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Rifle Gravel Pit#1 April 2022 <br /> material. The pond water will be in direct contact with the water table of the Colorado River <br /> via lateral migration through the underlying permeable gravels. Excavated material will be <br /> piled on the edge of the pond for approximately 24 hours, to allow drainage of free water <br /> from the material back into the pond. <br /> Sideload dump trucks will travel to the pond edge and will be loaded with the dried material <br /> on a daily basis. The dump trucks will transport the dried material from the active excavation <br /> area to the processing facility (a distance of 800 -1,500 feet depending upon the mining <br /> location), where the material will be stockpiled for washing, processing, and subsequent <br /> sale. <br /> Any agricultural return flows in the tailwater ditch, which are estimated at <2 cubic feet per <br /> second (cfs) during peak irrigation season, will be discharged into the pond, mixed with the <br /> alluvial aquifer, and migrate laterally through the permeable gravels into the larger Colorado <br /> River water table. Given the minimal flows in the ditch, the large size of the pond (estimated <br /> at approximately 6 acres within one year), and the highly permeable nature of the gravel, the <br /> agricultural return flows will have a negligible effect on water levels in the pond. As <br /> excavation proceeds, the tailwater ditch will be subsumed into the expanding pond <br /> boundaries, until under final conditions (Figure 11, Exhibit C6) the discharge point of the <br /> ditch to the pond will be located where the ditch enters the eastern boundary of the property. <br /> Reclamation activity will proceed in concert with the excavation (see Figure 9, Exhibit C4 <br /> through Figure 11, Exhibit C6). A six-foot wide fringe of 5:1 slope will be left at the inner <br /> edge of the perimeter berm and planted with wetland reclamation species. The intention is <br /> for the six-foot wide fringe to be nearly inundated during high-water periods as the water <br /> table rises, and then to be progressively exposed as the water table drops during the <br /> growing season. The remainder of the pit slope to the bottom of the pond will be <br /> approximately 3:1, not to exceed 2:1. Note that this reclamation effort follows local Garfield <br /> County guidelines and standards (LUC Section 7-1002.H). Formal wetland mitigation per <br /> USACE standards is not required, as no impacts to wetlands are proposed. <br /> 5.2.3.2 Water Diversions and Impoundments <br /> As previously described, the Last Chance Ditch tailwater channel, which currently terminates <br /> on the property west of the Affected Lands and Permitted Area, will be incorporated into the <br /> excavated pond where aggregate is being removed. The irrigation return flows in the ditch <br /> will be mixed with the alluvial groundwater that fills the pond, and the water will continue to <br /> migrate laterally through the underlying permeable gravels to reach the Colorado River. The <br /> exact point where the tailwater channel enters the pond will migrate as the excavated <br /> boundaries of the pond expand; under final conditions the Last Chance Ditch tailwater <br /> channel will discharge directly into the pond at the point where the ditch enters the property <br /> on the eastern boundary. <br /> 5.2.3.3 Water Handling and Dewatering <br /> Scott will comply with the State Engineer Office's (SEO) rules and regulations regarding any <br /> water depletions that may occur during mining operations from water lost with mined <br /> aggregate and water used for dust suppression. <br /> Any agricultural return flows in the tailwater ditch, which are estimated at <2 cubic feet per <br /> second (cfs) during peak irrigation season, will be incorporated into the pond, mixed with the <br /> alluvial aquifer, and eventually migrate laterally through the permeable gravels into the <br /> 30 <br />