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i <br />Introduction <br />Sediment Pond 010 was constructed in the NE4 of Section 8, TSN, R87W, 6th P. M. The <br />primary purpose of this pond and embankment will be to control runoff and sediment from <br />[he mining disturbance area almost 5000 feet to [he south of the pond. Construction was <br />started Ln SuLy 1996 and completed in August of 1996. The embankment was constructed with <br />a horizontal drainage system. A toe drain was installed that will collect the water and <br />discharge St below the toe of the embankment. This system Ss designed to act as <br />controlled seepage through the embankment. This sedimentation structure will be <br />maintained until reclamation of this structure is approved by Colorado DS vision of <br />Minerals and Geology ICDMGI. <br />Site Description <br /> Land Use. Sedimentation Pond 010 has a 948.4-acre watershed (see Exhlblt 13-2). This <br /> watershed will be disturbed by mi ning actlvl ti es as shown on E xhibits 12-1 and 20-1 and <br /> contemporaneously reclaimed as shown on Exhibit 19-1. The land condition of the watershed <br /> was conservatively based on the maximum disturbance at any one time within the proposed <br /> mining area, approximately 59 percenc undisturbed and 41 percent disturbed. <br />Embankment and Excavation. The embankment is a homogeneous earth fill structure. The top <br />width of the embankment is approximately 25 feet with upstream slope of 3.75h:1v and <br />downstream slopes of approximately 3.75h:1v. The principal spillway Ss a 6-inch diameter <br />dewatering orifice cut into a 36 Snch CMP riser which drops Into a 24 inch CM P; the <br />emergency spillway Ss a trapezoidal channel B feet wide (see Exhibit 13-4A). A portion of <br />the pond capacity was the result of excavaCing topsoil and material below natural ground <br />level. Excavated suitable material was used in embankment construction and came from the <br />Yoast Haul Road B between Stations 4+00 and 10+00 and Stations 13+00 to 15+00. <br />Design Analysis <br />General. This sediment a[lon pond was designed to meet or exceed the design and <br />performance requirements of CDMG while utilizing as much of the existing topography as <br />possible. Sedimentation Pond 010 was designed to adhere to the following specifications: <br />13-3A-1 Revised 08/30/96 <br />• <br />