Loading...
HomeMy WebLinkAboutDRC-2023-068886 - 0901a06881244bbd DRC-2023-068886 195 North 1950 West • Salt Lake City, UT Mailing Address: P.O. Box 144880 • Salt Lake City, UT 84114-4880 Telephone (801) 536-0200 • Fax (801) 536-0222 • T.D.D. (801) 536-4284 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 M E M O R A N D U M TO: Project File C-2023-34 THROUGH: Phil Goble, Section Manager FROM: Heather Mickelson, PE, PG DATE: July 27, 2023 SUBJECT: Review of the 1st Quarter 2023 (January to March, 2023) DMT Performance Standards Monitoring Report and Impoundment 4A and Impoundment 4BBAT Performance Standards Monitoring Report. Groundwater Discharge Permit (GWDP) UGW370004 and Radioactive Materials License (RML), 1900479, Amendment 10, Energy Fuels Resources, Inc. (EFR), White Mesa Mill, Blanding, Utah This is a summary of Utah Division of Waste Management and Radiation Control (DWMRC) staff review of the DMT Performance Standards Monitoring Report and Cell 4A and Cell 4B BAT Performance Standards Monitoring Report for the 2nd Quarter 2022 dated April 27, 2023 (DRC-2023- 004032). The requirements are listed given in the Ground Water Discharge Permit (GWDP), No UGW370004, Dated March 8, 2021, and Radioactive Materials License (RML), 1900479 Amendment 10, dated July 27, 2021. Compliance with these requirements is further discussed in the White Mesa Mill Discharge Minimization Technology (DMT) Monitoring Plan, Revision 12.4 (DMT Plan), dated December 2016. DWMRC received the Report on May 4, 2023 in both hard copy and CD formats. The due date for receipt of this report was June 1, 2023 (GWDP Part II.D). After review of this report, DWMRC staff findings and recommendations are as follows: Summary of Findings 1. Weekly monitoring of Impoundment 1 solution pool elevations occurred, as required, and the solution pool elevation remained below the specified limit. 7/27/23 07/27/2023 Review Memorandum, Project C-2023-34, 2023 First Quarter BAT/DMT Report July 27, 2023 Page 2 2. Weekly monitoring of Impoundment 4A solution pool elevations occurred, as required, to calculate acceptable leakage rates, and the leakage rate thus determined remained below the specified limit. 3. Weekly monitoring of Impoundment 4B solution pool elevations occurred, as required, and the solution pool elevation remained below the specified limit. 4. Data provided in Attachments C and D to the Report support a conclusion that EFR has generally met the requirement to keep fluid levels in the Impoundment 2 slimes drain as low as reasonably achievable. Fluid elevations continue to slowly decline. 5. Monitoring of the feedstock storage area occurred as required. The data support a conclusion that no feedstock existed outside the designated feedstock storage areas. 6. EFR met the requirements for inspection of the liner systems. 7. EFR has met the requirements for inspecting and maintaining the New and Existing Decontamination Pads. 8. EFR has met the requirements for inspection of the used oil and fuel storage tanks and associated concrete pads. 9. EFR has met the requirements for inspection of the HCl tanks and containment structure. 10. EFR has met the monitoring requirements for Impoundment 4A and 4B BAT performance and corrected all mechanical failures the same day as detected. 11. The leak detection systems in Impoundments 1, 2, and 3 appear to have operated properly, and no fluids were detected during the reporting quarter. 12. EFR has met the requirements for inspection and crack/joint repair of the Ammonium Sulfate Pad. 13. The report was dated April 27, 2023, and arrived in the Division offices on May 4, 2023, which prior to the June 1, 2023 due date. Summary of Recommendations 1. The DWMRC should issue a closeout letter for the review of this report. 2. Upon completion of the ET cover test regimen, the DWMRC should move rapidly to resolve final cover design questions, extend appropriate cover design approvals, and encourage placement of the final cover on Impoundment 2. 1.0 Impoundment Wastewater Pool Elevation Monitoring RML Requirement Part 11.3 requires a leak detection system for impoundments 4A and 4b and operation, maintenance, and monitoring system for impoundments 1, 2, and 3. Review Memorandum, Project C-2023-34, 2023 First Quarter BAT/DMT Report July 27, 2023 Page 3 GWDP Requirements Part I.F.2 requires EFR to submit a DMT Performance Standards Monitoring Report for Parts I.D.3 and I.E.7 of the GWDP. Part I.E.7(a) requires EFR to monitor and record weekly the elevation of the wastewater pool in Impoundments 1 and 3 to ensure compliance with Condition 10.3 of the License. DMT Plan Part 3.1(a) requires EFR to measure the solution pool elevation in Impoundments 4A and 4B weekly to determine compliance with FML leakage rate limitations. Results Non-conventional Impoundment 1 Attachment A to the Report contains weekly pool elevations for Impoundment 1 show compliance with the freeboard requirements. Conventional Impoundment 3 Impoundment 3 is nearly filled with tailing solids, there is no room for liquids at the surface of the tailings. Recognizing this, letters from the Director dated January 27, 2011 and March 14, 2011 formally eliminated the need for solution pool elevation measurement in Impoundment 3. The January 27, 2011 letter and a letter from the Director dated March 15, 2011 concluded a process ending the need for freeboard-related solution pool elevation monitoring in Impoundment 3. There is no requirement for weekly solution pool elevation measurement at Impoundment 3. Attachment A to the report reflects no measurements for the reported quarter. Conventional Impoundment 4A Attachment A to the Report contains weekly solution pool elevations for Impoundment 4A in support of calculating acceptable leak rates for the liner system. Non-conventional Impoundment 4B Attachment A to the Report includes solution pool elevation readings for Impoundment 4B indicating compliance with the prescribed freeboard requirements. Findings: The data presented in the report demonstrate that EFR is in compliance with the solution pool operational requirements of the RML, GWDP, and DMT plan in force during the quarter. 2.0 Slimes Drain Fluid Level Monitoring GWDP Requirements Part I.F.2 requires EFR to submit a DMT Performance Standards Monitoring Report for Parts I.D.3 and I.E.7 of the GWDP. Part I.D.3.b requires EFR to always maintain the fluid level in the slimes drain of Impoundments 2 and 3 as low as reasonably achievable, and to demonstrate that performance through adherence to the current DMT Monitoring Plan. Review Memorandum, Project C-2023-34, 2023 First Quarter BAT/DMT Report July 27, 2023 Page 4 Part I.E.7(b) requires quarterly monitoring and recording of the depth to wastewater in impoundments ls 2 and 3 slimes drain access pipe as described in Part I.D.3 of the GWDP and the current DMT Monitoring Plan. It also requires EFR to determine the recovery head with a slimes drain recovery head assessment. DMT Plan Part 3.l(b) lists activities for the Slimes Drain Water Level Monitoring for Impoundment 2. Impoundments 3, 4a, and 4b are currently active; therefore, no pumping is authorized. Results Much of this section repeats the corresponding section in previous report reviews in 2019 through 2022. The discussion is repeated here for ease of reference for the reader. Section 4.1 of the Report asserts that the above discussed monitoring requirements only pertain to Impoundment 2 for the reporting period, as dewatering operations have not commenced in Impoundments 3, 4A or 4B. I agree with this assessment. Weekly water level monitoring of the Impoundment 2 slimes drain is not required as part of the DMT plan but is required under Part I.D.3(b)(l) of the GWDP. EFR retains records of lmpoundment 2 slimes drain monitoring at the mill. Attachment D to the Report contains data from the quarterly recovery head measurements. The recovery head monitoring data provides indirect evidence that EFR has maintained the fluid level in the Impoundment 2 slimes drain as low as reasonably achievable, as required in GWDP, Part I.D.3(b)(l). From the graph of slimes drain recovery head data in Attachment D, it is apparent that the downward trend that occurred between May of 2011 and April of 2014 did not continue uninterrupted but approached a horizontal asymptote at approximately 28.5 feet below the top of the standpipe; then, commencing with construction of the Phase 1 Cover on the impoundment surface, the recovery head abruptly rose. The abrupt rise in the recovery head measurement is attributable to pressures resulting from the cover construction activity and will be discussed toward the end of this section. The trend again reversed and declined to the previous lows at about the same level, 28.5 feet below the top of the standpipe, appeared to stabilize for a time but has again begun trending lower. As detailed in the previous paragraph, using recovery head measurements to demonstrate success in the dewatering effort has limitations. The method assumes that the properties of the tailings mass are homogeneous, and, except for the degree of consolidation, unchanging. Were this the case, the fluid withdrawal rate would be predictable, and the recovery head tests would not have the variability shown in the Attachment D graph with consistent fluid withdrawal. The methodology used to generate the graph in Attachment D was used as an enforcement tool, and worked well, until late 2014, as discussed above. Noting that EFR was making all reasonable efforts to keep the fluid head declining, and forces beyond EFR's control were preventing full compliance with the directive to maintain declining fluid head, the method was abandoned as an enforcement tool during the license renewal in 2018. In reviews of previous Reports, prior to placement of the radon barrier material (the second and third layers of the cover system), Russ Topham stated that more information is required to understand whether hydraulic equilibrium has been reached with approximately 7.5 feet of hydraulic head (approximately 22.5 feet from the surface of the temporary cover on the impoundment) at the pumping point (Report for 4th Quarter, 2017, Appendix D). Table 2-1 on p. 7 of the Tailings Data Analysis Report Review Memorandum, Project C-2023-34, 2023 First Quarter BAT/DMT Report July 27, 2023 Page 5 (TDAR, April 2015) presents a water table at a depth of between 0.2 feet and 12.3 feet of the surface of the temporary cover. Likewise, Table 4-1 indicates the depth to top of saturated tailings varying from 3.92 feet to 11.58 feet below the temporary cover surface, with the greater depths occurring closer to the slimes drain alignment (TDAR, p. 17). These data indicate a substantial volume of fluid yet to be removed from the impoundment. Recent installation of additional cover material has surcharged the tailings, resulting in increase of approximately 2,000 gallons per month yield from the slimes drain as well as increased fluid level within the tailings mass due to consolidation. However, stabilizing of the head at the slimes drain may indicate that the withdrawal rate is equal to the percolation rate, and that no further improvements are possible without installing the final cover layers. The TDAR postulates the presence of gypsum in the interstices within the tailings mass (p. 11 ). This condition would reduce hydraulic conductivity within the tailings. The temporary cover is composed of random 'fill, which on visual inspection appears to be a sandy gravel or gravelly sand with cobbles and boulders. Sieve analysis reveals a fines fraction (material finer than the #200 sieve) of between 10% and 30%, with Atterberg Limits testing suggesting the presence of clay in the fines. However, the temporary cover was placed without significant densification, which would offset to some degree the ability of any clay present to resist percolation of water. The porosity of this cover would allow surface water to penetrate the tailings below. Surcharge of the tailings with the additional cover material will induce some consolidation of the random fill and tailings below. Furthermore, the compacted surface of the cover material would shunt aside much of the precipitation falling on the impoundment, reducing the amount available for percolation. With placement of the radon barrier, the temporary cover has consolidated as discussed above. However, no additional information is currently available regarding the postulated precipitation of gypsum in the interstices of the tailings mass below the phreatic surface. Furthermore, if the withdrawal rate from the slimes drain has achieved equilibrium with the percolation rate from above, the suggested conclusion is that the precipitation received is controlling the fluid balance. The licensee has placed piezometers at the settlement monitoring points and is now providing information gathered from the piezometers with this Report, as Attachment C. Russ Topham received weekly reports by email of fluid level measurements in the piezometers which showed a progressive rise in the phreatic surface as crews placed and compacted the first two layers of the final cover system, followed by a decline in, then a stabilization of the phreatic surface. During the reporting quarter, EFR pumped available fluid from the slimes drain. Using fluid level measurements in piezometers installed in the Impoundment 2 cover, EFR has constructed fluid level surface contour maps for each month for Impoundment 2. These maps and the associated data appear in Attachment C to the Report. Comparing these maps and the underlying data demonstrate that the fluid level has declined, appeared to have stabilized, and recommenced declining, much like the slimes drain data. If percolation and fluid withdrawal occur on equilibrium with each other, fluid levels will stabilize in the tailings mass. That condition appeared to have been achieved when the fluid levels paused in their decline. It is unclear whether the resumption in decline is a function of drought conditions at the surface or whether other factors are at work here. It is worth noting that reviews of the cover test cell monitoring program indicate only a small about of water percolating through the test cell compared to the precipitation, storage, and evapotranspiration occurring at the test cell. Vegetative conditions on the test cell not a great deal different than on the remainder of the currently installed cover. Review Memorandum, Project C-2023-34, 2023 First Quarter BAT/DMT Report July 27, 2023 Page 6 It appears from the data that EFR is removing fluid from the tailings mass as rapidly as it becomes available. Installation of final cover would provide more surcharge, squeezing out more fluid, and should impede or eliminate percolation. Installation of final cover is dependent upon approval of the evapotranspirative cover proposed for the site (ET cover), pursuit of another approvable cover system, or a decision to install the currently approved rock armor barrier. The ET cover is under study, and insufficient data exists currently to extend approval. It should be noted here that if the currently approved rock armor barrier is to be installed, a modified design to increase cover slope may be necessary to increase runoff rate and decrease percolation. It should also be noted that Energy Fuels has installed an additional secondary test section to evaluate an alternative seed mix to that originally proposed for the ET cover because the performance goals were not likely to be met. Findings: Data provided in Attachments C and D of the Report supports a conclusion that EFR has generally met the requirement to keep water levels in the Impoundment 2 slimes drain as low as reasonably achievable. It appears that the slimes removal rate matched the percolation rate from the cover surface for a time, but that the removal rate once again exceeds the percolation rate. Recommendation: The DWMRC and EFR should continue to monitor the licensee's efforts to remove slimes from the tailings mass. Upon completion of the ET cover test regimen, the DWMRC should move rapidly to resolve final cover design questions, extend appropriate cover design approval and encourage placement of the final cover. 3.0 Feedstock Storage Monitoring This section addresses both bulk conventional feedstock (ore) and alternate feed stored onsite. Ore is stored on the ore pad. Alternate feed is stored on the ore pad or a small quantity may be placed on a concrete pad near the intake features of the alternate feed circuit when the material is being staged for processing through the alternative feed circuit. GWDP Requirements Part I.D.3.E describes the physical area used for open-air or bulk storage of feedstock materials. I.D.11 lists the BAT Requirements for Feedstock Material stored Outside of the Feedstock Storage Area Part I.E.7.c describes the weekly feedstock storage area inspection. Part I.E.7.d describes inspection and criteria for storing Feedstock Material Stored Outside the Feedstock Storage Area. Part I.F.2 requires EFR to submit a DMT Performance Standards Monitoring Report for Parts I.D.3 and I.E.7 of the GWDP. Results Weekly inspection revealed no evidence of ore beyond the boundaries of the ore pad. Storage practices for alternate feeds appear compliant with GWDP requirements. During the monitoring period, the only location of alternate feed storage was on the ore pad. Review Memorandum, Project C-2023-34, 2023 First Quarter BAT/DMT Report July 27, 2023 Page 7 The current report highlighted seven instances of standing water on the ore pad after storms. Standing water was a result of precipitation during the quarter. On January 20, snow was covering the ore pad. Finding: Monitoring of the feedstock storage area occurred as required. The data support a conclusion that no feedstock existed outside the designated feedstock storage areas. Standing water problems were addressed during the quarter. 4.0 Tailings Impoundments Liner System Repairs GWDP Requirements Part I.E.7.e describes the inspections and repair of defect to liners Impoundments 1,2, and 3. Part I.E.8.c describes the liner maintenance and repair for Impoundment 4a Part I.E.12 .c describes the liner maintenance and repair for Impoundment 4b Results Inspection of all impoundments occurred daily during the period covered in the report. No leaks or liner breaches were identified. Finding: EFR met the requirements for inspection and repair of the liners. 5.0 Decontamination Pads Two decontamination pads exist at EFR and are called: New Decontamination Pad and Existing Decontamination Pad GWDP Requirements Part I.F.12 describes the annual inspection report for the New and Existing decontamination pads that is submitted on or before September 1 of each year. It further describes the inspection and repairs of the pads. Part I.D.14 lists maximum water level requirements and pad cleanliness requirements as part of the BAT Performance Standards for the New Decontamination Pad. Part I.E.7.f requires EFR to conduct a weekly inspection of the New decontamination Pad. Annual inspection and repair of both decontamination pads as required under Part I.F.12 of the GWDP and Section 4.2 of the DMT Plan occurred during May 2022. Repairs included sealing cracks greater than 1/8 inch. Results The monitoring portals of the New Decontamination Pad were dry during all inspections, indicating no leakage from primary containment. Surfaces have been repaired to prevent seepage of contaminants through the New and Existing Decontamination Pads and into the ground water. Most recently, cracks were repaired in May 2022. The pad will be inspected and repaired during the 2nd quarter of 2023. Finding: EFR has met the routine and annual requirements for inspecting both the Existing and New Decontamination Pads, finding no indication of leakage from secondary containment. Review Memorandum, Project C-2023-34, 2023 First Quarter BAT/DMT Report July 27, 2023 Page 8 6.0 Used Oil and Fuel Storage Tanks GWDP Requirement: Part I.D.3.f lists the mill site chemical reagent storage requirements. Part I.D.10 describes the Storm Management and Spill Control Requirements to manage all contact and non-contact stormwater and control containment spills. The Spill prevention, Control and Countermeasures Plan and the DMT Plan require annual inspection of the used oil and fuel storage tanks. The associated concrete is inspected and sealed in the same manner and on the same schedule as the decontamination pads. DMT Plan Section 4.4 describes the annual inspection of waste oil and fuel tanks. Results Plant personnel inspected the tanks and pads, noted no leakage from the tanks, and applied sealant to joints and cracks in the pads and containment walls as required. The requirement is annual, was completed during June 2022. The 2023 inspection will occur during the second quarter. Finding: EFR has met the routine requirements for inspecting the used oil and fuel tanks and associated secondary containment features and has sealed joints and cracks therein. 7.0 Ammonium Sulfate Pad Requirement Phase I of the Nitrate Corrective Action Plan required installation of a concrete pad to prevent water penetrating to nitrate-containing soils near the ammonium sulfate crystal tank. The DWMRC approved the construction by letter on June 26, 2015. Inspections and filling of cracks were required quarterly for eight consecutive quarters following approval and have been conducted annually thereafter. DMT Plan Section 5 describes the inspection of the ammonium sulfate cover area. Results Plant personnel inspected the pad and applied sealant to joints and cracks as. Annual inspection and maintenance activities were completed during May 2022. The 2023 inspection will occur during the second quarter. Finding: EFR has met the routine requirements for inspecting the Ammonium Sulfate Pad and has sealed joints and cracks therein. 8.0 HCl Tanks GWDP Requirements Part I.D.3.f lists the mill site chemical reagent storage requirements. Review Memorandum, Project C-2023-34, 2023 First Quarter BAT/DMT Report July 27, 2023 Page 9 Part I.D.10 describes the Storm Management and Spill Control Requirements to manage all contact and non-contact stormwater and control containment spills. Results Plant personnel inspected the HCl tanks and the secondary containment. No repairs or maintenance activities were required. This annual inspection occurred during the 2nd quarter of 2022. The 2023 inspection will occur during the second quarter. The 2023 inspection will occur during the second quarter. Finding: EFR has met the routine requirements for inspecting and maintaining the HCL tank and associated secondary containment. 9.0 Impoundments 4A and 4B BAT Performance Standards Monitoring GWDP Requirements Part 1.D.6a and Part 1.D.13 lists the BAT performance standards for impoundments 4A and 4B. These requirements include verifying that leak detection system equipment operates appropriately, verifying that fluid head in the leak detection system sumps does not exceed 1 foot above the lowest point in the secondary (lower) flexible membrane liner, and recording the volume of fluid pumped from the leak detection systems for the two impoundments. Part 1.E.8 and Part 1.E.12 list the BAT performance standards monitoring requirements for impoundments 4A and 4B. These requirements include continuous operation of leak detection system pumping and monitoring equipment (a time limit of 24-hour limit to repair equipment after it is found to be in-operable). Fluid in the embankment should not exceed a 1-foot level above the lowest point of the lower flexible membrane liner on the cell flow. A maximum daily volume of fluid limit from the leak detection system and a minimum freeboard limit. EFR must also record the fluid head in Impoundment 4B for compliance purposes, and in Impoundment 4A for computation of acceptable leakage rate in Impoundment 4A. DMT Plan Section 2.1 describes the daily measurements and monitoring for the leak detection systems in impoundments 4A and 4B. Section 3.1 describes the weekly measurements and monitoring for Impoundments 4A and 4B. Results The data provided in the report and its attachments provide evidence of compliance with Impoundments 4A and 4B BAT requirements for performance monitoring standards and performance monitoring standards monitoring in place during the 1st quarter of 2023. No failures were noted in the Impoundment 4A or Impoundment 4B leak detection systems during the second quarter. During the quarter, the fluid extraction pump experienced irregularity in the power supply. The faulty part was identified and replaced without missing any measurements. Finding: EFR has met the monitoring requirements for Impoundment 4A and 4B BAT performance. No mechanical failures were noted during the quarter. Review Memorandum, Project C-2023-34, 2023 First Quarter BAT/DMT Report July 27, 2023 Page 10 10.0 Impoundments 1, 2 and 3 Leak Detection System Monitoring RML Requirement Part 11.3 requires a leak detection system for impoundments 4A and 4b and operation, maintenance, and monitoring system for impoundments 1, 2, and 3. DMT Plan Section 2.1 describes the daily measurements and monitoring for the leak detection systems in impoundments 1, 2, and 3. Section 3.1 describes the weekly measurements and monitoring for Impoundments 1, 2, and 3. Requirement Leak detection system monitoring requirements for Impoundments 1, 2 and 3 appear in the Radioactive Materials License rather than the GWDP. For consistency, the DWMRC requested that this monitoring be included as part of the quarterly report and EFR has consented to do so. Results The report and its attachments contain weekly monitoring data for the operational status of the leak detection system equipment, fluid levels detected in the leak detection systems, and volumes of fluid pumped. From the data, EFR represents that no failures of the monitoring equipment occurred that were not corrected within 24 hours. Leak detection systems for the three impoundments measured dry; therefore, no fluids were pumped from them. Finding: The leak detection systems in Impoundments 1, 2 and 3 appear to have operated properly, and no fluids were detected therein during reporting period