DRC-2016-012281 - 0901a068806992eb

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
TO:
THROUGH
FROM:
DATE:
SUBJECT:
I. Review Summary:
The following Energy Fuels Resources (EFR) document was reviewed:
1. Energy Fuels Resources (USA) Inc., November 17, 2016, Transmittal of Revised Statistical
Analysis for Cadmium and Thallium in MW-24, White Mesa Mill Groundwater Discharge Permit
UGW370004 (Report)
This document was submitted by EFR in response to a September 14, 2016 Division of Waste Management
and Radiation Control (DWMRC) Request for Information Letter (RFI). The RFI was regarding review of
an EFR June 24, 2016 Source Assessment Report (SAR) which included statistical analysis for cadmium
and thallium in monitoring well MW-24. In the SAR, EFR proposed to set revised GWCL’s for these
parameters by a modified approach (highest historical value), which was considered appropriate by EFR
since the cadmium and thallium data sets showed upward trends and were not normally or log-normally
distributed.
The RFI specifically requested, uPer DWMRC review of the cadmium and thallium data sets it was noted
that a large number of non-detects are included in the early time data, and that after 2009, the
concentrations begin increasing. EFR attributes these increases as associated with declining pH due to
pyrite oxidation in groundwater. For comparison it would be helpful for EFR to provide a separate
analysis of the data sets as was provided in the December 9, 2015 SAR (Monitoring Well MW-31) using a
divided data set based on an identified point of inflection in the data. Specifically, a data inflection is
noted at approximately 2009for cadmium and thallium in monitoring well MW-24. This comparison test is
useful in that it may provide a normalized data set and a comparable and representative determination of
mean + 2«.”
MEMORANDUM
File
Phil Goble, Manager
Tom Rushing
December 15, 2016
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DEC-2014 -0I2Z81
Review of the November 17, 2016 Energy Fuels Resources (USA) Inc. Transmittal of
Revised Statistical Analysis for Cadmium and Thallium in MW-24
Ground Water Pennit No. UGW370004
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 cJcq Utah gov
Printed on 100% recycled paper
EFR November 17, 2016 Revised Statistics Report for MW-24
DWMRC Review Memo
Page 2
EFR Statistics -Adjusted Data Set based on a Point of Inflection
Attachment 2 of the Report provides a table of descriptive statistics for the original cadmium and thallium
data sets, and the adjusted post inflection data sets. It was noted that the post inflection data sets included
data from August 2009 through September 2016 and culled all data earlier than August 2009. This is
consistent with the DWMRC findings during review of the SAR and resulting RFI. It was noted that the
modified data sets included 29 data points for both cadmium and thallium and that essentially all of the
culled data point were non-detects. Both modified data sets were normally distributed and still show
increasing trends, although increasing trends are much less significant. Based on DWMRC review of the
modified data sets it appears that the modifications were appropriate and allow for calculation of a
representative modified GWCL for cadmium and thallium in monitoring well MW-24. DWMRC notes
that modifying a data set because of an identified point of inflection is discussed and condoned according
to the 2009 EPA Unified Statistical Guidance. Attachment 2 of the Report is below:
EFR Proposed Modified Approach - 95% Upper Tolerance Limit
EFR additionally calculated proposed GWCLs using the 95% Upper Tolerance Limit (UTL). This was
proposed as a potential solution for data which shows a significant increasing trend. Per DRC review of
the proposed GWCLs using the 95% UTL it was noted that the GWCL for cadmium is unreasonably high
(9.06 ug/L) in comparison with historical data, even when considering a significant increasing trend. This
issue was discussed during a conference call amongst DWMRC, EFR and Intera on November 9, 2016.
Per the conference call it appeared that the calculations used for the 95% UTL were not well understood,
and that it was not clear why such a high result was given for cadmium. Given this abnormally high
cadmium value and confusion regarding the statistical method, GWCL calculated by the proposed 95%
UTL were not considered appropriate by the DWMRC.
Cadmium
(ugiy
Thallium
digit)
Approach
2.5 1 * Original 6WO; fractions!
4.28 1.57 * DWMRC Approved GWCL; HHV
6.72 2.1 ' All Data Flowsheet* Revised GWCL; HHV
3.61 2.04 ■’All Data 95% UTL
6.43 2.01 * Recent data Flowsheet GWCL; Mean 4 20
9.06 2,55 'Recent Data 95% UTL
Conclusion
EFR November 17, 2016 Revised Statistics Report for MW-24
DWMRC Review Memo
Page 3
The table below summarizes the EFR proposed GWCL’s, calculated by various statistical methods and
which considers both the full historical data set and the adjusted data set (according to a point of
inflection). The table also includes a column summarizing the DRC findings regarding the original SAR
and revised Report, and recommends that the mean + 2a using the adjusted data set appears to be the most
appropriate.
1.
Well
Number
2.
Parameter
3.
Location
4.
Current
GWCL
ug/L
5.
Approved
2012
Modified
GWCL
ug/L
6.
Highest
Historic
Value
ug/L
7.
Calculated
Mean + 2a
Entire Data Set
(non normal or
log normal
distribution)
ug/L
8.
Calculated
Mean + 2a
Adjusted
Data Set
(normal
distribution)
ug/L
9.
Proposed
Modified
Approach
95% UTL
ug/L
10.
DRC Finding - Is
Proposed Revised GWCL
in Conformance with the
Statistical Flow Chart?
MW-24 Cadmium Down
Gradient
2.5 4.28 6.72 5.59 6.43 9.06 Per the flow chart 0-15
Percent Non Detects, and
normally distributed data,
GWCLs may be set by
Mean + 2a (or modified
approach if an upward
trend is apparent).
Proposed modified
approach (95% UTL) is
proposed, however, the
analysis has not been
vetted and calculation
results seem unreasonably
high. GWCL’s will be set
based on Mean + 2a of the
adjusted data set, column
8 (6.43 mg/L). This
concentration is slightly
lower, but within the
range of the highest
historic value.
MW-24 Thallium Down
Gradient
1 1.57 2.1 1.76 2.01 2.55 Per the flow chart 0-15
Percent Non Detects, and
normally distributed data,
GWCLs may be set by
Mean + 2a (or modified
approach if an upward
trend is apparent).
Proposed modified
approach (95% UTL) is
proposed, however, the
analysis has not been
vetted and calculation
results seem unreasonably
high. GWCL’s will be set
based on Mean + 2a
column 8 (2.01 mg/L).
This concentration is
slightly lower, but within
the range of the highest
historic value.
Based on review of the revised statistical calculations, as summarized on the table above, DWMRC staff
recommends that the GWCL’s for cadmium and thallium in monitoring well MW-24 be modified as
follows:
EFR November 17, 2016 Revised Statistics Report for MW-24
DWMRC Review Memo
Page 4
Well Number Parameter Current GWCL Modified GWCL Method of Analysis
MW-24 Cadmium 2.5 ug/L .6.43 ug/L Mean + 2a
MW-24 Thallium 1 ug/L 2.01 ug/L Mean + 2a
II. References
1 Energy Fuels Resources (USA) Inc., June 24, 2016, Source Assessment Report for MW-18 and MW-24,
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.
3Energy Fuels Resources (USA) Inc., November 17, 2016, Transmittal of Revised Statistical Analysis for
Cadmium and Thallium in MW-24, White Mesa Mill Groundwater Discharge Permit UGW370004
4 United States Environmental Protection Agency (USEPA), 2009, Statistical Analysis of Groundwater
Monitoring Data at RCRA Facilities, Unified Guidance, EPA 530/R-09-007
5 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.
6 INTERA Incorporated, 2007, Background Groundwater Quality Report: New Wells for Denison Mines
(USA) Corp. ’s White Mesa Uranium Mill Site, San Juan County, Utah.
1 INTERA Incorporated, 2Q\2, pH Report White Mesa Uranium Mill
8 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 the University of Utah
Department of Geology and Geophysics.
9 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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