2025-05-05_PERMIT FILE - C1981010 (23)

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• Inspection of Dams and Sediment Removal The sediment dams and embankments will be routinely inspected and maintained during the Iffe of the Trapper Mine. Quarterly inspection records will be kept on file at Trapper for Division review. Coyote Dam will be inspected by a certified dam inspector for the criteria of the State Engineer. The remainder of the sediment dams will be inspected by Trapper Mine personnel. The emergency spillways and prin- cipal spillway outlets will be maintained to protect against erosion. Vegetative growth will be cut when necessary to facilitate inspections and repairs. A quarterly report will be filed with the Division within 30 days of the end of the quarter, illustrating the condition of each sediment pond. If necessary, an annual report may be submitted to the Division by June 30th, after spring runoff. The report will designate which impoundments require sediment removal and/or other maintenance. Each sediment dam, except Coyote, will have the elevation showing 60% of the designed sediment stor- age capacity marked on either the principle spillway standpipe or on a staff gauge located near the spill- way. The sediment accumulated in Coyote Dam will be determined by probing each spring following spring runoff. This is necessary because the dam is large and always has water in it, making it impossi- ble to place or observe a mark at the desired level. Sedimert will be removed between late spring and early fall only when ground conditions allow equipment access. All sediment control systems, except Coyote, with 60% or more of the sediment storage volume used following spring runoff will have the sediment removed in the same year. Due to its large sediment storage capacity, Coyote however will • require sediment removal in the same year when the available runoff storage to the principal spillway is less than the in -flow volume attributed to a 10 -year, 24-hour storm plus two years of anticipated sediment deposition from the Coyote drainage area as calculated from the Universal Soil Loss Equation using cur- rent values. The material will be disposed in appropriate areas of the mine workings or used as a sub- soil. Dams collecting runoff from the mining area contain sediment suitable to use as a subsoil. Sediment Pond Removal The sediment ponds will remain in operation until revegetation of the disturbed area is complete and acceptable water quality is achieved. Written approval will then be requested from the Division prior to removal of any of the sediment ponds. The affected area at the sediment pond will be regraded, topsoiled and revegetated upon removal. • PR -3 ....-..-._-..__�-- ---`-....... 4-197 ----- REVISION MY DATE -__1_L-- I . I _j;