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a"~ <br />III III III III IIII III <br />STATE OF COLORADO <br /> <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Naw ral Resources <br />1313 Sherman SI., Room 215 <br />Denver, CO 80203 <br />Phone: (3031866-3567 <br />FAX: (3071 83 2-8106 <br />DATE: September 7, 1993 <br />TO: File C-80-007; Minor Revision No. 100 <br />FROM: Christine Johnsto~~ <br />RE: ABequacy Review; Aest Elk Mine; File No. C-80-007 <br />OF ~~[~ <br />`~{~, b <br />•. `~ o <br />re~ <br />Roy Rnmer <br />Governor <br />M¢haelB long <br />Dimsion Dveunr <br />After review of Minor Revision No. 100, which proposes a temporary <br />construction drainage plan during the building of the stack tube <br />and reclaim system, and enlargement of MB-3 and MB-6 (MB-2R), the <br />Division has the following concerns: <br />1. MB-3 (enlarged) does not have enough capacity to hold <br />flow from MB-2 (over the 1 inch storm) and MB-6. <br />Flow into MB-3: <br />0.39 acft from WS 15A and 15B <br />1.15 acft from MB-6 <br />0.42 acft from MB-2 (less than 1 in. storm) <br />0.28 acft from WS 15C and 14D <br />2.24 acft <br />Available storage in MB-3 (below the emergency <br />spillway): <br />1.54 acft (w/0.10 sediment level) <br />1.64 acft (w/out sediment) <br />MCC must provide an alternate plan, as MB-3 will not hold <br />the runoff. MCC should attempt to reduce the amount of <br />water which flows into MB-3, enlarge the pond, or <br />effectively discharge water through the principle <br />spillway (i.e. - water meets effluent limitations). The <br />Division will entertain any other options suggested by <br />MCC. <br />2. A four foot dike is not adequate to contain a 10-year event <br />which yields 2.52 acre feet. MCC should build the dike higher <br />in order to contain this volume of water. <br />3. The Division .is missing a ditch design for D7-9 temporary. <br />The Division has discussed this with Cathy Begej of Greystone, <br />