Laserfiche WebLink
• INTRODUCTION <br />Sediment Pond 009 was constructed in the SE4 SY'f of Section 11, Township 5 North, Range 88 <br />west in s tributary to Sage Creek. The pond and embankment was constructed as a temporary <br />sedimentation structure to control runoff end sediment from a watershed disturbed by <br />proposed mining ectivit iea. The construction was started in the fall of 1991 and <br />completed in June of 1992. This sedimentation structure will be maintained until <br />reclamation of this structure is approved by Colorado Mined Land Reclamation Division <br />(CMLRD). <br />SITE DESCRIPTION <br />Lend Use. Sediment Pond 009 has a 438.6-acre watershed that ie tributary to Sege Creek <br />(see Exhibit 13-2). This watershed will be disturbed by mining activities as shown on <br />Exhibits 12-2 end 20-t and eontemporeneoualy reclaimed as shown on Exhibit 14-1. The <br />watershed will be approximately 73 percent undisturbed and 27 percent disturbed. Design <br />of the pond was conservatively based on the msximum disturbance at any one time within the <br />proposed mining area. <br />Embankment and Excavation. The embankment ie a homogeneous earth fill structure. The top <br />width of the embankment is approximately 15 feet with upstream end downstream slopes of <br />3h:1v each. The principal spillway consists of en 18-inch diameter drop inlet culvert; <br />the emergency spi llwey is a trapezoi del channel 15 feet wide (see Exhibit 13-7A ). A <br />portion of the pond capacity is a result of excavsting topsoil and materiel below natural <br />ground level. Excavated suitable material was used in embankment construction. The <br />ponding area's side slopes ere 2h:1 v, typically. <br />~T-o~aose.a( 3(~ ' I v <br />DESIGN ANALYSIS <br />General. Sediment Pond 009 was designed to meet or exceed the design and performance <br />requirements of CMLRD while utilizing es much of the existing topography as possible. <br />Sediment Pond 009 was designed to adhere to 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 />2. Provide an emergency spillway tepeble of passing runoff from the 25-year, 24-hour <br />storm event; <br />3. Provide adequate storage for sediment generated es determined from SEDCADt utilizing <br />• the Revised Universal Soil Loss Equation. <br />13-SA-1 <br />