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sediment will be used as topsoil or subsoil if it meets the suitability criteria discussed under <br />Section 2.04.9. The Division will be notified of this determination if the material is selected <br />as overburden material that can be substituted for or as a supplement to topsoil. <br />All ponds will be designed so that the minimum elevation at the tap of the settled <br />embankment is at least one foot above the elevation of the water surface in the pond with the <br />emergency spilhvay flowing at design depth. <br />Colowyo wilt design, construct and maintain the sedimentation ponds to prevent short <br />circuiting to the extent possible. As a general rule, the inflow to the ponds will be at the <br />opposite end from the outflow area. The constructed height of the sedimentation pond <br />embankment tivill be designed to allow for settling. During construction, a registered <br />professional engineer will ensure that the appropriate embankment height is accomplished. <br />For all sedimentation ponds, the entire embankment, including the surrounding areas <br />disturbed by construction, will be seeded after the embankment is completed. The active <br />upstream side of the embankment where water will be impounded will be riprapped or <br />otherwise stabilized, where necessary. Areas in which revegetation is not successful or, <br />where rills and gullies develop, will be repaired and revegetated. <br />Sedimentation ponds that are subsequently approved as part of the post-mining land use will <br />remain in place after the termination of mining activities. <br />Colowyo will inspect the condition of each pond quarterly with the reports submitted <br />• annually. None of Colowyo's ponds meet the size criteria of 30 CFR 77.216(a)(1989) <br />4.0.7 Discharge Structures <br />The sedimentation ponds at Colowyo are designed to treat the theoretical l0year, 24-hour <br />storm event in accordance with Rule 4.05.6(3)(a). As such, the general operation of the ponds <br />will be a passive discharge system where water is allowed to discharge automatically as <br />necessary. Colowyo will sample discharges as appropriate to remain in compliance with <br />applicable CDPS Permit requirements. Pond dewatering through a manual headgate may be <br />performed as necessary to lower the water level depending on operational requirements. <br />Manual dewatering of ponds will meet applicable CDPS Permit standards. Discharge from <br />sedimentation ponds will be controlled by energy dissipaters and flow check devices where <br />necessary. All ponds utilize separate primary and emergency spillways with the emergency <br />spillway located at a minimum of 1 foot above the elevation of the principal spillway. The <br />emergency spillways are designed to pass the 25-year/24-hour storm event in accordance <br />with Rule 4.05.6(5). The design requirements can be found on each of the pond as-built <br />drawings or in Exhibit 7, Item 15. All sedimentation ponds will provide anon-clogging <br />dewatering device or conduit spillway to remove water storage from inflow. <br /> <br />4.05-7 Revision Date: 11/18/98 <br />Revision No.; TR-41 <br />