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• f) All pond dams will be designed to have a height of less than 10.0 feet measured from <br />the original ground in the middle of the dam to the top of the dam. The top of dam width will <br />be at least 10.0 feet in all areas. <br />g) All ponds will have a keyway cut along the entire width of the dam as shown on Map <br />2.05.3(3)-6-1. This keyway will be filled with competent material and compacted to the same <br />standards as the dam foundation. <br />h) All principal spillways will have 2 seep collars installed within the dam which will be at <br />least 2x the pipe diameter. All dam fill will be compacted around the seep collars and <br />principal spillway pipe to 90% of the maximum dry density of the fill material. <br />i) The emergency spillways will be a rip-rap lined trapezoidal channel of 10 feet bottom <br />width and 2:1 sideslopes. <br />k) Attachment 2.05.3(3)-15 demonstrates that the given materials on site have been <br />tested for suitability in constructing pond embankments and that the long term slope safety <br />factors exceed 1.3 in all cases, given the pond design parameters outlined above and in the <br />• Attachment. For this reason, no individual slope stability analyses are presented for the <br />ponds. <br />Pit dewatering may occur year round or during portions of a year. The dewatering process <br />will be a sporadic operation-controlled, occurrence depending on various factors which may <br />include the location of the pit inflows, the location of standing water in the pit, or the location <br />within the pit of the overburden and coal removal operations. When pit dewatering is <br />required, the anticipated dewatering rate will be in the range of one to two cubic feet per <br />second or less. Until Pond 011 is built, all pit dewatering discharges will be directed to Pond <br />007, which is the main pond for the permit area. However, once Pond 011 is constructed, <br />direct pit pumping into it may occur if conditions warrant. These procedures will be applied <br />for in WFC's NPDES Permit, which will be similar to Permit CO-0000213 for Ponds 007, 008 <br />and 009. The revised NPDES Permit is enclosed in Attachment 2.05.3(3)-18. <br />Actual water flow velocity going into Pond 010 (when built) will be controlled with adequate <br />energy dissipators (i.e., rock riprap, geotextiles, metal or concrete energy dissipator boxes, <br />• (Revised July 2006) 2.05.3(3)-19 <br />