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• • -iiiiiiiiiiiiiiiiiii <br />STATE OF COLORf ~~ <br />Roy Romer, Governor <br />DEPARTMENT OFNATURALRESOURCES <br />MINED LAND RECLAMATION DIVISION <br />DAVID C. SHELTON, Director <br />DATE: June 11, 1987 <br />T0: Gregg Squire <br />FROM: Candy Thompson <br />RE: Technical Revision #TR-34, C-81-010, Trapper Mining, Inc. <br />I have reviewed the above referenced, Technical Revision and have identified <br />the following inadequacies in the submittal. This information will need to be <br />submitted prior to Division approval. <br />Johnson Gulch Pond <br />The Johnson Gulch Pond configuration is presently approved as shown in <br />technical revision #25, submitted by Trapper mining on August 13, 1986. While <br />comparing the sediment input between the two revisions it was noted that <br />subwatershed 1,1,1 has a different acreage, curve number, and time of <br />concentration than the previously submitted data in #PR-25. The summary table <br />to precede the sediment run must be submitted for this watershed as was <br />submitted with watershed 3,1,3. <br />Spillway Design <br />The V-shape principal spillway is an acceptable design. However, the flat <br />portions of the emergency spillway and the sloping portions of the emergency <br />spillway across the dam embankment show no protection from erosion. Trapper <br />must submit calculations showing that allowable velocities for the emergency <br />spillway bed material will not be exceeded during a 25-year event or provide <br />for appropriate lining as required by Rule 4.05.6(3)(d). The ditch sizing <br />leading from the spillway must also be provided, demonstrating adequate <br />capacity and freeboard to carry the 25-year flow. <br />sak <br />0304E <br />423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567 <br />