DRC-2016-011505 - 0901a06880687bde

Div cf Waste Management
and Radiation Controlr
ENERGYFUELS
Energy Fuels Resources (USA) Inc.
225 Union Blvd. Suite 600
Lakewood, CO, US, 80228
303 974 2140
www.energyfuels.com
November 17, 2016
Sent VIA E-MAIL AND OVERNIGHT DELIVERY
PRC-Z0U>-OllSoB
Mr. Scott Anderson
Director of Waste Management and Radiation Control
Utah Department of Environmental Quality
195 North 1950 West
P.O. Box 144880
Salt Lake City, UT 84114-4880
Re: Transmittal of Revised Statistical analysis for Cadmium and Thallium in MW-24, White Mesa
Mill Groundwater Discharge Permit UGW370004
Dear Mr. Anderson:
Pursuant to the Division of Waste Management and Radiation Control (“DWMRC”) letter dated September 14,
2016, Energy Fuels Resource (USA) Inc.’s (“EFRI”) is submitting this revised statistical analysis for cadmium
and thallium in MW-24. This revised analysis supplements the Source Assessment Report (“SAR”) for MW-
24, at the White Mesa Mill, dated June 24, 2016.
If you should have any questions regarding this report please contact me.
Yours very truly,
Energy Fuels Resources (USA) Inc.
Kathy Weinel
Quality Assurance Manager
CC: David C. Frydenlund
Harold R. Roberts
David E. Turk
Logan Shumway
INTERA Incorporaced
SOOO Uptown Boulevard NE, Suite 220
Albuquerque, New Mexico 371 1 Q USA
GEOSCIENCE S ENGINEERING SOLUTIONS 505.246.1 BOO
TECHNICAL MEMORANDUM
DATE: November 17, 2016
FROM: Angela Persico, INTERA, Incorporated
TO:Kathy Weinel, Energy Fuels Resources, Inc.
SUBJECT: Revised statistical analysis for cadmium and thallium in MW-24
1.0 INTRODUCTION
This Technical Memorandum supplements the June 24, 2016 Source Assessment Report (SAR)
for MW-24 (INTERA, 2016) and has been prepared at the request of the State of Utah Division of
Waste Management and Radiation Control (DWMRC). In a letter dated September 19, 2016 (“the
Letter”), DWMRC requests additional infonnation, specifically a separate analysis of the data sets
for cadmium and thallium in MW-24 after a point of inflection in 2009 when concentrations of
cadmium and thallium began increasing. DWMRC states that this comparison between the
complete data set and the post-inflection data set is useful in that it may provide a normalized data
set and a comparable and representative determination of mean + 2a.
The Letter also states that the June 24, 2016 SAR supports the premise that increasing
concentrations in MW-24 are not caused by tailings solution based on (1) a review of plots of
indicator parameter concentration trends, (2) the University of Utah Study (2008) which included
age dating of the water in tailings cell 1 and comparison with groundwater age dating of water in
monitoring well MW-2 (near MW-24) which found that “stable isotope fingerprints do not suggest
contamination of groundwater by tailings cell leakage, evidence that is corroborated by trace metal
concentrations similar to historically observed concentrations,” (3) potential geochemical
influences from pyrite oxidation in the perched groundwater causing site-wide decreases in pH
and dissolution of metals including cadmium and thallium, and (4) potential analytical influences
caused by a change of analytical laboratories during the fourth quarter of 2012.
This technical memorandum provides the additional analyses for cadmium and thallium in
MW-24, following the approach that was provided in the December 9, 2015 SAR
(INTERA, 2015). The analyses are discussed here and results are included in the attachments.
Energy Fuels Resources, Inc.
November 17, 2016
Page 2
2.0 CADMIUM AND THALLIUM IN MW-24
Samples from MW-24 were first collected in June of 2005. Groundwater samples from MW-24
are collected and analyzed quarterly for out-of-compliance constituents (sulfate, pH, fluoride,
cadmium, and thallium), which are the constituents included in the June 2016 SAR. All other
permit constituents are collected and analyzed semi-annually.
At the time of the background report, cadmium and thallium concentrations in MW-24 were mostly
non-detected, and Groundwater Compliance Limits (GWCLs) were therefore determined by the
fractional approach in accordance with the Groundwater Data Preparation and Statistical Process
Flow for Calculating Groundwater Protection Standards, White Mesa Mill Site (INTERA, 2007)
(the “Flowsheet”). Cadmium and thallium concentrations in MW-24 were regularly detected in
groundwater samples beginning in 2009, and started exceeding their respective fractional GWCLs
in 2010. Cadmium and thallium were included in the 2012 SAR (INTERA, 2012), and in the June
2016 SAR (INTERA, 2016). The conclusion of both SARs was that the increase in cadmium and
thallium can be attributed to the site-wide decrease in pH.
2.1 Changes in Groundwater Conditions in MW-24
The June 2016 SAR includes a discussion about potential changes, events, and conditions that may
be influencing the behavior of constituents in MW-24. Although many variables are considered
when evaluating the source of increased concentrations, decreasing pH is the only variable that fits
with the timing of the change in concentrations of cadmium and thallium.
SIIMTERA
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November 17, 2016
Page 3
8
7.5 'c
7 Z3
6.5 ~oi—6 TOT35.5 C
5 ro+-I<SI4.5
4 X
o
Figure 1: Cadmium, thallium, and pH concentrations in MW-24 overtime. The orange vertical line indicates the
shift in concentrations. Data included in this analysis were collected after the shift, from August 2009 to September
2016.
2.2 Post-Inflection Analysis
In the Letter, DWMRC states that a data inflection is noted at approximately 2009 for cadmium
and thallium in MW-24. For the additional analysis presented in this memo, only data collected
after second quarter of 2009 were included. The post-inflection data set was analyzed following
the Flowsheet. A summary table of the flowsheet analysis is included in Attachment 1, equivalent
to the DWMRC-requested revised Table B-l of the June 2016 SAR. Attachment 2 is a descriptive
statistics summary comparing the complete data set and the post-inflection data set. Attachment 3
lists the post-inflection data included in this analysis. Attachment 4 is box plots of the post­
inflection and complete data sets. Attachment 5 is histograms of the post inflection and complete
data sets.
The revised data sets do not contain any outliers (Attachment 4) and are normally or lognormally
distributed (Attachment 5). Linear regression analysis shows increasing trends for both cadmium
and thallium. The trend for cadmium is not significant and is far less pronounced after the 2009
shift in concentrations. The trend for thallium remains significant using the post-inflection data.
(Attachment 6).
SSIIMTERA
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November 17, 2016
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2.3 Modified Approach to Groundwater Compliance Limits
According to the DWMRC-approved Flowsheet, if an increasing trend is present, a modified
approach should be considered for determining GWCLs. The complete data sets for cadmium and
thallium in MW-24 are exhibiting significantly increasing trends that can be attributed to one or
more of the following: (1) natural background conditions; (2) pyrite oxidation in the aquifer, which
can decrease pH and increase mobility of metals and sulfate; (4) effects of recent events on
groundwater in MW-24 such as well redevelopment, increased sampling frequency, change in
water levels, and analytical method/laboratory change, as described in the June 2016 SAR. The
historic lack of trends in these constituents have become significant trends due to a shift in
concentrations that seem to correspond with the decreasing pH. The following modified
approaches have been considered for calculating GWCLs in wells that have been thoroughly
investigated and where the causes of increasing trends are not due to potential tailings system
seepage or other Mill-related impacts that are not already addressed.
1. Using 95% upper tolerance limit with 95% confidence and 95% coverage.
This approach follows the DWMRC-approved Flowsheet until an increasing trend is identified.
When a trend is identified, the data set can then be used to calculate the 95% upper tolerance limit
(UTL). This value gives a 95% confidence that the UTL will contain at least 95% of the distribution
of observations in background. The 95% UTL is typically a greater value than the mean+2o,
allowing for a longer and more successful compliance period.
2. Using recent data to calculate GWCLs
According to the Unified Guidance document, developed by the United States Environmental
Protection Agency (EPA), “If a discrete shift in concentration level is evident, a confidence limit
should be computed based on the most recent stable measurements.” (EPA, 2009 p. 7-16). The
Guidance also states “If a change is evident, it may be necessary to delete some of the earlier
background values from the updated background sample, so as to ensure that compliance testing
is based on current groundwater conditions and not on outdated measures of groundwater quality.”
(EPA, 2009 p. 5-15). This approach follows the DWMRC-approved Flowsheet by taking into
account increasing trends and processing the data consistently with previously determined
GWCLs. In this approach, the complete data set, which exhibits an increasing trend over the history
of the well record, is divided into subset(s) of data based on identification of a point of inflection
where the results appear more stable, even at higher concentrations. The data subset is then used
to calculate GWCLs in accordance with the existing Flowsheet.
T
GEOSCIENCE S ENGINEERING SOLUTIONS
Energy Fuels Resources, Inc.
November 17, 2016
Page 5
This approach allows for a more representative data set, but does not account for trends that may
be present in the data subset. In this example, cadmium and thallium GWCLs are calculated using
the mean +2c of the data subset since both data subsets are normally or lognormally distributed.
3. Using 95% UTL with recent data to calculate GWCLs
This approach combines the previous two approaches, and is the preferred approach, following the
DWMRC-approved Flowsheet until the increasing trend is identified. When a trend is identified,
the data set is divided up into subset(s) of data based on identification of a point of inflection where
the results appear more stable. The post-inflection data set can be used to perform the Flowsheet
analysis. If a trend remains in the data subset, a GWCL can be calculated using the greater of the
fractional approach, 95% UTL, mean + 2 a, or the highest historical value. If no trend is present
in the data subset, GWCLs can be calculated following the existing Flowsheet approach (mean +
2g or equivalent). This approach is the preferred approach because it fits into the existing
Flowsheet structure while utilizing methods suggested by the Unified Guidance including using a
more recent data subset, and calculating 95% UTL, allowing for a GWCL that is more
representative of current conditions in the well.
SIIMTERA
GEOSCIENCE & ENGINEERING SOLUTIONS
Energy Fuels Resources, Inc.
November 17, 2016
Page 6
3.0 CALCULATION OF GROUNDWATER COMPLIANCE LIMITS
Existing GWCLs for cadmium and thallium and GWCLs calculated using the above approaches
are summarized in Table 1. INTERA recommends using recent data which are representative of
current conditions in groundwater to calculate a 95% UTL to be used as a GWCL. The 95% UTL
is a higher value than other approaches, is supported by the Unified Guidance, and will allow for
compliance for constituents that are variable and increasing in concentration.
Table 1
GWCL Alternatives
Cadmium
(ug/L)
Thallium
(ug/L)
Approach
2.5 1 a Original GWCL; Fractional
4.28 1.57 b DWMRC Approved GWCL; HHV
6.72 2.1 c All Data Flowsheet- Revised GWCL; HHV
3.61 2.04 d All Data 95% UTL
6.43 2.01 8 Recent data Flowsheet GWCL; Mean + 2a
9.06 2.55 'Recent Data 95% UTL
Notes:
HHV = highest historical value
SD = standard deviation
a = 2011 Groundwater Discharge Permit
(GWDP)
b = DWMRC-Approved revised GWCLs
presented in SAR (INTERA, 2012)
c = GWCL calculated using complete historic
data set (June 2016 SAR)
d= Modified Approach 95% UTL using complete data set
(Alternative 1)
e = Modified Approach GWCL calculated using representative
data (8/2009-9/2016) as requested by DWMRC in the
September 19, 2016 letter (Alternative 2)
f= Modified Approach 95% UTL using representative data
(8/2009-9/2016), This is the preferred approach (Alternative 3)
SIIMTERA
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November 17, 2016
Page 7
4.0 REFERENCES
Division of Waste Management and Radiation Control (DWMRC), State of Utah. 2016. Letter
from Scott T. Anderson of DWMRC to Kathy Weinel of Energy Fuels Resources (USA)
Inc. Re: Energy Fuels Resources (USA) Inc. June 24, 2016, Transmittal of Source
Assessment Report for Monitoring Well MW-18 and MW-24, White Mesa Uranium Mill
Groundwater Discharge Permit No. UGW370004 (Permit). September 14.
Environmental Protection Agency (EPA), United States. 2009. Statistical Analysis of
Groundwater Monitoring Data at RCRA Facilities, Unified Guidance, EPA 530/R-09-
007.
INTERA Incorporated. 2007. Revised Background Groundwater Quality Report: Existing Wells
for Denison Mines (USA) Corp.’s White Mesa Mill Site, San Juan County, Utah.
Prepared for Denison Mines (USA) Corp. October
---------. 2012. Source Assessment Report White Mesa Uranium Mill. Blanding, Utah. Prepared
for Energy Fuels Resources (USA) Inc. October 10.
. 2015. Source Assessment Report for MW-31, White Mesa Uranium Mill, Blanding,
Utah. Prepared for Energy Fuels Resources (USA) Inc. December 9.
. 2016. Source Assessment Report for MW-18 And MW-24, White Mesa Uranium Mill,
Blanding, Utah. Prepared for Energy Fuels Resources (USA) Inc. June 24.
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 T. Grant Hurst and D. Kip
Solomon, Department of Geology and Geophysics, University of Utah. May 2008.
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Attachment 1: Summary of Flowsheet Analysis for Cadmium and Thallium in MW-24 Using Modified Data Set
Well Constituent N
% Non-
Detected
Values Mean
Standard
Deviation
Shapiro-Wilk Test for
Normality Normally or
Lognormally
distributed?
Linear Regression Analysis
Significant
Trend
Highest
Historical
Value (HHV)Mean + 2o
Current
GWCL
Flowsheet
GWCL
Flowsheet
GWCL Rationale
Modified Approach;
95% UTLwPR2P
MW-24 Cadmium (uq/L)29 0.00 2.98 1.72 0.95 0.17 Yes 0.07 0.17 No 6.720 6.430 4.280 6.430 Mean + 2o 9.06
MW-24 Thallium (uq/L)29 0.03 1.09 0.46 0.95 0.23 Yes 0.16 0.03 Yes 2.100 2.014 1.570 2.014 Mean + 2a 2.55
Notes:
o = sigma N = number of valid data points
%ND = percent of non-detected values p = probability
pg/L = micrograms per liter W = Shapiro Wilk test value
mg/L = milligrams per liter r2 = The measure of how well the trendline fits the data where represents a perfect fit.
Analysis performed on data collected August 2009 through September 2016
Distribution = Distribution as determined by the Shapiro-Wilk distribution test for constituents with % Detect > 50% and N>8
Mean = The arithmatic mean as determined for normally or log-normally distributed constituents with % Detect > 50%
Standard Deviation = The standard deviation as determined for normally or log-normally distributed constituents with % Detect > 85%
Highest Historical Value = The highest observed value for constituents with % Detect < 50%
Revised Statistical Analysis for MW-24
White Mesa Uranium Mill
Attachment 2: Descriptive Statistics for Modified Data Set and All Data
Data Set Post-
Inflection ALL Data Post-
Inflection ALL Data
Analyte Cadmium Cadmium Thallium Thallium
Units pg/L ng/L ng/L ng/L
% Non-Detects 0 31 0.034 36
N 29 46 29 46
Normal or
Lognormal?Yes No Yes No
Mean 2.98 2.02 1.09 0.871
Min. Cone.1.06 0.5 0.5 0.5
Max. Cone.6.72 6.72 2.1 2.1
Std. Dev.1.72 1.79 0.46 0.447
Range 5.66 6.22 1.6 1.6
Geometric Mean 2.55 1.41 1.00 0.781
Skewness 0.87 1.30 0.68 1.27
Q25 1.50 0.51 0.70 0.5
Median 2.61 1.41 0.96 0.69
Q75 3.97 2.74 0.37 1.09
Post Inflection = Data collected August 2009 through September 2016
Revised Statistical Analysis for MW-24
White Mesa Uranium Mill IIMTERA
Attachment 3: MW-24 Data Used for Analysis
Field Sample ID Location ID Date Sampled Parameter Name Report
Result
Report Units Lab Qualifier Detected Sample
Matrix
Sample
Purpose
Sample
Type
MW 24_08242009 MW-24 8/24/2009 Cadmium 1.48 ug/L Y WATER REG GW
MW 24_10282009 MW-24 10/28/2009 Cadmium 1.06 ug/L Y WATER REG GW
MW 24_01192010 MW-24 1/19/2010 Cadmium 2.63 ug/L Y WATER REG GW
MW 24_05062010 MW-24 5/6/2010 Cadmium 4.28 ug/L Y WATER REG GW
MW 24_09212010 MW-24 9/21/2010 Cadmium 5.06 ug/L Y WATER REG GW
MW 24_11172010 MW-24 11/17/2010 Cadmium 3.22 ug/L Y WATER REG GW
MW-24_02102011 MW-24 2/10/2011 Cadmium 2.78 ug/L Y WATER REG GW
MW-24_04052011 MW-24 4/5/2011 Cadmium 2.61 ug/L Y WATER REG GW
MW-24_08042011 MW-24 8/4/2011 Cadmium 1.46 ug/L Y WATER REG GW
MW-24_10112011 MW-24 10/11/2011 Cadmium 1.78 ug/L Y WATER REG GW
MW-24_02232012 MW-24 2/23/2012 Cadmium 2.25 ug/L Y Water REG GW
MW-24_05102012 MW-24 5/10/2012 Cadmium 2.01 ug/L Y WATER REG GW
MW-24_07182012 MW-24 7/18/2012 Cadmium 4.7 ug/L Y WATER REG GW
MW-24_11292012 MW-24 11/29/2012 Cadmium 1.35 ug/L Y WATER REG GW
MW-24_03142013 MW-24 3/14/2013 Cadmium 2 ug/L Y WATER REG GW
MW-24_05222013 MW-24 5/22/2013 Cadmium 1.32 ug/L Y WATER REG GW
MW-24_07192013 MW-24 7/19/2013 Cadmium 6.72 ug/L Y WATER REG GW
MW-24_12122013 MW-24 12/12/2013 Cadmium 1.15 ug/L Y WATER REG GW
MW-24_03062014 MW-24 3/6/2014 Cadmium 5.92 ug/L Y WATER REG GW
MW-24_05302014 MW-24 5/30/2014 Cadmium 2.91 ug/L Y WATER REG GW
MW-24_09172014 MW-24 9/17/2014 Cadmium 1.5 ug/L Y WATER REG GW
MW-24_11192014 MW-24 11/19/2014 Cadmium 1.17 ug/L Y WATER REG GW
MW-24_02122015 MW-24 2/12/2015 Cadmium 3.31 ug/L Y WATER REG GW
MW-24_06242015 MW-24 6/24/2015 Cadmium 1.79 ug/L Y WATER REG GW
MW-24_07292015 MW-24 7/29/2015 Cadmium 1.88 ug/L Y WATER REG GW
MW-24_11182015 MW-24 11/18/2015 Cadmium 3.75 ug/L Y WATER REG GW
MW-24_02172016 MW-24 2/17/2016 Cadmium 6.31 ug/L Y WATER REG GW
MW-24_04282016 MW-24 4/28/2016 Cadmium 6.07 ug/L Y WATER REG GW
MW-24_09222016 MW-24 9/22/2016 Cadmium 3.97 ug/L Y WATER REG GW
MW 24_08242009 MW-24 8/24/2009 Thallium 0.62 ug/L Y WATER REG GW
MW 24_10282009 MW-24 10/28/2009 Thallium 0.55 ug/L Y WATER REG GW
MW 24_01192010 MW-24 1/19/2010 Thallium 0.84 ug/L Y WATER REG GW
MW 24_05062010 MW-24 5/6/2010 Thallium 1.3 ug/L Y WATER REG GW
MW 24_09212010 MW-24 9/21/2010 Thallium 1.57 ug/L Y WATER REG GW
Revised Statistical Analysis for MW-24
White Mesa Uranium Mill
Attachment 3: MW-24 Data Used for Analysis
Field Sample ID Location ID Date Sampled Parameter Name Report
Result
Report Units Lab Qualifier Detected Sample
Matrix
Sample
Purpose
Sample
Type
MW 24_11172010 MW-24 11/17/2010 Thallium 1.09 ug/L Y WATER REG GW
MW-24_02102011 MW-24 2/10/2011 Thallium 1.42 ug/L Y WATER REG GW
MW-24_04052011 MW-24 4/5/2011 Thallium 1.07 ug/L Y WATER REG GW
MW-24_08042011 MW-24 8/4/2011 Thallium 0.5 ug/L U N WATER REG GW
MW-24_10112011 MW-24 10/11/2011 Thallium 0.62 ug/L Y WATER REG GW
MW-24_02232012 MW-24 2/23/2012 Thallium 0.96 ug/L Y Water REG GW
MW-24_05102012 MW-24 5/10/2012 Thallium 0.74 ug/L Y WATER REG GW
MW-24_07182012 MW-24 7/18/2012 Thallium 1.36 ug/L Y WATER REG GW
MW-24_11292012 MW-24 11/29/2012 Thallium 0.666 ug/L Y WATER REG GW
MW-24_03142013 MW-24 3/14/2013 Thallium 0.88 ug/L Y WATER REG GW
MW-24_05222013 MW-24 5/22/2013 Thallium 0.618 ug/L Y WATER REG GW
MW-24 07192013 MW-24 7/19/2013 Thallium 1.64 ug/L Y WATER REG GW
MW-24_12122013 MW-24 12/12/2013 Thallium 0.707 ug/L Y WATER REG GW
MW-24_03062014 MW-24 3/6/2014 Thallium 1.85 ug/L Y WATER REG GW
MW-24_05302014 MW-24 5/30/2014 Thallium 1.23 ug/L Y WATER REG GW
MW-24_09172014 MW-24 9/17/2014 Thallium 0.6 ug/L Y WATER REG GW
MW-24_11192014 MW-24 11/19/2014 Thallium 0.821 ug/L Y WATER REG GW
MW-24_02122015 MW-24 2/12/2015 Thallium 1.27 ug/L Y WATER REG GW
MW-24_06242015 MW-24 6/24/2015 Thallium 0.796 ug/L Y WATER REG GW
MW-24_07292015 MW-24 7/29/2015 Thallium 0.85 ug/L Y WATER REG GW
MW-24_11182015 MW-24 11/18/2015 Thallium 1.37 ug/L Y WATER REG GW
MW-24_02172016 MW-24 2/17/2016 Thallium 2.04 ug/L Y WATER REG GW
MW-24_04282016 MW-24 4/28/2016 Thallium 2.1 ug/L Y WATER REG GW
MW-24_09222016 MW-24 9/22/2016 Thallium 1.57 ug/L Y WATER REG GW
Revised Statistical Analysis for MW-24
White Mesa Uranium Mill 5IIMTERA
Attachment 4: Box Plots
Post-inflection
Cadmium in MW-24
Percent nondetect: 0%
Min: 1.06, Mean: 2.98, Max: 6.72, Std Dev: 1.72
Upper extreme threshold (Q75 + 3xH): 11.38
Lower extreme threshold (Q25 - 3xH): -5.91
All data
Cadmium in MW-24
O)
E3
(0O
6 -
5 -
4 -
3 -
2 -
1 -
oo
Percent nondetect: 30%
Min: 0.5, Mean: 2.02, Max: 6.72, Std Dev: 1.79
Upper extreme threshold (Q75 + 3xH): 9.4325
Lower extreme threshold (Q25 - 3xH): -6.1775
o Outlier
❖ Extreme
Revised Statistical Analysis for MW-24
White Mesa Uranium Mill
Th
a
l
l
i
u
m
(u
g
/
L
)

"
Th
a
l
l
i
u
m
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g
/
L
)
Attachment 4: Box Plots
Post-inflection
Thallium in MW-24
2.0 -
1.5 -
1.0 -
0.5 -
Percent nondetect: 3%
Min: 0.5, Mean: 1.09, Max: 2.1, Std Dev: 0.46
Upper extreme threshold (Q75 + 3xH): 3.359
Lower extreme threshold (Q25 - 3xH): -1.282
Thallium in MW-24
Upper extreme threshold (Q75 + 3xH): 2.84
Lower extreme threshold (Q25 - 3xH): -1.255
o Outlier
❖ Extreme
Revised Statistical Analysis for MW-24
White Mesa Uranium Mill IIMTERA
Attachment 5: Histograms
Post-Inflection Data
Cadmium (ug/l) in MW-24
SW-W = 0.9486, p = 0.1687
All Data
■sr
>.oc03
CTo
o
00
CO
CM
O
Cadmium (ug/L) in MW-24
SW-W = 0.9073, p = 0.0014
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
Log Result
ItMTERARevised Statistical Analysis for MW-24
White Mesa Uranium Mill
Attachment 5: Histograms
Post- Infection Data
Thallium (ug/L) in MW-24
SW-W = 0.9535, p = 0.2254
r^
CD
>»oc0)DCT0)
ID
^r
co
o
-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4
Log Result
All Data
Thallium (ug/L) in MW-24
SW-W = 0.8689, p = 1e-04
Log Result
Revised Statistical Analysis for MW-24
White Mesa Uranium Mill IIIMTERA
Attachment 6: Linear Regression Analysis
Post-Inflection Data
Cadmium in MW-24
r = 0.2613 p = 0.1709 r = 0.0683
2010 2012 2014 2016
Sample Date
All Data
Cadmium in MW-24
o>3
Eg
E■oCOO
2006 2008 2010 2012 2014 2016
Sample Date
Revised Statistical Analysis for MW-24
White Mesa Uranium Mill IIMTERA
Attachment 6: Linear Regression Analysis
Post -Inflection Data
Thallium in MW-24 r = 0.3938 p = 0.0346 r2 = 0.1551
2010 2012 2014 2016
Sample Date
All Data
Thallium in MW-24
Sample Date
IIMTERARevised Statistical Analysis for MW-24
White Mesa Uranium Mill