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Sazicrt ~ 2.05.3 The principle spillway is an 18-inch discharge culvert with riser with the lowermost • discharge orifice set an elevation of 6,127 feet. Because Elk Creek is culverted through the entire Elk Creek support facihties area, the Pond D discharge culvert will tie into the existing 9-foot diameter Elk Creek culvert southeast of the comer of the pond. The emergency spillway, at elevation 6,134 feet, is an open channel emptying to a drop inlet and 12-inch culvert, which ako ties into the existing Ells Creek culvert. Design information for Sedimentation Pond D is provided in Exhibit 2.05-E3, Drainage and Sediment Control Plan, and the pond configuration u illustrated by the Sedimentation Pond B Map, (Map 20.5-M5D). E. East Yard Sedimentation Pond -The East Yard Sedimentation Pond is l«ated at the base of the hillslope halfway between the Elk Creek facilities area and the Sanbom Creek Mute portak and north of the Sanbom Leek Mtne haul road and overland conveyor. This pond provides drainage and sediment control for the East Yard area, including the East Yard storage and coal st«kpile areas. The Eas[ Yard Pond is a fully incised pond in a natural ground with a bottom elevation of 6,084 feet. Pond interior sideslopes are at 3H:1V. The pond can be dewatered through a 4-inch gated trickle tube at elevation 6,085 feet. Design information for the East Yard Sedimentation Pond is provided in Exhibit 2.05-E3, Drainage and Sediment Control Plan, and the pond configuration is illustrated by the East Yard Sedimentation Pond Map, (Map 2.05-MSE). F. Substation No. 3 Sedimentation Pond -The Substation No. 3 Sedimentation Pond is 1«ated on the north side of old Highway 133 approximately two miles east of the Sanbom Geek Mute portals. This pond provides drainage and sediment control for the Substation No. 3 and the GGulch ventilation shaft areas. The Substation No. 3 • Pond is an incised pond with a bottom elevation of 6,180 feet. Pond interior sideslopes are at 2HIV. The pond can be dewatered either through a 2-inch gated trickle rube at elevation 6,181 feet or through an open slot emergency spillway at elevation 6,182.8 feet. Design information for the Substation No. 3 Sedimentation Pond is provided in Exhibit 2.05-E3, Drainage and Sediment Control Plan, and the pond configuration is illustrated by the Substation No. 3 Sedimentation Pond Map, (Map 2.05-MSF). Design calculations and the pond design configuration were reviewed and revised, as appropriate, to address increases in the disturbance area ass«iated with construction of the GGuk h Ventilation Shah. G. Upper Hubbard Gulch Sedimentation Pond - The Upper Hubbard Gulch Sedimentation Pond u 1«ated adjacent to Hubbard Creek and downslope of the Upper Hubbani Gulch disturbance area providing drainage and sediment control for thu partially reclaimed area. The Upper Hubbard Gulch Pond is a partially incised pond with a bottom elevation of 6,348 feet. Pond interior sideslopes are at 3H:1V. The pond can be dewatered through either a 4-inch gated trickle rube at elevation 6,349 feet or an open slot spillway at elevation 6,351 feet. Design information for the Upper Hubbard Gulch Sedimentation Pond is provided in Exhibit 2.05-E3, Drainage and Sediment Control Plan, and the pond configuration is illustrated by the Upper Hubbard Gulch Sedimentation Pond Map, (Map 2.05-MSG). H. Sanbom Geek Mrtte Dewatering Pond -See previous disctusion under "Mate Water Storage and Discharge." Sedimentation ponds have been designed and coastmcted in compliance with applicable regulatory requirements including applicable provisions for foundation preparation, embankment constnrcuon, (avoidance of process waste and other deleterious materials and compaction) embankment protection, and installation of non-clogging discharge structures. Ponds are rrupected on a regular basis to assure that they continue to function as designed and to detect any indications of significant PR04 2.05-35 Revised August 2000