2023-07-19_REVISION - M2021052 (16)

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Rifle Gravel Pit #1 J_fly 2023 provide fill in the instance mining ceases. This material will be sold as a secondary commodity, to allow for the expansion of mining during the 60% to the 100% mining stages during Phase 3. The excess topsoil (9,539 CY)will also be stored and stabilized with an upland seed mix. The topsoil will be sold as a secondary commodity during the 60% to 100% mining stages during Phase 3, to allow for mining expansion. Approximately 533 CY of the excess topsoil will be needed to reclaim the greenbelt areas during final reclamation during Phase 3 and Phase 4. The location of the stockpile areas is depicted on Figure 9, Exhibit C4 and located to provide physical separation between the stockpiles, mining activity, and any wetland or tailwater channel buffer areas and intended to prevent inadvertent sediment discharges off- site. Earthwork volume calculations are provided in Figure 14, Exhibit E1. Size of Area Worked The size of area involved with this Phase is 19.00 acres. See Exhibit E1, for the earthwork quantity estimates, including the areas and volumes, as applicable. o Overburden stockpile ■ 30,423 CY, acreage varies o Topsoil stockpiles o Excess topsoil retained through 60% and sold gradually as a secondary commodity (estimate): ■ 9,006 CY o Excess topsoil for use in post-mining greenbelt reclamation, Phase 3, will be temporarily stabilized with the upland seed mix(estimate): ■ 533 CY 5.2.1.3 Water Diversions and Impoundments No water diversions will be required as part of the planned mining activities. Scott will complete minor repairs and maintenance on an existing culverted crossing of the Last Chance Ditch tailwater channel, to provide vehicle access from one side of the ditch to the other. The crossing is currently serviceable but not adequate for the operation of the proposed mining activity. This repair work will consist of placing additional overburden on the existing culvert, to replace material that has been eroded by previous ranch use (cattle loafing, irrigation flows, and general erosion). The crossing will be maintained at a 12-foot travel width. Maintenance activities of this nature undertaken on existing structures located on irrigation ditches are not a regulated activity under Section 404 as administered by the U.S. Army Corps of Engineers (USACE). 5.2.1.4 Water Handling, Dewatering, and Permits Scott applied for coverage under Permit No. COR400000, Colorado Discharge Permit System (CDPS) General Permit (for) Stormwater Discharges Associated with Construction Activity (Attachment G). This permit has requirements that address water quality and stormwater management, including monitoring and reporting, and the development and implementation of a Stormwater Management Plan (SWMP). Scott will also install the erosion and sediment control BMPs as depicted in Figure 13, Exhibit D2. 24