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- ~~~~ 2.05.4(2)(b) Reclamation Cost Estimate 8. For any reclamation plan modifications proposed within the revision submittal, please include sufficient documentation regarding cost factors (e.g. material volumes, grades, distances, etc., to allow the Division to amend the torten( reclamation cost estimate as appropriate). 2.05.4(2)(c) Stream Channel ReconsWdion 9. Performance of the relocated segment of the Coal Creek Channel immediazely downstream from the `tirpper dip section' culverts on Haul Road 4, has raised concerns regarding the final reclamation suitability of the four rock check dam drop structures installed along the channel segment Lutallation of the check dams has accelerated aggradation within the relocated channel, and necessitated frequent maintenance activity. Following major flow events, the channel has become choked with sediment, and has attempted to break out and bypass several of the check dams. Check dams have also been undercut on their downgradient sides. Finally, aggradation has progressed upstream from the sWCtures, and has on several occasions plugged the upper dip section culverts, as well as the primary spillway outlets from Sediment Pond 10 and Sediment Pond 6. [n sunurrary, the relocated channel segment appears to be out of equilibrium with the natural (low regime, with both immediate and long term negative consequences. We request that the reclamation plan be reevaluated and amended as appropriate to ensure that the channel segment will be in equilibrium with the flow regime. This may entail removal of the check dam structures and establishment of a constant grade through the segment. If so, accumulated excess sediment should be harvested for use as refuse cover soil, and the rock material should be used as a deflector berm along the tce of CRDA-l, or for other reclamation uses. The reclamation plan should also be amended to specify removal of [he concrete ramp road crossing and associated culverts at the upper dip section, upon completion of CBA-2 soil salvage operations. This will allow [he channel gradient to adjust as necessary to accommodate the relocated channel. 2.05.4(2)(c) Road Removal or Modification 10. Haul Road 4 has been approved for the poslmine land use to provide access to public lands in Coal Cattyon. In addition to the upper dip section crossing described in Item ]0, the road crosses Coal Canyon drainage just below the Haul Road 2 junction, and also crosses Coal Gulch drainage, in the vicinity of Pond 11. The Coal Gulch crossing employs a 72" culvert, and the lower Coal Carryon drainage crossing employs two, 81"x59" culverts. These large culverts occasionally become clogged following major flow events, and cleanout requires equipment mobilization. Given the nature of road use anticipated following completion of mine reclamation, lower maintenance "low water" crossings typical of the drainage crossings further up Coal Canyon would be appropriate. The Division requests that the reclamation plan be amended to address removal of the referenced culverts and associated fill, and installation of low water crossings in these locations. Retention of these culverts would be approvable only if documentation is provided to demonstrate that the road would better serve the future public use with the culverts ta place, and that provisions for prudent future maintenance are assured. 2.05.4(2)(d) Topsoil Removal, Storaee and Redistribution 11. Certain topsoil stockpiles are heavily infested with cheatgmss (Bromus (ectorum), an aggressive weedy annual brome. Redistribution of topsoil wntaining large quantities of viable cheatgrass seed as the surface soil on reclaimed areas will likely result in excessive competition and suppression of seeded species, unless mitigative measures with respect to soil handling, operational timing, or other treatments are applied. Please amend the soil handling/revegetation