2023-07-19_REVISION - M2021052 (16)

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Rifle Gravel Pit#1 July 2023 • The six-foot wide greenbelt area with a 5:1 slope will be surfaced using the topsoil retained from Phase 1 (533 CY) and planted with wetland reclamation species using a mix of seed and containerized stock, as mining activity progresses subject to operational requirements and seasonal constraints. The remainder of the pit slope to the bottom of the pond will not exceed 3:1 slopes. Note that this reclamation effort follows Garfield County LUC standards (LUC Section 7-1002.H). Formal wetland mitigation per USACE standards is not required, as no impacts to wetlands are proposed. It should be noted that the existing topography is variable between the distance of the toe of the 3:1 to 5:1 transition slope across the site, hence creating an estimated 3.57 acres that will need to be reclaimed throughout Phase 3 and potentially during Phase 4 (noted as the Berm Area or Berm to Greenbelt Area on Figure 14, Exhibit E1). 5.2.3.2 Water Diversions and Impoundments As previously described, the Last Chance Ditch tailwater channel, which currently terminates on the property west of the Affected Lands and Permitted Area, will be incorporated into the excavated pond where aggregate is being removed. The irrigation return flows in the ditch will be mixed with the alluvial groundwater that fills the pond, and the water will continue to migrate laterally through the underlying permeable gravels to reach the Colorado River. The exact point where the tailwater channel enters the pond will migrate as the excavated boundaries of the pond expand; under final conditions the Last Chance Ditch tailwater channel will discharge directly into the pond at the point where the ditch enters the property on the eastern boundary. 5.2.3.3 Water Handling and Dewatering The perimeter berm, installed during Phase 1, will keep all on-site activities from impacting adjacent properties including, but not limited to stormwater, process wash water, dust- control, and aggregate dewatering. This perimeter berm will essentially provide a zero discharge of water, sediment-laden water, off-site. Scott will comply with the State Engineer Office's (SEO) rules and regulations regarding any water depletions that may occur during mining operations from water lost with mined aggregate and water used for dust suppression. A copy of the SEO permit applications to address depletions is included in Attachment C. Any agricultural return flows in the tailwater ditch, which are estimated at <2 cubic feet per second (cfs) during peak irrigation season, will be incorporated into the pond, mixed with the alluvial aquifer, and eventually migrate laterally through the permeable gravels into the larger Colorado River water table. Given the minimal flows in the ditch, the large size of the pond (estimated at 6 acres within one year), and the highly permeable nature of the gravel, the agricultural return flows will have a negligible effect on water levels in the pond. As excavation proceeds, the tailwater ditch will be subsumed into the expanding pond boundaries, until under final conditions the discharge point will be where the ditch enters the eastern boundary of the property. 5.2.4 Explosives Explosives will not be used during mining or reclamation of the property. 6.2.5 Schedule of Operations 31