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Introduction <br />• Sediment Pond 017 was constructed in the SW'/< NE'/a, Section 34, TSN, R88W, 6'h P.M. <br />The primary purpose of this pond and embankment will be to control runoff and <br />sediment from the mining disturbance area to the east of the pond. Construction was <br />initiated in October and completed in November 2002. This sedimentation structure will <br />be maintained until reclamation of this structure is approved by the Colorado Division of <br />Minerals & Geology (CDMG). <br />Embankment and Excavation <br />The embankment is a homogeneous earth fill structure. The top width of the <br />embankment is approximately 15 feet with upstream slope of 3H:1 V and downstream <br />slope of 3.SH:1V. The principal spillway consists of a 36-inch CMP riser which drops <br />into a 36-inch CMP; the emergency spillway is a trapezoidal channel 20 feet wide (see <br />Exhibit 13-9B, Pond 017 As Built). The keyway was constructed in the embankment at a <br />depth of 15 feet and approximately 15 feet in width. A portion of the pond capacity was <br />• the result of excavating topsoil and material below natural ground level. The material <br />used in the embankment construction came from suitable material in the surrounding <br />area. The unsuitable material excavated from the impoundment area was disposed of in <br />the adjacent disturbed mining area. <br />Designn An~Ivsis <br />Sedimentation Pond 017 was designed to meet or exceed the design and performance <br />requirements of CDMG while utilizing as much of the existing topography as possible <br />and was designed to adhere to the following specifications: <br />1. Provide storage and treatment for the runoff fLOm the 10-year, 24-hour storm <br />event without experiencing any discharge through the emergency spillway; <br />2. Provide an emergency spillway capable of passing runoff from the 25-year, 24- <br />hour storm event; <br />• 3. Provide adequate storage for sediment generated as determined from the <br />SEDCAD 4 computer program. <br />7 3-5H-1 <br />