2025-03-14_PERMIT FILE - M2025016 (22)

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// PAGE 5 EXHIBIT L Raptor Materials, LLC Cogburn Sand, Gravel, and Reservoir Project February 2025 A Regular Impact (112) Construction Permit Application – Colorado Division of Reclamation Mining and Safety, Office of Mined Land Reclamation to be completed. The reservoir volume for P125B for the 5-year condition was calculated a 3D computer- aided design (CAD) program using the stage-storage curves for the static water surface elevations (WSELs) listed in Table 1. Determination of static WSELs for each pit is detailed in Exhibit D – Extraction Plan. Table 4. Initial Dewatering Cost Estimate Pit Reservoir Vol (WSEL = 4,782’) [gal] Unit Discharge Cost [$] Total Job Cost [$] P125B 73,884,623 $0.000107 $7,906 Following initial dewatering, a 30-day dewatering need was assumed for completion of lining and regrading. A 30-day continuous dewatering volume was calculated based on the individual pit inflow estimate provided in the AWES Dewatering Estimate memo dated October 28, 2024 (attached as an addendum). As Pit P125B will not be fully extracted at the 5-year mark, inflow was reduced proportionally to the length of pit wall that will be exposed at year 5. Table 5. 30-Day Continuous Dewatering Cost Estimate Pit Inflow [MGD] Pit wall length [ft] Pit wall length exposed [ft] % of Tot Inflow Inflow over 30 days [gal] P125B 0.56 5,963 5,290 88.71 14,903,907 Unit Cost: $0.000107 Total Job Cost: $1,595 The total dewatering cost (initial plus continuous) is estimated at $9,500. During dewatering, the basins will be lined or otherwise segregated from the area groundwater, to liberate the water otherwise retained to supplement loss from evaporation in the unlined state. Liner At the 5-year mark, liner will have been keyed into the base of the Pit P125B side walls at depths greater than 30 feet and installed up to 25 feet bgs, as detailed in Exhibit E – Reclamation Plan. Pit P125_S1 will be completely backfilled and Pit P125A will be regraded, lined, and backfilled. Liner installation was separated into four stages for the purposes of cost estimation: grading the slope under the liner, hauling liner material to the pit area, mixing material for the liner, and compacting the liner. The surface required to be regraded was assumed to be from either the base of the pit where no interim liner exists, or above the existing base liner where installed, to the top of the pit wall, at a thickness of 1 foot. Liner material was assumed to be installed at a thickness of 4 feet on the slope with a 4-foot-by-4-foot keyway where applicable to a height of 5 feet bgs. Half of the liner material was estimated to require mixing; all the liner material was assumed to require compaction. Surface areas for wall to be regraded and liner installation were measured based on the above-described mining plan, further detailed in Exhibit D – Extraction Plan, for the 5-year mining condition surface in a 3D CAD program. P125B pit bottom elevations 30 feet bgs or shallower were measured to determine remaining keyway length to be installed; these sections are indicated on Exhibit L – Financial Warranty Map. As material