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Mr.Lucas J. West <br /> January 2,2026 <br /> Page 2 <br /> Table 2-Monthly Piezometer Elevations <br /> Monitoring Well Piezometer Depth Depth to Water Depth of Water <br /> Identification Observation Date (ft) (ft) (ft) _ <br /> P6 12/31/2025 72.46 DRY N/A <br /> P7 12/31/2025 92.50 DRY N/A <br /> P8 12/31/2025 97.51 96.70 0.80 <br /> P9 12/31/2025 72.30 72.00 0.30 <br /> P10 12/31/2025 58.30 57.47 0.83 <br /> P11 12/31/2025 41.80 41.42 0.38 <br /> P12 12/31/2025 41.71 41.66 0.05 <br /> P13 12/31/2025 41.34 41.02 0.32 <br /> P14 12/31/2025 41.24 DRY N/A <br /> P15 12/31/2025 41.10 40.87 0.23 <br /> The leak detection system at the LTF Collection Pond was inspected December 31, 2025, and 1,060 gallons were <br /> evacuated from the leak detection system and pumped to the LTF. The LTF underdrain system was visually inspected <br /> December 31,2025,and the flow rate was measured to be approximately 26.5 gallons per minute(gpm). <br /> West Pit Waste Water Treatment Plant <br /> During the month of December 2025, the West Pit Waste Water Treatment Plant (WWTP) was operated <br /> intermittently(3 to 4 days per week)under Colorado Department of Public Health and Environment(CDPHE)CDPS <br /> Permit No. C00045675 for discharge into the Rito Seco alluvial aquifer. During the month, 5,626,600 gallons <br /> (17.27 acre-feet)of treated water was discharged to the Rito Seco and 456,600 gallons (1.40 acre-feet) of water was <br /> transferred from the West Pit to the Lined Tailing Facility (LTF). Additionally, no water was reinfiltrated into the <br /> West Pit in December. <br /> BMRI performed the monthly visual seepage expression inspections on December 31, 2025, in the historic seepage <br /> area identified in Figure 2 of the permit. No seepage expressions were observed in the historic seepage area. <br /> BMRI measured the monthly West Pit backfill, alluvial and monitoring wells as required under the QA/QC Plan. <br /> Measurements obtained for the monthly wells are shown in Table 3. <br /> Table 3-Monthly and Quarterly Groundwater Depth to Water <br /> Monitoring Well Identification Observation Date Depth to Water <br /> (ft) <br /> BF-4 12/31/2025 24.93 _ <br /> BF-5R 12/31/2025 30.8 <br /> BF-6 12/31/2025 30.96 <br /> M-6 12/31/2025 DRY <br /> M-7 12/31/2025 DRY <br /> M-8 12/31/2025 DRY <br /> M-9 12/31/2025 141.26 _ <br /> M-10 12/31/2025 23.84 <br /> M-11R 12/31/2025 37.85 <br /> M-12 12/31/2025 174.43 <br /> M-13R 12/31/2025 125.79 <br /> M-14 12/31/2025 130.62 <br /> M-16 12/31/2025 17.33 <br /> M-17 12/31/2025 16.47 <br />