DRC-2023-004839 - 0901a06881208df7

May 24, 2023
Sent VIA E-MAIL AND EXPRESS DELIVERY
Doug Hansen
Director
Division of Waste Management and Radiation Control
State of Utah Department of Environmental Quality 195 North 1950 West Salt Lake City, UT 84116
Energy Fuels Resources (USA) Inc.
225 Union Blvd. Suite 600
Lakewood, CO, US, 80228
303 974 2140 www.energyfuels.com
Div of Waste Ma'1ageme'1l
anJ Rad t1M Cor trol
MA'f 3 0 2�23
Re: Transmittal of Plan and Time Schedule under Utah Ground Water Discharge Permit
UGW370004 Part I.G.4 (c) White Mesa Mill (the "Mill")
Dear Mr. Hansen:
This letter transmits Energy Fuels Resources (USA) Inc.'s ("EFRI's") Plan and Time Schedule pursuant to
State of Utah Groundwater Discharge Permit UGW370004 (the "Permit") Part I.G.4(c) for MW-11 and MW-37
for the first quarter of 2023. Part I.G.2 of the Permit provides that out-of-compliance ("OOC") status exists when the concentration of a pollutant in two consecutive samples from a compliance monitoring point exceeds a groundwater compliance limit ("GWCL"). While consecutive exceedance have been noted in other wells at the site, a plan and time schedule have not been required or appropriate in light of other actions currently being
undertaken by EFRI or in light of other reports submitted by EFRI.
This Plan covers selenium in MW-11 and field pH in MW-37 that was identified as being in violation of Part I.G.2 of the Permit, in the First Quarter 2023 Exceedance Notice, dated April 25, 2023.
Please contact me if you have any questions or require any further information.
Yours very truly, ENERGY FUELS RESOURCES (USA) INC.
1( rttut Jv�
Kathy W einel
Director, Regulatory Compliance
cc: Jordan App Scott Bakken
David Frydenlund Garrin Palmer Logan Shumway Terry Slade Angie Persico (Intera) Stewart Smith (HGC)
DRC-2023-004839
1.INTRODUCTION
Energy Fuels Resources (USA) Inc. ("EFRI") operates the White Mesa Uranium Mill (the "Mill"), located near Blanding Utah, under State of Utah Ground Water Discharge Permit UGW370004 (the "Permit").
This is the plan and time schedule (the "Plan") required under Part I.G.4(c) of the Permit relating to violations of Part I.G.2 of the Permit for the MW-11 and MW-37 for the first quarter of 2023. Part I.G.2 of the Permit provides that out-of-compliance status exists when the concentration of a pollutant in two consecutive samples from a compliance monitoring point exceeds a groundwater compliance limit ("GWCL") in Table 2 of the Permit. Selenium concentrations in MW-11 and field pH in MW-37 exceeded their respective GWCLs during the first quarter of 2023 and are the subject of this Plan. While consecutive exceedances of other constituents may have been noted in MW-11 and/or MW-37, a P&TS and SAR have not been required or appropriate in light of other actions currently being undertaken by EFRI or in light of other reports submitted by EFRI, and as determined by Division of Waste Management and Radiation Control ("DWMRC") Staff. Specifically, consecutive exceedances, which occurred in previous reporting periods are discussed in previous SARs submitted to DWMRC. A description of the other actions and reports which have affected the requirement to submit a P&TS are as follows:
1.Nitrate + nitrite and chloride in monitoring wells at the site have been the subject ofongoing investigations at the Mill. Based on the results of the previous investigations,EFRI and the Director acknowledge that it has not been possible to date to determine thesource(s), cause(s), attribution, magnitudes of contribution, and proportion(s) of the localnitrate + nitrite and chloride in groundwater. However, as the commingled nitrate andchloride plumes (collectively the nitrate/chloride plume) extended upgradient of thetailings management system {"TMS"), it can be concluded that at least the northern portionof the plume had an upgradient source. EFRI submitted a Corrective Action Plan ("CAP")in February 2012 for nitrate+ nitrite and chloride in groundwater. The CAP was approvedon December 12, 2012 and the activities associated with the CAP are on-going. Based oninformation provided by DWMRC in teleconferences on April 27, and May 2, 2011, dueto the ongoing activities and actions, the 30-day plan and schedule for assessment is notrequired for nitrate + nitrite and chloride exceedances at this time.
2.A P&TS will not be prepared for monitoring wells with two successive exceedances, ifthose successive exceedances were reported in a previous quarter and /or were included ina previous SAR during the current permit period beginning March 8, 2021, because theconclusions and actions delineated in those reports were accepted by DWMRC.
3.A chloroform plume commingles with the central portion of the nitrate/chloride plume.Chloroform and associated daughter product methylene chloride are the subject of the
ongoing chloroform pumping program and are covered by State of Utah Notice ofViolation ("NOV") and Groundwater Corrective Action Order ("CAO") State of UtahDepartment of Environmental Quality ("UDEQ") Docket No. UGW-20-01. As a result,the 30-day plan and schedule for assessment of chloroform and its daughter productexceedances is not required.
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Groundwater at the Mill site has been evaluated in multiple recent investigations and reports, including the 2007 Revised Background Groundwater Quality Report and the 2008 New Wells Background Report, an isotopic investigation performed by Hurst and Solomon in 2008, the 2012 Pyrite Report, and multiple SARs. Based on a review of the Background Reports and other information and analyses the Director re­opened the Permit and modified the GWCLs to be equal to the mean concentration plus two standard deviations or the equivalent of background for each constituent on an intra well basis. The modified GWCLs became effective on January 20, 2010. A new GWDP was issued on January 19, 2018. The January 19, 2018 GWDP incorporated the revised GWCLs that resulted from previous SARs. Revised GWDPs were issued on March 19, 2019 and March 8, 2021. The revised GWDPs incorporated the revised GWCLs that resulted from previous SARs among other changes. Part I.G.4 c) of the GWDP states, with respect to exceedances of GWCLs, "that the Permittee shall prepare and submit within 30 calendar days to the Executive Secretary a P&TS for assessment of the sources, extent and potential dispersion of the contamination, and an evaluation of potential remedial action to restore and maintain groundwater quality to insure that Permit limits will not be exceeded at the compliance monitoring point and that DMT or BAT will be reestablished." Pursuant to this requirement, EFRI has previously submitted P&TSs and SARs to address previous dual exceedances (as required in light of other actions currently being undertaken by EFRI and as determined by DWMRC Staff and stated in teleconferences with EFRI on April 27 and May 2, 2011). This Plan covers selenium in MW-11 and field pH in MW-37, identified as being in violation of Part I.G.2 of the Permit, in the First Quarter 2023 Exceedance Notice, dated April 25, 2023. 2.CONSTITUENTS AND WELLS SUBJECT TO THIS PLANThe following constituents are covered by this Plan: Table 1 Constituent and Well Subject to this Plan
Constituent POCWell Current Results GWCL Q4 Ql 2022 2023 17.5, Selenium (ug/L) MW-11 12.5 15.5 17.7, 14.9 Field pH (pH Units) MW-37 6.61-8.5 6.60 6.55 It should be noted that the first quarter 2023 Exceedance Notice identifies a number of wells, with consecutive exceedances of other constituents. None of those constituents are included in this Plan, for the reasons stated in Section 1 above and in the First Quarter Exceedance Notice. 2
Chloride concentrations in MW-11 are associated with the Nitrate/Chloride plume, and are currently covered by the December 12, 2012 Stipulation and Consent Order.
3.CATEGORIES FOR ANALYSIS
Previously EFRI has categorized wells and constituents in several categories as follows:
1.Constituents Potentially Impacted by Decreasing pH Trends Across the Site2.Newly Installed Wells with Interim GWCLs3.Constituents in Wells with Previously Identified Rising Trends4.Pumping Wells5.Other Constituents
Selenium can fall within the first category when downward pH trends are noted, and pH in MW-11 does exhibit a decreasing trend. In the case of MW-11, selenium falls into the fifth category: Other Constituents. Assessment of this constituent in MW-11 will follow the process noted below with additional considerations to address the fact that MW-11 is within the boundaries of the chloride plume. Field pH in MW-37 falls within the fifth category: Other Constituents. Assessment of this constituent in MW-37 will also follow the process noted below.
3.1. Other Constituents
3.1.1 MW-11
The location of MW-11 is important when determining potential sources of selenium contamination. MW-11 is directly downgradient of the nitrate/chloride plume. Nitrate concentrations at MW-5 (adjacent to MW-11) and MW-11 have historically been low (non-detect to approximately 1 mg/L ). These low nitrate concentrations are consistent with the relative stability of the downgradient margin of the nitrate plume. However, since 2019, low but detectable nitrate at MW-11 (up to a maximum of approximately 3.5 mg/L), and post-2019 increases in chloride, are consistent with the ongoing (but slow) downgradient migration of the nitrate/chloride plume. The increasing chloride and relatively low nitrate concentrations at MW-11 suggest that a natural attenuation process that is affecting nitrate but not chloride is occurring up gradient of MW-11. A process that would degrade nitrate but leave chloride unaffected is reduction of nitrate by pyrite. Increases that are statistically significant are attributable primarily to: the oxidation of naturally­occurring pyrite that contains selenium as a contaminant; and mobilization of naturally occurring selenium by nitrate as the nitrate plume migrates towards MW-11. The process of pyrite oxidation in the perched zone is discussed in HGC, December 7 2012; Investigation of Pyrite in the Perched Zone, White Mesa Uranium Mill Site, Blanding, Utah. A more detailed discussion is presented in HGC, December 11, 2017; Nitrate Corrective Action Comprehensive Monitoring Evaluation ("CACME") Report, White Mesa Uranium Mill Near Blanding, Utah. The release of naturally­occurring contaminants such as selenium via pyrite oxidation is discussed in HGC, June 6, 2014; Hydrogeology of the White mesa Uranium Mill, Blanding, Utah.
With regard to chloride, it is important to consider that, although the absence of a rising trend in chloride concentration would indicate that there has been no impact from the TMS, a rising trend
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in chloride concentrations as well as in other indicator parameters could also be due to natural influences (see Section 12.0 of INTERA, 2007a).
Concentrations of indicator parameter fluoride display an overall stable to decreasing trend. Stable to decreasing fluoride indicates that MW-11 is un-impacted by the TMS. Recent increases in chloride, sulfate and uranium have occurred but similar increases have occurred in the past including in 1988-1989; 1995-1996; and 2000-2001 which were followed by decreases. In addition, although sulfate is trending upward, an increasing trend was present at the time of the 2008 Hurst and Solomon isotopic study, which concluded that no impacts to ground water from the TMS were occurring, thereby indicating that the source of the sulfate trend was not the TMS.
3.1.2 MW-37
The consecutive exceedances of field pH in MW-37 are likely due to background influences and a small and unrepresentative background data set used to calculate the GWCLs at the time of the Background Report. Given the recent analyses and investigations at the site, there is no indication that the exceedances of field pH in MW-37 are due to Mill-related impacts or to any potential tailings seepage.
Indicator parameter analysis demonstrates that there are no significant increasing trends in chloride, fluoride, sulfate or uranium concentrations.
4.PLAN
4.1. General
This Plan is a plan and time schedule for assessment of the sources, extent and potential dispersion of the contamination, and an evaluation of potential remedial action to restore and maintain groundwater quality to ensure that Permit limits will not be exceeded at the compliance monitoring point and that, to the extent applicable, discharge minimization technology and best available technology will be reestablished.
Given the recent site-wide analyses in the Background Reports, SARs, and Pyrite Report and other recent information relating to the Chloroform and Nitrate/Chloride investigations at the site, EFRI believes that exceedances in MW-11 and MW-37 are likely due to background influences (including changing water levels in some wells and other factors), disruption of the aquifer by pumping, and/or the geochemical influences of the existing chloroform and nitrate/chloride plumes. The head of the nitrate/chloride plume extends more than 1.000 feet upgradient of the TMS.
Therefore, the first step in the analysis will be to perform an assessment of the potential sources for each exceedance to determine whether the exceedance is due to background influences or Mill activities. If an exceedance is determined to be due to background influences then it will not be necessary to perform any further evaluations on the extent and potential dispersion of the contamination or to perform an evaluation of potential remedial actions. Monitoring will continue, and where appropriate revised GWCLs will be proposed to reflect changes in background conditions at the site.
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However, if any of the exceedances are determined to be caused by Mill activities, then EFRI will proceed to the next step and will consider the extent and potential dispersion of the contamination, and will perform an evaluation of potential remedial actions to restore and maintain groundwater quality to ensure that Permit limits will not be exceeded at the compliance monitoring point.
This two-step approach is necessary, because, in light of the varied background conditions at the site, it can't be assumed that consecutive exceedances of a constituent in a well represents contamination that has been introduced to the groundwater. It is first necessary to establish whether or not the exceedances represent background influences.
4.2. Approach for Analysis
The first step in the analysis will be to perform an assessment of the potential sources for selenium in MW-11 and field pH in MW-37 to determine whether the exceedances are due to background influences or Mill activities. This assessment will include an analysis of selenium and field pH as well as the other indicator parameters chloride, sulfate, fluoride and uranium to determine if the behavior of the water in MW-11 and MW-37 has changed since the time of the Background Reports. If the exceedance is determined to be caused by background influences, then it is not necessary to perform any further evaluations on the extent and potential dispersion of the contamination or to perform an evaluation of potential remedial actions. Monitoring will continue, and revised GWCLs will be proposed to reflect changes in background conditions at the site.
The revised GWCL process will include a statistical analysis of selenium data from MW-11 and the field pH data from MW-37 using the methods described in the Existing Wells Background Report (INTERA, 2007a) and the State of Utah Department of Environmental Quality approved Flowsheet ("the Flowsheet").
As mentioned in the SARs, the United States Environmental Protection Agency ("EPA") has recognized the need to update compliance limits periodically to reflect changes to background conditions.
In 2009 guidance, EPA states:
"We recommend that other reviews of background also take place periodically.
These include the following situations:
•When periodically updating background, say every 1-2 years•When performing a 5-10 year permit review
During these reviews, all observations designated as background should be evaluated to ensure that they still adequately reflect current natural or baseline groundwater conditions. In particular, the background samples should be investigated for apparent trends or outliers. Statistical outliers may need to be removed, especially if an error or discrepancy can be identified, so that subsequent compliance tests can be improved.
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If trends are indicated, a change in the statistical method or approach may be warranted." and "Site-wide changes in the underlying aquifer should be identifiable as similar trends in both upgradient and compliance wells. In this case, it might be possible to remove a common trend from both the background and compliance point wells and to perform interwell testing on the trend residuals." (EPA 530/R-09-007, March 2009, Statistical Analysis Of Groundwater Monitoring Data At RCRA
Facilities Unified Guidance, Environmental Protection Agency, Office Of Resource Conservation And Recovery.) 4 .3. Experts Reports to be Prepared The results of the statistical analysis and, if appropriate, recalculation of the GWCL will be compiled as a SAR that will be submitted to DWMRC within 90 days of the approval of this Plan. The SAR will detail the results of all analyses to be performed and the conclusions to be drawn from such analyses, including proposed revision to the existing GWCL. Specifically, the SAR will follow the format of the originally submitted SAR (October 10, 2012) and will include discussions, results and conclusions of the analyses and appendices containing the following: A Statistical analysis of SAR Parameters Comparison of calculated and measured TDS for samples with complete major ions Charge balance calculations Descriptive statistics Box plots to identify extreme outliers Histograms and Shapiro Wilk test for normality Regression or Mann Kendall trend analysis Evaluation of inflection points and data subsets Proposed Revised GWCLs A statistical analysis of Indicator Parameters Descriptive Statistics Box plots to identify extreme outliers Histograms and Shapiro Wilk test for normality Regression and/or Mann Kendall trend analysis 5.TIME SCHEDULEThe SAR will be submitted'to the Director within 90 days after approval of this Plan. The SAR contemplated by this submission, may be combined with any subsequent SARs resulting from other Plans and Schedules for other out of compliance constituents, as necessary. 6
6.CONCLUSION
Given the varied background groundwater quality at the site it cannot be assumed that consecutive exceedances of a constituent in a monitoring well means that contamination has been introduced
to groundwater in that well.
The location of MW-11 is important when determining potential sources of contamination. MW-11 is directly downgradient of the nitrate/chloride plume. Nitrate concentrations at MW-5
(adjacent to MW-11) and MW-11 have historically been relatively low (non-detect to approximately 1 mg/L ). Relatively low nitrate concentrations at MW-11 are consistent with the relative stability of the downgradient margin of the nitrate plume. However, since 2019, low but detectable nitrate at MW-11 (up to a maximum of approximately 3.5 mg/L), and post-2019 increases in chloride, are consistent with the ongoing (but slow) downgradient migration of the nitrate/chloride plume.
The relative stability of the downgradient (southern) margin of the nitrate component of the nitrate/chloride plume implies a degradation mechanism that affects nitrate but not chloride; the most likely mechanism is degradation (reduction) of nitrate by naturally-occurring pyrite in the formations hosting perched groundwater at the site.
Concentrations of the indicator parameter fluoride display an overall stable to decreasing trend. Stable to decreasing fluoride indicates that MW-11 is un-impacted by the TMS. In addition, although sulfate is trending upward, an increasing trend was present at the time of the 2008 Hurst and Solomon isotopic study, which concluded that no impacts to ground water from the TMS were occurring, thereby indicating that the source of the trend was not the TMS.
The consecutive exceedances of field pH in MW-37 are likely due to background influences and a small and unrepresentative background data set used to calculate the GWCLs at the time of the
Background Report. Given the recent analyses and investigations at the site, there is no indication that the exceedances of field pH in MW-37 are due to Mill-related impacts or to any potential tailings seepage.
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