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- ] S- <br />identification letters. The LRCI•'E Plate i, Sedimentation Fonds, Energ}'::ine; <br />So. i and 2, and Ecluman Pari: shows the typical ditch section and a schedule of <br />information for the ditches. The design frequency for the ditches is either <br />10 years or 100 years depending on whether ditch overflow would cause signifi- <br />cant problems for downstream ponds. The ditches were sized to handle the <br />peak rate of runoff for the desired frequency for the tributary area to the <br />ditch. Feak flow rates were determined in accordance with the SCS publica- <br />tion titled Procedure for Determining Peak Flows in Colorado, (1977). The <br />ditche=_ were designed in accordance with a document titled Design Charts for <br />Open Channel Flow, published in 1961 by the U. S. Bureau of Public Roads. <br />The ditches were assumed to be stabilized with grass lining; design velocit- <br />ies were kept under 6-feet per second to prevent erosion and additional con- <br />tribution of sediment to runoff. <br />PONDS <br /> The LRCWE Plate 1, Sedimentation Ponds, Energy Mines No. 1 and 2, and Eckman <br /> Park contains a schedule contining information describing the 18 ponds. The; <br /> range in height from 2.7 to 20.5 feet in height using the height criteria <br /> specified in 30CFR816.46 (q), from upstream toe to emergency spil lway crest. <br /> Only Pond 0 exceeds 20.0 feet. The ponds range in size from 1.9. to 210 acre- <br /> feet. Ponds A, D, E, F, G, and K exceed 20 acre-feet. <br />It is recommended that the upstream face of Pond A be protected with 18-inches <br />of riprap on a 6-inch gravel filter from the dam crest [o one-foot below the <br />elevation of the lowest set of riser holes. Dam crests and embankment slopes <br />of all ponds should be protected with vegetative cover. Side slopes are <br />specified at 3:1, and all embankments should be homogeneous. <br />~• <br />Permit Renewal No. 3 Exhibit 8q 1 /15/00 <br />Page 17 of 22 <br />