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• <br /> <br /> <br />RESPONSE: <br />Discussion of the permanent channel is set forth in Section 4.05 as well <br />as in Appendix 1. The Drainage and Sediment Control Plan Appendix <br />(Appendix 1) details the design parameters of Diversion Ditch No. 1 in <br />addition to the locations being shown on the Mine Facilities Map (Map <br />12) and the Regional Hydrology Map (Map 6). <br />6 <br />RFCDnNCF• <br />ows. <br />Diversion Ditch No. 2 is temporary and will be removed upon successful <br />reclamation. Therefore, the channel will be reestablished into the <br />gulch as shown on the Postmining Topography Map (Map 14). <br />7. Ditch No. 1, the oermanent diversion should be designed to handle <br />If Ditch No. 2 is temporary and will be removed upon successful <br />reclamation, then Mao 14, Postminina Tooograohv should show this <br />the riows from uitch no. 'L ana the aisturbeo area since u on <br />rec amation these areas wi f ow into t e permanent iversion. <br />RESPONSE: <br />Diversion Ditch No. 1 has been designed as a permanent diversion to <br />handle all the flows of Coal Gulch including the mining operation and <br />the drainage basin of Diversion Ditches No. 2 No. and 3. Two (2) cases <br />have been evaiuated for Diversion Ditch No. I. As shown in Appendix 1, <br />both the reclaimed and mining cases have been evaluated. The estimate <br />of peak flow for the 100-year, 24-hour precipitation event in the <br />reclaimed case indicates that flows will be approximately 6~ greater <br />than that expected during mining. Therefore, the ditch design for the <br />mining case has not been altered due to utilization of 1.0 foot <br />freeboard for the ditch. Estimates of the additional flow through the <br />ditch will raise the water level less than 0.1 foot. Therefore, <br />redesign for the reclaimed or postmining case is not necessary. <br />-41- <br />