of
the Work Plan (MWH 2013). In addition, MWH points out that the estimates of the top of
saturated tailings as now presented in the TDAR (April 2015) should be sufficient to provide
conservative estimates for use in technical analyses. The DRC has assessed that the
revisions included in the most recent TDAR have adequately addressed this issue, see
Part 1, Comment No. 5 of this Technical Memorandum.
8. Section 4.2:
In DRC 2015b-ATM, AECOM further commented on possible shortcomings of the
methodology of using dynamic pore pressures to estimate saturated tailings. As stated above,
The DRC has assessed that the revisions included in the most recent TDAR have
adequately addressed this issue, see Part 1, Comment No. 5 of this Technical
Memorandum.
9. Section 4.2, p. 12:
In DRC 2015b-ATM, AECOM questions if there are additional data available that would
confirm perched zones are seasonal vs. ‘perennial’ in nature, as implied in the statement by
MWH that “there are also some lenses of elevated pore pressures at shallow depths, but these
are considered perched zones in the interim cover and/or tailings due to seasonal fluctuations”.
MWH responded by adding text to the second paragraph of Section 4.2, that there is no data
“but considering the climate at the White Mesa site,…” the perched zones are expected to be
seasonal in nature. The DRC considers that this item has been adequately addressed.
10. Section 4.2:
In DRC 2015b-ATM, AECOM further comments that their interpretation of the CPT static
dissipation tests indicates that there is near hydrostatic pressure below the ground surface. As
stated above, the DRC has assessed that the revisions included in the most recent TDAR
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have adequately addressed this issue, see Part 1, Comment No. 5 of this Technical
Memorandum.
11. General Comment:
In DRC 2015b-ATM, AECOM indicated that it was not clear how the delineation of sand,
sand-slime, and slime tailings will be used for future calculations/analyses/models. AECOM
recommended also looking at plasticity indices and densities to evaluate material behavior.
These issues were also a concern of DRC staff and the DRC has provided closing comments
to this issue in Part 1, Comment No. 4 of this Technical Memorandum. The DRC has
assessed that the revisions included in the most recent TDAR have adequately addressed
this issue.
12. Section 4.3, p. 14:
In DRC 2015b-ATM, AECOM requests MWH to clarify/verify what figure or figures (e.g.,
Figures E.3-1 and E.3-2?) are relevant to the derivation of the recommended density values
listed in Table 4-3. In MWH 2015b, MWH describes that density values provided in Table 4-
3 of the TDAR are average measured density values for the tailings samples collected during
the October 2013 field investigation. Figures E.3-1 and E.3-2 show laboratory-measured total
and dry density versus depth, respectively, for the tailings samples tested. The DRC
considers that this item has been adequately addressed.
13. Section 4.4:
In DRC 2015b-ATM, AECOM requests that there be additional discussion on how hydraulic
conductivity values presented in this section will be used in future analysis. This comment is
similar to that contained above in Part 3, Comment No. 5 of this Technical Memorandum.
Please see the closing discussion provided by the DRC in Part 3, Comment No. 5, and on this
basis the DRC considers this item adequately addressed.
AECOM also requested additional information on the tested confining pressures that the
hydraulic conductivity tests were performed at and how the tested confining pressures were
selected. In response MWH added text to Section 4.4 of the TDAR regarding confining
pressures used for the hydraulic conductivity tests. The DRC has assessed that the revisions
included in the most recent TDAR have adequately addressed this issue.
14. Section 4.4, pp. 15-16 and Table 4-6:
In DRC 2015b-ATM, AECOM requests that there be additional discussion comparing the
estimated hydraulic conductivity values listed in Table 4-6 for sand tailings to previous
estimates of tailings hydraulic conductivity as described in Comment No. 5 of DRC 2015b-
ATM. AECOM requests that MWH describe how the different estimates were developed and
provide a discussion of the reliability and representativeness of these estimates of in-situ
conditions in the tailings as they relate to characterization of areas/locations within tailings
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cells that may consist of more sandy material based on the current investigation and previous
tailings testing results. Provide additional information regarding how the current and previous
tailings testing data will be used to represent the potential variability in hydraulic conductivity
values across the tailings management cells, especially with regard to sand tailings.
This comment is similar to that contained above in Part 2 and 3, Comment No. 5 of this
Technical Memorandum. The DRC has provided closing comments to this issue in Part 2,
Comment No. 5. However, due to the importance of this issue the DRC has repeated those
comments.
The DRC understands that the tailings have high spatial variability and acknowledges the
hydraulic conductivity testing indicates values lower than previously used for modeling. It is
also noted that the geometric mean value for sand-slime in Table 3.2 is outside and below the
range previously published for sand-slime tailings in Keshian and Rager, 1988 and as
previously assessed by the DRC (see Comment No. 4 of DRC 2015a) that MWH had
difficulty obtaining representative samples of the coarser tailings sand and therefore the
tailings sands appear to have been under represented in the laboratory data analysis contained
in the TDAR. Therefore, as stated in the introduction of this Technical Memorandum, the
DRC will look closely at future geotechnical analyses to determine that there have been
sufficient parametric analyses to identify the behaviors and parameters of most importance to
the computed responses. And then in a final assessment has the licensee included a statement
regarding what properties are most important to the performance of the tailings impoundments
on a long term basis, and is the basis for selecting the values for those most important
properties well documented and transparent. The licensee will need to evaluate if there is
sensitivity to the range of kv rates, or to the relative percentages of material categories. And in
order for the DRC to make an informed decision, have the final evaluations clearly
documented how the licensee’s analyses have demonstrated that the key uncertainties have
been accounted for and that additional information (from exploration or analysis) could
reasonably be expected to change (or not) the outcome. On this basis the DRC considers
this item adequately addressed.
15. Section 4.5:
In DRC 2015b-ATM, AECOM requests 1) that there be additional discussion on how the
values of horizontal coefficient of consolidation will be used in future analysis; 2) and that
there be additional discussion on how the vertical coefficient of consolidation (cv) values listed
in Table 4-7 compare with estimates of cv that may be derived from horizontal coefficient of
consolidation (ch) estimates/values (e.g., estimated ch values in Table 4-8) using published
empirical methods (e.g., Robertson et al. 1992) and discuss implications, if any, of apparent
differences. In response MWH revised the third paragraph of Section 4.5 of the TDAR. The
DRC has assessed that the revisions included in the most recent TDAR have adequately
addressed this issue. See also closing comments in Part 2, Comment No. 8 of this
Technical Memorandum.
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16. Direct Push Sampling:
In DRC 2015b-ATM, AECOM requested additional comment as to the reason for the poor
recovery and also indicate where (at what interval) the recovery was obtained. AECOM’s
comment is similar to concerns raised by the DRC in Comment No. 2 of DRC 2015b. In
response MWH clarified the logs and added additional narrative to Section 2.2 of the TDAR.
The DRC has provided closing comments to these issues in Comment No. 2 of DRC 2015a as
well as in Part 1, Comment No. 2 of this memorandum. The DRC considers this item
adequately addressed.
17. Consolidation Test Sample Size:
In DRC 2015b-ATM, AECOM points out that consolidation test samples were not sized
according to the minimum specimen diameter of ASTM D2435 and requested clarification.
AECOM’s comment is similar to concerns raised by the DRC in Comment No. 3 of DRC
2015b as well as in Comment No. 3 of DRC 2015a. In response MWH expanded the narrative
of Section 3.0 and Section 4.5 of the TDAR to address these comments. The DRC has
provided closing comments to these issues in Part 1, Comment No. 3 of this memorandum.
The DRC considers this item adequately addressed.
18. Sampling Distribution
In DRC 2015b-ATM, AECOM requested additional comment on the adequacy of the
sampling distribution within each cell and spatial variation within each cell. MWH responded
in MWH 2015b that the approved work plan (MWH, 2013) listed two direct push sampling
locations per tailings cell (four total), which were to be selected during the field program
based on the results of the CPT soundings. Direct push sampling was actually conducted at
six sampling locations in Cell 2 and two sampling locations in Cell 3. The locations were
selected to span the range of material responses (e.g. pore pressures, soil behavior types)
measured during CPT testing, as well as to provide sufficient tailings samples for laboratory
testing. Based on this response it can be inferred that MWH exceed the expected Work
Plan goals. The DRC considers this item adequately addressed.
19. In DRC 2015b-ATM, AECOM noted that there were typographical errors on the drilling logs
with respect to the permeability, cc, and cv values. MWH corrected the errors which were on
several of the logs. The DRC considers this item adequately addressed.
20. In DRC 2015b-ATM, AECOM commented that on Figures E.2-1 through E.2-8 it would be
helpful to show the pore pressure in feet associated with the static dissipation test and not only
the elevation where the test was performed. In response MWH revised the figures to show
pore pressure in feet along the right hand side of each of these figures. The DRC considers
this item adequately addressed.
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21. In DRC 2015b-ATM, AECOM noted that there were discrepancies between values obtained
from the laboratory testing and values reported in Table 4-7. MWH corrected the errors
between the laboratory testing and Table 4-7. The DRC considers this item adequately
addressed.
22. In DRC 2015b-ATM, AECOM noted that the sample recovery noted on boring logs is at a
different interval than noted on the laboratory testing results. In preparing the TDAR dated
March 2015 MWH reviewed the field logging procedures with regards to sample recovered
and revised many of the sample identifications as well as the associated laboratory test result
sheets and references thereto. For closing comments see also the 1st and 3rd paragraphs of
Comment No. 2 of DRC 2015a. The DRC considers this item adequately addressed.
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References:
ASTM Designation: D2435-11, Standard Test Methods for One-Dimensional Consolidation
Properties of Soils Using Incremental Loading, American Society for Testing and Materials,
Annual Book of ASTM Standards, Section Four, Construction, Vol. 04.08, West
Conshohocken, Pennsylvania. 2013. www.astm.org.
Denison Mines (USA) Corporation. (2011). Reclamation Plan, Revision 5.0, White Mesa Mill,
Blanding, Utah. September 2011.
Energy Fuels Resources (USA) Inc., (2012). Radioactive Materials License, Response to Utah
Division of Radiation Control (“DRC”) Round 1 Interrogatory on Reclamation Plan Revision
5.0, Second Submittal. August 15, 2012.
Keshian, B., and Rager, R.E. (1988). Geotechnical Properties of Hydraulically Placed Uranium
Mill Tailings. In D.J.A. Van Zyl and S. Vick, Editors, Hydraulic Fill Structures, a Specialty
Conference sponsored by the Geotechnical Engineering Division of the American Society of
Civil Engineers, Geotechnical Special Publication No. 21, pgs. 227-254.
Larson, N. B., and Mitchell, B. (1986). Cone Penetrometer Use on Uranium Mill Tailings. In
Samuel P. Clemence, Editor, Use of In Situ Tests in Geotechnical Engineering: Proceedings
on In Situ’86, a Specialty Conference sponsored by the Geotechnical Engineering Division of
the American Society of Civil Engineers, Geotechnical Special Publication No. 6, pgs. 700-
713.
Lunne, T., Robertson, P.K., and Powell, J.J.M., (1997). Cone Penetration Testing in Geotechnical
Practice. Blackie Academic & Professional, reprinted E&FN Spon/Routledge, New York.
MWH Americas, Inc. (2015a). Energy Fuels Resources (USA) Inc., White Mesa Mill, Tailings
Data Analysis Report, April.
MWH Americas, Inc. (2015b). Responses to Review Comments on Energy Fuels Resources
(USA) Inc., White Mesa Mill Tailings Data Analysis Report (January and March 2015), and
Probabilistic Seismic Hazard Analysis Report (March 2015). April 24, 2015.
MWH Americas, Inc. (2015c). Energy Fuels Resources (USA) Inc., White Mesa Mill, Tailings
Data Analysis Report, March.
MWH Americas, Inc. (2014). Energy Fuels Resources (USA) Inc., White Mesa Mill, Tailings
Data Analysis Report, October.
MWH Americas, Inc. (2013). Energy Fuels Resources (USA) Inc., White Mesa Mill Tailings
Characterization and Analysis Work Plan, July.
Utah Department of Environmental Quality, Division of Radiation Control, (2015a), Geotechnical
Review of Energy Fuels Resources (USA) Inc. White Mesa Mill, Tailings Data Analysis
Report dated March 2015, and Probabilistic Seismic Hazard Analysis Report dated March
2015,. RML# UT1900479, San Juan County, Utah. March 31, 2015.
Utah Department of Environmental Quality, Division of Radiation Control, (2015b), Geotechnical
Review of Energy Fuels Resources (USA) Inc. White Mesa Mill, Tailings Data Analysis
Page 18
Geotechnical Review of Tailing Data Analysis Report
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Report dated October 2014,Prepared by MWH Americas, Inc., RML# UT1900479, San Juan
County, Utah. January 22, 2015.
Utah Department of Environmental Quality, Division of Radiation Control, (2013), Review of
August 15, 2012 (and May 31, 2012) Energy Fuels Resources (USA) Inc. Response to Round
1 Interrogatories on Revision 5 Reclamation Plan Review, White Mesa Mill Site, Blanding,
Utah, report dated September 2011. February 13, 2013.

195 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144850 • Salt Lake City, UT 84114-4850
Telephone [phone] • Fax [phone] • T.D.D. [phone]
www.deq.utah.gov
Printed on 100% recycled paper
State of Utah

GARY R. HERBERT
Governor

SPENCER J. COX
Lieutenant Governor
Department of
Environmental Quality

Alan Matheson
Executive Director

DIVISION OF RADIATION CONTROL
Rusty Lundberg
Director

T E C H N I C A L M E M O R A N D U M on P S H A

Geotechnical Review of Energy Fuels Resources (USA) Inc., White
Mesa Mill Probabilistic Seismic Hazard Analysis Report dated April
2015, Prepared by MWH Americas, Inc., RML# UT1900479, San Juan
County, Utah. May 28, 2015
Introduction
This Technical Memorandum prepared by Division of Radiation Control (DRC) staff presents
updated final geotechnical review comments on the subject Probabilistic Seismic Hazard Analysis
report (PSHA) prepared by MWH Americas, Inc. (MWH) for Energy Fuels Resources (USA)
Inc., (EFRI). The subject report dated April 2015 (MWH 2015a) is a revision to the report
previously dated March 2015 (MWH 2015c).
This DRC Technical Memorandum is intended to document concluding resolution of AECOM’s
(formerly URS) comments identified in the AECOM Technical Memorandum dated March 31,
2015 on the PSHA that were a part of DRC’s March 31, 2015 review package DRC 2015a
(hereafter referred to as DRC 2015a-ATM). With regards to the updated PSHA report by MWH,
it is noted that AECOM has pointed out in the initial paragraph of their March 2015 review that
“The PSHA described in the report [MWH 2015a] represents the state-of-the-practice with two
exceptions.” The following sections of this Technical Memorandum consider the specific
AECOM review comments contained in the AECOM Technical Memorandum. The comments
have been reduced to specific questions and narrative how or why DRC staff considered the
review comments to be adequately addressed and therefore closed.
Major Findings
1. Section 4.2.1:
In DRC 2015a-ATM, AECOM stated that it was not clear why a truncated exponential model
was not used in calculating the recurrence for the Colorado Plateau and Intermountain Seismic
Belt (ISB) and requested that the authors explain why? AECOM also illustrated that there is
uncertainty in the recurrence parameters that could impact the hazard and that this uncertainty
was not accounted for by MWH in their PSHA. AECOM suggested that MWH may want to
evaluate its impact on their hazard results. In MWH 2015b, MWH responded that a truncated
exponential model was used (see 3rd sentence, 2nd paragraph of Section 4.2.1) in the hazard
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code and provided the plots for the Colorado Plateau and Intermountain Seismic Zone in
Figures 1 and 2.
In response to the reviewers suggestion, MWH investigated the variation of the minimum
magnitude (3.0 as compared to 3.5) used in the calculations. A test run was performed to
evaluate if increasing the minimum magnitude would impact the hazard. Using a minimum
magnitude of 3.5 to calculate the recurrence resulted in a decrease in the overall hazard from
0.19g to 0.17g. Therefore, this uncertainty in the recurrence parameters was evaluated and the
results are not significant enough to revise the hazard calculations. No changes have been
made to the report by MWH. On this basis the DRC considers this item adequately
addressed.
2. Section 4.2:
In DRC 2015a-ATM, AECOM commented that the background seismicity in the Colorado
Plateau and the ISB is assumed to be uniformly distributed in the MWH study. Most state-of-
the-practice PSHAs use Gaussian smoothing of the seismicity with or without uniform seismic
source zones such as the USGS in the National Seismic Hazard Maps. AECOM indicated this
probably does not have a significant impact on the hazard computed by MWH but they should
acknowledge this fact in their report. MWH responded by revising Section 6.2.1 of the PSHA
report to state that the analysis does not include Gaussian smoothing. On this basis the DRC
considers this item adequately addressed.
Minor/Editorial Findings
3. Section 1.1, 2nd paragraph, 1st sentence:
In DRC 2015a-ATM, AECOM commented that the subject sentence is awkward and needs to
be reworded. AECOM suggested it should read something to the effect: “The PSHA was
performed to estimate the probabilistic hazard at the site by characterizing potential seismic
sources and assessing the likelihood of earthquakes of various magnitudes occurring on those
sources and the likelihood of the earthquakes producing ground motions over a specified
level.” MWH responded by revising Section 1.1 of the PSHA report and which now reads:
“The PSHA was performed to estimate the seismic hazard at the project site within a
probabilistic framework by characterizing potential seismic sources.” On this basis the
DRC considers this item adequately addressed.
4. Section 2.1, last sentence:
In DRC 2015a-ATM, AECOM noted that the northern Naciimiento fault is located in
northwestern New Mexico, not northeastern New Mexico. MWH responded by correcting
Section 2.1 of the PSHA report. The DRC considers this item adequately addressed.
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5. Section 6.3, 1st paragraph:
In DRC 2015a-ATM, AECOM noted that the subject paragraph describes the PGA results but
references Figure 9 which are the Uniform Hazard Spectra (UHS). AECOM requested that
the paragraph be reworded to acknowledge that UHS were computed. In response MWH
reworded Section 6.3 of the PSHA report to acknowledge that the UHS was computed.
Figures 9 and 10 were switched such that Figure 9 shows the total hazard curve and Figure 10
shows the UHS. The DRC considers this item adequately addressed.
6. Section 7, last paragraph:
In DRC 2015a-ATM, AECOM pointed-out that the USGS National Seismic Hazard Map
methodology is no different than the methodology used in the MWH report or any other
PSHA. Hence the statement that the estimation of hazard at 10,000 years is “outside the
intended use of the data and likely explain the differences in the PGA” is incorrect. There are
probably legitimate reasons that the USGS PGA value is higher. One reason could be the
smoothing window used by the USGS is generally 50 km, which tends to spread the hazard to
greater distances. Hence for a particular site, the hazard will be higher due to contributions
coming from a larger range of distances than the MWH study where smoothing was not
performed. In response MWH revised Section 7 of the PSHA report. The DRC considers
this item adequately addressed.
7. Figure 11:
In DRC 2015a-ATM, AECOM comments that the subject figure indicates the controlling
earthquake at the site for a return period of 10,000 years. Is this the mean or modal magnitude
and distance? Since the PGA computed in the MWH study is to evaluate the liquefaction
potential of the reclaimed tailings cells, there should be a short discussion in the report on the
controlling earthquake. In response, MWH revised the last paragraph of Section 6.3 of the
PSHA report to include discussion about the controlling earthquake. On this basis the DRC
considers this item adequately addressed. In addition the DRC also notes that the
earthquake maximum magnitude required for liquefaction potential studies is Mw 6.75
as described in Section 4.2.1 and Section 6.2.1 of the PSHA.
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References:
Denison Mines (USA) Corporation. (2011). Reclamation Plan, Revision 5.0, White Mesa Mill,
Blanding, Utah. September 2011.
Energy Fuels Resources (USA) Inc., (2012). Radioactive Materials License, Response to Utah
Division of Radiation Control (“DRC”) Round 1 Interrogatory on Reclamation Plan Revision
5.0, Second Submittal. August 15, 2012.
MWH Americas, Inc. (2015a). Energy Fuels Resources (USA) Inc., White Mesa Mill,
Probabilistic Seismic Hazard Analysis, April.
MWH Americas, Inc. (2015b). Responses to Review Comments on Energy Fuels Resources
(USA) Inc., White Mesa Mill Tailings Data Analysis Report (January and March 2015), and
Probabilistic Seismic Hazard Analysis Report (March 2015). April 24, 2015.
MWH Americas, Inc. (2015c). Energy Fuels Resources (USA) Inc., White Mesa Mill,
Probabilistic Seismic Hazard Analysis, March.
Utah Department of Environmental Quality, Division of Radiation Control, (2015a), Geotechnical
Review of Energy Fuels Resources (USA) Inc. White Mesa Mill, Tailings Data Analysis
Report dated March 2015, and Probabilistic Seismic Hazard Analysis Report dated March
2015, RML# UT1900479, San Juan County, Utah. March 31, 2015.
Utah Department of Environmental Quality, Division of Radiation Control, (2015b), Geotechnical
Review of Energy Fuels Resources (USA) Inc. White Mesa Mill, Tailings Data Analysis
Report dated October 2014,Prepared by MWH Americas, Inc., RML# UT1900479, San Juan
County, Utah. January 22, 2015.
Utah Department of Environmental Quality, Division of Radiation Control, (2013), Review of
August 15, 2012 (and May 31, 2012) Energy Fuels Resources (USA) Inc. Response to Round
1 Interrogatories on Revision 5 Reclamation Plan Review, White Mesa Mill Site, Blanding,
Utah, report dated September 2011. February 13, 2013.