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Mr. Lucas J. West <br /> June 3,2025 <br /> Page 2 <br /> Table 2 -Monthly Piezometer Elevations <br /> Monitoring NVell Piezometer Depth Depth to Water Depth of Water <br /> Identification Observation Date (ft) (ft) (ft) <br /> P6 5/29/2025 72.46 DRY N/A <br /> P7 5/29/2025 92.50 DRY N/A <br /> P8 5/29/2025 97.51 96.75 0.76 <br /> P9 5/29/2025 72.30 71.98 0.32 <br /> P10 5/29/2025 58.30 57.48 0.82 <br /> Pl l 5/29/2025 41.80 41.41 0.39 <br /> P12 5/29/2025 41.71 41.65 0.06 <br /> P13 5/29/2025 41.34 41.02 0.32 <br /> P14 5/29/2025 41.24 DRY N/A <br /> P15 5/29/2025 41.10 40.87 0.23 <br /> The leak detection system at the LTF Collection Pond was inspected May 28, 2025, and 890 gallons were evacuated <br /> from the leak detection system and pumped to the LTF. The LTF underdrain system was visually inspected May 28, <br /> 2025,and the flow rate was measured to be approximately 28.5 gallons per minute(gpm). <br /> West Pit Waste Water Treatment Plant <br /> During the month of May 2025, the West Pit Waste Water Treatment Plant(WWTP) was operated intermittently (3 <br /> to 4 days per week) under Colorado Department of Public Health and Environment (CDPHE) CDPS Permit No. <br /> C00045675 for discharge into the Rito Seco alluvial aquifer. During the month, 6,974,400 gallons (21.40 acre-feet) <br /> of treated water was discharged to the Rito Seco and 378,700 gallons (1.16 acre-feet) of water was transferred from <br /> the West Pit to the Lined Tailing Facility(LTF). Additionally, no water was reinfiltrated into the West Pit in May. <br /> BMRI performed the monthly visual seepage expression inspections on May 28, 2025, in the historic seepage area <br /> 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 5/31/2025 24.88 <br /> BF-5R 5/31/2025 30.83 <br /> BF-6 5/31/2025 30.92 <br /> M-6 5/31/2025 DRY <br /> M-7 5/31/2025 DRY <br /> M-8 5/31/2025 DRY <br /> M-9 5/31/2025 141.19 <br /> M-10 5/31/2025 23.66 <br /> M-11R 5/31/2025 38.21 <br /> M-12 5/31/2025 174.27 <br /> M-13R 5/31/2025 125.64 <br /> M-14 5/31/2025 130.5 <br /> M-16 5/31/2025 21.94 <br /> M-17 5/31/2025 29.68 <br />