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HomeMy WebLinkAboutDRC-2023-001936 - 0901a0688119eaee/ii,;� �'f;NERGYFUELS February 24, 2023 Sent VIA E-MAIL AND EXPRESS DELIVERY Mr. Doug Hansen Director Division of Waste Management and Radiation Control Utah Department of Environmental Quality 195 North 1950 West Salt Lake City, UT 84114-4880 [nerg) Fuels Resources (USA) Inc. 225 Union Blvd. Suite 600 Lakenood, CO, US, 80228 303 974 2140 www.energyfuels.com Re: Transmittal of White Mesa Uranium Mill Cell 2 Reclamation Cover 2022 Annual Performance Monitoring Report Dear Mr. Hansen: In accordance with the Stipulation and Consent Agreement ("SCA" dated February 23, 2017) between the Division of Waste Management and Radiation Control ("DWMRC") and Energy Fuels Resource (USA) Inc. ("EFRI"), EFRI constructed a cover performance monitoring test section ("Primary Test Section") on Cell 2 in 2016, completed Phase l cover placement on Cell 2 in 2017, constructed a supplement vegetation monitoring test section ("Supplemental Test Section") in 2017, and initiated performance monitoring. This letter transmits the 2022 annual performance monitoring report for the reclamation cover and includes monitoring results for both test sections. For your convenience, two hard copies of the report and two CDs, each containing a word searchable electronic copy of the files, will be mailed to DWMRC. If you should have any questions regarding this transmittal please contact me at 303-389-4134. Yours very truly, ENERGY FUELS RESOURCES (USA) INC.Kathy Weinel Director, Regulatory Compliance CC: Jordan App Dav id F rydenl und Garrin Palmer Logan Shumway Scott Bakken John Uhrie DRC-2023-001936 Div of Waste Management and Radiation Control MAR 02 2023 ?1!);~ C:'T:NERGYFUELS February 24, 2023 Sent VIA E-MAIL AND EXPRESS DELIVERY Mr. Doug Hansen Director Division of Waste Management and Radiation Control Utah Department of Environmental Quality 195 North 1950 West Salt Lake City, UT 84114-4880 Energy Fuels Resources (USA) Inc. 225 Union Blvd. Suite 600 Lakewood, CO, US, 80228 303 974 2140 www .energy fuels .corn Re: Transmittal of White Mesa Uranium Mill Cell 2 Reclamation Cover 2022 Annual Performance Monitoring Report Dear Mr. Hansen: In accordance with the Stipulation and Consent Agreement ("SCA" dated February 23, 2017) between the Division of Waste Management and Radiation Control ("DWMRC") and Energy Fuels Resource (USA) Inc. ("EFRI"), EFRI constructed a cover performance monitoring test section ("Primary Test Section") on Cell 2 in 2016, completed Phase 1 cover placement on Cell 2 in 201 7, constructed a supplement vegetation monitoring test section ("Supplemental Test Section") in 2017, and initiated performance monitoring. This letter transmits the 2022 annual performance monitoring report for the reclamation cover and includes monitoring results for both test sections. For your convenience, two hard copies of the report and two CDs, each containing a word searchable electronic copy of the files, will be mailed to DWMRC. If you should have any questions regarding this transmittal please contact me at 303-389-4134. Yours very truly, ENERGY FUELS RESOURCES (USA) INC. Kathy Weinel Director, Regulatory Compliance CC: Jordan App David Frydenlund Garrin Palmer Logan Shumway Scott Bakken John Uhrie White Mesa Uranium Mill Cell 2 Reclamation Cover 2022 Annual Performance Monitoring Report February 24, 2023 Prepared for: Energy Fuels Resources (USA) Inc. Prepared by: Stantec Consulting Services Inc. ~ Stantec Document Review and Revision Record Rev. Description Author(s) Quality Check Independent Review 0 Draft for client review C. Romano, S. Regis 1.26.2023 M. Davis 2.17.2023 C. Strachan 02.22.2023 1 Final for client M. Davis 2.24.2023 WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT Table of Contents 1.0 INTRODUCTION .......................................................................................................... 1.1 1.1 BACKGROUND ............................................................................................................ 1.1 1.2 MONITORING REQUIREMENTS ................................................................................. 1.1 1.3 REPORT ORGANIZATION .......................................................................................... 1.2 2.0 COVER AND TEST SECTION DESIGNS .................................................................... 2.1 3.0 PRIMARY TEST SECTION HYDROLOGIC MONITORING ......................................... 3.1 4.0 PRIMARY AND SUPPLEMENTAL TEST SECTIONS VEGETATION INSPECTION ............................................................................................................... 4.1 5.0 CELL 2 SETTLEMENT AND WATER LEVEL MONITORING...................................... 5.1 5.1 SETTLEMENT MONUMENTS...................................................................................... 5.1 5.2 PIEZOMETERS ............................................................................................................ 5.2 6.0 CONCLUSIONS ........................................................................................................... 6.1 7.0 REFERENCES ............................................................................................................. 7.1 LIST OF TABLES Table 1 Primary Test Section Water Balance for 2016 – 2022 Table 2 Cell 2 Top Surface Settlement Measured Between April 2016 and December 2022 Table 3 Piezometer Water Level Elevations During and After Phase 1 Cover Placement LIST OF FIGURES Figure 1 Regional Location Map Figure 2 Site Location Map Figure 3 Cover Profile within Lysimeter Figure 4 Settlement Monument and Piezometer Locations LIST OF APPENDICES Appendix A 2022 Field Hydrology Of The Cell 2 Primary Test Section At The White Mesa Mill Appendix B 2022 Revegetation Evaluation Cell 2 Primary And Supplemental Test Sections Appendix C Cell 2 Settlement Monitoring Data Appendix D Cell 2 Standpipe Piezometer Water Levels IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 1.1 1.0 INTRODUCTION This report documents the 2022 monitoring and inspection results for the reclamation cover and Primary and Supplemental Test Sections on the Cell 2 tailings management cell at the Energy Fuels Resources (USA) Inc. (EFRI) White Mesa Uranium Mill site (Mill site). Reclamation cover performance monitoring for Cell 2 was initiated in 2016. Calibration monitoring was conducted from 2018 through 2019. Official cover performance monitoring and required reporting began January 1, 2020. Stantec prepared this report at the request of EFRI for submittal to the Utah Department of Environmental Quality, Division of Waste Management and Radiation Control (DWMRC). The Mill site is located in San Juan County in southeastern Utah, approximately 6 miles south of Blanding, Utah. Figure 1 shows a regional location map and Figure 2 shows the site layout. EFRI site facilities are within an approximately 686-acre restricted area and consist of a uranium processing mill and lined tailings management/evaporation ponds. 1.1 BACKGROUND EFRI and the DWMRC executed a Stipulation and Consent Agreement (SCA) on February 23, 2017 (DWMRC, 2017) defining the commitments and timeframes for completing placement of reclamation cover on Cell 2 and performance assessment of the cover system, in accordance with the Reclamation Plan (EFRI, 2016). The Reclamation Plan was updated on February 8, 2018 to Revision 5.1B (EFRI, 2018), but the guidelines, monitoring, and reporting requirements for the test sections did not change. Cell 2 Phase 1 cover placement commenced in April 2016, was completed in April 2017, and is documented in Stantec (2017b). EFRI constructed a cover performance monitoring section on Cell 2 (Primary Test Section) in fall 2016 and a supplemental vegetation monitoring section (Supplemental Test Section) in fall 2017 (Stantec, 2017a; 2018a). The Primary Test Section was constructed to assess the overall performance of the entire reclamation cover system profile. The Supplemental Test Section was constructed as a supplemental vegetation monitoring section to the Primary Test Section. The Supplemental Test Section does not include evaluation of the entire cover profile but was constructed to demonstrate that vegetation can be established and that erosional influences will not be detrimental to long-term vegetation establishment. In 2021, EFRI constructed a Supplemental Test Section No. 2 adjacent to the Supplemental Test Section to provide additional data for the Cell 2 cover test section performance monitoring and to evaluate the revegetation plan to promote vegetation success. The as-built report for this test section was provided in Stantec (2022). 1.2 MONITORING REQUIREMENTS Per the SCA, the Primary Test Section and the Supplemental Test Section are required to be monitored for vegetation performance and the Primary Test Section is required to be monitored for percolation. IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 1.2 Performance criteria are outlined in the SCA (DWMRC, 2017) and summarized in this section. EFRI started calibration monitoring of the test sections on January 1, 2018 and official performance monitoring on January 1, 2020. EFRI also monitored the test sections for informational purposes after constructing the test sections and prior to starting calibration monitoring. Official monitoring ends on December 31, 2024 and the cover performance success will be evaluated at that time. EFRI has provided quarterly data quality reports to DWMRC since 2017 and monitoring results are summarized in annual performance monitoring reports (Stantec, 2018b, 2019, 2020, 2021, and 2022). This report is the annual monitoring report for 2022. Percolation monitoring procedures are outlined in the Reclamation Plan (EFRI, 2018). The percolation rate from the base of the lysimeter in the Primary Test Section will be used as the percolation performance parameter for the cover system. The cover design will be considered to have performed adequately if the average annual percolation rate is 2.3 mm/yr or less over the official performance monitoring time period. Vegetation sampling and monitoring procedures for the test sections follow recommendations outlined in the Reclamation Plan (EFRI, 2018). The vegetation component of the cover will be considered successful if: (1) a minimum vegetation cover of 40 percent is achieved, and (2) acceptable vegetation diversity per EFRI (2018) (perennial grasses, forbs and shrubs) is met for the Supplemental and Primary Test Sections by the end of the five-year performance monitoring period. Although not required by the SCA, EFRI is conducting vegetation sampling and monitoring of the Supplemental Test Section No. 2 (constructed in the spring of 2021) to provide additional data for the Cell 2 cover test section performance monitoring. EFRI is using the same vegetation sampling and monitoring procedures as the other test sections, and the survey results are included in this report for information purposes. As part of Cell 2 reclamation, EFRI is also conducting settlement monitoring of the Phase 1 cover surface and monitoring water levels in the Cell 2 using procedures outlined in the Reclamation Plan (EFRI, 2018). Monitoring results for settlement and water levels and interpretation of these results are included in this report. Settlement and dewatering data will be evaluated after completing the cover performance monitoring. The evaluation will determine if sufficient settlement has occurred to facilitate Phase 2 cover placement and minimize maintenance of the final cover surface. Per the SCA, decreasing trends in settlement followed by a maximum of 0.1 feet (30 mm) of cumulative settlement over 12 months (for at least 90 percent of the settlement monuments), will be considered acceptable to proceed with placement of the Phase 2 Cell 2 cover. 1.3 REPORT ORGANIZATION This report provides an overview of the cover and test section designs (Section 2.0), Primary Test Section hydrologic monitoring (Section 3.0), Primary and Supplemental Test Sections vegetation survey results (Section 4.0), Cell 2 settlement and water level monitoring (Section 5.0), and conclusions (Section 6.0). IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 2.1 2.0 COVER AND TEST SECTION DESIGNS The Reclamation Plan (EFRI, 2018) provides detailed design information for the cover and test sections and the designs are summarized below. The cover system is a monolithic water balance cover, designed to minimize percolation, meet the radon emanation standard, and minimize maintenance over the short- and long-term. The design reclamation cover thicknesses for the tailings management cells range from 9.5 to 10.5 feet. The minimum design cover thickness of 9.5 feet was used for the lysimeter area of the Primary Test Section to evaluate the lower bound reclamation cover thickness for the tailings management cells. The remaining area within the test section was constructed to the full-depth Cell 2 cover profile (10.5 feet). The cover profile within the lysimeter is shown on Figure 3. The reclamation cover contains the following layers, listed in order from top to bottom: Layer 4 – 0.5 feet thick Erosion Protection Layer (topsoil-gravel admixture) Layer 3 – 3.5 feet thick Growth Medium Layer (loam to sandy clay) Layer 2 – 3.0 to 4.0 feet thick Compacted Cover (highly compacted loam to sandy clay) Layer 1 – 2.5 feet thick (minimum) Interim Fill Layer (loam to sandy clay) The Primary Test Section is in the southeast corner of Cell 2, as shown in Figure 2. The test section was constructed as a design-build project during reclamation cover construction using procedures adopted from the test section installation instructions developed by the United States Environmental Protection Agency (EPA) Alternative Cover Assessment Program (ACAP) (Benson et al., 1999, 2001). Test section as-built information is provided in Stantec (2017a). The test section is approximately 100 feet by 100 feet, with a 32-feet by 64-feet lysimeter centered within the test section. The longer side of the lysimeter is oriented parallel to the cover slope. The lysimeter collects percolation from the base of the cover, surface runoff, and interflow from the textural interface between the interim fill (Layer 1) and compacted cover (Layer 2). Sensors monitor hydrologic state variables (temperature and water content) within the cover. Percolation rate, lateral drainage, runoff, internal state conditions, and meteorological data are recorded continuously using a data logger near the southern edge of the test section. The Supplemental Test Section was constructed in a location representative of cover conditions on the tailings management system cells (see Figure 2) and construction information is provided in Stantec (2018a). The Supplemental Test Section is 100 feet by 100 feet in size to match the dimensions of the Primary Test Section. The slope of the test section is greater than 1 percent (the maximum reclamation cover slope). The cover design includes addition of gravel to the topsoil for slopes greater than 0.5 percent. However, gravel was not added to the topsoil for the test section to evaluate the short-term impact of erosion on the vegetative cover without gravel addition. Successful Supplemental Test Section performance will then translate to the cover both with and without the addition of gravel for erosion protection. Mulch was placed to provide erosion protection for the seeds during germination and early seedling growth. IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 2.2 The Supplemental Test Section No. 2 (see Figure 2) was constructed similar to and adjacent to the Supplemental Test Section as outlined in the as-built report provided in Stantec (2022). The revegetation plan used for the test section was based on the plan provided in EFRI (2018) with modifications to address the squirrel tail dominance occurring on the Primary Test Section and the poor seeding establishment on the Supplemental Test Section. IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 3.1 3.0 PRIMARY TEST SECTION HYDROLOGIC MONITORING Data collected from the Primary Test Section from September 9, 2016 to December 31, 2022 (last automated data download of 2022) are described in the annual Primary Test Section Report in Appendix A. Data in this report represent the first six full calendar years (2017 through 2022) of monitoring. Table 1 summarizes the water balance results. Table 1. Primary Test Section Water Balance for 2016 to 2022 Calendar Year Water Balance Quantities (mm) Precipitation Runoff Lateral Flow ET Change Storage Percolationc 2016a 60 0.0 0.0 35 17 0.0 2017b 223 0.0 0.0 325 39 0.6 2018 163 0.0 0.0 125 38 0.9 2019 308 0.3 0.0 325 3 1.0 2020 128 0.0 0.0 171 -63 0.9 2021 223 0.0 0.0 242 -20 0.6 2022 180 0.0 0.0 169 25 0.3 Notes: a. Partial year, monitoring began on September 9, 2016. b. Damage from vault flooding precluded measuring flows 7 February 2017 – 25 March 2017 c. All water balance quantities rounded to nearest mm number except percolation, which is rounded to 0.1 mm. The hydrology of the test section during 2022 was consistent with expectations for a water balance cover in a semi-arid environment with lower-than-average annual precipitation. Precipitation in 2022 (180 mm) was substantially lower than the long-term average for the nearby Blanding, Utah station (355 mm, located at 37° 62' N, 109° 47' W with elevation 1829 m) operated by the National Weather Service, but was only modestly lower than the average annual precipitation recorded during monitoring the test section (204 mm from 2017 to 2022). Winter and spring in 2022 were considerably drier than average. Summer and fall in 2022 were wetter than winter and spring, but drier than average. Soil water storage gradually diminished throughout the year, continuing a trend that began in 2019, as water contents continued to gradually diminish at all depths except at the near surface. At the end of 2022, soil water storage was at the lowest point since construction. Nearly all precipitation that reached the test section was returned to the atmosphere as evapotranspiration. A trace of runoff (0.1 mm) and lateral flow (0.01 mm) were transmitted. Annual percolation was 0.3 mm, the lowest measured for a full year during the monitoring period. Thermally driven flow has been the most significant mechanism contributing to the percolation recorded to date. IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 4.1 4.0 PRIMARY AND SUPPLEMENTAL TEST SECTIONS VEGETATION INSPECTION Cedar Creek Associates, Inc. visited the Mill site on June 7, 2022 and September 12, 2022, to inspect the status of plant development on the Primary and Supplemental Test Sections. Inspection results are summarized below, and Appendix B presents a full report with photos. Precipitation conditions in the months prior to the spring revegetation evaluations were not favorable for plant growth (31% of average). Regionally, 2022 can be considered a dry year with well below average precipitation. Vegetation observed during the spring evaluation exhibited below average plant vigor and growth in response to unfavorable precipitation conditions. The spring months of March, April, and May are particularly important to plant growth and these months received 19.9 mm (75% of normal), 0.7 mm (3% of normal), and 0 mm (0% of normal) of precipitation, respectively. Precipitation prior to the fall revegetation evaluation was also below average (81% of average) but not as drastically as the spring evaluation. July, August, and September were all below average with 21.4 mm (73% of normal), 25.1 mm (72% of normal), and 31.8 mm (98% of normal) of precipitation, respectively. Vegetation observed during the fall evaluation also exhibited below average plant vigor and growth in response to unfavorable precipitation conditions. The revegetation performance criteria applicable to the Primary Test Section and Supplemental Test Section are summarized in Appendix B. As described in the SCA, success is not evaluated until the end of the official monitoring time period. Therefore, the performance evaluation presented Appendix B is for discussion purposes. The spring evaluations were selected for the performance evaluation because the test sections are dominated by cool season species, which should be evaluated in the spring. The results of the performance evaluation are summarized in Appendix B. In Year 3 (2022) of the performance period, both the Primary and Supplemental Test Sections are not passing several of the success criteria. For the Primary Test Section, vegetation performance criteria pertaining to diversity and woody plant density are not being met. This is primarily due to placement of topsoil on the Primary Test Section with a large source of squirreltail seed. This presence of squirreltail seed in the topsoil was unknown at the time of construction and its dominance is impacting the vegetation diversity by preventing establishment of other species. Below average precipitation and available water through the end of 2020, into the spring of 2021, and spring of 2022 did not facilitate improved vegetation growth and vigor in the Primary Test Section. For the Supplemental Test Section, the seeding never established due to poor precipitation conditions following seeding. Local native species are slowly volunteering on the test section. Perennial species cover has remained diminished, and cover of annual species dominates. Annual cover was decreasing significantly each year until favorable precipitation in 2022 caused an increase in annual cover for the year. IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 4.2 For the Supplemental Test Section No. 2, seedling emergence was not identified during the spring survey likely due to very low precipitation during the months of April and May following the seeding and prior to the survey (June 2021). However, the fall survey conducted in September 2022 identified moderate densities of emerging seedlings dominated by perennial grasses. The diversity of species observed at the Supplemental Test Section No. 2 is encouraging and indicates the potential for better performance in favorable (wet) precipitation conditions for this test section. Further revegetation development is expected to occur throughout the performance period and future monitoring efforts to track the trajectory of revegetation development will occur annually, in the spring, for the remainder of the performance period. In addition, EFRI will monitor the Supplemental Test Section No. 2 to provide additional data for Cell 2 cover test section performance monitoring. IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 5.1 5.0 CELL 2 SETTLEMENT AND WATER LEVEL MONITORING Cell 2 includes settlement monuments and piezometers (Figure 4 shows locations). Settlement monuments were installed between 1989 and 2010. Existing settlement monuments were extended upward during Phase 1 cover construction. Standpipe piezometers were installed in June 2016 across Cell 2 during Phase 1 cover construction to monitor water levels within the tailings. After official performance monitoring is complete for the Primary and Secondary Test Sections, the settlement and dewatering data will be evaluated to determine if sufficient settlement has occurred to facilitate Phase 2 cover placement. The following sections discuss settlement monitoring and monitoring of water levels in the tailings during and after Phase 1 cover construction. 5.1 SETTLEMENT MONUMENTS Appendix C contains graphs showing settlement monument measurements from installation (June 2016) through December 2022. Table 2 lists the settlement measured since the start of Phase 1 cover construction (April 2016) through December 2022. Settlement totals during this period range from 0 to 0.6 feet. Settlement of the cover surface due to the Phase 1 cover loading is occurring as expected, with a relatively quick response to the additional loading, as occurred when the initial interim fill was placed on the tailings. The majority of total settlement due to Phase 1 cover placement is estimated to have occurred. Settlement is showing a decreasing trend and less than 0.05 feet of annual settlement was measured for 2022 for all the monuments (ranging from 0.04 feet settlement to 0.03 feet upward movement). Negative values indicate upward movement. Prior to initiating Phase 2 cover placement, additional fill will be added to settled areas and the top surface of the compacted cover layer will be recompacted. Table 2. Cell 2 Top Surface Settlement Measured Between April 2016 and December 2022 Settlement Monument April 2016 to December 2022 Settlement (ft) 2022 Settlement (ft) Settlement Monument April 2016 to December 2022 Settlement (ft) 2022 Settlement (ft) 2W1 0.16 0.01 2W6-N 0.19 0.00 2W2 0.26 -0.02 2W6-C 0.31 0.00 2W3 0.25 -0.02 2W6-S 0.43 0.00 2W3-S 0.27 -0.03 2W7-N 0.00 0.03 2W4-N 0.19 -0.01 2W7-C 0.16 0.02 2W4-C 0.23 -0.02 2W7-S 0.39 0.04 2W4-S 0.44 -0.02 2E1-N 0.25 0.02 2W5-N 0.15 -0.01 2E1 0.36 0.03 2W5-C 0.22 -0.02 2E1-1S 0.41 0.03 2W5-S 0.34 -0.02 2E1-2S 0.57 0.04 IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 5.2 5.2 PIEZOMETERS Standpipe piezometers were installed across Cell 2 prior to the first phase of final cover placement to monitor changes in water levels in the tailings due to dewatering from the sump prior to and after final cover placement. These piezometers were completed within the tailings to provide information on the rate and extent of dewatering of the tailings. The piezometers were primarily adjacent to the settlement monuments to minimize damage to the piezometers during cover construction, while providing sufficient locations to evaluate tailings water levels. Appendix D presents figures showing water levels in the piezometers since installation (June 2016) through December 1, 2022. Figure D.1 shows the water levels for all the piezometers. For comparison, Figures D.2, D.3, and D.4 show the water levels in the piezometers on the west side of Cell 2 (excluding locations near the sump), near the sump, and on the east side of Cell 2 (excluding locations near the sump), respectively. Figures D.2 through D.4 show water levels are lower near the sump, indicating migration of water towards the sump. The figures show that piezometer water levels increased during the Phase 1 cover placement (late 2016 to early 2017), and then generally decreased until the wet winter/spring of 2019. The increase in water levels was expected during Phase 1 cover placement and is due to the excess pore water pressure from consolidation associated with the loading from the additional cover. In 2019 water levels for piezometers increased or were generally level for the majority of the year. These conditions are likely due to the significantly wet 2019 winter/spring. For the piezometers with increasing water levels in 2019, water level readings returned to a decreasing trend at the end of 2019. In 2020, water levels for piezometers were generally level for the majority of the year. Four piezometers, C2-P01, C2-P02, C2-P03, C2-P04, showed an increase in water levels from May to September 2020, then decreased at the end of 2020. These fluctuations in water level appeared to continue for these four piezometers throughout 2021 but appear to be trending more level than prior years. Overall, water levels have decreased since Phase 1 cover placement by approximately 1 to 5 feet (net), which is summarized in Table 3. Water balance results from monitoring the cover show the Primary Test Section is performing well with annual percolation of 1 mm or less, even during the very wet 2019 winter/spring which allowed less than 0.1 percent of precipitation to percolate through the cover. These results indicate that after the Phase 2 cover is placed across Cell 2, the cover is expected to effectively minimize infiltrating precipitation from migrating into tailings. A wet precipitation season would have minimal impact on the water levels in the tailings. IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 5.3 Table 3. Piezometer Water Level Elevations During and After Phase 1 Cover Placement Piezometer Location on Cell Maximum Measured Water Level Elevation during Phase 1 Cover Placement (ft) Measured Water Level Elevation on 12/2/2022 (ft) Change in Water Level Elevation since Phase 1 Cover Placement (ft)* C2-P01 West 5612.55 5610.89 -1.66 C2-P02 West 5613.30 5610.98 -2.32 C2-P03 West 5612.31 5609.78 -2.53 C2-P04 West 5613.97 5611.08 -2.89 C2-P05 West 5608.39 5605.50 -2.89 C2-P06 West 5609.21 5606.37 -2.84 C2-P07 West 5610.08 5606.92 -3.16 C2-P08 West 5605.25 5602.77 -2.48 C2-P09 Near Sump 5602.94 5600.99 -1.95 C2-P10 Near Sump 5601.54 5599.96 -1.58 C2-P11 Near Sump 5602.38 5599.02 -3.36 C2-P12 Near Sump 5599.45 5594.59 -4.86 C2-P14 Near Sump 5603.99 5603.49 -0.5 C2-P15 Near Sump 5604.01 5601.68 -2.33 C2-P16 Near Sump 5604.37 5601.54 -2.83 C2-P13 East 5605.72 5601.92 -3.80 C2-P17 East 5607.49 5605.78 -1.71 C2-P18 East 5607.82 5604.41 -3.41 C2-P19 East 5609.09 5606.34 -2.75 C2-P20 East 5610.63 5608.73 -1.90 C2-P21 East 5612.40 5609.16 -3.24 C2-P22 East 5613.39 5609.47 -3.92 C2-P23 East 5614.24 5609.77 -4.47 *Negative number indicates a decrease in water level. IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 6.1 6.0 CONCLUSIONS Hydrology of the Primary Test Section during 2022 was consistent with expectations for a water balance cover in a semi-arid environment. Nearly all precipitation at the test section returned to the atmosphere via evapotranspiration. Runoff and lateral flow were essentially nil, and percolation was 0.3 mm. The annual percolation rate is similar to percolation rates reported in the literature for water balance covers in similar climates. The test section is functioning as expected and is consistent with the expectations for water balance covers in semi-arid climates. Vegetation observed during the 2022 spring evaluation exhibited below average plant vigor and growth in response to unfavorable (below-average) precipitation conditions. The results of the performance evaluation indicate that the Primary and Supplemental Test Sections are not trending to pass several success criteria. Per the SCA, success is not evaluated until the end of the official monitoring period. Further revegetation development is expected to occur throughout the performance period and future monitoring efforts to track the trajectory of revegetation development will occur annually for the remainder of the performance period. In addition, EFRI will monitor the Supplemental Test Section No. 2 to provide additional data for Cell 2 cover test section performance monitoring and to evaluate modifications to the revegetation plan to promote vegetation success. Total Cell 2 cover surface settlement ranged from 0 to 0.6 feet. This represents total settlement from the start of Phase 1 cover construction (April 2016) through December 2022. Settlement trends are similar to settlement monitoring after the initial interim fill was placed, with a quick response to the additional loading. The majority of total settlement due to Phase 1 cover placement is estimated to have occurred. Settlement is showing a decreasing trend and less than 0.05 feet of cumulative settlement with some minimal upward movement for 2022. Water levels for piezometers increased during the Phase 1 cover placement (late 2016 to early 2017) and then generally decreased until the wet winter/spring of 2019. In 2020 and 2021, water levels for piezometers were generally static for the majority of the year. However, a few locations showed increasing and then decreasing water levels, but now appear to be trending toward more static conditions. There was a slight rise in piezometer reading elevations for early 2022 but have generally stabilized throughout the year. Overall, water levels have decreased since Phase 1 cover placement by approximately 1 to 5 feet. Based on performance of the Cell 2 Primary Test Section, placement of the Phase 2 cover on Cell 2 would minimize precipitation infiltrating into the tailings and wet precipitation seasons would have minimal impact on water levels in the tailings. IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT 7.1 7.0 REFERENCES Benson, C., T. Abichou, X. Wang, G. Gee, and W. Albright, 1999. Test Section Installation Instructions – Alternative Cover Assessment Program, Geotechnics Report 99-3, Geological Engineering, University of Wisconsin-Madison. Benson, C., Abichou, T., Albright, W., Gee, G., and Roesler, A. 2001. Field Evaluation of Alternative Earthen Final Covers, International J. Phytoremediation, 3(1), 1-21. Energy Fuels Resources (USA) Inc. (EFRI), 2016. Reclamation Plan, White Mesa Mill, Blanding Utah, Revision 5.1, December 5. Energy Fuels Resources (USA) Inc. (EFRI), 2018. Reclamation Plan, White Mesa Mill, Blanding Utah, Revision 5.1, February 8. Stantec Consulting Services Inc. (Stantec), 2017a. White Mesa Uranium Mill, Cell 2 Cover Performance Test Section As-Built Report, June 30. Stantec Consulting Services Inc. (Stantec), 2017b. White Mesa Uranium Mill, Cell 2 Phase 1 Cover As- Built Report, July 18. Stantec Consulting Services Inc. (Stantec), 2018a. White Mesa Uranium Mill, Cell 2 Supplemental Test Section As-Built Report, February 26. Stantec Consulting Services Inc. (Stantec), 2018b. White Mesa Uranium Mill, Cell 2 Reclamation Cover 2017 Annual Performance Monitoring Report, May 2. Stantec Consulting Services Inc. (Stantec), 2019. White Mesa Uranium Mill, Cell 2 Reclamation Cover 2018 Annual Performance Monitoring Report, April 5. Stantec Consulting Services Inc. (Stantec), 2020. White Mesa Uranium Mill, Cell 2 Reclamation Cover 2019 Annual Performance Monitoring Report, February 14. Stantec Consulting Services Inc. (Stantec), 2021. White Mesa Uranium Mill, Cell 2 Reclamation Cover 2020 Annual Performance Monitoring Report, February 22. Stantec Consulting Services Inc. (Stantec), 2022. White Mesa Uranium Mill, Cell 2 Reclamation Cover 2021 Annual Performance Monitoring Report, February 24. Utah Department of Environmental Quality Division of Waste Management and Radiation Control (DWMRC). 2017. Executed Stipulation and Consent Agreement. White Mesa Uranium Mill. Radioactive Materials License Number UT 1900479. February 23. IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT FIGURES REGIONAL LOCATION MAP FIGURE 1 1009740 LOC MAP WHITE MESA MILL TAILINGS RECLAMATION FEB 2023ENERGY FUELS I !:I ; f I I i I ! i J l .--•,:,,--: 0 ~ ,~ _, _...,. V~i-_ .. \s . i~ C, r"~ A{ ... ~ ~ I ; .::;;i - . \, .. ..:.· ADAPTED FROM FIGURE 1-1 IN DENISON MINES (USA) CORPORATION, 2009 RECLAMATION PLAN WHITE M BLANDING, UTAH. VERSION 4.0. NOVEMBER ESA MILL, . -./ ':/ ;~-:7 .... ~ ~- ,;\. ~-~ PROJECT limimLEr--_______ _J() Stantec DATE I i .:i ____ ..1....--___ ____l... _____ ~====1 FILE NAME SUPPLEMENTAL TEST SECTIONS LOCATION MILL SITE BOUNDARY CELL 1 CELL 2 CELL 3 CELL 4A CELL 4B DESIGNED APPROVED FIGURE CHECKED ENERGY FUELS WHITE MESA MILL TAILINGS RECLAMATION BLANDING, UTAH SITE LOCATION MAP 2 233001001 FEB 2023 K REED B VAN M DAVIS PRIMARY TEST SECTION QRAWINQ RfffBfNCEOO· 1. ML C00IIDINM'ES REFER 10 UTNt STATE PLANE 90UTH. IWJU. US SURVEY FEET. 2.IWGEIIY'SOURCE:l!IING.2011 () Stantec 9.5' 0.5' 3.5' 3.0' 2.5' EROSION PROTECTION LAYER LAYER 3 - GROWTH MEDIUM LAYER 1 - INTERIM FILL LAYER 2 - COMPACTED COVER TAILINGS VEGETATION COVER PROFILE WITHIN LYSIMETER FIGURE 3 1009740 WM ET COVR FEB 2023 WHITE MESA MILL TAILINGS RECLAMATION ENERGY FUELS PROJECT ITI'i[E""TITL£ _____ _J () Stantec DATE FILE NAME RESTRICTED AREA BOUNDARY CELL2-P01 CELL2-P10 CELL2-P11 CELL2-P16 LEGEND: CELL 2 CELL 3 MILL SITE CELL 1 COVER PERFORMANCE TEST SECTION EXISTING GROUND SURFACE CONTOURS (IN FEET)(SEE DRAWING REFERENCE 2) LIMIT OF TOPOGRAPHIC SURVEY DESIGNED APPROVED FIGURE CHECKED ENERGY FUELS WHITE MESA MILL TAILINGS RECLAMATION BLANDING, UTAH CELL 2 SETTLEMENT MONUMENT AND PIEZOMETER LOCATIONS 4 233001001 FEB 2023 K REED B VAN M DAVIS 06 2\J/tELL2- CELL2-P04 06 2W3-S .-~·.········· · /,. · C)" 1/;. ·· .... ,' -. . . . v -P09 06 2W~ 5622 CELL2-P14 0 ~ 2W6-C CELL2-P07 06 2W4-S 0 0: CELL2-P15 1. EXISTING TOPOGRAPHY BASED UPON FILE PROVIDED FROl.l ENERGY FUELS ON JULY 20, 2015. PER ENERGY FUELS, GROUND SURFACE CONTOURS ARE FROt.l 2012 AERIAL SURVEY CONDUCTED BY JONES &: DaMILLE ENGINEERING INC., EXCEPT FOR CELLS 2 AND 3. CELL 2 TOPOGRAPHY FROM ENERGY FUELS SURVEY CONDUCTED OCTOBER 2013. CELL 3 TOPOGRAPHY FROM ENERGY FUELS SURVEY CONDUCTED ON JULY 8, 201 +. 2. EXISTING TOPOGRAPHY BASED ON FILES PROVIDED FROM ENERGY FUELS IN MAY 2017. CONTOURS ARE FROM DRONE SURVEY CONDUCTED BY JONES & DEMILLE ENGINEERING ON JUNE 9, 2017. • G~ C!':LL2-P18 06 2W7-C "' () Stantec 7 EXISTING GROUND SURFACE ELEVATION, FEET (SEE REFERENCE 1) EXISTING ROAD EXISTING WATER EXISTING TRAIL --x--EXISTING FENCE □ EXISTING STRUCTURE 6 EXISTING SETTLEMENT MONITORING POINT 0 CELL 2 PIEZOMETER LOCATIONS ,,,~ APPROXIMATE SUMP AND DRAIN I \ '-/ ACCESS LOCATION j I ,-_ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT APPENDICES IJ WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT Appendix A 2022 FIELD HYDROLOGY OF THE CELL 2 PRIMARY TEST SECTION AT THE WHITE MESA MILL IJ FIELD HYDROLOGY OF THE CELL 2 PRIMARY TEST SECTION AT THE WHITE MESA MILL ANNUAL REPORT FOR CALENDAR YEAR 2022 WHITE MESA MILL – TAILINGS MANAGEMENT CELL 2 ENERGY FUELS RESOURCES (USA) INC. SAN JUAN COUNTY, UTAH Craig H. Benson, PhD, PE, NAE 10 February 2023 i EXECUTIVE SUMMARY This report describes monitoring data collected from the Primary Test Section at the White Mesa Mill in San Juan County, Utah, which is being used to evaluate the water balance cover for Cell 2 of the tailings management area at the mill. The data were collected during the period 29 September 2016 to 31 December 2022. The data set includes the six full calendar years (2017 - 2022) of monitoring for the test section. This report emphasizes data collected in 2022. The water balance of the test section is summarized as follows: Calendar Year Water Balance Quantities (mm) c Precipitation Runoff Lateral Flow Evapo-transpiration ∆ Storage Percolation 2016 a 60 0 0 35 17 0.0 2017b 223 0 0 325 39 0.6 2018 163 0 0 125 38 0.9 2019 308 0 0 325 3 1.0 2020 128 0 0 171 -63 0.9 2021 223 0 0 242 -20 0.6 2022 180 0 0 169 25 0.3 Notes: a2016 is partial year; bdamage from vault flooding precluded measuring flows 7 Feb. 2017 – 25 March 2017; call water balance quantities rounded to nearest mm number except percolation, which is rounded to 0.1 mm. The hydrology of the test section during 2022 was consistent with expectations for a water balance cover in a semi-arid environment with lower-than-average annual precipitation. Precipitation in 2022 (180 mm) was substantially lower than the long-term average for the nearby Blanding, Utah station (355 mm, located at 37° 62' N, 109° 47' W with elevation 1829 m) operated by the National Weather Service, but was only modestly lower than the average annual precipitation recorded during monitoring the test section (204 mm from 2017 to 2022). Winter and spring in 2022 were considerably drier than average. Summer and fall in 2022 were wetter than winter and spring, but drier than average. Soil water storage gradually diminished throughout the year, continuing a trend that began in 2019, as water contents continued to gradually diminish at all depths except at the near surface. At the end of the 2022, soil water storage was at the lowest point since construction. Nearly all precipitation that reached the test section was returned to the atmosphere as evapotranspiration. A trace of runoff (0.1 mm) and lateral flow (0.01 mm) were transmitted. Annual percolation was 0.3 mm, the lowest measured for a full year during the monitoring period. Thermally driven flow has been the most significant mechanism contributing to the percolation recorded to date. ii TABLE OF CONTENTS EXECUTIVE SUMMARY i LIST OF TABLES AND FIGURES iii 1. INTRODUCTION 1 2. METEOROLOGICAL DATA 4 3. TEST SECTION DATA 7 4. SUMMARY AND CONCLUSIONS 17 5. REFERENCES 18 iii LIST OF TABLES AND FIGURES Table 1. Water balance quantities for the final cover test section at White Mesa from 09/29/16 to 12/31/22. Fig. 1. Schematic of cover profile evaluated at White Mesa. Fig. 2. Cross-section of test section showing layering (orange = interim layer, yellow = compacted layer, green = growth medium layer), lysimeter, pipe runs, and vault used to monitor flows. Fig. 3. Comparison of on-site meteorological data to historical data from the Blanding station operated by NWS: cumulative precipitation (a) and air temperature (b). Fig. 4. Cumulative precipitation and potential evapotranspiration (PET) on-site during 2022. PET was computed using the FAO method described in Allen et al. (1998) with on-site meteorological data. Fig. 5. Water balance graph for test section through 31 December 2022. Fig. 6. Relationship between annual precipitation (Pa), annual potential evapotranspiration (PETa), and annual evapotranspiration (ETa) for test section at White Mesa (solid squares) and from ACAP and other international studies (solid blue circles) as reported by Apiwantragoon et al. (2014). Fig. 7. Water content in the cover profile at each of depth of monitoring during the monitoring record. Symbols shown only on 0.5% of data for clarity (green = growth medium, orange/brown = compacted layer, blue = interim layer). Fig. 8. Soil water storage and cumulative percolation over time for the test section. Vertical dashed lines correspond to annual onset and cessation of percolation. Fig. 9. Daily average air temperature and daily average soil temperature at various depths in the test section (green = growth medium, orange = compacted layer, yellow = interim layer). Fig. 10. Thermal gradient in test section, thermal flow computed from thermal gradient using method in Globus and Gee (1995), and percolation recorded with the monitoring system. Fig. 11. Annual percolation for the test section at White Mesa in context of data from other sites in ACAP and other international studies as reported by Apiwantragoon et al. (2014). 1 1. INTRODUCTION The Primary Test Section was constructed at the White Mesa Mill in San Juan County, Utah in Summer 2016 to evaluate the field-scale hydrology of the final cover placed over the Cell 2 tailings management cell. The profile of the final cover design is shown in Fig. 1 and a cross- section of the test section is shown in Fig. 2. The cover is an earthen design employing water balance principles that is comprised of four layers (bottom to top): well-graded interim layer (760 mm, 2.5 ft), fine-textured compacted layer (915 mm, 3.0 ft), growth medium layer (1070 mm, 3.5 ft), and gravel-amended topsoil layer (150 mm, 0.5 ft) (Fig. 1). Construction documentation for the test section is described in Stantec (2017). The test section includes a drainage lysimeter and associated instruments (Fig. 2) based on the lysimeter design developed for the Alternative Cover Assessment Program (ACAP) as described in Benson et al. (1999, 2001). The instruments are used to monitor fluxes from the cover profile (runoff, lateral flow, percolation), state variables (soil water content and temperature at discrete monitoring points), and meteorological conditions. A datalogger collects data from the sensors at intervals ranging from hourly to as short as 30 seconds depending on the hydrological condition. A cellular modem transmits data stored on the datalogger to a computer off site on a daily basis. Data collection began on 29 September 2016 and continues uninterrupted. The sensors and data acquisition system used to monitor the test section are maintained and recalibrated annually. A data quality evaluation is conducted monthly for measurements from all sensors, and a data quality report (DQR) is issued quarterly. Instrumentation calibration and maintenance is conducted annually, most recently on 13 July 2022. This report describes data collected since inception of the test section, with particular emphasis on data collected in 2022. Section 2 compares meteorological data collected on-site to historical data from a nearby monitoring station operated by the National Weather Service (NWS). Section 3 describes hydrological data from the test section. Section 4 provides a summary and conclusions. 2 Fig. 1. Schematic of cover profile evaluated at White Mesa. 0.5 ft Erosion Layer 3.5 ft Growth Medium 3.0 ft Compacted Cover 0 2.5 ft Interim Layer = WCR or thermocouple 3 Fig. 2. Cross-section of test section showing layering (orange = interim layer, yellow = compacted layer, green = growth medium layer), lysimeter, pipe runs, and vault used to monitor flows. 5640 5640 I-w w u. 5630-r-5630 I-w w u. 'Z ---'Z 0 5620-5620 0 i= ' ~ ~ .L..l '-w cfj ..J 5610-"r-5610 -' w w ..__ I I I 5600 0+00 1+00 2+00 2+20 DISTANCE, FEET 4 2. METEOROLOGICAL DATA Detailed comparisons are made quarterly between the on-site meteorological data and meteorological data compiled by the National Weather Service at the Blanding, Utah station ( 37° 62' N, 109° 47' W, elevation 1829.1 m). Comparisons to NWS data in the quarterly DQRs indicate general agreement between the measurements on site and those made by NWS. Fig. 3 compares average daily precipitation (Fig. 3a) and average daily air temperature (Fig. 3b) measured on-site with long-term historical averages reported by NWS at the Blanding station. On-site precipitation in 2022 was considerably lower than the long-term average annual precipitation at the Blanding station (180 vs. 355 mm, Fig. 3a). Precipitation was lower only in 2018 (163 mm) and 2020 (128 mm) (Table 1). Annual precipitation has been below average recorded at the Blanding station throughout the entire monitoring period. All seasons were drier than average, with winter and spring particularly dry. Average air temperature at the test section generally falls within the long-term high and low temperatures recorded at the Blanding station (Fig. 3b). The long-term average precipitation record does not exhibit the short-term variability inherent in the actual precipitation record. Smoothing associated with long-term temporal averaging makes the long-term precipitation record smoother and more gradually varying compared to actual records. When a daily precipitation record is averaged over long periods, the number of days with non-zero precipitation diminishes (in the limit, the number of non-zero precipitation days is zero). The number of days with large precipitation events diminishes as well. For this reason, long-term precipitation records are not recommended for use in simulating the hydrology of covers (Albright et al. 2010), but they are useful for comparative analysis. Fig. 4 shows cumulative precipitation and potential evapotranspiration (PET) computed with the FAO method (Allen et al. 1998) for 2022. PET far exceeds precipitation throughout much of the year, indicating an excess of energy for evaporation and transpiration relative to the amount of water to manage. 5 Fig. 3. Comparison of on-site meteorological data to historical data from the Blanding station operated by NWS: cumulative precipitation (a) and air temperature (b). 400 -350 E E 300 ..__. C: 0 :.;::::; 250 (I] -·c.. ·u 200 Q) .... a.. Q) 150 > :.;::::; (I] "S 100 E ::::, u 50 0 N N --...... --...... 40 -30 u o..__. ~ .a 20 ~ Q) a. E 10 ~ 0 -10 N ~ ...... --...... --Blanding Historical Average --On-Site 2022 N N N N --N --N --...... ...... ...... --(W) --ll) --...... --Blanding Historical Max --Blanding Historical Min --On-Site Daily Avg. 2022 N ~ ...... --(W) N N --...... --O> N ~ ...... --...... ...... N N --...... --...... ...... (a) (b) (W) N --...... --...... 6 Fi g . 4 . Cu m u l a t i v e p r e c i p i t a t i o n a n d p o t e n t i a l ev a p o t r a n s p i r a t i o n ( PE T ) o n -si t e d u r i n g 20 2 2. P E T co m p u t e d u s i n g t h e F A O m e t h o d d e s c r i b e d i n A l l e n e t a l . ( 1 9 9 8 ) w i t h o n -si t e me t e o r o l o g i c a l d a t a . Cumulative On-Site Precipitation and Potential Evapotranspiration (mm) ...... ...... ...... ...... N ~ m ~ o N ~ m 0 0 0 0 0 0 0 0 1/1 /220 0 0 0 0 0 0 0 0 3/1/22 5/1/22 7/1/22 9/1/22 11/1/22 -0 ~ 0 -a· ~ g: ::, "'U m --i 1/1/23 ...... , .............................................................................................................................................. ....... 7 3. TEST SECTION DATA Table 1 summarizes the annual water balance for the test section. Fig. 5 shows the water balance graph for the test section. Table 1. Water balance quantities for the final cover test section at White Mesa from 09/29/16 to 12/31/22. Calendar Year Water Balance Quantities (mm) Precipitation Runoff Lateral Flow ET ∆ Storage Percolationc 2016a 60 0 0 35 17 0.0 2017b 223 0 0 325 39 0.6 2018 163 0 0 125 38 0.9 2019 308 0 0 325 3 1.0 2020 128 0 0 171 -63 0.9 2021 223 0 0 242 -20 0.6 2022 180 0 0 169 25 0.3 Notes: a2016 is partial year; bdamage from vault flooding precluded measuring flows 7 Feb. 2017 – 25 March 2017; call water balance quantities rounded to nearest mm number except percolation, which is rounded to 0.1 mm. Fig. 5 shows cumulative quantities for each water balance flux (precipitation, evapotranspiration, runoff, lateral flow, and percolation) as a function of time. Percolation is the flux from the base of the cover that is captured by the geocomposite drain in the base of the lysimeter and would normally flow into the tailings. Lateral flow is the flux of liquid occurring laterally at the interface between the growth medium and the compacted layer and is captured by a collection point at the downslope edge of the lysimeter. Fig. 5 also shows soil water storage (total water stored in the cover per unit surface area) as function of time. Soil water storage is computed by integrating the water content measurements over the volume of the test section at a given point in time. Each water balance quantity is measured directly except for evapotranspiration (ET), which is computed as the non-negative residual of the daily water balance: ET = P – R – L – Pr – ∆S (1) 8 Fig. 5. Water balance graph for test section through 31 December 2022. 1500 5 White Mesa, UT 0 C 3 C C o-m ;.:;E 4 -~E <" a.-(D ·-C :;o () 0 ~ ;.:; ET C a.. l! 1000 ::::J 0 G) --_=11 > a. --UJ 3 r -c (U (U m ::::J~ -Soil Water Precipitation (D E o ... ::::J a. IC m 0~ 'Tl CDW 0 C) G) 2 -~ (U > m ... -o-::::J -(U a. Cl) ::::J 500 ._ E ""(J G) ::::J __I (D aio ... 0 ~"C Surface 0 C 1 m ·o (U Runoff !:!: 0 Cl) ::::J -3 3 Lateral Flow - 0 0 9/20/16 10/7/17 10/24/18 11/10/19 11/26/20 12/13/21 12/31/22 9 where P = daily precipitation, R = daily runoff, L = daily lateral flow, Pr = daily percolation, and ∆S = daily change in soil water storage. ET computed with Eq. 1 includes actual ET and any errors in the water balance. For 2022, 169 mm of ET was computed using Eq. 1, which is slightly lower than annual precipitation. Cumulative annual ET computed with Eq. 1 is in agreement with the generalized relationship between annual ET, PET, and precipitation for water balance covers and natural watersheds, as shown in Fig. 6. Annual PET in Fig. 6 was computed with the on-site meteorological data using the FAO method described in Allen et al. (1998). The overall seasonal water balance trends shown in Fig. 5 are consistent with expectations for a water balance cover in a semi-arid climate with below average precipitation. During 2022, soil water storage continued to diminish gradually throughout the year, a trend that began in 2019. Water contents have been gradually diminishing at all depths except at the near surface (Fig. 7), with nearly all water cycling occurring in the upper 500 mm of the profile except in much wetter years. Under more typical conditions, soil water storage would accumulate significantly in fall and winter, and diminish in spring and summer, with water contents rising and falling at greater depths. Percolation began on 1 July 2022 and ceased on 5 November 2022, consistent with the beginning and end of percolation in all years except 2018, which had a very wet fall that caused percolation to persist longer than normal. In general, percolation begins between mid-June and mid-July, and ends between mid-October and mid-November (Fall 2018 is an exception). For each year in the record, initiation of percolation is unrelated to the magnitude of soil water storage, occurring when soil water storage is near a minimum. This indicates that mechanisms other than hydraulic gradients contribute to percolation from the cover. Thermal gradients likely have a significant influence on percolation from the cover profile, as thermally driven flows can comprise a substantial portion of deep drainage in semi-arid and arid environments (Milly 1996). The air and soil temperature records for the test section are shown 10 Fig. 6. Relationship between annual precipitation (Pa), annual potential evapotranspiration (PETa), and annual evapotranspiration (ETa) for test section at White Mesa (solid squares) and from ACAP and other international studies (solid blue circles) reported by Apiwantragoon et al. (2014). ....... 1-w a.. al -al 1-0.80 oW --cc o.Q .:::..., (U ~ ._ __ ·a a-o.so u, C C (U ~ ... --o O a. a. (U (U Ji Ji 0.40 -(U (U __ ::::,-c C C (I) <(o a.. 0.20 m :::J C C <( • ■ On-Site 2017 D On-Site 2018 D On-Site 2019 D On-Site 2020 D On-Site 2021 D On-Site 2022 • 0. 00 ...__...._____.____, _ _.__......____.__.,__...._____.____, _ _.__......____.__.,__...._____.____, _ _.__......___, 0 5 10 15 20 Annual Potential Evapotranspiration/Annual Precipitation (PET /P ) a a 11 Fig. 7. Water content in the cover profile at each of depth of monitoring during the monitoring record. Symbols shown only on 0.5% of data for clarity (green = growth medium, orange/brown = compacted layer, blue = interim layer). Growth Medium --------45 7 m m --------------6 8 6 m m ---+---914 mm Compacted Layer Interim Layer -----.-1 5 2 4 m m ~ 2 7 4 3 m m ~ 1 8 2 9 m m ----k-2134 mm 0.5 .------r-""T"""""T---r--.------r---r-T---r--.------r---r-T---r-T"""""T"""T""""T---r-T"""""T""""T"""""">C"""T"""T"""""T""""T"""""">C"""T""""T"""""T"---r--.------r-"T"""""T"---.-----, White Mesa 2 0.4 -C Cl) -C 0 U 0.3 L.. Cl) ~ 0 ·;:: 02 G) - E ::::, ~ 0.1 0.0 ~~~~~~~~~~~~~~~~~~~~ 9/1/16 9/1/17 9/1/18 9/1/19 9/1/20 9/1/21 9/1/22 12 . Fig. 8. Soil water storage and cumulative percolation over time for the test section. Vertical dashed lines correspond to annual onset and cessation of percolation. 800 6.0 I I I I I I t--00 I I I I I t--O> O> O> I 0 I N ..... ..... 0 ..... ..... N ..... N ..... > ..... ..... N N N N N 0 C .... -> > ::i ::i (13 ::i 0 > :j """) z ~ 0 ::i 0 ::i 0 0 """) """) """) z """) z """) z ,;:t-('I') N ..... ('I') 00 ,;:t-('I') ..... 5.0 ..... ..... N 0 N N ..... t--0 t--0 LO 700 0 ..... 0 (') -C E I 3 E 4.0 £ -D> (I) -C) 600 <" m (D L. "1J 0 -I 3.0 (D <f) Soil a L. Water 0 (I) D> -m 500 Storag~ -$'. o· J I 2.0~ 0 <f) 3 3 -I 400 Percolatio~ 1.0 I I I 300L=:t=~....L...L....L..----1.1.----l..----l:..,__LL...-.1....-...&...-..u..........!L..---'-.....I..L___J,L-L......1....L......J::I 0. 0 9/1/16 9/21/17 10/12/18 11/1/19 11/21/20 12/11/21 1/1/23 13 in Fig. 9. The temporal variation is consistent each year. The thermal regime changes orientation with the seasons, with the highest soil temperatures near the surface of the cover in early summer, and at the base of the cover in early winter. Temperatures are relatively uniform with depth in early spring and early fall. Consequently, the thermal gradient (hot to cold) is downward from late spring to late fall, and upward during the other portion of the year, as illustrated in Fig. 10. The thermal gradient in Fig. 10 was computed using the soil temperatures measured at 686 mm bgs and 2743 mm bgs. Temperatures recorded by the thermocouple second from the surface (686 mm bgs) were used to compute the thermal gradient, rather than temperatures from the uppermost thermocouple (457 mm bgs), to avoid variability in soil temperature associated with short-term fluctuations in air temperature. Positive thermal gradients correspond to downward heat flow and negative thermal gradients correspond to upward heat flow. The gradient varies systematically with the seasons each year, with a maximum of approximately +4 oC/m in early July to a minimum of approximately -4 oC/m in early January. Thermal fluxes were computed using the method in Globus and Gee (1995) and the thermal gradient in Fig. 10 using: (2) where qT is the thermal flux, KT is the thermal water conductivity (set at 2x10-11 m2/s-oC, Globus and Gee 1995), and ∆T/∆z is the thermal gradient. The cumulative downward thermal flux computed using this approach, which is captured in the drainage layer at the base of the lysimeter, is shown in Fig. 10. The timing and magnitude of the computed thermal flux resembles the percolation rate, suggesting that thermally driven flows are significant contributors to percolation. Fig. 11 shows annual percolation from the test section for each year in the record along with data compiled from USEPA’s Alternative Cover Assessment Program (ACAP) and other data sources, as reported by Apiwantragoon et al. (2014). Percolation data for 2017, 2018, 2020, and QT =K AT T -Az 14 Fig. 9. Daily average air temperature and daily average soil temperature at various depths in the test section (green = growth medium, orange = compacted layer, yellow = interim layer). • 457 mm -6-1524mm ---z:'.l--2 7 43 mm ■ 686 mm -----v-18 29 mm Air On-Site • 914 mm ----h--21 34 mm 40 40 35 30 ,--... 0 0 30 20 Ill 0 '< ......... Q) )> I.... 25 10 < J CD +-' -, cu Ill I.... (C Q) 20 CD c.. 0 ?. E -, ~ 15 ~ -10 3 0 "'C CD (f) 10 -, -20 Ill ..... C -, CD 5 -30 0 -40 U) ...... CX) O> 0 ...-N ...-...-...-T""" ~ ~ ~ - - --T""" ...-T""" T""" ...-...-...-- - --- - -O> O> O> O> O> O> O> 15 Fig. 10. Thermal gradient in test section, cumulative downward thermal flow computed from thermal gradient using method in Globus and Gee (1995), and percolation recorded with the monitoring system. _ 6.0 ,._.,.._......,....,.......,....._..._...~,._-................. _..._.._...,._.,.._......,.. ................... 10 E E -X :::, 5.0 u.. (0 E m 4.0 .c I- "-0 C 3.0 0 1u 0 ~ 2.0 n.. (I) > +i m 1.0 :::, E :::, Thermal Gradient Measured Percolation Computed Thermal Flux 5 --i :::,- <D 3 D> G> o m a. <D. :::, r+ -0 {) --5 ~ 0 0.0 l:::::l:::11:::::1::::~.1....L...1....1....&....1....l....L....1...1....i....&....l....&....&...1....a....ii....L..L...L...1...1....L...L.1....1...1....1....a....L..1....J -10 9/1/16 9/1/17 9/1/18 9/1/19 9/1/20 9/1/21 9/1/22 16 Fig. 11. Annual percolation for the test section at White Mesa in context of data from other sites in ACAP and other international studies as reported by Apiwantragoon et al. (2014). ■ On-Site 2017 D On-Site 2019 C On-Site 2021 D On-Site 2018 D On-Site 2020 C On-Site 2022 -100 E E -C: 0 :;::::; (U 0 ~ (I) a.. "'ffi :::, C: C: <( 10 1 • • ■□□co ·~ • • 0 0.1 ----- 0-250 6. 6. /',. £:,,L, 6. /',. /',. □ 6. 6. /',. /',. /',. /',. 6. ♦ ■ •♦ ■ ■ •• ■ ■ ■ •• ACAP Data -Solid Symbols Other Data -Open Symbols White Mesa -Large Solid Squares ·---■ □ 250-500 500-750 >750 Annual Precipitation (mm) 17 2022 fall in the middle of the data reported by Apiwantragoon et al. (2014) for the bin corresponding to annual precipitation between 0 to 250 mm/yr. For 2019, the percolation falls at the lower end of the data reported by Apiwantragoon et al. (2014) for annual precipitation between 250 and 500 mm/yr. This agreement indicates consistency with other water balance covers in similar climates. 4. SUMMARY AND CONCLUSIONS This report describes hydrological and meteorological data collected from the Cell 2 test section at the White Mesa Mill near Blanding, Utah. Data are reported for the period 29 September 2016 to 31 December 2022, with the discussion emphasizing data collected in 2022. The monitoring system for the test section has been collecting the required data, except for a short period in 2017 (7 February 2017 through 25 March 2017) when the flow monitoring systems were not functioning due to flooding damage. The following observations and conclusions are made based on the data collected: • The test section is functioning as expected, and the hydrology of the cover profile is consistent with the expectations for water balance covers in semi-arid climates. • Precipitation at the test section in 2022 (180 mm) was considerably lower than the long-term average recorded at the Blanding, Utah station (355 mm) operated by the NWS. Precipitation in winter and spring were much lower than average. Summer and fall were wetter, but still below average for the latter half of the year. • The test section hydrology is consistent with expectations for water balance covers in semi- arid and arid locations in the western US. Nearly all precipitation at the test section was returned to the atmosphere via evapotranspiration. A trace of runoff and lateral flow were recorded, and percolation was 0.3 mm. The annual percolation rate is similar to percolation rates reported in the literature for water balance covers in similar climates. 18 • Thermally driven flow has been the primary mechanism contributing to percolation. Each year percolation begins when soil water storage is near its lowest, and the thermal gradient is downward. Percolation ceases when the thermal gradient transitions to upward. Thermal fluxes computed using soil temperature data collected from thermocouples in the test section yielded a cumulative thermal flux comparable in timing and magnitude to the measured percolation rate. 5. REFERENCES Albright, W., Benson, C., and Waugh, W. (2010), Water Balance Covers for Waste Containment: Principles and Practice, ASCE Press, Reston, VA, 158 p. Allen, R., Pereira, L., Raes, D., and Smith, M. (1998), Crop Evapotranspiration-Guidelines for Computing Crop Water Requirements.” FAO Irrigation and Drainage Paper 56, Food and Agricultural Organization of the United Nations, Rome. Apiwantragoon, P., Benson, C., and Albright, W. (2014), Field Hydrology of Water Balance Covers for Waste Containment, J. Geotech. and Geoenvironmental Eng., 04014101-1-20. Benson, C., Abichou, T., Albright, W., Gee, G., and Roesler, A. (2001), Field Evaluation of Alternative Earthen Final Covers, International J. Phytoremediation, 3(1), 1-21. Benson, C., Abichou, T., Wang, X., Gee, G., and Albright, W. (1999), Test Section Installation Instructions – Alternative Cover Assessment Program, Environmental Geotechnics Report 99-3, Dept. of Civil & Environmental Engineering, University of Wisconsin-Madison. Cedar Creek (2020), White Mesa Mill Site, 2019 Revegetation Evaluation Cell 2 Primary and Supplemental Test Sections, report prepared for Energy Fuels Resources Inc by Cedar Creek Associates, Inc., Fort Collins, CO. Globus, A. and Gee, G. (1995), Method to Estimate Water Diffusivity and Hydraulic Conductivity of Moderately Dry Soil, Soil Sci. Soc. Am. J., 59, 684-689. Milly, P. (1996), Effects of Thermal Vapor Diffusion on Seasonal Dynamics of Water in the Unsaturated Zone, Water Resources Research, 32(3), 509-518. Stantec Consulting Services Inc. (Stantec), 2017, White Mesa Uranium Mill, Cell 2 Cover Performance Test Section As-Built Report, June 30. WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT Appendix B 2022 REVEGETATION EVALUATION CELL 2 PRIMARY AND SUPPLEMENTAL TEST SECTIONS IJ White Mesa Mill Site 2022 REVEGETATION EVALUATION CELL 2 PRIMARY AND SUPPLEMENTAL TEST SECTIONS FEBRUARY 2023 PREPARED BY: i Table of Contents 1.0 INTRODUCTION ................................................................................................................................... 2 1.1 General .............................................................................................................................................. 2 1.2 Background ....................................................................................................................................... 2 1.3 Precipitation ....................................................................................................................................... 3 2.0 REVEGETATION PERFORMANCE CRITERIA ................................................................................... 5 3.0 REVEGETATION MONITORING RESULTS ........................................................................................ 7 3.1 Primary Test Section ......................................................................................................................... 9 3.2 Supplemental Test Section ............................................................................................................... 2 3.2 Supplemental Test Section No. 2 ...................................................................................................... 5 4.0 PERFORMANCE EVALUATION .......................................................................................................... 8 5.0 REFERENCES .................................................................................................................................... 10 List of Charts and Tables Table 1. 2022 Site and Long-term Average Monthly Precipitation ......................................................... 4 Chart 1. Monthly Precipitation, White Mesa Mill Site, Blanding UT ......................................................... 4 Table 2. Summary of Species Observed on Each Test Section .............................................................. 7 Table 3. Summary of Average Cover .................................................................................................. 8 Chart 2. Average Ground Cover by Lifeform ....................................................................................... 9 Table 4. Primary Test Section Woody Plant Density ........................................................................... 10 Chart 3. Primary Test Section Perennial & Annual Cover Trend (Spring Survey) ................................... 12 Table 5. Supplemental Test Section Woody Plant Density………………………………………………………….………13 Chart 4. Supplemental Test Section Perennial & Annual Cover Trend (Spring Survey) .......................... 15 Table 6. Supplemental Test Section No. 2 Emergent Density .............................................................. 17 Chart 5. Supplemental Test Section No. 2 Emergent Density .............................................................. 17 Table 7. Success Criteria Comparison ............................................................................................... 20 2 White Mesa Mill Site 2022 Revegetation Evaluation Cell 2 Primary and Supplemental Test Sections 1.0 INTRODUCTION 1.1 General Cedar Creek Associates, Inc. (Cedar Creek) was contracted to evaluate revegetation performance on the Primary and Supplemental Test Sections for the Cell 2 tailings management cell at the Energy Fuels Resources (USA) Inc. (EFRI) White Mesa Uranium Mill Site (Mill Site). Cedar Creek conducted spring and fall onsite evaluations of revegetation on the test sections at the Mill site. These evaluations occurred on June 7, 2022, and September 12, 2022, respectively. This report summarizes findings from the spring and fall revegetation evaluations. A full analysis of results from the spring evaluation was also completed to evaluate progress towards meeting the revegetation success standards for the metrics of vegetation cover, species diversity, and woody plant density. The spring evaluations were selected for success comparisons because the test sections are dominated by cool season species, which are best evaluated in the spring. Fall evaluations will continue being conducted for the purpose of closely monitoring effects of precipitation on revegetation. 1.2 Background The Primary Test Section was constructed in 2016 within the Cell 2 cover, with subsequent seeding occurring in the fall of 2016. The test section is approximately 100 feet by 100 feet, with a 32-feet by 64- feet lysimeter centered within the test section. The test section was constructed with the full-depth Cell 2 cover profile. The Supplemental Test Section was constructed and seeded in fall of 2017. The Supplemental Test Section was constructed as a supplemental vegetation monitoring section to the Primary Test Section and is not being used to evaluate the entire cover profile. The test section is 100 feet by 100 feet in size to 3 match the dimensions of the Primary Test Section and is located to the north of the tailings management cells. EFRI constructed the test sections in accordance with the Stipulation and Consent Agreement (SCA) between EFRI and the Utah Department of Environmental Quality (UDEQ), Division of Waste Management and Radiation Control (DWMRC) executed on February 23, 2017. The SCA defines commitments and timeframes for completing placement of reclamation cover on Cell 2 and performance assessment of the cover system, in accordance with the approved Reclamation Plan. In 2021, EFRI constructed a Supplemental Test Section No. 2 adjacent to and similar to the Supplemental Test Section. This test section was constructed to provide additional data for the Cell 2 cover test section performance monitoring and to evaluate the revegetation plan to promote vegetation success. 1.3 Precipitation Table 1 and Chart 1 display precipitation on site for January 2018 to present compared with the long- term normal precipitation for the nearby town of Blanding, Utah. Regionally, 2022 can be considered a dry year with well below average precipitation. Precipitation conditions in the months prior to the spring revegetation evaluations were not favorable for plant growth (31% of average). Vegetation observed during the spring evaluation exhibited below average plant vigor and growth in response to unfavorable precipitation conditions. The spring months of March, April, and May are particularly important to plant growth and these months received 19.9 mm (75% of normal), 0.7 mm (3% of normal), and 0 mm (0% of normal) of precipitation, respectively. Precipitation prior to the fall revegetation evaluation was also below average (81% of average) but not as drastically as the spring evaluation. July, August, and September were all below average with 21.4 mm (73% of normal), 25.1 mm (72% of normal), and 31.8 mm (98% of normal) of precipitation, respectively. Vegetation observed during the fall evaluation also exhibited below average plant vigor and growth in response to unfavorable precipitation conditions. 4 Table 1 White Mesa - Precipitation - 2022 Site and Long-term Average Monthly Precipitation Site Precipitation Percent of Normal Site Precipitation Percent of Normal Site Precipitation Percent of Normal Site Precipitation Percent of Normal Site Precipitation Percent of Normal (mm)(%)(mm)(%)(mm)(%)(mm)(%)(mm)(%)(mm) January 8.2 23% 46.7 132% 17.1 48% 20.6 58%0.2 1%35.3 February 4.2 14% 65.6 214% 5.4 18% 17.4 57%7.9 26%30.7 March 8.3 31% 62.2 233% 23.7 89% 16.6 62% 19.9 75%26.7 April 3.0 14% 12.2 55%1.1 5%0.0 0%0.7 3%22.1 May 6.6 37% 36.7 203% 1.8 10%3.2 18%0.0 0%18.0 June 11.7 102% 2.3 20% 15.8 138% 11.2 98%5.8 51%11.4 July 6.4 22%4.7 16% 24.9 85% 35.4 121% 21.4 73%29.2 August 10.0 29%8.7 25%0.5 1%47.2 135% 25.1 72%35.1 September 1.5 5%0.0 0%22.0 68% 28.1 87% 31.8 98%32.5 October 81.7 222% 5.2 14%0.7 2%23.8 65% 17.6 48%36.8 November 5.6 21% 21.1 79%3.4 13%0.3 1%19.9 75%26.7 December 10.4 31% 42.5 126% 13.9 41% 19.7 58% 29.5 87%33.8 A NNUA L 157.6 47% 307.9 91% 130.3 39% 223.4 66% 179.8 53% 338.3 Mar-May 17.9 27% 111.1 166% 26.6 40% 19.8 30% 20.6 31% 66.8 July-Oct 17.9 18% 13.4 14% 47.4 49% 110.7 114% 78.3 81% 96.8 2018 2019 2020 2021 2022 Long Term Average Jan 8.2 46.7 17.1 20.6 0.2 35.3 Feb 4.2 65.6 5.4 17.4 7.9 30.7 Mar 8.3 62.2 23.7 16.6 19.9 26.7 Apr 3.0 12.2 1.1 0.0 0.7 22.1 May 6.6 36.7 1.8 3.2 0.0 18.0 Jun 11.7 2.3 15.8 11.2 5.8 11.4 Jul 6.4 4.7 24.9 35.4 21.4 29.2 Aug 10.0 8.7 0.5 47.2 25.1 35.1 Sep 1.5 0.0 22.0 28.1 31.8 32.5 Oct 81.7 5.2 0.7 23.8 17.6 36.8 Nov 5.6 21.1 3.4 0.3 19.9 26.7 Dec 10.4 42.5 13.9 19.7 29.5 33.8 2020 Blanding Long Term Average 2018 2019 2021 2022 8.2 4.2 8.3 3.0 6.6 11.7 6.4 10.0 1.5 5.6 10.4 46.7 12.2 36.7 2.3 4.7 8.7 0.0 5.2 21.1 42.5 17.1 5.4 23.7 1.1 1.8 15.8 24.9 0.5 22.0 0.7 3.4 13.9 20.6 17.4 16.6 0.0 3.2 11.2 35.4 47.2 28.1 23.8 0.3 19.7 0.2 7.9 19.9 0.7 0.0 5.8 21.4 25.1 31.8 17.6 19.9 29.5 0 15 30 45 60 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mi l l i m e t e r s Chart 1 -Monthly Precipitation, White Mesa Mill Site, Blanding, UT -2022 20182019202020212022Long Term Average 65.6 62.2 81.7-= --- 5 2.0 REVEGETATION PERFORMANCE CRITERIA Official performance monitoring of the Primary Test Section commenced on January 1, 2020, after two calendar years of calibration monitoring were completed. As defined in the SCA, performance monitoring will be conducted for five years (the "Performance Period"). Revegetation efforts will be considered successful when the following performance criteria per the SCA are met for both the Primary Test Section and Supplemental Test Sections at the end of the Performance Period. Criterion 1: Species Composition 1. Total vegetative cover shall be composed of at least: a. Five (5) perennial grass species, four (4) of which must be native species; b. One (1) perennial forb species; and c. Two (2) shrub species. All species applied towards this success standard must be a listed component of the reclamation seed mix, which can be found in Table D.1. of the Updated Tailings Cover Design Report (MWH 2015). Seeded species recorded during monitoring are indicated on tables below. Criterion 2: Vegetative Cover Criteria 1. Average cover must be at least 40%; 2. Individual grass and forb species applied towards the minimum 40% average cover criterion must have a relative cover of no less than 4% and no greater than 40%; 3. Reclaimed areas shall be free of state and county listed noxious weeds; and 4. Vegetative cover must be self-regenerating and permanent. Self-regeneration must be demonstrated by evidence of reproduction (i.e. seed production). All species applied to the minimum average cover success standard must be a listed component of the reclamation seed mix (MWH 2015). Species not on the list may be applied towards the vegetative cover criterion if it can be demonstrated that the species is native and is a desirable component of the revegetation community. Criterion 3: Shrub Density Criteria 1. A minimum woody plant density of 500 woody plants per acre must be achieved; and 2. Shrubs must be healthy and have survived at least two complete growing seasons before being evaluated against success criterion. 6 Per the SCA, if the vegetation criteria are not met, or more time is needed to satisfy the criteria, DWMRC may set new vegetation acceptance criteria based on lysimeter findings (i.e. percolation performance), revised ground water modeling, or consideration of change in annual precipitation and rate of vegetation growth on the test sections. During the 2022 spring vegetation survey, Cedar Creek added a Native Reference Area that will now be surveyed annually along with the test sections to collect information on how the test sections are performing in comparison to native vegetation communities. Native reference areas or analog sites are commonly used as a suitable comparison for revegetation success. Each year, the reference area is sampled, and the resulting data is used to establish a benchmark, then success criteria are set as a percentage of benchmark performance (typically between 70-90% of the reference area). In general, this approach is preferable to technical standards for revegetation performance criteria because the reference area benchmark accounts for local climatic conditions, where vegetation cover increases in surplus precipitation years and diminishes in droughty years. Essentially, using a reference area approach allows for the success criteria to adjust to site climate conditions. 7 3.0 REVEGETATION MONITORING RESULTS The results of 2022 vegetation monitoring at the Primary Test Section and Supplemental Test Section are described for each seasonal survey in the sections below. Table 2 provides a summary of all species observed in the test sections, including both those captured by cover sampling metrics and those noted as incidental observations. Table 3 provides a summary of average cover by species as determined by the 2022 monitoring surveys. Chart 2 presents a summary of relative cover by lifeform at each test section as determined by the 2022 monitoring surveys. Comparison between the Primary and Supplemental Test Section are made as they are both in their third growing season. Results of the Supplemental Test Section No. 2 and the Native Reference area are described separately below. Table 2 White Mesa -Vegetation Cover -2022 Summary of Species Observed on Each Test Section Primary Test Supplemental Area-> Section Test Section Grasses Spring Fall Spring Fall I A Bromus tectorum Cheatgrass X X X N p * Elymus elymoides Squirreltail X X N p Elymus lanceo/atus Thickspike Wheatgrass X N p * PascoJJvrum smithii Western Wheatqrass X X X N p * Poa secunda Sandberg Bluegrass X N A Vu/JJia octof/ora Six Weeks Fescue X Forbs N A Descurainia oinnata Western Tansvmustard X I A Descurainia sophia Fixweed X I A Erodium cicutarium Redstem Stork's Bill X I A Kochia scof)aria Summer Cvp~E:!~~ X X I A Portulaca o/eracea Little Hogweed X I A Sa/so/a tragus Russian Thistle X X X X I A Sisymbrium a/tissimum Tall Tumblemustard X X N p SJJhaera/cea coccinea Scarlet Globemallow X X N p Sohaera/cea orossu/arifo/ia Gooseberrvleaf Globemallow X Shrubs, Sub-shrubs, Cacti & Trees N p * Atrip/ex canescens Fourwing Saltbush X X N p Gutierrezia sarothrae Broom Snakeweed X X N p Lycium andersonii Waterjacket X N p Lvcium oal/idum Pale Desert-thorn X Species Observed Seeded Speci es Encountered 3 2 2 1 Total Species Encountered 7 16 * Indicates a seeded species N = Native, I = Introduced, P = Perennial, B = Biennial, A = Annual 8 Table 3 White Mesa -Vegetation Cover -2022 Summary of Average Cover Percent Ground Cover Based on Point-Intercept Sampling Primary Test Section SU,IJJ)lemental Test Area --> Section Grasses Spring Fall SJ)ring Fall I A Bromus tectorum Cheatgrass 0.2 0.1 0.6 - N p * Elymus elymoides Sq u i rrelta i I 8.0 0.3 -- N p * Pascopyrum smithii Western Wheatgrass 0.1 -0.1 0.1 N p * Poa secunda Sandberg Bluegrass -·-0.1 - N A Vulpia octollora Six Weeks Fescue --0.1 - Forbs N A Descurainia pinnata Western Tansymu.stard --0.2 - I A Erodium cicutarium Redstem Stork's Bill --7.3 - I A Kochia scoparia Summer Cypress 2.4 --- I A POrtulac.a oleracea Little Hogw eed ---0.2 I A Salsola tragus Russian Thistle 6.7 3.1 9.4 27.7 I A Sisvmbrium altissimum Tall Tumblemu.stard --0.7 - N p Sphaeralcea cocdnea Scarlet Globemallow --0.1 - Shrubs, Sub-shrubs, Cacti & Trees N p * Atriplex c.anescens Fourwing Saltbush 5.1 9.3 -- N p Gutierrezia sarothrae Broom Snakew eed --0.5 0.9 N p LycJum pal!idum Pale Desert-thorn --0.2 - Mean Total Plant Cover 22 .. 5 12.8 19.3 28.9 Rock 6.9 6.1 0.6 0.2 litter (including JJlant senscence in fall) 44.8 46.3 30.1 19.4 Bareqround 25.9 34.8 50.0 51.5 Total Perennial Cover 1.3.1 9.5 1.0 1 .. 0 Summary by Lifefonn: Perennial Grasses 8.1 0 . .3 0.1 0.1 Annual Grasses 0.2 0.1 0.7 0.0 Perennial Forbs 0.0 0.0 0.1 0.0 Annual & Biennial Forbs 9.1 3.1 17.7 27.9 Noxious / Aggressive Weeds ---- Shrubs, Sub-shrubs, Cacti & Trees 5.1 9..3 0.7 0.9 Sample Adeouacv Calculations: Mean= 22.5 12.8 19.3 28.9 Variance= 24.1 75.0 44.4 71.8 n= 15 15 15 15 n:min = 6.4 82.8 21 .. 5 15 .. 5 * Indicates a seede•d species N = Native, I = Introduced, P = Perennial, B = Biennial, A = Annual 9 3.1 Primary Test Section Spring 2022 Findings The Primary Test Section was evaluated with 15 transects during the spring survey of the sixth growing season. Table 2 displays all species observed in the Primary Test Section in 2022 including species recorded by cover sampling metrics and incidental observations. Raw data from the spring 2022 cover evaluation are presented in Appendix B. There was a total of 6 species observed, 3 of which were included in the seed mix used on the plot. Total ground cover in the Primary Test Section consisted of 22.5% live vegetation, 6.9% rock, 44.8% litter, and bare ground exposure of 29.5%. Perennial cover across the test section averaged 13.1%, with annual and biennial cover averaging 9.3%. No noxious weeds were observed. Below average precipitation and available water through the end of 2020 and into the spring of 2021 and spring of 2022 did not facilitate improved vegetation growth and vigor in the Primary Test Section vegetation. Dominant taxa were squirreltail (Elymus elymoides) averaging 8.0% cover and Russian Thistle (Salsola tragus) averaging 6.7% cover, with fourwing saltbush (Atriplex canescens) averaging 5.1% cover. These 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Spring Fall Spring Fall Primary Test Section Supplemental Test Section Pe r c e n t G r o u n d C o v e r Chart 2White Mesa -Revegetation Monitoring Average Ground Cover by Lifeform -2022 Bare ground Rock Litter (including plant senscence in fall) Noxious / AggressiveWeeds Annual & Biennial Forbs Annual Grasses Shrubs, Sub-shrubs,Cacti & Trees Perennial Forbs Perennial Grasses □ ■ C ■ C C □ C ■ 10 were the only Primary Test Section species with greater than 4% cover in spring 2022, and none of the species were overly dominant (contributing greater than 40% relative cover). The Primary Test Section had 28 fourwing saltbush plants present across the entire seeded area (lysimeter and surrounding area), which equates to 122 woody plants per acre shown in Table 4 below. This does not currently meet the success criteria of 400 woody plants per acre but has been generally increasing with each growing season. The following photos show the site conditions on the Primary Test Section during the spring 2021 evaluation compared with the spring 2022 evaluation. Primary Test Section – Spring Survey – June 8, 2021 Primary Test Section – Spring Survey – June 7, 2022 Table 4 White Mesa - Woody Plant Density - 2022 Summary of Woody Plant Density Area ——> Lifeform Scientific Name Common Name Shrub Atriplex canescens Fourwing Saltbush 28 Woody Plants Per Acre 122 Primary Test Section (0.23 acres) 11 Fall 2022 Findings The Primary Test Section was also evaluated with 15 transects during the fall survey of the sixth growing season. Table 2 displays all species observed in the Primary Test Section in 2022. Raw data from the fall 2022 cover evaluation are presented in Appendix B. There was a total of 5 species observed, 4 of which were captured by cover sampling metrics, of which 2 were included in the seed mix. Ground cover in the Primary Test Section consisted of 12.8% live vegetation, 6.1% rock, 46.3% litter (including plant senescence in fall), and bare ground exposure of 34.8%. Perennial cover across the test section averaged 9.5%, with annual and biennial cover averaging 3.3%. No noxious weeds were observed. Dominant taxa were fourwing saltbush averaging 9.3% cover and annual Russian thistle averaging 3.1% cover. These two species were the only species that met the minimum relative cover criterion of 4% but fourwing saltbush contributed to greater than 40% relative cover at 72.4%. The following photos show the site conditions on the Primary Test Section during the fall 2021 evaluation compared with the fall 2022 evaluation. Primary Test Section – Fall Survey –September 22, 2021 Primary Test Section – Fall Survey – September 12, 2022 1 Revegetation Performance Trend Chart 3 displays the perennial and annual cover on the Primary Test Section during the spring survey of the calibration period and year 1 through 3 of the performance period. The chart shows that perennial cover steadily increased through 2020. Annual species cover was particularly elevated in 2019 due to favorable precipitation conditions. After two spring growing seasons with below average precipitation in 2021 and 2022, perennial species cover has continued to decrease. 100 80 .. ., ""60 8 "II-"' j e (:, ~40 ~ ., a. 20 0 Chart 3 White Mesa -Revegetation Monitoring Primary Test Section Perennial/ Annual Cover Trend (Spring Survey} Year1 {2018) Year2 {2019) Calibration Period Year 1 {2020) Year 2 {2021) Year3 (2022) Performance Period Dt.lnnual Species Cover l!I PerennTal Species Cover Year4 (2023) SCA Perftomance Criteria =-400/o Years (2024) 2022 Native Ref Area 2 3.2 Supplemental Test Section Spring 2022 Findings The Supplemental Test Section was evaluated with 15 transects during the spring survey of the fifth growing season. Table 2 displays all species observed in the Supplemental Test Section in 2022. Raw data from the spring 2022 cover evaluation are presented in Appendix B. There was a total of 11 species observed, all of which were captured by cover sampling metrics and 2 of which were included in the seed mix. Ground cover in the Supplemental Test Section consisted of 19.3% live vegetation, 0.6% rock, 30.1% litter, and bare ground exposure of 50.0%. Perennial cover across the test section averaged 1.0%, with annual and biennial cover averaging 18.3%. No noxious weeds were observed. The dominant taxa were annual Russian thistle and Redstem Stork’s Bill (Erodium cicutarium), with 9.4% and 7.3% average cover, respectively. Russian thistle contributed greater than 40% relative cover. No seeded species met the minimum cover criterion of 4%. The Supplemental Test Section had 59 snakeweed (Gutierrezia sarothrae) and 22 waterjacket (Lycium andersonii) plants present across the entire seeded area, which equates to 353 woody plants per acre shown in Table 4 below. This does not currently meet the success criteria of 500 woody plants per acre but has been generally increasing with each growing season. The following photos show the site conditions on the Supplemental Test Section during the spring 2021 evaluation and spring 2022 evaluation. Table 5 White Mesa - Woody Plant Density - 2022 Summary of Woody Plant Density Area ——> Lifeform Scientific Name Common Name Subshrub Gutierrezia sarothrae Snakeweed 59 Shrub Lycium andersonii Waterjacket 22 Woody Plants Per Acre 353 Supplemental Test Section (0.23 acres) 3 Supplemental Test Section – Spring Survey – June 8, 2021 Supplemental Test Section – Spring Survey – June 7, 2022 Fall 2022 Findings The Supplemental Test Section was evaluated with 15 transects during the fall survey of the fifth growing season. Table 2 displays all species observed in the Supplemental Test Section in 2022. Raw data from the fall 2022 cover evaluation are presented in Appendix B. There was a total of 10 species observed in the Supplemental Test Section in the fall, only 4 of which were captured by cover sampling metrics and 1 of which was included in the seed mix. Ground cover in the Supplemental Test Section consisted of 28.9% live vegetation, 0.2% rock, 19.4% litter, and bare ground exposure of 51.5%. Perennial cover across the test section averaged 1.0%, with annual and biennial cover averaging 27.9%. No noxious weeds were observed. The dominant taxon was Russian thistle, with 27.7% average cover. All other species had less than 1% average cover. No seeded species met the minimum cover criterion of 4% and Russian thistle contributed more than 40% relative cover at 95.9% relative cover. The following photos show the site conditions on the Supplemental Test Section during the fall 2021 evaluation and fall 2022 evaluation. N NE I E SE 330 0 30 60 90 120 15 •I• I• l •I • I• I• I• I • I • I • I • I • I • I • I • I• t • l • I 4 Supplemental Test Section – Fall Survey – September 21, 2021 Supplemental Test Section – Fall Survey – September 12, 2022 Revegetation Performance Trend Chart 4 displays the perennial and annual cover of the revegetation on the Supplemental Test Section during the spring survey of the calibration period and year 1 through 3 of the performance period. The chart shows that perennial species cover has remained diminished, and cover of annual species dominates. Annual cover was decreasing significantly each year until favorable precipitation in 2022 caused an increase in annual cover for the year. Chart 4 White Mesa -Revegetation Monitoring Supplemental Test Section Perennial / Annual Cover Trend (Spring Survey) 100 □Annual Species Cover c Pe~onial Spec.ies Cover 80 SCA Perf1·0man.ce Criteria = 400/o "'70.!. ~ - 43.9 20 -3.20 0 :u I I 18.39 9.9 .iT__ --•-& . -·-Year1 Year2 Year1 Year 2 Year 3 Year4 Year s 2022 {2018) (2019} {2020} {2021) (2022} (2023) (2024} Calibration Period Performance Period Native Ref Area 5 3.2 Supplemental Test Section No. 2 Spring 2022 Findings The Supplemental Test Section No. 2 was evaluated with 15 transects during the spring survey of the third growing season. Raw data from the spring 2022 cover evaluation are presented in Appendix B. There was a total of 17 species observed, all of which were captured by cover sampling metrics and 2 of which were included in the seed mix. Total ground cover in the Supplemental Test Section No. 2 consisted of 17.7% live vegetation, 1.1% rock, 16.8% litter, and bare ground exposure of 64.4%. Perennial cover across the Supplemental Test Section No. 2 averaged 5.5%, with annual and biennial cover averaging 12.2%. No noxious weeds were observed. The dominant taxa were annual Redstem Stork’s Bill and Russian thistle, with 6.3% and 5.3% average cover, respectively. No species had over 40% relative cover. No seeded species met the minimum cover criterion of 4%. The diversity of species observed is encouraging for eventual performance in favorable conditions. A photo showing the site conditions during the spring evaluation in 2022 is presented below. Fall 2022 Findings The Supplemental Test Section No. 2 was evaluated with 15 transects during the fall survey of the third growing season. Raw data from the spring 2022 cover evaluation are presented in Appendix B. There was a total of 8 species observed, all of which were captured by cover sampling metrics and 1 of which were included in the seed mix. Total ground cover in the Supplemental Test Section No. 2 consisted of Supplemental Test Section No. 2 SE s I SW w W 150 180 210 240 270 300 I • I • I • I • I • I • I • I • I • I • I • I • I • I • I • I • I • I • I • 0 215°SW (T) @ 37°33'4"N, 109°29'46"W ±19ft & 5691ft 6 19.2% live vegetation, 0.1% rock, 14.9% litter, and bare ground exposure of 65.8%. Perennial cover across the Supplemental Test Section No. 2 averaged 2.3%, with annual and biennial cover averaging 16.9%. No noxious weeds were observed. The dominant taxa were Russian thistle averaging 16.8% cover and James’ Galleta (Pleuraphis jamesii) averaging 1.2% cover. Russian thistle contributed greater than 40% relative cover at 87.5%. No seeded species met the minimum cover criterion of 4%. The diversity of species observed is encouraging for eventual performance in favorable conditions. A photo showing the site conditions during the fall evaluation in 2022 is presented below. 3.3 Native Reference Area Spring 2022 Findings The Native Reference Area was evaluated with 15 transects during the spring survey. Raw data from the spring 2022 cover evaluation are presented in Appendix B. There was a total of 4 species observed, all of which were captured by cover sampling metrics. Total ground cover in the Native Reference Area consisted of 19.7% live vegetation, 0.3% rock, 27.9% litter, and bare ground exposure of 52.1%. Perennial cover across the Native Reference Area averaged 19.5%, with annual and biennial cover averaging 0.2%. No noxious weeds were observed. A photo showing the site conditions during the spring evaluation in 2022 is presented below. Supplemental Test Section No. 2 7 Spring Survey Conditions (June 7th 2022) Fall 2022 Findings The Native Reference Area was evaluated with 15 transects during the fall survey. Raw data from the fall 2022 cover evaluation are presented in Appendix B. There was a total of 3 species observed, all of which were captured by cover sampling metrics. Total ground cover in the Native Reference Area consisted of 25.3% live vegetation, 0.1% rock, 17.9% litter, and bare ground exposure of 56.7%. Perennial cover across the Native Reference Area averaged 19.9%, with annual and biennial cover averaging 5.4%. No noxious weeds were observed. E SE Sf SW W 90 120 150 18 210 240 270 l•l•l•l•l•l•l•l•l•l•l•l•l•l•l•l•l•l•I• 0182°S (T) @ 37°32'35"N, 109°29'51"W ±55ft & 5656ft 8 4.0 PERFORMANCE EVALUATION The revegetation performance criteria applicable to the Primary Test Section and Supplemental Test Section are fully described in Section 2.0. As described in the SCA, success is not evaluated until the end of the Performance Period. Therefore, this performance evaluation is only presented for discussion purposes. The spring evaluations were selected for the performance evaluation because the test sections are dominated by cool season species, which should be evaluated in the spring. Fall evaluations will continue to be conducted based on the implication that precipitation events have a strong effect on the establishment of revegetation. These effects are best monitored during the two seasons in which most of the areas annual precipitation falls, which are spring and the fall monsoonal season. The results of the performance evaluation are summarized in Table 7. In Year 3 (2022) of the performance period, both the Primary and Supplemental Test Sections are not passing several of the success criteria. However, further revegetation development is expected to occur throughout the performance period and future monitoring efforts to track the trajectory of revegetation development will occur annually, in the spring and fall, for the remainder of the performance period. The results from the native area sampling provide some context to the revegetation performance. The poor precipitation conditions have also diminished perennial communities in undisturbed areas, enough that even native ground could not pass the success criteria. At this point of the evaluation period, it is unlikely that the Primary and Supplemental sections will meet performance criteria by the end of the final year of the Performance Period (year 5), primarily due to the limited grass diversity on the Primary Test Section and the general poor performance of the Supplemental Test Section. It is too early to determine how well Supplemental Test Section No. 2 will progress. The Supplemental Test Section No. 2, which EFRI constructed with a modified revegetation plan as noted above, is also performing as expected in an unfavorable (dry) precipitation year. However, the diversity of species observed at the Supplemental Test Section No. 2 is encouraging and indicates the potential for better performance in favorable (wet) precipitation conditions for this test section. 9 Primary Test Section Supplemental Test Section Supplemental Test Section #2 1. Species Composition a. 5 or greater perennial grass species 2 2 10 4 or greater grass species are native 2 2 9 b. At least 1 perennial forb 0 1 2 c. At least 2 shrub species 1 2 1 2. Vegetative cover a. 40% or greater total vegetative cover*13.1%1.0%5.5% b. Comprised of species with relative cover between 4% and 40%*1 2 3 c. Free of State and County listed noxious weeds None None None d. Self generating and permanent+Observed Observed Observed 3. Shrub Density a. Minimum 500 stems per acre 144 536 Not Sampled Yet b. Healthy, surived minimum 2 growing seasons Observed Observed Not Sampled Yet * Species listed in Table D.1 must be used to achieve the cover performance criteria (MWH 2015). Individual species not listed in Table D.1 may be acceptable if the species is native or adapted to the area and is a desirable component of the reclaimed project site. + Self-regeneration shall be demonstrated by evidence of reproduction, such as tillers or seed production. Table 6 White Mesa - Success Evaluation - 2022 Performance Comparison 10 5.0 REFERENCES MWH America’s, Inc. 2015. Updated Tailings Design Cover Report. Prepared for Energy Fuels Resources (USA) Inc. Appendix A Vegetation Sampling Methodology VEGETATION SAMPLING METHODOLOGY Determination of Ground Cover Ground cover at each sampling site was determined utilizing the point-intercept methodology as illustrated on Figure 1, with the exception of the procedure for determining sample site location. Due to the size of the test sections, sample points were instead determined in the field to preclude overlapping transects. Cedar Creek utilizes state-of-the-art instrumentation that it has pioneered to facilitate much more rapid and accurate collection of data. Implementation of the technique for the sampling effort occurred as follows: First, a transect of 10 meters length was extended from the starting point of each sample site toward the direction of the next site to be sampled. Then, at each one-meter interval along the transect, a “laser point bar” was situated vertically above the ground surface, and a set of 10 readings were recorded as to hits on vegetation (noted by species), plant, litter, rock (>2mm), or bare ground. Hits were determined at each meter interval by activating a battery of 10 specialized lasers situated along the bar at 10-centimeter intervals and recording the variable intercepted by each of the narrow (0.02”) focused beams (see Figure 1). In this manner, a total of 100 intercepts per transect were recorded resulting in 1 percent cover per intercept. This methodology and instrumentation facilitate the collection of the most unbiased, repeatable, precise, and cost-effective ground cover data possible. Furthermore, the point-intercept procedure has been widely accepted in the scientific community as the protocol of choice for vegetation monitoring and is used extensively within the mining industry in connection with bond release determinations. As noted in the 2019 monitoring report, the abundance of available water throughout the early growing season facilitated above average growth and vigor in both test sections. An abnormally tall canopy of 2019 senesced vegetation had obscured much of the 2020 new growth, producing results that significantly underestimate the true extent of live vegetative ground cover. In an effort to capture a more accurate quantification of 2020 new growth, hits that would have been recorded on perennial live vegetative cover if not for overlying litter were recorded separately from both a species hit and litter. These hits were treated as live vegetative hits during data analysis and were counted towards the cover success criteria. Figure 1: Sampling Procedure Ground Cover Transect (Set-up points at 1-meter intervals) Sample Site (Starting Point) \ ~ ~ 1/1 ij .,.. .,..r --~ Re vegetated Unit laser/ Point-Intercept Bar (Intercepts at 1 O cm intervals - note path of'' beams'' for" hits" on ground cover) Note: 10 set~up points per transect with 1 o fnte(cepts per set-up point results in 100 intercepts per transect Laser Bar 1 Laser Focused Beam (0.02' spot) j (Special J.. for Daylight Visiblllty) \ / ~---1-.; Hit recorded as ~em/species / I ~---I I I I Determination of Woody Plant Density Woody plant density was evaluated during the spring evaluation of the Primary and Supplemental Test Sections. Determination of woody plant density was completed using total enumeration to facilitate a more accurate comparison of shrub survival between sampling years. Cedar Creek traversed the Test Sections in a systematic manner while counting all shrubs encountered by species. These totals were used to quantify woody plants per acre by species. Due to the relative stability in shrub populations lacking significant disturbance, woody plant density only requires a single sampling each year and was conducted during the spring 2022 evaluations. Sample Adequacy Determination Ground cover sampling was conducted to a minimum of number of 15 samples. The procedure is such that sampling continues until an adequate sample, nmin, has been collected in accordance with the Cochran formula (below) for determining sample adequacy, whereby the population is estimated to be within 10% of the true mean (µ) with 90% confidence. These limits facilitate a very strong estimate of the target population. When the inequality (nmin ≤ n) is true, sampling is adequate and nmin is determined as follows: nmin = (t 2s 2) / (0.1 )2 where: n = the number of actual samples collected (initial size = 15) t = the value from the one-tailed t distribution for 90% confidence with n-1 degrees of freedom; s 2 = the variance of the estimate as calculated from the initial samples; = the mean of the estimate as calculated from the initial samples. As indicated above, this formula provides an estimate of the sample mean to within 10% of the true population mean (µ) with 90% confidence. Calculations of the mean and variance are based on “total plant cover” or total live vegetative cover. x x - I Appendix B Raw Data Table 7 White Mesa -Veaetation Cover -2022 Primary Test Section -Spring Survey Percent Ground Cover Based on Point-InterceDt Samnllnn Transect No.-> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Average Relative Grasses Cover Cover Freq. I A Bromus tectorum Cheatgrass 1 2 0.2 0.9 13 . ~ N p Elymus elymoides Squirreltail 6 11 9 18 6 6 9 9 4 8 13 3 5 8 5 8.0 35.6 100 N p Pascoovrum smithii Western Wheatarass 1 0.1 0.3 7 rorbs I A Kochia scoparia Summer cypress 1 5 6 3 5 4 4 1 1 1 3 1 1 2.4 10.7 87 I A Sa/so/a traous Russian Thistle 3 3 2 5 5 7 14 11 7 11 6 8 8 11 6.7 30.0 93 Shrubs, Sub-shrubs, cacti & Trees N p Atria/ex canescens Fourwina Saltbush 13 14 3 14 10 14 8 5.1 22.6 47 Mean Total Plant Cover 20 19 18 24 30 15 23 24 30 16 24 20 30 19 25 22.5 Rock 1 6 4 2 1 11 8 14 9 7 7 9 10 6 8 6.9 Litter 62 44 59 46 45 24 32 35 34 54 46 45 39 56 51 44.8 Bare around 17 31 19 28 24 50 37 27 27 23 23 26 21 19 16 25.9 Perennial Plant Cover 19 11 9 18 20 6 12 9 18 8 13 14 19 8 13 13.1 Sample Adequacy calculations: Plant Cover Mean = 22.47 t= 1.35 n= 15 Variance = 24.12 Omin = 8.65 N = Native, I = Introduced, P = Perennial, 8 = Biennial, A = Annual Table 8 White Mesa - Vegetation Cover -2022 Primary Test Section - Fall Survey Percent Ground Cover Based on Point-Intercept Samolin<l TransectNo.-> I 1 2 3 4 5 I 6 7 8 9 10 11 12 13 14 15 Average Relative Grasses Cover Cover Freq. I A Bromus tectorum Cheatgrass 2 0.1 1.0 7 N p EIYmus e!Ymotdes SQUlrreltall 2 ! ! 0.3 2.1 20 Forbs I A Sa/so/a traous Russian Thistle 4 2 4 4 2 3 2 5 3 11 2 5 3.1 24.5 80 Shrubs, Sub-shrubs, cacti & Trees N p Atrip/ex ecnescens Fourwino Saltbush 8 8 8 17 18 17 22 3 33 5 9.3 72.4 67 Mean Total Plant Cover 14 10 13 5 19 20 3 2 5 20 22 11 5 33 10 12.8 Rock 9 1 5 5 7 6 7 8 6 3 8 4 6 5 11 6.1 Litter 49 65 43 57 41 53 62 60 47 47 14 47 45 44 21 46.3 Bare <1round 28 24 39 33 33 21 28 30 42 30 56 38 44 18 58 34.8 Perennial Plant Cover 10 8 9 1 17 18 0 0 0 17 22 0 3 33 5 9.5 Sample Adequacy calculations: Plant Cover Mean = 12.80 t= 1.35 n= 15 Variance = 75.03 nm;n = 82.85 N = Native, I = Introduced, P = Perennial, B = Biennial, A = Annual Table 9 White Mesa -Vegetation Cover -2022 Supplemental Test Section -Spring Survey Petcent Ground Cover Based on Point-Int ercept Sampi ng Transect No.-> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Average Relative Cover Cover Freq. Grasses I A Bromus tedorum Cheatgrass 4 2 2 1 0.6 3.1 27 N p Pascopyrum smithii Western Wheatgrass 1 0.1 0.3 7 N p Poasecunda Sandbero Blueorass 1 0.1 0.3 7 N A Vu/pia odoflora Six Weeks Fescue 1 0.07 0.3 7 Forbs N A Descurainia pinnata Western Tansymustard 1 1 1 0.2 1.0 20 I A Erodium dcutarium Redstem Stork's Bill 6 4 3 3 6 7 5 15 20 4 2 14 13 8 7.3 37.9 93 I A Sa/so/a traous Russian Thistle 17 12 19 6 5 17 17 7 6 7 3 10 8 7 9.4 48.6 93 I A Sisymbrium altissimum Tall Tumblemustard 1 1 2 7 0.7 3.8 27 N p SPhaeralcea cocdnea Scarlet Globemallow 1 1 0.1 0.7 13 Shrubs, Sub-shrubs, cacti & Trees N p Gutierrezia sarothrae Broom Snakew eed 2 6 0.5 2.8 13 N p Lydum pa/lidum Pale Oc::;crt-thorn 2 1 0.2 1.0 13 Mean Total Plant Cover 20 19 26 10 8 27 26 18 21 27 7 15 23 22 21 19.3 Rock 2 0 2 0 0 0 0 0 0 0 2 1 1 0 1 0.6 Litter 25 41 37 35 52 20 18 20 15 24 50 50 24 20 20 30.1 Bare qround 53 40 35 55 40 53 56 62 64 49 41 34 52 58 58 50.0 Perennial Plant Cover 2 0 2 0 o r o • o • 3 0 0 0 2 • 0 0 6 1.0 Sample Adequacy Calculations: Plant Cover Mean = 19.33 t= 1.35 n= 15 Variance = 44.38 nm;n = 21.48 N = Native, I = Introduced, P = Perennial, B = Biennial, A = Annual Table 10 White Mesa -Veaetation Cover -2022 Supplemental Test Section -Fall Survey Percent Ground Cover Based on Point-Intercept Samphng Transect No.-> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Average I Relative I Cover Cover Freq. Grasses N p Pascopyrum smithii Western Wheatorass 1 1 0.1 I 0.5 I 13 Forbs I A Portu/aa, o/eracea Little Hogweed 1 1 1 0.2 I 0.7 I 20 I A Sa/so/a traous Russian Thistle 26 15 25 32 22 16 20 43 34 22 45 27 23 37 29 27.7 95.9 100 Shrubs, Sub-shrubs, cacti & Trees N p Gutierrezia Sarothrae Broom Snakeweed 3 5 5 0.9 I 3.0 I 20 Mean Total Plant Cover 27 15 26 32 22 19 25 44 35 28 45 27 23 37 29 28.9 Rock 0 1 0 0 0 1 0 0 0 0 0 0 1 0 0 0.2 Litter 38 44 22 18 22 13 19 19 17 15 10 21 7 10 16 19.4 Bare Qround 35 40 52 50 56 67 56 37 48 57 45 52 69 53 55 51.5 Perennial Plant Cover 1 0 0 0 0 3 5 0 1 5 0 0 0 0 0 1.0 Sample Adequacy Calculations: Plant Cover Mean = 28.93 t= 1.35 n= 15 Variance = 71.78 nm;n = 15.51 N = Native, I = Introduced, P = Perennial, B = Biennial, A = Annual Table 11 White Mesa - Vegetation Cover - 2022 Supplemental Test Section No. 2 - Spring Survey Percent Ground Cover Based on Point-Intercept Sampling Transect No.——> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 N P Achnatherum hymenoides Indian Ricegrass 1 1 0.1 0.8 13 N P Elymus elymoides Squirreltail 1 1 0.1 0.8 13 N P Elymus lanceolatus ssp psammophilus Streambank Wheatgrass 1 0.1 0.4 7 N P Elymus trachycaulus ssp trachycaulus Slender Wheatgrass 1 0.1 0.4 7 N P Pascopyrum smithii Western Wheatgrass 2 1 1 1 1 0.4 2.3 33 N P Pleuraphis jamesii James' Galleta 1 1 3 2 1 2 2 0.8 4.5 47 N P Poa secunda Sandberg Bluegrass 1 1 2 1 2 0.5 2.6 33 N P Pseudoroegneria spicata Bluebunch Wheatgrass 3 2 3 2 3 1 1 1 1 1 1.2 6.8 67 N P Sporobolus cryptandrus Sand Dropseed 1 1 0.1 0.8 13 I P Thinopyrum intermedium Intermediate Wheatgrass 1 2 4 1 3 1 3 1 1 2 2 1 3 2 1.8 10.2 93 I A Erodium cicutarium Redstem Stork's Bill 9 2 6 6 5 5 9 4 11 2 5 6 13 11 6.3 35.3 93 N A Lappula redowskii Flatspine Stickseed 1 0.1 0.4 7 I A Salsola tragus Russian Thistle 7 4 5 3 2 13 8 9 4 7 3 2 1 5 6 5.3 29.7 100 I A Sisymbrium altissimum Tall Tumblemustard 1 2 2 5 0.7 3.8 27 N P Sphaeralcea coccinea Scarlet Globemallow 1 0.1 0.4 7 N P Sphaeralcea grossulariifolia Gooseberryleaf Globemallow 1 1 0.1 0.8 13 N P Gutierrezia sarothrae Broom Snakeweed 1 0.1 0.4 7 Total Plant Cover 20 11 15 14 15 24 24 21 22 11 16 13 13 24 23 Rock 2 0 1 1 4 1 0 0 3 0 3 0 0 1 0 Litter 15 10 29 37 28 4 3 2 1 6 31 34 37 7 8 Bare ground 63 79 55 48 53 71 73 77 74 83 50 53 50 68 69 Perennial Plant Cover 3 5 4 5 7 6 5 8 5 2 8 5 7 6 6 Plant Cover Mean =t=1.35 n=15 Variance =nmin = N = Native, I = Introduced, P = Perennial, B = Biennial, A = Annual 64.4 Average Cover Relative Cover Freq.Grasses Forbs Shrubs, Sub-shrubs, Cacti & Trees Mean 17.7 1.116.8 5.5 Sample Adequacy Calculations:17.73 24.78 14.26 , Table 12 White Mesa - Vegetation Cover - 2022 Supplemental Test Section No. 2 - Fall Survey Percent Ground Cover Based on Point-Intercept Sampling Transect No.——> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 N P Achnatherum hymenoides Indian Ricegrass 1 0.1 0.3 7 N P Bouteloua gracilis Blue grama 1 1 1 1 2 2 1 2 1 0.8 4.2 60 N P Pascopyrum smithii Western Wheatgrass 1 1 0.1 0.7 13 N P Pleuraphis jamesii James' Galleta 3 5 1 2 3 3 1 1.2 6.3 47 N P Sporobolus cryptandrus Sand Dropseed 1 0.1 0.3 7 I P Thinopyrum intermedium Intermediate Wheatgrass 1 0.1 0.3 7 I A Salsola tragus Russian Thistle 20 28 24 13 18 20 15 5 16 13 11 23 7 17 22 16.8 87.5 100 I A Sisymbrium altissimum Tall Tumblemustard 1 0.1 0.3 7 None 0.0 0.0 0 Total Plant Cover 25 29 25 20 20 21 15 5 18 15 17 24 12 19 23 Rock 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 Litter 8 5 6 13 8 11 19 32 17 22 20 24 17 14 8 Bare ground 67 66 69 67 72 67 66 63 65 63 63 52 71 67 69 Perennial Plant Cover 5 0 1 7 2 1 0 0 2 2 5 1 5 2 1 Plant Cover Mean =t=1.35 n=15 Variance =nmin = N = Native, I = Introduced, P = Perennial, B = Biennial, A = Annual 65.8 Average Cover Relative Cover Freq.Grasses Forbs Shrubs, Sub-shrubs, Cacti & Trees Mean 19.2 0.114.9 2.3 Sample Adequacy Calculations:19.20 35.74 17.54 . Table 13 White Mesa - Vegetation Cover - 2022 Native Reference Area - Spring Survey Percent Ground Cover Based on Point-Intercept Sampling Transect No.——> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 None 0.0 0.0 0 I A Salsola tragus Russian Thistle 3 0.2 1.0 7 N P Artemisia tridentata Big Sagebrush 2 3 7 5 4 18 1 5 3.0 15.2 53 N P Gutierrezia sarothrae Broom Snakeweed 8 12 8 9 27 18 16 19 13 22 20 25 11 19 19 16.4 83.1 100N P Opuntia polyacantha Plains Pricklypear 2 0.1 0.7 7 Total Plant Cover 10 15 8 16 32 20 16 19 13 25 24 25 29 20 24 Rock 0 0 0 1 0 0 0 0 0 0 0 0 0 2 1 Litter 31 41 10 37 37 17 35 35 33 28 18 28 23 21 25 Bare ground 59 44 82 46 31 63 49 46 54 47 58 47 48 57 50 Perennial Plant Cover 10 15 8 16 32 20 16 19 13 22 24 25 29 20 24 Plant Cover Mean =t=1.35 n=15 Variance =nmin = N = Native, I = Introduced, P = Perennial, B = Biennial, A = Annual 52.1 Average Cover Relative Cover Freq.Grasses Forbs Shrubs, Sub-shrubs, Cacti & Trees Mean 19.70.3 27.9 19.5 Sample Adequacy Calculations:19.73 46.92 21.80 I I I I I I I I Table 14 White Mesa -Vegetation Cover -2022 Native Reference Area -Fall Survey Percent Ground Cover Based on Point-Intercept Sampling Transect No.-> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Average I Relative I Cover Cover Freq. Grasses None 0.0 I 0.0 I 0 Forbs I A Portulaca o/eracea Little Hogweed 1 2 1 3 3 1 3 3 1.1 I 4.5 I 53 I A Sa/so/a traous Russian Thistle 17 8 2 3 5 18 2 2 7 4.3 16.8 60 Shrubs, Sub-shrubs, cacti & Trees N p Artemisia tridentata Big Sagebrush 7 12 4 4 1 25 11 10 9 5.5 I 21.8 I 60 N p Gutierrezia sarothrae Broom Snakeweed 15 2 8 11 16 9 22 7 10 9 16 21 23 24 23 14.4 56.8 100 Mean Total Plant Cover 16 28 16 24 21 16 31 29 37 20 26 21 33 29 33 25.3 Rock 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0.1 Litter 14 26 23 21 30 36 20 22 21 9 8 1 16 14 8 17.9 Bare qround 70 46 61 54 49 48 49 49 42 71 66 78 51 57 59 56.7 Perennial Plant Cover 15 9 8 23 16 13 26 8 35 20 26 21 32 24 23 19.9 Sample Adequacy Calculations: Plant Cover Mean = 25.33 t= 1.35 n= 15 Variance = 46.38 nm;n = 13.07 N = Native, I = Introduced, P = Perennial, B = Biennial, A = Annual WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT Appendix C CELL 2 SETTLEMENT MONITORING DATA IJ  5,590  5,595  5,600  5,605  5,610  5,615 Jun‐16 Dec‐16 Jun‐17 Dec‐17 Jun‐18 Dec‐18 Jun‐19 Dec‐19 Jun‐20 Dec‐20 Jun‐21 Dec‐21 Jun‐22 Jan‐23 Wa t e r  Le v e l  El e v a t i o n  (f t ) Date Figure C.1 ‐Cell 2 Standpipe Piezometers Water Level Elevations C2‐P01 C2‐P02 C2‐P03 C2‐P04 C2‐P05 C2‐P06 C2‐P07 C2‐P08 C2‐P09 C2‐P10 C2‐P11 C2‐P12 C2‐P13 C2‐P14 C2‐P15 C2‐P16 C2‐P17 C2‐P18 C2‐P19 C2‐P20 C2‐P21 C2‐P22 C2‐P23 Note: (1) Pieozometer C2‐P01 reading for Mar 20, 2019 was erroneous due to  an issue with the water level meter (2) Piezometer C2‐P10 was hit by a vehicle on September 1, 2022.  Soil  fell in the casing and the water level increased by about 2 feet (1) (2) -....... -+---e----+-  5,590  5,595  5,600  5,605  5,610  5,615 Jun‐16 Dec‐16 Jun‐17 Dec‐17 Jun‐18 Dec‐18 Jun‐19 Dec‐19 Jun‐20 Dec‐20 Jun‐21 Dec‐21 Jun‐22 Jan‐23 Wa t e r  Le v e l  El e v a t i o n  (f t ) Date Figure C.2 ‐Cell 2 Standpipe Piezometers Water Level Elevations West Side of Cell (excluding locations near sump) C2‐P01 C2‐P02 C2‐P03 C2‐P04 C2‐P05 C2‐P06 C2‐P07 C2‐P08 (1) Note (1): Pieozometer C2‐P01 reading for March 20,  2019 was erroneous due to an issue with the water  level meter ........ --+-  5,590  5,595  5,600  5,605  5,610  5,615 Jun‐16 Dec‐16 Jun‐17 Dec‐17 Jun‐18 Dec‐18 Jun‐19 Dec‐19 Jun‐20 Dec‐20 Jun‐21 Dec‐21 Jun‐22 Jan‐23 Wa t e r  Le v e l  El e v a t i o n  (f t ) Date Figure C.3 ‐Cell 2 Standpipe Piezometers Water Level Elevations Locations Near Sump C2‐P09 C2‐P10 C2‐P11 C2‐P12 C2‐P14 C2‐P15 C2‐P16 (2) Note: (2) Piezometer C2‐P10 was hit by a vehicle on September 1, 2022.  Soil  fell in the casing and the water level increased by about 2 feet ........ --+-  5,590  5,595  5,600  5,605  5,610  5,615 Jun‐16 Dec‐16 Jun‐17 Dec‐17 Jun‐18 Dec‐18 Jun‐19 Dec‐19 Jun‐20 Dec‐20 Jun‐21 Dec‐21 Jun‐22 Jan‐23 Wa t e r  Le v e l  El e v a t i o n  (f t ) Date Figure C.4 ‐Cell 2 Standpipe Piezometers Water Level Elevations East Side of Cell (excluding locations near sump) C2‐P13 C2‐P17 C2‐P18 C2‐P19 C2‐P20 C2‐P21 C2‐P22 C2‐P23 ....... WHITE MESA URANIUM MILL CELL 2 RECLAMATION COVER 2022 ANNUAL PERFORMANCE MONITORING REPORT Appendix D CELL 2 STANDPIPE PIEZOMETER WATER LEVELS IJ 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.1White Mesa MillCell 2W1 Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I ••• -- 'I ' -- 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.2White Mesa MillCell 2W2 Settlement Plate Measurements (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I -Mi---• I -- i II 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.3White Mesa MillCell 2W3 Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I ·--- II II ,. ,_ -T ,._ -l • J~ 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.4White Mesa MillCell 2W4 Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I I I ] .._ ---1 -----T' 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.5White Mesa MillCell 2E1 Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I ·-· -J --' 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.6White Mesa MillCell 2E1-N Settlement Plate Measurements (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I --• ' 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.7White Mesa MillCell 2E1-1S Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I ~ I • - ' Iii - 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.8White Mesa MillCell 2E1-2S Settlement Plate Measurements (1) (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I ·--II II I ,. I' - 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.9White Mesa MillCell 2W7-C Settlement Plate Measurements Note:  (1) Settlement plate had three feet of rod extended October 2014 month because interim cover was added in this area of Cell 2  (1) I --- -.. ' 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.10White Mesa MillCell 2W5-N Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I .. ... • --,, .ll. - 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.11White Mesa MillCell 2W3-S Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I ·-- II - 11... ~ ......... -■ 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.12White Mesa MillCell 2W5-S Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I . .._ 11 i --T 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.13White Mesa MillCell 2W7-N Settlement Plate Measurements (2) Notes:  (1) Settlement plate had three feet of rod extended in October 2014  because interim cover was added in this area of Cell 2  (2) Settlement plate extended  during phase 1 cover construction (1) I ,. ~ ~ 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.14White Mesa MillCell 2W7-S Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I -- Ill • - ■- 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.15White Mesa MillCell 2W6-N Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I - I I ~ 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.16White Mesa MillCell 2W6-C Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I - I • I L.. - i 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.17White Mesa MillCell 2W6-S Settlement Plate (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I 1• ii - ,_ --- 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.18White Mesa MillCell 2W5-C Settlement Plate (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I - I I ,... ' 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.19White Mesa MillCell 2W4-N Settlement Plate (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I II - I 1 5612 5614 5616 5618 5620 5622 5624 5626 5628 5630 5632 Dec-88 Dec-91 Dec-94 Dec-97 Dec-00 Dec-03 Dec-06 Dec-09 Dec-12 Dec-15 Dec-18 Dec-21 Dec-24 El e v a t i o n , f e e t m s l Figure D.20White Mesa MillCell 2W4-S Settlement Plate Measurements (1) (1) Note:  (1) Settlement plate extended during Phase 1 cover construction.   I . .._ I I -, ,.