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. EFCI has established a permanent clean water diversion to route <br />• runoff from undisturbed areas above the coal refuse stockpile around <br />the stockpile and into an adjacent unnamed natural drainage. This <br />diversion has been designed to safely pass peak flows resulting from <br />a 100-year, 24-hour storm event and has been revegetated or riprapped <br />as appropriate based upon design flow velocities to minimize erosion <br />and insure long term stability and integrity of the diversion <br />channel. <br />EFCI has also constructed permanent collection ditches around the <br />coal refuse stockpile to collect and route disturbed area drainage <br />to Sedimentation Pond No. 4. These ditches have been designed to <br />pass peak flows from the 100-year, 24-hour storm event and have been <br />revegetated or riprapped as appropriate to control flow velocities <br />and minimize erosion. The refuse pile drainage system includes the <br />west, north, and south collection ditches. in response to a <br />clarification of the CMLRD's ditch design requirements, EFCI reviewed <br />and modified the designs to accommodate the 100-year, 24-hour storm <br />• event in mid-1989. The ditches were subsequently reconstructed. The <br />west and north collection ditches were completed to their ultimate <br />design limits, and modifications to the south collection ditch were <br />completed to the limit of topsoil stripping. As construction of the <br />coal refuse stockpile progresses to the west, EFCI will extend the <br />south collection ditch in sequence with associated topsoil removal / <br />operations to insure that disturbed area drainage is controlled at " <br />all times. <br /> <br />in the loadout area, three temporary perimeter ditches collect and <br />route runoff to Ponds L1 and L2. These ditches are designed to pass <br />the peak flows resulting from -year, 24-hour storm event. <br />• <br />c:~eso~rx-z3 <br />os/i9/ss 2:13pm k.p 2.05.3-50 Revised - May 1995 <br />