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. Introduction <br /> The replacement principal spillway construction was initiated and completed <br /> during August 2005. Th e replacement principal spillway is an 8-inch <br /> diameter straight plastic corrugated pipe set at an invert elevation o£ <br /> 6,998.2 feet. A screened cage is fitted to the inflow end to collect trash <br /> and debris. <br />Sediment Pond 004 was originally constructed in 1982. The pond is located <br />in the SW/4, Section 12, Township 5 North, Range 67 West (see Exhibit 13- <br />2A, Postmining Topography and Permanent Features) in the Cow Camp Creek <br />drainage, which is tributary to Fish Creek. The contributing watershed is <br />approximately 575 acres, of which 522 acres were disturbed by mining <br />activities, and which have since been reclaimed and revegetated. <br />Pond 009 was constructed as an earthen fill embankment pond (see Exhibit 7- <br />12, Pond #009). The original principal spillway consisted of a 36-inch <br />straight CMP pipe, with a 6-inch opening. During the April 2005 inspection <br />following snow and ice melt, Seneca Coal Company (SCC) representatives <br />determined that the 6-inch discharge barrel was deteriorated such that the <br />existing principal spillway warranted replacement. SCC submitted a <br />technical revision (TR-39) which presented the design and replacement plan <br />for a new principal spillway in June 2005. <br />The redesign did not affect or include the pond embankment configuration or <br />the existing emergency spillway. The pond embankment has a top width of <br />approximately 15 feet, with upstream and downstream slopes of approximately <br />3H:1V, respectively. The existing emergency spillway is a trapezoidal open <br />channel with a bottom width of 12-feet and 9H:1V side slopes. The crest is <br />a vegetated channel, while the outslope channel has a riprap lining with a <br />Dso of 6-inches. <br />1986 Design Analysis <br /> <br />Pond 004 was originally designed to meet <br />performance requirements of the Regulations <br />Reclamation Board for Coal Mining and <br />specifications: <br />1 <br />TR-92 <br />or exceed the design and <br />of the Colorado Mined Land <br />adhere to the following <br />Revised 12/06 <br />