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Introduction <br />Pond 010 is proposed to be constructed in the NE% of Section 8, TSN, R87N, 6th P.M. The <br />primary purpose of this pond will be to control sedimentation from the mining disturbance <br />area almost 5000 feet to the south of the pond. Sedimentology estimations, es calculated <br />by SEDCAD, are shown in the following design. It has been Senecas experience that ponds <br />situated this distance from the dfsturbance area receive little or no sedimentation. <br />Therefore, sediment storage capacity, as designed, should, in practice, be highly <br />conservative and pond clesnout should not be required for quite some time. This pond is <br />proposed to be constructed in 1995. <br />Site Deseriotlon <br />Lend Use. Sedimentation Pond 010 has a 948.4-ecre watershed (see Exhibit 13-2). This <br />watershed will be disturbed by mining activities as shown on Exhibits 12-1 and 20-1 end <br />reclaimed as shown on Exhibit 20-2. The lend condition of the watershed was <br />conservatively based on [he maximum disturbance et any one time within the proposed mining <br />area, approximately 59 percent undisturbed and 41 percent disturbed. <br />Embankment end Excavation. The embankment is a homogeneous earth fill structure. The top <br />width of the embankment is approximately 15 feet with upstream slope of 3h:1v and <br />downstream slopes of approximately 3h:1v. The principal spillway is a 6-inch diameter <br />dewatering orifice cut into a 36 inch CMP riser which drops into a 24 inch CM P; the <br />emergency spillway is a trapezoidal channel 12 feet wide (see Exhibit 13-4). A portion of <br />the pond capacity was the result of excavating topsoil and materiel below natural ground <br />level. The embankment material will come from the facilities area. <br />Design analysis <br />General. This sedimentation pond was designed to meet or exceed the design end <br />performance requirements of CDNG while utilizing as much of the existing topography es <br />possible. Sedimentation Pond 010 was designed to adhere [o the following specifications: <br />1. Provide storage and treatment for the runoff from the 10-year, 24-hour storm event <br />without experiencing any discharge through the emergency spillway; <br />13-3-1 Revised 06/19/95 <br />