DRC-2020-009852 - 0901a06880c84290

NERGY FUELS
May 8, 2020
Sent VIA OVERNIGHT DELIVERY
Energy Fuels Resources (USA) Inc.
225 Union Blvd. Suite 600
Lakewood, CO, US, 80228
303 974 2140
DRC-2o2o- oa91352. www.energyfuels.com
Div of Waste Management and Radiation Control
MAY 1 3 2020 Mr. Ty L. Howard
Director
Division of Waste Management and Radiation Control
Utah Department of Environmental Quality
195 North 1950 West
Salt Lake City, UT 84116
Re: Transmittal of Energy Fuels Resources (USA) Inc. ("EFRI") Low Flow Sampling Plan for White
Mesa Uranium Mill, Groundwater Program, State of Utah Groundwater Discharge Permit No.
UGW370004
Dear Mr. Howard:
By letter dated January 13, 2020, DWMRC noted that several third quarter 2019 groundwater dissolved oxygen
("DO") field results were above 100% oxygen saturation and that the results were greater than the Division of
Waste Management and Radiation Control ("DWMRC") expected in area groundwater. DWMRC and EFRI
discussed the third quarter results by conference call on December 11, 2019. Initial evaluation by the EFRI
consultant discussed that oxygen was likely introduced into the samples due to the low permeability and small,
saturated thickness of the perched aquifer combined with agitation during purging and sampling. Per discussion
with DWMRC, it was agreed that additional evaluation would be conducted by EFRI to determine potential
effects of the sample oxygenation, and evaluation of alternate micro-purge/low-flow sample collection to
evaluate the impact of DO in the groundwater samples. EFRI agreed to submit a plan for low flow sampling,
including a planned date for a final report submission to DWMRC for review and approval, on or before April
9, 2020. The deadline for submission of the plan was extended to May 9, 2020 due to COVID-19 issues and
teleworking requirements.
Attached is the EFRI Low Flow Sampling Plan for review and approval.
If you should have any questions regarding this plan, please contact me at 303-389-4134.
Yours very truly,
ENERGY FUELS RESOURCES (USA) INC.
Kathy Weinel
Quality Assurance Manager
CC: David C. Frydenlund
Paul Goranson
Logan Shumway
Scott Bakken
Terry Slade
White Mesa Uranium Mill
Low Flow Sampling Plan
State of Utah
Groundwater Discharge Permit No. UGW370004
Prepared by:
(-- ENERGY FUELS
Energy Fuels Resources (USA) Inc.
225 Union Boulevard, Suite 600
Lakewood, CO 80228
May 8, 2020
Contents
1.0 INTRODUCTION 1
2.0 BACKGROUND 1
3.0 GEOLOGY/HYDROGEOLOGY 2
4.0 EPA GUIDANCE FOR LOW FLOW SAMPUNG 4
5.0 WELLS INCLUDED IN THIS PLAN 5
6.0 PROCEDURES 5
6.1 Volume-Based Purging Method 6
6.2 Low Flow (Minimal Purge) Sample Method 6
6.2.1 Low Flow Well Purging: 6
6.2.2 Low Flow Well Sampling 7
7.0 QUALITY CONTROL ("QC") SAMPLES 7
8.0 SCHEDULE 8
9.0 REPORTS 8
10.0 REFERENCES 9
1.0 INTRODUCTION
Part I.E.1.d.1, of the State of Utah Groundwater Discharge Permit ("GWDP") dated March 19,
2019, required the addition of Dissolved Oxygen ("DO") to the list of field parameters collected
during groundwater purging. As required by the March 19, 2019 GWDP, Energy Fuels
Resources (USA) Inc. ("EFRI") revised the Quality Assurance Plan ("QAP") to include the
collection of DO during purging. EFRI submitted Revision 7.6 of the QAP for the Division of
Waste Management and Radiation Control ("DWMRC") approval on August 22, 2019.
DWMRC approved Revision 7.6 of the QAP by letter dated September 10, 2019. DO
measurements commenced in the third quarter of 2019. No DO measurements were collected
during the second quarter 2019 groundwater sampling program because the second quarter
sampling program was completed prior to the receipt of the DWMRC's approval of Revision 7.6
of the QAP.
EFRI submitted the third quarter groundwater report on November 13, 2019. By letter dated
January 13, 2020, DWMRC stated that it appeared all applicable requirements of the GWDP
were met, and that the submitted groundwater monitoring data were reliable, and the review was
closed.
The DWMRC letter dated January 13, 2020, noted that several DO monitoring well results were
above 100% oxygen saturation and that the results were greater than DWMRC expected in area
groundwater. DWMRC and EFRI discussed the third quarter results by conference call on
December 11, 2019. Initial evaluation by the EFRI consultant (HydroGeoChem) discussed that
oxygen was likely introduced into the samples due to the low permeability and small, saturated
thickness of the perched aquifer combined with agitation during purging and sampling. Section
2.0 below summarizes the previously submitted EFRI concerns regarding DO measurements and
the limited usability of those data. Per discussion with DWMRC, it was agreed that additional
evaluation would be conducted by EFRI to determine potential effects of the sample
oxygenation, and evaluation of alternate micro-purge/low-flow sample collection to evaluate the
impact of DO in the groundwater samples. EFRI agreed to submit a plan for low flow sampling,
including a planned date for a final report submission to DWMRC for review and approval, on or
before April 9, 2020. The deadline for submission of the plan was extended to May 9, 2020 due
to COVED-19 issues and teleworking requirements.
This plan is being submitted to meet the requirement for a plan to assess low-flow sampling at
the White Mesa Mill (the "Mill").
2.0 BACKGROUND
As stated above, EFRI previously noted potential issues associated with the collection of DO
measurements in the perched aquifer at the Mill. Below is a summary of the potential issues
noted?
Accurate measurement of DO in groundwater collected from perched monitoring wells is
problematic at the Mill due to the low permeability of the formation hosting the perched
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groundwater and the consequent low productivity of wells installed to monitor the perched
groundwater.
First, the low rates of perched groundwater flow exacerbate the impact of wells on perched
groundwater oxygen concentrations near the wells. Water flowing through the wells is in contact
with oxygen introduced into the well casings for substantial periods, allowing for substantial
diffusion of oxygen into the groundwater within and near the wells. Transport of oxygen into
perched groundwater is additionally enhanced by barometrically-induced water level fluctuations
within the wells.
Second, most of the wells have screens extending into the vadose zone which allows diffusion of
oxygen into the vadose zone directly above the water table in these wells. This diffusion occurs
in all directions, including upgradient with respect to groundwater flow. This gas-phase
diffusion, which occurs approximately four orders of magnitude more rapidly than aqueous-
phase diffusion, creates a large reservoir of gas-phase oxygen in contact with groundwater near
the wells. Because oxygen from this reservoir is in contact with a relatively large area of
groundwater, diffusive transport to the groundwater is enhanced. In addition, air contains
approximately 30 times more oxygen on a mass per volume basis than groundwater saturated
with oxygen, which increases the mass of oxygen available to be transported to groundwater near
each well. Barometrically-induced water table fluctuations near the wells also enhances transport
of oxygen from this vadose reservoir to the wells.
Third, because of the extremely low productivity of many of the sampled wells, the purging
alone may have a substantial impact on DO. The substantial degree of water level fluctuation
resulting from purging enhances oxygen transport to the groundwater in the immediate vicinity
of the sampled wells. Consequently, wells with lower permeability that have larger fluctuations
as a result of the purging and sampling process will be impacted more than wells having smaller
fluctuations. Furthermore, some wells that purge dry due to low productivity are not sampled
until the following day, allowing more time for oxygen to be transported into the well water.
All these factors are important because they impact oxygen concentrations in groundwater near
the wells prior to sampling. Water at distance from the wells likely contains much lower oxygen
concentrations.
It is important to note that localized elevated DO measurements are noted in other wells in the
vicinity of the Mill. The Ute Mountain Ute ("UMU") wells WM_GWMW_E and
WM_GWMW_W both reported elevated DO results from samples collected in April 2011. The
results were 105.9% and 96.8% respectively (as reported in data tables provided by UMU Tribe
Representative in October 2015).
3.0 GEOLOGY/HYDROGEOLOGY
The following discussion is based primarily on TITAN (1994) and HydroGeoChem (2018).
The Mill has an average elevation of approximately 5,600 feet above mean sea level (ft. amsl)
and is underlain by unconsolidated alluvium and indurated sedimentary rocks. The indurated
rocks consist primarily of sandstone and shale and are relatively flat lying with dips generally
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less than 3°. The alluvial materials consist primarily of aeolian silts and fine-grained aeolian
sands with a thickness varying from a few feet to as much as 25 to 30 feet across the site. The
alluvium is underlain by the Dakota Sandstone and Burro Canyon Formation, and where present,
the Mancos Shale. The Dakota and Burro Canyon are sandstones having a total thickness ranging
from approximately 55 to 140 feet, and, because of their similarity, are typically not
distinguished in lithologic logs at the site. Beneath the Burro Canyon Formation lies the
Morrison Formation, consisting, in descending order, of the Brushy Basin Member, the
Westwater Canyon Member, the Recapture Member, and the Salt Wash Member. The Brushy
Basin and Recapture Members of the Morrison Formation, classified as shales, are very fine-
grained, have a very low permeability, and are considered aquicludes. The Brushy Basin
Member is primarily composed of bentonitic mudstones, siltstones, and claystones. The
Westwater Canyon and Salt Wash Members also have a low average vertical permeability due to
the presence of interbedded shales.
Beneath the Morrison Formation lies the Summerville Formation, an argillaceous sandstone with
interbedded shales, and the Entrada Sandstone. Beneath the Entrada lies the Navajo Sandstone.
The Navajo and Entrada Sandstones constitute the primary aquifer in the vicinity of the site. The
Entrada and Navajo Sandstones are separated from the Burro Canyon Formation by
approximately 1,000 to 1,100 feet of materials having a low average vertical permeability.
Groundwater within this system is under artesian pressure in the vicinity of the site, is of
generally good quality, and is used as a secondary source of water at the site. Although the water
quality and productivity of the Navajo/Entrada aquifer are generally good, the depth
(approximately 1,200 feet below land surface [ft. bls]) makes access difficult.
The shallowest groundwater beneath the site occurs within the Dakota Sandstone and Burro
Canyon Formation. This groundwater is referred to as the 'perched' groundwater and is used on
a limited basis to the north (upgradient) of the site because it is more easily accessible than the
Navajo/Entrada aquifer. Although perched groundwater extends into the overlying Dakota
Sandstone within areas having greater saturated thicknesses, perched groundwater at the site is
hosted primarily by the Burro Canyon Formation, which consists of a relatively hard to hard,
fine- to medium-grained sandstone containing siltstone, shale and conglomeratic materials.
Perched groundwater originates mainly from precipitation and local recharge sources such as
unlined reservoirs (Kirby, 2008) and is supported within the Burro Canyon Formation by the
underlying aquiclude (Brushy Basin Member of the Morrison Formation). Saturated thicknesses
at the site range from less than 1 foot along the downgradient edge of the tailings management
system to approximately 80 feet in upgradient wells located near formerly used unlined wildlife
ponds.
Perched water quality is generally poor due to high total dissolved solids ("TDS") in the range of
approximately 1,100 to 7,900 milligrams per liter ("mg/L"), and is used primarily for stock
watering and irrigation. The saturated thickness of the perched water zone generally increases to
the north of the site, increasing the yield of the perched zone to wells installed north of the site.
Perched water flow across the site is generally from northeast to southwest. This general flow
pattern has been consistent based on perched water level data collected beginning with the initial
site investigation described in Dames and Moore (1978). Perched water discharges in seeps and
springs located to the west, southwest, east, and southeast of the site.
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The perched zone has generally low permeability. Hydraulic conductivity ranges from
approximately 2 x 10-8 to 0.01 cm/s and has a geometric average (based on slug tests) of
approximately 3 x 10-5 cm/s. The generally low permeability of the perched zone limits well
yields. Although sustainable yields of as much as 4 gallons per minute ("gpm") have been
achieved in site wells penetrating higher transmissivity zones near unlined wildlife ponds, yields
are typically low (<0.5 gpm) due to the generally low permeability of the perched zone. Even site
wells that yielded as much as 4 gpm during the first few months of pumping eventually saw
yields drop to about 1 gpm or less. Total achievable pumping from the 17 wells used to
remediate chloroform and nitrate plumes at the site is less than 7 gpm. In addition, many of the
perched monitoring wells purge dry and take several hours to more than a day to recover
sufficiently for groundwater samples to be collected. During a well redevelopment effort during
2010 and 2011, many of the perched wells went dry during surging and bailing and required
several sessions on subsequent days to remove the proper volumes of water (HGC, 2011).
4.0 EPA GUIDANCE FOR LOW FLOW SAMPLING
EFRI consulted several EPA references regarding micro-purge low-flow sampling including
Low-Flow (Minimal Drawdown) Ground-Water Sampling (Puls and Barcelona, 1996), Ground-
Water Sampling Guidelines for Superfund and RCRA Project Managers (Yeskis and Zavala,
2002), and EQASOP-GW4, Region 1 Low-Stress (Low-Flow) SOP, Rev 4 (EPA 2017). All of
these reference documents contained limitations on the use of low-flow sampling based on well
screen lengths. Specifically regarding well screens, Puls and Barcelona, 1996 "suggested that
short (e.g., less than 1.6 m) screens be incorporated into the monitoring design where possible so
that comparable results from one device to another might be expected"; Yeskis and Zavala, 2002
states "This method is applicable primarily for short well-screen lengths (less than 5feet (1.6
meters)) to better characterize the vertical distribution of contaminants. This method should not
be used with well-screen lengths greater than 10 feet (3 meters); " EPA Region 1 states "This
procedure is designed for monitoring wells with an inside diameter (1.5 inches or greater) that
can accommodate a positive lift pump with a screen length or open interval 10 feet or less and
with a water level above the top of the screen or open interval."
In addition, the general goal of the 2017 EPA Guidance is to achieve minimal disturbance during
purging and sampling. The Guidance therefore calls for minimal drawdown, especially in wells
having screens extending above the static water level. Although not mandatory, EPA
recommends that drawdowns be limited to 0.3 feet. If this condition cannot be met, the EPA
recommends that at least stable drawdowns be achieved. In wells having fully submerged
screens, EPA recommends that water levels do not drop into the screened interval during
purging.
The well screens in the groundwater wells at the Mill are greater than 10 feet and many have
screened intervals that extend above the static water levels. These factors may adversely affect
the data collected for the following reasons:
1) Relatively short screens ensure the collection of low-flow samples that are generally
representative of the relatively small aquifer thicknesses intercepted. However, low-flow
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samples collected from long screens may be representative neither of the entire screened
intervals nor of the relatively large aquifer thicknesses intercepted. Conversely, standard
purging and sampling of wells with long screened intervals at the Mill generally ensures
that samples are representative of the entire thickness of aquifer intercepted.
2) Permeabilities of materials penetrated by many of the wells at the Mill are so low that
small or even stable drawdowns may not be achievable during micro-purging; and for
wells having fully submerged screens, preventing water levels from dropping into the
screened intervals may not be possible. The large drawdowns that will unavoidably occur
in many of the wells would essentially defeat the minimal disturbance goal of the
method.
3) Furthermore, the large storage capacity of a long screened interval may prevent
parameter stabilization during micro-purging even if purging of low-permeability wells
continues long enough that unacceptably large drawdowns have not occurred. Under
these conditions, it may not be possible to collect a sample that is both 'undisturbed' and
representative of 'fresh' formation water.
5.0 WELLS INCLUDED IN THIS PLAN
Far upgradient monitoring wells MW-01, MW-18, and MW-19 will be sampled during this
study. These three wells represent a wide range of both hydraulic conductivities and DO results.
Hydraulic testing indicates a three order of magnitude range in hydraulic conductivity:
approximately 7.7 x 10-7 cm/s for MW-1; 1.7 x 10-5 cm/s for MW-19; and 2.9 x 104 cm/s for
MW-18. The value for MW-19 is close to the site geometric average of approximately 3 x 10-5
cm/s. The fourth quarter DO results for MW-01, MW-18, and MW-19 were 12.0%, 1.0% and
103.5% respectively. These wells are sampled semi-annually and to date only one quarter of DO
data are available.
In addition, these wells display a relatively large range in saturated thicknesses. Fourth quarter,
2019 saturated thicknesses were approximately 47 feet at MW-01; 67 feet at MW-18; and 79 feet
at MW-19.
6.0 PROCEDURES
To complete this study, EFRI will collect groundwater samples from MW-01, MW-18 and MW-
19 using the routine volume-based, purging techniques in the DWMRC-approved QAP in
accordance with the schedule set forth in Section 8.0 below. The low-flow samples will be
collected the following quarter using the procedures outlined in Section 6.2 below, in accordance
with the schedule in Section 8.0 below.
All samples collected during this study will be submitted to the analytical laboratories currently
used for the monitoring programs at the Mill. Sample containers, shipping and analysis methods
will be consistent with current Mill practices.
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The analytical data from both sampling methodologies will be collected and assessed in a final
report as specified in Section 9.0.
6.1 Volume-Based Purging Method
The volume-based, routine purging and sampling procedures detailed in the DWMRC-approved
QAP will be used. No changes are required for this study.
6.2 Low Flow (Minimal Purge) Sample Method
The U.S. EPA recommends the use of adjustable-rate bladder and electric submersible pumps
during low-flow purging and sampling activities. The following procedures will be completed
using the existing, dedicated, low-flow, bladder pumps currently used at the Mill for routine
sampling. The dedicated pumps will not be moved and the placement within the screened
interval will not be adjusted during this study to minimize disturbances during the study and after
the completion of the study. Previous experience at the Mill indicates that moving or disturbing
well pumps adversely impacts the sample data collected after pump disturbances. Minimizing
disturbance is a primary goal of the low-flow method.
The following procedures will be used for low flow sampling:
6.2.1 Low Flow Well Purging:
1. Prepare sampling equipment including calibration of field meters prior to use.
2. Place water level probe in well and record static water level on the field sheet. Do not
remove the water level probe.
3. Begin purging the well at the minimum pumping rate of 100 milliliters per minute
(mL/min) and slowly increase the pumping rate to no more than 500 mL/min. Monitor
and record drawdown in well (if any).
4. Record data on field sampling sheet. If drawdown exceeds 0.3 feet from static, adjust
flow rate until drawdown stabilizes (if possible).
5. For wells screened below the static water level, if the drawdown does not stabilize at a
pumping rate of 100 mL/min, continue pumping until the drawdown reaches a depth of
two feet above the top of the well screen. Stop pumping and collect a groundwater
sample once the well has recovered sufficiently to collect the appropriate sample volume.
Document the details of purging, including the purge start time, rate, and drawdown on
the field sheet.
6. For wells screened across the static water level, if the drawdown does not stabilize at
100 mUmin, continue pumping. HoWeyer, do not draw down the water level more than
25 percent of the distance between the static water level and pump intake depth. If the
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recharge rate of the well is lower than the minimum pumping rate, then collect samples at
this point even though indicator field parameters have not stabilized. Begin sampling as
soon as the water level has recovered sufficiently to collect the required sample volumes.
Allow the pump to remain undisturbed in the well during this recovery period to
minimize the turbidity. Document the details of purging on the field sheet.
7. For wells with stable drawdown, start recording field parameters on the field sheet every
3 minutes. Purging should continue at a constant rate until the parameters stabilize.
Stabilization is considered achieved when three sequential measurements are within the
ranges listed below:
• pH ± 0.1 standard units
• Specific Conductance ± 3%
• Temperature ± 3%
• ORP ± 10 millivolts
• Turbidity ± 10% (for values greater than 5 NTUs)
• Dissolved Oxygen ± 10%
6.2.2 Low Flow Well Sampling
1. After specified parameters have stabilized, reduce flow rate on control box to
approximately 100 mL/min.
2. Fill necessary sample bottles. Label sample bottles with a unique sample number (e.g.
MW-01LF_01012020), time and date of sampling, the initials of the sampler, and the
requested analysis on the label. Additionally, provide information pertinent to the
preservation materials or chemicals used in the sample. Record comments pertinent to the
color and obvious odor. Record sampling information on field sheet.
3. Fill all sample containers. Immediately seal each sample and place the sample on ice in a
cooler to maintain sample temperature preservation requirements. Fill bottles in the
following order:
a) VOCs, 3 sample containers, 40 ml each;
b) Nutrients (ammonia, nitrate/nitrite as N), 1 sample container, 250 ml;
c) All other non-radiologics (anions, general inorganics, TDS, total cations and total
anions), 2 sample containers, 500 and 250 ml,;
d) Gross alpha, 1 sample container, 250 ml, filtered; and
e) Metals, 1 sample container, 250 ml, filtered.
7.0 QUALITY CONTROL ("QC") SAMPLES
QC samples collected during this study will be the same as those specified in the DWMRC-
approved QAP and will include VOC trip blank and duplicates. Rinsate blanks are not required
as all sampling equipment is dedicated and therefore rinsates are not required.
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One of the quarterly duplicate samples collected during the routine volume-based, purging and
the associated sampling will be from one of the wells included in this study. A duplicate will be
collected from the same well (if possible) during the low-flow sampling portion of the study.
8.0 SCHEDULE
Per Part I.E.1.c.2.i of the GWDP specifies a semi-annual sampling schedule for MW-01, MW-18
and MW-19. These wells are sampled semi-annually during the second and fourth quarters of
each year.
Based on the routine sampling schedule, this study will begin the even numbered quarter (either
second or fourth) after the receipt of the DWMRC approval of this study plan. The volume
based purging and sampling will be conducted during the even numbered quarter per the routine
schedule specified in the GWDP.
The following quarter (either first or third), the low-flow sampling will be conducted as specified
herein.
9.0 REPORTS
A final report detailing the sampling conducted, any issues encountered and summarizing the
data will be completed and submitted to DWMRC within 90 days after the end of the final
quarter of sampling.
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10.0 REFERENCES
Dames and Moore, 1978. White Mesa Uranium Project, San Juan County, Utah. For Energy
Fuels Nuclear, Inc. January 30, 1978.
HydroGeoChem (HGC), 2011. Redevelopment of Existing Perched Monitoring Wells. White
Mesa Uranium Mill Near Blanding, Utah. September 30, 2011.
HGC, 2018. Hydrogeology of the White Mesa Uranium Mill and Recommended Locations of
New Perched Wells to Monitor Proposed Cells 5A and 5B. July 11, 2018.
Kirby, 2008. Geologic and Hydrologic Characterization of the Dakota-Burro Canyon Aquifer
Near Blanding, San Juan County, Utah. Utah Geological Survey Special Study 123.
TITAN, 1994. Hydrogeological Evaluation of White Mesa Uranium Mill. Submitted to Energy
Fuels Nuclear.
United States Environmental Protection Agency, 2002, Ground-Water Sampling Guidelines for
Superfund and RCRA Project Managers, Ground Water Forum Issues Paper, Yeskis and Zavala.
United States Environmental Protection Agency, 1996, Ground Water Issue, Low-Flow
(Minimal Drawdown) Ground-Water Sampling Procedures, Puls and Barcelona.
United States Environmental Protection Agency, Region 1. 2017. EQA SOP-GW4 Region 1
Low-Stress (Low-Flow) SOP. Revised September 19, 2017.
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