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12c. The operator did not provide a plan for excavation of accumulatetl sediment or an alternative plan for stabilization of the Coal Canyon Drainage segment between the Haul Road 4 crossing (the large double culverts) and the Pond 13 spillway channel as requested. Rule 4.05.3(1)(e) requires that diversions and ephemeral streams must be designed, located, constructed, maintained and used to minimize adverse impacts to the hydrologic balance, and to be stable. Rule 4.03.1{1){a) requires that "...post-mining conditions of haul roads...will control or prevent erosion and siltation.. ". Channel erosion has initiated at the lower end of the segment, due to a nick-paint in the channel apparently formed by sediment build-up associated with the former Haul Road 2 channel crossing. In response to the original adequacy item, the operator stated that their preference would be to allow the channel to reach geomorphic stability and see if scour protection is required below the large double culverts. Because the channel segment is not stable, and because the instability is associated with mining and reclamation operations that modified the channel, the operator's proposed approach tloes not comply with the cited regulations. Please submit a plan for excavation of accumulated sediment from the channel segment, to establish a relatively uniform gradient through the channel segment, consistent with the channel gradient immediately downstream of the Pond 13 outlet, or an appropriate alternative plan for preventing accelerated channel erosion associated with the nick-point. The plan should include appropriate scour protection at the upper end, below the outlets of the large double culverts. The plan should include channel cross sections and profiles, and other information as necessary to demonstrate compliance with Rule 4.05.4. In addition, please assess the volume and quality of material that could be excavated from the channel segment with respect to its potential use as a source of subsoil or topsoil for future reclamation. 12d. The SEDCAD design for the proposed ephemeral channels indicate that the channels would be stable, with adequate capacity if installed as designed, however the stable design incorporates extensive use of riprap. These channels would be constructed to tie in with upland native ephemeral channels following removal of the existing temporary diversion ditch. 4.05.3(6) states that, when a temporary diversion of an ephemeral stream is removed, the ephemeral channel "shall be reestablished to functionally blend with the undisturbed drainage above and below the area to be reclaimed". "Functional blentling" would logically incude channel dimensions that approximate premining conflguratlon, with provision of geomorphicaUy appropriate meander patterns and gradient, such that the channel would remain in dynamic equilibrium with the larger drainage system. These concepts are spec~cally addressed in Rule 4.05.4(4) for ephemeral drainages with watersheds of at least one square mile. This rule further specifies that art~cial structural controls not be employed unless approved by the Division. The proposed channel designs incorporate extensive use of riprap (artificial structural control) throughout their lengths. Flow velocities in these channels are relatively low, and it would appear that modification of the designs through some combination of increasetl flow length (incorporation of meanders), slightly modified channel geometries (minor widening), excavation to "incise" the drainages in their steep upper reaches, vegetative stabilization, and selective use of riprap, would be practicable. The resulting land-form would more closely mimic natural conditions, and the reconstructed drainages would functionally blend with the native channels, with lesser reliance on artificial structural controls. In design and constructign of the channels, it is critical that flow from the upland drainage chutes be fully captured by the reclaimed drainages. Some excavation of native ground may be necessary to ensure that the redamatiort channels are properly tied into