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Trout Creek Sandstone Test Site The sediment control for this site will include reveeetating site and use of existing down slope vegetation (i.e. vegetation filter). The site is approximately 1.2 acres in size and is surrounded by existing vegetation, which will serve to limit amount of runoff onto site. During active drilling a berm around the site will keep upland from entering area. Fish Creek Tipple The sediment control at Fish Creek Tipple involves diversion ditches, culverts, riprap, and one sedimentation pond. Pond E. Details associated with the sedimentation control system is found within pages 2.05-16 through 2.05-19 of the Fish Creek Tipple Appendix, Volume VIII. NMD Power Borehole The sediment control for this site involves using gravel on the pad and the surrounding vegetation as a downslope vegetative filter. The site is approximately 1 acre and will be surrounded on three sided by topsoil stockpiles, which will limit the amount of runoff entering the pad. The SAE demonstration is presented in Exhibit 8.6. NW Mains Ventilation Shafr and Thickener Underflow Project (TR 01-39) Drainage and sediment control for the NW Mains ventilation shaft site is provided by an upgradient diversion ditch and access road ditch, a short containment berm at the southern limit of the pad, gravel surfacing, and the combination ofa gravel filter at the low point of the berth and the natural vegetative filter existing between the shaft site and Fish Creek. As a relatively small area (approximately 1.8 acres), and given the effectiveness of the drainage and sediment control measures, the additional disturbance that would be involved in constructing a sediment pond is not warranted and ofi site sediment contributions can effectively be controlled by these measures under a Small Area Exemption, consistent with applicable provisions of Rule 4.05.2(3)(6). There will be no discharge or mixing of mine water with surface drainage from the site. • Given the limited site area, a "D" soil type (Binco silty clay loam), the drainage and sediment control measures, and a distance of approximately 500' between the shaft site and Fish Creek, calculated peak flow and runoff from the site for the ]0-year 24-hour storm event would be approximately 1.65 cfs and 0.13 acre-feet, respectively. Gravel and vegetative filter efficiency was modeled using the SEDCAD4 check dam and grass filter utility, the demonstration is presented in Exhibit 8 S. The estimated settleable solids concentration under peak discharge conditions would be approximately 0.42 mUl. This settleable solids level is consistent with natural sediment levels for runoff from undisturbed lands, given similar conditions, and would be sigpificantly reduced as the runoff passes over the vegetated area between the shaft site and Fish Creek. (5) Topsoil. A narrative explaining the method of removal and the amount to be removed and the plan for storage of topsoil, subsoil, and other material within the permit area subject to requirements of the topsoil removal performance standards of 4.06.2. This narrative shall specify the depth of material to be salvaged from all disturbed areas based on the soil information required by 2.04.9 and shall specify the volume of each type of material to be salvaged. A map of any proposed storage structures shall accompany the narrative. The maps shall be prepared according to the requirements of 2.10. RESPONSE See response to 2.05.4, Reclamation Plan, below for details concerning the Foidel Creek Mine. Twentymile Coal Company does not propose to disturb any additional land within the Fish Creek Tipple permit area. The Fish Creek Tipple and adjoining haulroad were constructed prior to the promulgation of regulations mandating topsoil salvage and storage. Thus, the best plant growth medium available is a mixture of spoil and soil materials which will be substituted for topsoil. This situation is further discussed within the Fish Creek Tipple/Loadout Appendix, pages 2.04-36 through 2.04-38 and pages 2.05-37 through 2.05-38 of Volume VIII. • TR 01-39 2.05-84 8/]0/0]