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1.0 Introduction <br />• This design report presents the Coal Stockpile Sump system design. The sumps are designed to <br />control runoff and sediment loads from the South Surface Facilities Area of the Peabody Sage Creek <br />Mine, as well as, serve as a surge pond for mine water discharge from the underground mine <br />workings. The location of the two sumps are the SEA, Section 34, Township 6 North, Range 87 <br />West, of the 6 P.M. (see Map 2.05.3 M4, Drainage and Sediment Control Plan). <br />The two coal stockpile sumps (Upper Coal Stockpile Sump [UCSS] and Lower Coal Stockpile Sump <br />[LCSS]) are located immediately adjacent to each other; the LCSS discharges to Channel PM -1 and <br />ultimately to Pond 002. A two sump system was designed because space constraints prevented the <br />sizing of a single structure with adequate capacity to contain all runoff contributions from the entire <br />South Surface Facilities Area. The UCSS is designed to be the primary treatment structure from coal <br />stockpile pad runoff — it also will be a backup surge pond for mine water discharges from the <br />underground mine workings. The LCSS is the primary treatment structure for runoff from the <br />remainder of the South Surface Facilities Area, as well as, secondary treatment for runoff from the <br />coal stockpile pad. Using the Coal Stockpile Sumps as pre - treatment structures will minimize the <br />downstream delivery of coal fines and untreated underground mine water. <br />• Both ponds will be designed and constructed using similar methods. <br />2.0 Embankment and Excavation <br />The embankments for both ponds will be homogeneous earthen filled structures. Borrow source <br />material, which will be used to construct the embankments, will be sourced from the underground <br />mine portal area. <br />Upper Coal Stockpile Sump (UCSS): The embankment height, as measured from the ground surface <br />of native material to the invert of the emergency spillway, will be approximately 10 feet. The top <br />width of the embankment crest will be approximately 20 feet; embankment outslope and inslopes <br />will be 2H:1 V and 4H:1 V, respectively. A keyway will be constructed into impervious materials <br />below the embankment footprint. The keyway will be a minimum of 5 feet deep and 10 feet wide. <br />Lower Coal Stockpile Sump (LCSS). The embankment height, from the ground surface of native <br />material to the invert of the emergency spillway, will be approximately 10eet. The top width of the <br />embankment crest will be approximately 15 feet; embankment outslope and inslopes will be 2H: IV <br />and 3H:1V, respectively. A keyway will be constructed into impervious materials below the <br />• embankment footprint.. The keyway will be a minimum of 5 feet deep and 10 feet wide. <br />2.05.3 -E2.E1 12/09 <br />