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Doc Date:1211112001 III'llllllll'lll ~II <br />sss <br />u <br />//F Section 816.47 Hydrologic balance: Discharge structures. <br />Discharge from sedimentation ponds, permanent and temporary impoundments, coal <br />processing waste dams and embankments, and diversions shall be controlled by <br />energy dissipaters, riprap channels, and other devices, where necessary, to reduce <br />erosion, to prevent deepening or enlargement of stream channels, and to minimize <br />disturbance of the hydrologic balance. Discharge structures will be designed according <br />to standard engineering-design procedures. <br />r 1 <br />LJ <br />The rates of flow in the temporary diversion ditches, and the rates of design discharge <br />from sedimentation pond riser pipes is provided in Exhibit 42, Drainage and Sediment <br />Control Plan, under the discussion of "flood routing". As documented by these <br />specifications, the design out-flow from sediment control facilities in the Kerr Mine and <br />Tipple areas will be low, on the order of five cubic feet per second. While discharge <br />structures will be installed where site-specific conditions demand, no specifications for <br />pre-fabricated energy dissipaters are proposed due to the low discharge rates. <br />Discharge flow rates from surface water facilities will be controlled through proper <br />grading of spillways and discharge pipes and by use of energy dissipating and flow <br />check methods. Water <br />TR-19 <br />818-61 a <br />Revised 11198 <br />