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COLORADO <br />Division of Reclamation, <br />Mining and Safety <br />Department of Natural Resources <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />June 29, 2016 <br />To: Tabetha Lynch <br />From: Jason Musick <br />RE: Trapper Mine, C-1981-010 <br />TR -115, Adequacy Review Memo <br />Per your request, I have reviewed the proposed two diversions identified as the Deal Diversion and the <br />Deacon/Jeffway Diversion designs associated with the above referenced revision. The review included <br />the proposed SEDCAD modeling submitted with the revision to determine if the the demonstrations meet <br />the design criteria for Rules 4.05.3. <br />Based on the Division's review, the Deal Diversion will divert run-off from a proposed disturbed sub - <br />watershed of 23.74 acres to the Deal 1 sediment Pond. The Deacon/Jeffway Diversion will divert run-off <br />from a proposed disturbed sub -watershed of 83.78 acres to the East Flume sediment pond. Based on the <br />information provided with the TR115 submittal these SWS totals appear accurate. <br />The Division has the following adequacy comments: <br />With regard to the Deal Diversion SEDCAD model, the Division must review all variables used to <br />derive the structure outputs. Based on the Division's review all variables appear adequate for <br />the diversion. However, the structure networking and individual structures associated with the <br />drainage of the watershed require clarification. The SEDCAD model for the Deal Diversion <br />identifies the watershed itself as structure #1 and the Deal Diversion as structure #2. Based on <br />proposed Map M51, the Deal Diversion is identified as structure #1 flowing into a drainage labeled <br />stru 1, sws 2, which flows into Junction 1, which flows into the Deal 1 Pond. In order for the <br />Deal Diversion design to be adequate, every structure must have a designated down -gradient <br />structure. Based on the Deal Diversion design the diversion does not have a designated down - <br />gradient structure. Please provide clarification to the Deal Diversion model to discuss all <br />linkages and appropriate run-off calculations derived from the linkages to ensure that the <br />diversion is adequately designed and to account for the additional run-off to all down - <br />gradient structures. <br />Based on the information in comment #1 above. A revised design for the Deal 1 Pond which <br />would include the Deal Diversion run-off, was not included in the TR115 submittal. In order to <br />ensure that the Deal 1 Pond will have the adequate capacity to contain and treat the run-off or <br />inflow entering the pond, the Deal 1 Pond design must include the additional inflow resulting <br />QF cQlO <br />1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http://mining.state.co.us <br />John W. Hickenlooper, Governor I Mike King, Executive Director I Virginia Brannon, Director * 1876 {` <br />