DRC-2021-009748 - 0901a06880eeb2af

DRC-2021-009748 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.utah.gov
Printed on 100% recycled paper
State of Utah
SPENCER J. COX Governor DEIDRE HENDERSON Lieutenant Governor
Department of Environmental Quality
Kimberly D. Shelley Executive Director
DIVISION OF WASTE MANAGEMENT AND RADIATION CONTROL Douglas J. Hansen Director July 21, 2021
Kathy Weinel, Quality Assurance Manager
Energy Fuels Resources (USA) Inc.
225 Union Blvd., Suite 600 Lakewood, CO 80228 RE: Energy Fuels Resources (USA) Inc. March 29, 2021. White Mesa Uranium Mill Low Flow Sampling Report
Utah Groundwater Discharge Permit No. UGW370004 Dear Ms. Weinel:
The Division of Waste Management and Radiation Control (DWMRC) has reviewed the Energy Fuels
Resources (USA) Inc. (EFRI) March 29, 2021, White Mesa Uranium Mill Low Flow Sampling Report (Report). The Report was received by DWMRC on March 30, 2021. Field measured dissolved oxygen (DO) was incorporated by the DWMRC into the White Mesa Mill Groundwater Discharge Permit Number UGW370004 (Permit), in a DWMRC March 19, 2019 Permit
modification. EFRI subsequently reported field readings of DO above expected oxygen levels at certain monitoring wells with the 3rd Quarter 2019 Groundwater Monitoring Report. In accordance with DWMRC review findings of the 3rd Quarter 2019 Groundwater Monitoring Report, additional actions to investigate the anomalous DO readings were discussed and agreed upon and included in the review
close-out letter.
EFRI submitted an amended July 20, 2020, Low Flow Sampling Plan (Plan), including updates in response to a May 27, 2020, DWMRC Request for Additional Information, regarding the previous May 8, 2020 version. The Plan includes citations of EPA guidance regarding low flow sampling, a list of wells for inclusion in the EFRI study, procedures for monitoring well purging and sampling and
Quality Control (QC) sampling and review procedures. The Plan includes 10 existing White Mesa Mill (Mill) groundwater monitoring wells for inclusion in the study (MW-01, MW-12, MW-14, MW-18, MW-19, MW-23, MW-27, MW-31, MW-39, and MW-40).
These wells were discussed and agreed upon for inclusion by DWMRC and EFRI.
(Over)

The low flow well purging procedures outlined in the Plan are based on guidance from the U.S. Environmental Protection Agency (EPA), including maximum drawdown criteria, with notes that the
pump locations in the well screens were left at current locations to minimize disturbance and potential
future complications with groundwater sampling. QC samples and review included in the Plan are based on the currently approved Groundwater Quality Assurance Plan for the Mill. DWMRC noted some inconsistencies regarding the Report discussion of figures and tables and the content of the referred appendix, for example the Report Part 3.1 indicates that table 3.1.1 shows the
date and time for each sample collected, however, table 3.1.1 does not show the sample time. Also, it was noted that the Hydro Geo Chem, Inc. groundwater sampling forms for the static and low flow sampling that the column for reporting dissolved oxygen lists the units as mg/L DO. Per DWMRC review the numbers reported in the column are more likely for DO % Saturation. The review
inconsistencies are only noted as a general comment and did not affect the Report review
Some of the monitoring well purging and/or field readings did not meet Plan criteria including: 1. Per the Report, field parameters for MW-39 did not meet field parameter stabilization criteria to prevent the well from going dry prior to collecting a sample for standard purge. Specifically,
turbidity and DO did not reach stabilization. 2. Per the Report, temperature in MW-19 was not measured for 3 stabilized readings prior to sampling due to an oversight. 3. Per the Report, turbidity did not stabilize for MW-01, MW-18, MW-27, MW-39 (as discussed
above) and MW-40. As noted in the Report, the most current low flow guidance does not
support turbidity as an appropriate low-flow parameter to show stabilization. These inconsistencies do not affect the DWMRC Report conclusions since the EFRI data comparisons by low flow and standard purge show similar results. This indicates that data quality is likely not affected by introduction of oxygen into the sample during field sampling.
The Report Part 5.6 discusses that introduction of DO into samples during well purging is likely caused by monitoring well construction and low permeability of the perched aquifer. EFRI finds that DO is higher in select samples whether using low flow sampling methods or standard purging methods (half in
the low flow sampled wells and half in the standard purge) and that the different purging methods are
impacted by the low permeability of the formation (Dakota/Burro Canyon), open screen intervals above the zone of saturation, varying depths of saturation, and potentially to well stratification and deeper water sampled by the low flow purge (MW-40). In addition to these factors, the Report states “wells in close proximity to formerly used unlined wildlife
ponds (such as MW-19 and MW-40) are expected to receive water having high background DO
concentrations.” DWMRC review of impacts of the upper and lower wildlife ponds and dissipation/distribution of seepage from the ponds is ongoing and currently the scope of impacts from the wildlife ponds is not specifically delineated. However, such impacts to DO and other monitoring
constituents is likely due to the infiltration of oxygenated surface water into the perched aquifer.
Section 5.6 also includes a discussion of comparisons of DO in the sample vs. iron and trace metal concentrations and finds that there is no difference or relationship of the concentrations of metals in the results with higher DO samples. The Report hypothesizes that this is due to general aerobic groundwater conditions in the perched aquifer using evidence that the nitrate and chloroform plumes are

showing little natural degradation. Degradation of nitrate and chloroform would be expected in anaerobic conditions.

Report Conclusions and DWMRC Ongoing Review of Site Data: Per EFRI conclusions/findings of the Report, there is an “apparent” lack of impact of DO on analytical results and EFRI concludes that there is no compelling reason to change to a low flow sampling method based on high DO present at the time of sampling. EFRI proposes to continue standard purge and notes:
1. A change to low flow groundwater sampling “would require the undesirable re-establishment of background conditions for each well.” 2. “Could result in at least temporary trends in analyte concentrations that are unrelated to any
potential site impacts.”
3. “May not yield samples representative of the entire water column in low permeability wells
(such as MW-01, MW-03A, MW-05, MW-19, MW-20, MW-22, MW-23, MW-28, MW-37and MW-39.” 4. “Low permeability wells that also have small saturated thicknesses (such as MW-3A) would likely not be compatible with low flow methods.”
5. “The differences between currently employed standard methods for some wells and the
purging dry of very low permeability small saturated thickness wells is much smaller than the difference between employing low flow for some wells and purging dry very low permeability small saturated thickness wells. Adopting low flow methods for some MW series wells would
result in three different sampling methodologies at the Mill.”
Per the above discussion, DWMRC has reviewed the Report to ensure that the field sampling and analysis was done according to the Plan and has reviewed the sample laboratory result comparisons. Per the Report comparisons, there was not a large difference in the low flow vs. 2 casing volume and purge dry sample results for GWCL’s, even in samples that showed a relatively large difference in DO
saturation. According to review findings, it is acceptable/appropriate for EFR to continue current protocols for well purge and sampling as are included in the Mill QAP. Review of DO and monitoring parameters by DWMRC is ongoing and future findings may necessitate additional EFRI actions to evaluate the impacts of DO on sample results.

If you have any questions, please call Tom Rushing at [phone]. Sincerely,
Phil Goble, Uranium Mills and Radioactive Materials Manager Division of Waste Management and Radiation Control
PRG/TR/as
c: Mike Moulton, Interim Health Officer, San Juan County Public Health Department Ronnie Nieves, Environmental Health Director, San Juan County Public Health Department Russell Seeley, UDEQ District Engineer