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1.0 Introduction <br />• Sediment Pond 002, also known as the Wadge Impoundment, was established in 1976. The pond is <br />located in the Little Grassy Creek drainage, which is tributary to Grassy Creek. Pond 002 is an <br />incised impoundment without an embankment. The pond configuration is shown on Map 2.05.3 - <br />E2.A, Sediment Pond 002 As- Built. It was created by leaving the Wadge Pit highwall from the <br />Seneca II Mine "pre -law" mine area open and letting the pit fill with water. The pond is <br />approximately 60 feet deep at its deepest point and covers approximately 9 acres. The spillway <br />system is a single open - channel trapezoidal spillway with a bottom width of seven (7) feet, a left side <br />slope of 2H:1V and a right side slope of 1H:1V. The channel is well vegetated, with additional <br />protection provided by rock riprap. The spillway is located at the 100 percent sediment storage level. <br />The pond was approved as a permanent, postmine structure by the Colorado Division of <br />Reclamation, Mining and Safety (CDRMS) as part of Technical Revision No. 42 (TR -42) for the <br />Seneca II Mine permit (C -80 -003) on September 12, 2007. However, surface facilities construction <br />activities for the Peabody Sage Creek Mine re- disturbed a portion of the watershed area; <br />consequently, Sage Creek Coal Company has evaluated the pond design and storage capacity to <br />assure continued compliance with the applicable regulations of the Colorado Mined Land <br />Reclamation Board for Coal Mining. <br />The contributing watershed is approximately 3,028 acres; approximately 1,630 acres are undisturbed, <br />• another 1,220 acres previously disturbed by surface mining operations at the closed Seneca II Mine <br />(Permit C -80 -003) have been reclaimed and revegetated. As of the date of the Peabody Sage Creek <br />Mine permit application package (PAP) submittal, the majority of the reclaimed and revegetated <br />lands has been approved, or has approval pending, for Phase 11 bond release. Surface facilities <br />construction activities for the Peabody Sage Creek Mine re- disturbed approximately 177 acres. The <br />contributing watershed area, including the disturbed area, is shown on Map 2.05.3 -M4, Drainage and <br />Sediment Control Plan. <br />As noted above, the pond was originally constructed in 1976 by a precursor company to Seneca Coal <br />Company (SCC), the Seneca II Mine operator and permittee under Coal Mine Permit C -80 -003. To <br />assure design continuity, the design and construction information for Pond 002 previously approved <br />have been included as part of this design report. Following is a summary of the design and <br />construction history. <br />• The pond design was evaluated by SCC in 1986 as part of the first Seneca II Mine permit <br />term renewal (RN -01). The 1986 design evaluation demonstrated that the pond was <br />designed and constructed to meet the requirements of Rule 4.05.6. The 1986 design is <br />included in this report as Attachment 2.05.3- E2.A -1. <br />• SCC prepared an as -built report in 2005 as part of TR -37 which certified the pond met the <br />requirements of Rules 4.05.6(3)(a), 4.05.9(2)(b) and 4.05.9(2)(c)(ii). The 2005 as -built <br />report is included in this design report as Attachment 2.05.3- E2.A -2. <br />0 <br />2.05.3 -E2.Al 12/09 <br />