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Introduction <br />• Sediment Pond 004 was constructed in 1982. The pond is located in the <br />SW/4, Section 12, Township 5 North, Range 87 West (see Exhibit 13-2A, <br />Postmining Topography and Permanent Features) in the Cow Camp Creek <br />drainage, which is tributary to Fish Creek. <br />Pond 004 was constructed as an earthen fill embankment pond (see Exhibit 7- <br />12, Pond #004). 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 replacement principal spillway construction was initiated and completed <br />during August 2005. The replacement principal spillway is an 8-inch <br />diameter straight plastic corrugated pipe set at an invert elevation of <br />6,948.2 feet. A screened cage is fitted to the inflow end to collect trash <br />and debris. <br />• The 2005 redesign did not affect or include the pond embankment <br />configuration or the existing emergency spillway. The pond embankment has <br />a top width of approximately 15 feet, with upstream and downstream slopes <br />of approximately 3H:1V, respectively. The existing emergency spillway is a <br />trapezoidal open channel with a bottom width of 12-feet and 4H:1V side <br />slopes. The crest is a vegetated channel, while the outslope channel has a <br />riprap lining with a D50 of 6-inches. <br />SCC corrected the Pond 004 watershed boundary in response to field <br />observations made during a Phase II bond release inspection in August 2009. <br />The field observations noted that landscape areas which had been included <br />in the Pond 004 watershed area actually drained to Pond 008. An August <br />2009 survey of the watersheds corrected the drainage divide and shows the <br />contributing watershed to Pond 004 is 547 acres. Approximately 470 acres <br />were disturbed by mining activities and have been reclaimed and <br />revegetated. <br />The As-Built Report was revised in August 2009 to reflect the corrected <br />contributing watershed area. There were no modifications to the pond <br />configuration, embankment or spillway structures. <br />• <br />TR-51 1 Revised 09/09