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

Home Browse Search

// PAGE 8 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 and onsite material, resulting in very short on-site push distances. As backfill material will be sourced from the same locations as the liner material, the estimated average haul distance is the same: 2,390 feet. Backfill will be placed and graded from the ground surface to the pit bottom to create finished 3H:1V slopes for the entire Pit P125B. Similar to material excavated for lining, material excavated for backfill is expected to swell and is therefore assigned a swell factor for cost estimating purposes. The backfill concepts for walls shallower and deeper than 30 feet bgs is portrayed in Figure 1 and Figure 2 in the preceding subsection: Liner. The cost estimate for backfilling Pit P125B, summarized in Table 6 below, is based on unit costs taken from the recent DRMS-provided P124 Two Rivers (M2022-013) cost estimate. Table 8. Reclamation Backfill Cost Estimate Activity Initial Vol [cu.yd] Swell/Compaction Factor Loose/Compacted Vol [cu.yd] Unit Cost [$/cu.yd] Total Job Cost Haul 120,692 N/A 120,692 $1.053 $127,089 Grade 120,692 1.215 146,641 $0.301 $44,139 Total Backfill Cost: $171,227 Topsoil Topsoil demand will be limited to the cut basin slopes remaining above the static water level for pits reclaimed as reservoirs (P125A and P125B) and to the entirety of the backfilled disturbed surface for Pit P125_S1. Topsoil will be placed at a depth of approximately 6 inches over both even ground and cut slopes and seeded with a cover of stabilizing vegetation, as detailed in Exhibit E – Reclamation Plan. At the 5-year mark, Pit P125_S1 is expected to have been completed backfilled, re-soiled, and revegetated; Pit P125A is expected to be lined, backfilled, re-soiled, and revegetated. Therefore, the only remaining area to receive topsoil should be the cut slopes reclaimed at 3H:1V above the static water surface elevation (4,782’) in Pit P125B. Determination of the static WSEL is detailed in Exhibit D – Extraction Plan. The cut slope surface area above the static WSEL was calculated from the P125B reclaimed surface in a 3D CAD program. Topsoil application was separated into two stages for the purposes of cost estimation: hauling topsoil from the stockpile to Pit P125B, and spreading topsoil on the banks. Similar to material excavated for backfill, topsoil is expected to swell and is therefore assigned a swell factor for cost estimating purposes The cost estimate for topsoiling the exposed cut slopes of Pit P125B, summarized in Table 7 below, is based on unit costs taken from the recent DRMS-provided P124 Two Rivers (M2022-013) cost estimate. The average haul route distance from the topsoil stockpile in the north corner of Pit P125A to the banks of Pit P125B was estimated at 2,130 feet. Table 9. Topsoil Application Cost Estimate Activity Exposed P125B S.A. above WSEL [sq.ft] Topsoil Depth [ft] Initial Vol [cu.yd] Swell/Compaction Factor Loose/Compacted Vol [cu.yd] Unit Cost [$/cu.yd] Total Job Cost Haul 248,445 0.5 4,601 N/A 4,601 $1.073 $4,937 Grade 248,445 0.5 4,601 1.215 5,590 $0.272 $1,521 Total Topsoil Application Cost: $6,457