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<br />STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St, Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866.3567 <br />FAX: (303) 832-8106 <br />TO: Dan Mathews <br />Bill Owens <br />Govemor <br />INTEROFFICE MEMORANDUM Russell George <br />Executive Director <br />Ronald W. Cattany <br />Division Director <br />Natural Resource Trustee <br />FROM: Mike Boulay I? 1& <br />DATE: October 26, 2007 <br />SUBJECT: Munger Canyon Mine, Permit No. C-1981-020 <br />Technical Revision No. 23 (TR-23) <br />I have reviewed the TR-23 application submitted by J.E. Stover & Associates, Inc. with regard to <br />modifications to ditch/channel specifications as requested. I have the following comments which <br />should be forwarded to the operator. <br />1. New SEDCAD utility runs were provided for ditches K, L, C, D, F, I and J for the Gob <br />Pile Ditches. In several instances including ditches K, D, I, and J the design discharge <br />was changed but the Subwatershed Hydrology Detail and Structure Summary information <br />contained in the original SEDCAD demonstrations beginning on page M (vii)-31 for <br />interim configuration and on page M (vii)-52 for Final Reclamation of the approved <br />permit were not updated. This hydrology detail is necessary to support the revised design <br />discharges. The presentation is confusing and there are inconsistencies between the <br />SEDCAD demonstrations (original subwatershed hydrology detail and new utility runs <br />submitted with TR-23). Updated ditch and culvert summary sheets, M (vii)-29 and 51 for <br />the interim and reclaimed configurations, respectively show the same design discharge <br />which also appears to be incorrect. Please revise the SEDCAD demonstrations, <br />channel utility runs, and all ditch design summary tables as appropriate, so that all <br />information presented in Appendix M (vii) is consistent and supported by the <br />subwatershed hydrology detail. <br />2. The Culvert Summary provided on revised page M (vii)-29 shows a peak flow of 8.8 cfs <br />which does not match any of the design information presented in either the interim or <br />reclaimed configuration SEDCAD demonstrations. There is no design information <br />presented for CMP-3. Please revise the Culvert Summary or SEDCAD <br />demonstrations as necessary to be consistent for Culvert CMP-2 and provide a <br />design for CMP-3. <br />COLORADO <br />DIVISION O F <br />RECLAMATION <br />MINING <br />SAFETY <br />Office of Office of <br />Mined Land Reclamation . Active and Inactive Mines