DRC-2013-003137 - 0901a068803bb958

State of Utah
Department of
Environmental Quality
Amanda Smith
Executive Director
II DRC-2013-003137 II
GARY R. HERBERT
Governor
DIVISION OF RADIATION CONTROL
Rusty Lundberg
Director
GREG BELL
Lieutenant Governor
MEMORANDUM
TO: File
THROUGH: Phil Goble, Compliance Section Manager
FROM: Tom Rushing, P.G. ^ *)/l?//3
DATE: ^September 17,2013
SUBJECT: Review of the Energy Fuels Resources (USA) Inc., White Mesa Uranium Mill, Blanding,
Utah August 30,2013 Source Assessment Report for Selenium in Monitoring Well
MW-31, Ground Water Discharge Permit UGW370004
An August 30,2013 Source Assessment Report ('SAR") for Selenium in Monitoring Well MW-31was
submitted to the Director by Energy Fuels Resources (USA) Inc. ("EFR"), received on September 3,2013
for review and approval of a proposed revised Ground Water Compliance Limit (GWCL) for Selenium at
monitoring well MW-31.
The SAR is broken up into two primary sections, 1. An approach for analysis of potential sources of the
contamination, and 2. A discussion and tables of data used for statistical evaluation and generation of
proposed modified GWCL's. " , y
The SAR notes that Selenium is increasing at many monitoring wells across the site including MW-3,
MW-3A, MW-11, MW-12, MW-14, MW-15, MW-17, MW-18, MW-22, MW-27, MW-30, MW-31, and
MW-35. Per previous EFR studies it has been theorized and EFR ''''believes that increasing selenium
concentrations in MW-31 are due to background influences, including the natural decreasing trend in pH
across the site" Per the EFR Pyrite Report (Hydro Geo Chem., December 7,2012) the site wide declines
in pH are thought to be caused by regional dissolution of pyrite in the Burro Canyon Formation mineral
matrix.
Figure 1 below depicts the rising selenium concentration trend in monitoring well MW-31 using all
available historical data. DRC notes that the most recent five laboratory results for selenium in
monitoring well MW-3 lhave been above the GWCL (71 mg/L), with the highest historical value being
81.8 mg/L per the March 19, 2013 sample laboratory results. Figure 2 depicts the pH plot for all
historical data available for monitoring well MW-31.
Summary
EFR White Mesa August 30, 2013 MW-31 Selenium Source Assessment
DRC Review Memo
Page 2 of8
Figure 1 - Selenium Data Plot of Historical Data at MW-31 - Increasing Trend
90
80
70
60
50
1 40
30
20
10
MW-31 Selenium Trend
• Seriesl
Linear (Seriesl)
1 1 1 1
Jan-04 Oct-06 Jul-09 Apr-12 Dec-14
Date
Figure 2 - pH Data Plot of Historical Data at MW-31—Slight Decreasing Trend
10
=4
5
pH
• Seriesl
Linear (Seriesl)
Jan-04 Oct-06 Jul-09
Date
Apr-12 Dec-14
Investigations of Potential Sources of Selenium Contamination at Monitoring Well MW-31
1. Discussion of Tailings Solution Groundwater Indicator Parameters at Monitoring Well
MW-31
The SAR Section 3.1 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 MW-31 is screened within a 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 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. Based on these conditions, Fluoride and
Uranium are the best indicator parameters for cell leakage detection at monitoring well MW-31 as
follows:
EFR White Mesa August 30,2013 MW-31 Selenium Source Assessment
DRC Review Memo N
Page 3 of8
1. Fluoride is the fastest-moving available indicator of tailings seepage at monitoring well MW-31.
It is expected that fluoride would travel as fast as selenium (contaminant of concern) in the
groundwater at the site. Average concentrations of selenium in the Tailings Cell 1 solution is
approximately 10,000 pg/L while average concentrations of fluoride in Tailings Cell 1 solution
is approximately 457 mg/L. Therefore, as an indicator of tailings solution release EnergyFuels
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, recent fluoride concentrations
in monitoring well MW-31 have been as low as 0.73 mg/L and are showing a decreasing trend.
A plot including all available historical data available for fluoride at monitoring well MW-31 is
included in Figure 3 below.
Figure 3 - Fluoride Plot of Historical Data at MW-31 - Slight Decreasing Trend
1.4
1.2
_, 1
"S3
E 0.8 <u
TJ
*§ 0.6
= 0.4
0.2
MW-31 Fluoride
— • Seriesl
Linear (Seriesl)
0 -i 1 1 1 <
Jan-04 Oct-06 Jul-09 Apr-12 Dec-14
Uranium - Uranium concentrations in monitoring well MW-31 are low for the site, in the 6 to 9
uL range and are not exhibiting a significant upward trend. A plot including all available
historical data available for uranium at monitoring well MW-31 is included in Figure 4 below.
Figure 4 - Uranium Plot of Historical Data at MW-31
E
E
3 "E re
D
10
8
6
4
2
MW-33, yranium
i
• Seriesl
Linear (Seriesl)
Jan-04 Oct-06 Jul-09 Apr-12 Dec-14
Date
Energy Fuels Resources (USA) Inc. ("EFR") concludes that "based on the indicator parameters that are
available for MW-31, namely, fluoride and uranium, it can be concluded that the increases in
EFR White Mesa August 30,2013 MW-31 Selenium Source Assessment
DRC Review Memo
Page 4 of 8
concentrations of selenium are not due to potential tailings cell leakage." Per review of the report
findings and histoncal data plots of fluoride and uranium DRC staff concurs that the data does not appear
to indicate contamination from the tailings cells.
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 July 2007 (Final Report of Study Findings Dated May, 2008). 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 ofthe Mill in 1980.
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. Figure 5 below is taken from the
University of Utah ("U of U") Report (Hurst and Solomon 2008) and depict atmospheric concentrations
of tritium in the southwest by year.
' 7igure 5 - Concentrations of Atmospheric Tritium in the Southwestern United States
4.000 (
2,500
2 2.000
P
1,500
1.000
19SO
-•—Salt Lake G*y, Utah
-•— Abuqufirque. Hem Msidoo
•*— Ragstafl^ Arizona
•* • -Salt LatetSty (estimated)
* • •- Atmquecque' (esttmatod)
*- Ra^H (estimated)
——*&nd HoBow (estimated)
1953 1960 1965 1970 1975 1980 1985 1990 1995 2O0O
Based on review ofthe 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.
3. Source Assessment Conclusions
Based on findings related to indicator parameter analysis and age dating studies conducted by the U of U
(Hurst and Solomon 2008), and also supported by the slight decreasing pH trend at monitoring well MW-
31, DRC staff concur with the EFR finding that elevated selenium concentrations in the well are not due
to seepage discharge of tailings solution from the White Mesa Mill tailings cells to the groundwater. It
therefore appears appropriate to attribute the elevated selenium concentrations to background
groundwater sources and modify the current Permit GWCL for selenium in monitoring well MW-31.
EFR White Mesa August 30,2013 MW-31 Selenium Source Assessment
DRC Review Memo
Page 5 of8
EFR Proposed Modified GWCL Statistical Evaluation of Data:
The following statistical methods were used to develop the EFR proposed modified GWCL for Se in
monitoring well MW-31:
Standard Deviation Calculation
Shapiro-Wilk Test for Normality
Least Squares Regression Analysis
A DRC cross-check of the Shapiro-Wilk Test for normality and standard deviation was conducted (n =
34) and is attached as an appendix to this memo. The DRC calculation results were essentially the same
as the EFR conclusions. The EFR proposed modified GWCL is based on the mean value of historic data
plus two standard deviations and appears to be in conformance with the Director approved statistical flow
chart which outlines a decision making process when calculating background GWCL's (Intera 2007).
The table below summarizes the EFR calculations and background rationale for the proposed selemum
GWCL.
Table of EFR Proposed Revised GWCL for Selenium at Monitoring Well MW-31:
Well
Number
Parameter Location Current
GWCL
(mg/L)
EFR
Proposed
GWCL
Revision
(mg/L)
EFR
Background
Rationale
EFR
Method to
Determine
GWCL
DRC Finding -
Is Proposed
GWCL in
Conformance
with the
Statistical Flow
Chart?
MW-31 Selenium Downgradient
Cells 1 and 2
71 79 Indicator
Parameters Fl
andU
U of U Study
Decreasing
Trend
Mean +
2(SD)
Yes
Mean + 2(SD)
Conclusions:
Based on DRC staff review of the SAR it is recommended that a correspondence letter which summarizes
the DRC review of the proposed modified GWCL for selenium at monitoring well MW-31 be sent to
EFR. The letter will provide a recommendation that the proposed modified GWCL (Se 79 mg/L) be
included in the Permit renewal. Notification that the modification is subject to public notice and public
participation requirements of the permitting process, and will not be effective until formal issuance of the
updated Permit, will be included in the letter.
EFR White Mesa August 30, 2013 MW-31 Selenium Source Assessment
DRC Review Memo
Page 6 of8
14. References
1 Energy Fuels Resources (USA) Inc., August 30,2013, Transmittal of Source Assessment Report for
Selenium in MW-31 White Mesa Mill Groundwater Discharge Permit UGW370004 Conditional Approval
of May 30, 2013 Plan and Time Schedule
2 Energy Fuels Resources (USA) Inc., June 6,2012, White Mesa Uranium Mill Ground Water Monitoring
Quality Assurance Plan (QAP), Revision 7.3
3 Energy Fuels Resources (USA) Inc., October 12,2012, Source Assessment Report, Prepared by Intera
4 Energy Fuels Resources (USA) Inc., November 9,2012, pH Report, Prepared by Intera
5 Hurst, T.G., and Solomon, D.K. University of Utah, 2008, Summary of Work Completed, data Results,
Interpretations and Recommendations for the July 2007 Sampling Event at the Denison Mines, USA
White Mesa Uranium Mill Near Blanding, Utah, Prepared by Department of Geology and Geophysics
6 Hydro Geo Chem, December 7,2012, Pyrite Investigation Report
7 Intera, 2007, Groundwater Data Preparation and Statistical Process Flow for Calculating Groundwater
Protection Standards, White Mesa Mill Site, San Juan County, Utah
8 Utah Department of Environmental Quality, August 24, 2012, Utah Division of Radiation Control,
Ground Water Discharge Permit, Permit No. UGW370004, Energy Fuels Resources (USA) Inc.
\
Attachment - DRC cross check of Shapiro Wilk Test for Normality of Data and
Development of a proposed revised GWCL based on Mean + 2a for Selenium
evaluation of Monitoring Well MW-31
Shapiro Wilk (n<50) Method DRC Cross Check Data Entered 9/10/2013 TR
Energy Fuels Monitoring Well MW-31 Selenium Shapiro Wilk
x(i) x(n-1+1) x(n-i+1)^x0) a(n-i+1) bi
53.8 81.8 28 0.4127 11.5556
54.4 76.9 22.5 0.2854 6.4215
55.3 75.9 20.6 0.2439 5.02434
55.6 74.1 18.5 0.2132 3.9442
56.1 74.0 17.9 0.1882 3.36878
564 72.9 16.5 0.1667 2.75055
56.6 70.2 13.6 0.1475 2.006
58.2 70.1 11.9 0.1301 1.54819
58.4 68.8 10.4 0 114 1.1856
10 58.6 680 9.4 0.0988 0.92872
11 59.2 67.8 8.6 0.0844 0.72584
12 59.6 66.2 6.6 0.0706 0.46596
13 60.0 65.8 5.8 0.0572 0.33176
14 60.8 65.2 4.4 0.0441 0.19404
15 60.8 64.6 3.8 0.0314 0.11932
16 62.3 64.4 2.1 0.0187 0.03927
17 62.5 62.6 0.1 0.0062 0.00062
18 62.6 62.5 -0.1
19 64.4 62.3 -2.1
20 64.6 60.8 -3.8
21 65.2 60.8 -4.4
22 65.8 60.0 -5.8
23 66.2 59.6 -6.6
24 67.8 59.2 -8.6
25 68.0 58.6 -9.4
26 68.8 58.4 -10.4
27 70.1 58.2 -11.9
28 70.2 56.6 -13.6
29 72.9 56.4 -16.5
30 74.0 56.1 -17.9
31 74.1 55.6 -18.5
32 75.9 55.3 -20.6
33 76.9 54.4 -22.5
34 81.8 53.8 -28 total =
Standard Deviation Calculation:
40.61029
Mean = 64.05588235 Variables = 1742.663824
Standard Deviation = 7.159247051
W Statistic = 0.975042493 .01 Critical n(34) = 0.908
DRC Calculated Limit 78.4
I Energy Fuels Calculated Limit 79