DRC-2023-070750 - 0901a06881260684

Department of
Environmental Quality
State of Utah
Alan Matheson
Executive Director
GARY R. HERBERT
Governor
DIVISION OF WASTE MANAGEMENT
AND RADIATION CONTROL
Scott T. Anderson
SPENCER J. COX
Lieutenant Governor
TO:
FROM:
DATE:
SUBJECT:
Director
MEMORANDUM
Phil Goble f/2 6 ¼-/4 ½,
Dean Henderson ,t:ll!' f-lf~z-y
August 18, 2023
Review of the March 30, 2022, Chloroform Corrective Action Comprehensive
Monitoring Evaluation (CACME) Report White Mesa Uranium Mill, near Blanding,
Utah. Energy Fuels Resources (USA) Inc. ("EFRI")
The March 30, 2022, Chloroform Corrective Action Comprehensive Monitoring Evaluation (CACME)
Report ("CA CME 2022") is a required report by Part III.H of the Groundwater Corrective Action Plan
("GCAP") found in Attachment 1 of the Stipulation and Consent Order ("SCO") Docket No. UGW20-
01.
REVIEW OF CACME 2022
. GCAP Part 111.H requires: "Two-Year Corrective Action Comprehensive Monitoring Evaluation
("CA CME'') Report-on or before March 312016, and every two-years thereafter, EFR shall submit a
comprehensive groundwater monitoring evaluation report for Director review and approval. "
An electronic copy of the Chloroform CA CME 2022 report was submitted to the Director of Division of
Waste Management and Radiation Control ("Director") on March 30, 2022. A hard copy of the
· CACME 2022 was received by the Director on April 4, 2022 (DRC-2022-005561) and therefore meets
the requirement in GCAP Part III.H.
GCAP Part 111.H.1 requires: "Summarize and interpret results of all past quarterly groundwater
monitoring performed after December 31, 2012 in accordance with Parts IIIA through E of the GCAP."
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.deq.11tnl1.gov
Printed on I 00% recycled paper
DRC-2023-070750
Page2
Summary and Interpretation Results Between the 4th Quarter 2012 and 4th Quarter 2021
Chloroform Groundwater Monitoring
Since December 31, 2012, 36 quarterly chloroform groundwater monitoring reports (1 st quarter 2013
through 4th quarter 2021) have been submitted by EFRI. These monitoring reports were reviewed and
appeared to follow requirements in Parts III.A through E of the GCAP and approved by the Director.
Approval by the Director was documented with close out letters for all 36 quarterly chloroform
groundwater monitoring reports.
The Table 1 below is the summarizes compliance wells, performance wells, and pumping wells as of the
4th quarter 2021.
Table 1
Compliance Wells Performance Pumping Wells
Wells
MW-32 TW4-28 TW4-7 MW-4 TW4-40
TW4-3 TW4-30 TW4-10 MW-26 TW4-41
TW4-5 TW4-31 TW4-16 TW4-1
TW4-6 TW4-32 TW4-24 TW4-2
TW4-8 TW4-33 TW4-26 TW4-4
TW4-9 TW4-34 TW4-29 TW4-11
TW4-12 TW4-35 TW4-19
TW4-13 TW4-36 TW4-21
TW4-14 TW4-38 TW4-22
TW4-18 TW4-42 TW4-25
TW4-23 TW4-43 TW4-37
TW4-27 TW4-39
GCAP Part LB Table IA needs to be modified to reflex the above changes.
During the 4th quarter 2012 and 4th quarter 2021 hydraulic gradients have been reduced between 33% to
10% and the average saturated thickness within the plume has decreased approximately 37%. Since
2012, although recharge has been reduced, water levels in many wells marginal to the chloroform plume
is increasing to stable, while water levels in all wells within the plume are decreasing.
There are 14 chloroform pumping wells. Since the 4th quarter 2012 the chloroform pumping system
have removed approximately 565 lbs. of chloroform from the plume. Chloroform pumping since 2015
has exceed the calculated 'background flow' though the plume (3.4 gpm) by between 0.9 and 2.5 gpm,
that indicates that the pumping system is adequate to control the plume. Approximately 85% of the
plume area, and 97% of the plume mass are under hydraulic capture as of the 4th quarter of 2021.
Chloroform mass removal rates and the chloroform plume residual estimates have trended downward.
This trend is a consequence of both reduced chloroform concentrations within the plume and reduced
saturated thickness due to pumping system and the termination of water delivered to the north and south
wildlife ponds in March 2012.
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Expansion of the chloroform plume boundaries between 1st quarter 2012 and 4th quarter 2015 were
relatively stable. Between the 4th quarter 2015 and 4th quarter 2017 the chloroform plume boundaries
expanded eastward and crossgradient in the vicinity of TW 4-9 that may be the result of reduced dilution
from northern wildlife ponds and in the southerly downgradient vicinity of TW4-26 which is the result
of more southerly gradients because of the decay of the southern wildlife pond. In October 2016 well
TW4-38 was drilled and installed to bound the chloroform plume east of TW4-9. Chloroform
concentrations collected in quarterly sampling events after TW4-38 was installed were <1.0 µg/1
demonstrating that this well bounds the chloroform plume east of TW 4-9.
The southern portion of the plume is bounded by TW4-42, and far to the south by MW-22 and MW-40
(all non-detect for chloroform). TW4-40 was installed once concentrations at TW4-26 exceeded 70 µg/L
for two consecutive quarters. Also, TW4-42 was installed once concentrations at TW4-40 exceeded 70
µg/L for two consecutive quarters. TW4-40 has been converted to a pumping well in May 2019.
At the southeast extremity of the plume, relatively stable to decreasing chloroform at TW4-33 (no longer
within the plume) and generally increasing to stable concentrations at downgradient well TW4-29
suggest that chloroform migration may have been arrested at TW4-33 by TW4-4 and TW4-41 pumping
and that increasing to stable chloroform at TW4-29 results from a remnant of the plume that migrated
downgradient from TW4-33 to TW4-29; then toward TW4-30 (which formerly bounded the plume to
the east). Once chloroform concentrations at TW4-30 exceeded 70 ug/L for two consecutive quarters,
new compliance well TW4-43 was installed approximately 200 feet east-southeast ofTW4-30.
Decreasing chloroform concentrations at downgradient well TW 4-6 since the first quarter of 2015 and
increasing to stable concentrations at TW4-26 since the first quarter of2016 suggest that chloroform
migration has been captured in the vicinity of TW 4-6 by pumping wells TW 4-4 and TW 4-41.
Chloroform trends at wells within and near the southern extremity of the plume are influenced by TW4-
4 and TW4-42 pumping. Continued migration of chloroform to the east in the vicinity of TW4-30 may
change because hydraulic gradient near TW4-30 is now more southerly than easterly, by the influence
on both TW 4-4 and TW 4-41 pumping and reduced wildlife pond recharge.
TW4-40 began pumping during the second quarter of 2019. TW4-40 is located within the downgradient
(southern) toe of the plume, south ofTW4-26. Pumping ofTW4-40 well help reduce or prevent
further downgradient plume migration. Chloroform detected in the vicinity ofTW4-26 and TW4-40
appears to be within the hydraulic capture zone of TW4-40.
It appears that the chloroform plume is under control, and it appears the GCAP is effective in protecting
public health and the environment. In addition, natural attenuation by dilution, hydrodynamic
dispersion, volatilization, and abiotic suggest that all chloroform will be below the GCAL within less
than 200 years. Therefore, continued implementation of the GCAP and the current pumping system is
recommended.
GCAP Part 111.H.2 requires: "Review the chloroform mass removal rates resulting from pumping to
evaluate the performance of the pumping Wells. In the event that the mass removal rates have dropped
substantially, such evaluation shall include a determination whether the removal rates have dropped as
a result of reduced concentrations within the plume, lost well productivities or a general reduction in
saturated thickness; "
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Since the 3rd quarter 2015 chloroform mass removal rates and the chloroform plume residual estimates
have trended downward. This trend is a consequence of both reduced chloroform concentrations within
the plume and reduced saturated thickness and decrease in hydraulic gradients due to pumping system
and the termination of water delivered to the north and south wildlife ponds in March 2012.
TW4-40 began pumping during the second quarter of 2019. TW4-40 is particularly valuable because it
is located within the downgradient (southern) toe of the plume, south of TW4-26, and is relatively
productive. Pumping of TW 4-40 is likely to more effectively reduce or prevent further downgradient
plume migration than can be expected by pumping at the more upgradient locations. Chloroform
detected in the vicinity of TW4-26 and TW4-40 appears to be within the hydraulic capture zone of
TW4-40.
Investigation to Determine the Valure of Replacing Abandoned Pumping Well TW 4-20
TW4-20 collapsed during July 2020 and was abandoned during October 2020. The collapse was caused
by failure of the pump timing device during the 2nd quarter of 2020. The timing device cycles the pump
on and off to prevent drying up of the well and damage to the pump. Failure of the timing device at
TW4-20 caused nearly continuous pumping that dried up the well and irreparably damaged both the
pump and the well casing. Below is a summary of the EFRI investigation to determine the value of
replacing abandoned pumping well TW4-20. All data and figures presented for the investigation were
verified by DWMRC staff and appear to be accurate and reprehensive.
Summary of EFRI Investigation
Analysis of analytical, groundwater level, and pumping rate data from adjacent pumping wells TW4-19,
TW4-37 and TW4-39 from the 3rd quarter of2020 through the 4th quarter of2021demonstrate that
TW4-20 abandonment had little or no impact on total pumping, mass removal rates, groundwater levels,
hydraulic gradients, or flow directions in the vicinity of TW4-20. ·
Pumping at TW4-20 was historically low due to low hydraulic conductivity at TW4-20 (5.9 x 10-s
centimeters per second [cm/s]) is less than half the hydraulic conductivity of TW4-37 (1.43 x 10-4 cm/s);
and less than one-quarter of the hydraulic conductivity at TW 4-19 (2.4 x 10-4 cm/s ). In addition,
although concentrations at TW4-20 were historically high, concentrations at TW4-37 were similar in
magnitude and extraction rates several times higher, such that mass removal rates at TW4-37 exceeded
those at TW4-20. Between the 2nd quarter of2015 (initiation ofTW4-37 pumping) and the 1st quarter
of 2020, a total of approximately 228 lbs of chloroform were removed from TW 4-3 7 compared to only
40 lbs from TW4-20.
In the CACME 2022 report figure 33B shows the sum of chloroform mass removal rates at TW4-19,
TW4-20 and TW4-37 from the 3rd quarter of2015 through the 1st quarter of 2020; and the sum of
chloroform mass removal rates at TW4-19 and TW4-37 from the 3rd quarter of2020 (after TW4-20
failure) through the 4th quarter of 2021. TW4-19 and TW4-37 are the pumping wells closest to TW4-20.
The plot excludes the anomalous data from the 2nd quarter of 2020, during which the timing device at
TW4-20 failed, and nearly continuous pumping dried up the well, damaging. both the pump and the well
casing. As indicated, the general trend in the sum of mass removal was downward through the 1st
quarter of2020; and appears to be upward since the 3rd quarter of 2020, subsequent to TW4-20 failure.
The change in trend is related to both the increase in pumping at TW4-19 once TW4-20 failed; and to
the leveling off of the concentration trenq at TW4-37 since the 3rd quarter of 2020 (Figure 10). An
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analysis of total pumping at TW4-19, TW4-20, TW4-37 and TW4-39, starting with the 4th quarter of
2016 (initiation of pumping at TW4-39), shows that, as a result of the increase in TW4-19 pumping
subsequent to TW4-20 failure, total pumping in this area actually increased.
In the CA CME 2022 report shown in Figures 30 and 34, the increase in pumping rates at TW 4-19 after
failure ofTW4-20 more than compensated for the loss of pumping at TW4-20. Average pumping at
TW4-19 between the 4th quarter of2016 (start of TW4-39 pumping) and the 1st quarter of2020 was
approximately 107,000 gallons/quarter; and between the 3rd quarter of2020 and 4th quarter of2021
approximately 144,000 gallons/quarter. The increase of more than 37,000 gallons per quarter was nearly
three times more than the approximately 13,000 gallons/quarter average of TW4-20 between the 4th
quarter of 2016 and 1st quarter of 2020.
Since the 3rd quarter of 2020, pumping rates at TW4-19 and TW4-37 have generally declined likely due
to generally reduced saturated thicknesses within the plume; and pumping at TW4-39 has remained
relatively stable. However, between the 1st quarter of 2020 and the 4th quarter of 2021, capture within
the vicinity ofTW4-20 has decreased only slightly. The lack of a significant change in capture near
TW4-20 is consistent with changes in water levels in TW4-19, TW4-37 and TW4-39. Between the 1st
quarter of 2020 and 4th quarter of 2021, the water level at TW 4-19 decreased by approximately 5 feet;
the water level at TW4-37 remained about the same; and the water level at TW4-37 increased by
approximately 7 feet (Figure 14A). The net change of only 2 feet resulted in almost no change in capture
within this area of the plume. In addition, the lack of significant change in capture implies that no
significant change in groundwater flow directions occurred within this area of the plume.
Because of the following factors that include: 1) the negligible impact ofTW4-20 abandonment on mass
removal rates and capture zone extent in this area of the plume; 2) the increase in pumping rates in this
area subsequent to TW4-20 abandonment; and 3) the likelihood that interference between pumping
wells would counteract any potential benefits that may accrue should TW4-20 be replaced; therefore, at
this time there is no technical justification at this time for replacing TW 4-20. In addition, due to
anticipated reductions in achievable pumping in nearby wells as a result of interference, replacing TW 4-
20 would likely achieve no significant benefit with regard to control of the chloroform plume.
Based on the EFRI investigation the DWMRC staff agrees that a replacement pumping well for TW4-20
is not necessary at this time.
DWMRC CONCLUSIONS
The DWMRC staff agrees with EFR that chloroform plume appears to be under control, and it appears
the GCAP is effective in protecting public health and the environment. Continued implementation of
the GCAP and the current pumping system should continue. Therefore, a letter will be drafted for the
Division Director Signature, notifying EFR of the review and closing out the 2022 Chloroform
Corrective Action Comprehensive Monitoring Evaluation (CACME) Report.
GCAP MODIFICAITIONS
GCAP Part LB Table IA needs to be modified to reflex the ab.ove changes in Table 1 above in this
memorandum.
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References
Utah Division of Waste Management and Radiation Control, Stipulation and Consent Order Docket No.
UGW20-01, Attachment 1, Groundwater Corrective Action Plan found in Attachment 1, September 14,
2015.