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Ponds, Impoundments, Diversions <br />Information on the sediment and runoff control system can be found in <br />Section 2.05 and Exhibit 13 of the Permit Document, Appendix 1 of the Adequacy <br />Responses and on Map 12, Mine Facilities and Map 6, Regional Hydrology Map. <br />The applicant proposed one sediment pond, one catchment basin and several <br />diversions as part of the hydrologic control system. Coal Gulch had <br />previously been diverted around the mine site and the applicant submitted <br />designs to ensure this diversion is in compliance with applicable regulations. <br />Based upon visual observations during inspections conducted by the Division, <br />the berm separating Coal Gulch from the mine area exhibits seepage from Coal <br />Gulch past the berm into the facilities area. Eventually, this water which <br />seeps through, enters the sediment pond; however, the pond is not designed to <br />handle these flows. The following stipulation is necessary to ensure <br />satisfactory berm construction. <br />Stipulation No. 9 <br />WITHIN THIRTY (30) DAYS OF PERMIT ISSUANCE, THE APPLICANT MUST SUBMIT A <br />PLAN TO PREVENT SEEPAGE FROM COAL GULCH THROUGH THE BERM INTO THE <br />FACILITIES AREA. THIS PLAN MUST BE APPROVED BY THE DIVISION AND <br />IMPLEMENTED PRIOR TO COMMENCEMEN7 OF MINING. <br />The Coal Gulch permanent diversion was designed to handle a 100-year, 24-hour <br />storm both during mining and after reclamation. The designs presented were <br />not adequate for this storm, however, the channel will handle the 10-year, <br />24-hour storm during mining. The velocities in the channel are excessive. <br />Riprap designs presented for the 100-year, 24-hour storm were not adequate. <br />Adequate designs would require riprap with a median diameter greater than the <br />channel depth. The Division is only approving this diversion as a temporary <br />structure, <br />Stipulation No. 10 <br />WITHIN THIRTY (30) DAYS OF PERMIT ISSUANCE, THE APPLICANT MUST SUBMIT TO <br />THE DIVISION FOR APPROVAL, A PLAN FOR RECLAMATION OF THE COAL GULCH <br />DIVERSION AND PLANS FOR RE-ESTABLISHMENT OF THE PERMANENT POST-MINING <br />COAL GULCH CHANNEL. THE DESIGNS MUST BE APPROVED IN WRITING BY THE <br />DIVISION PRIOR TO THIS STIPULATION BEING SATISFIED. <br />Stipulation No. 11 <br />WITHIN THIRTY (30) DAYS OF PERMIT ISSUANCE, THE APPLICANT MUST SUBMIT TO <br />THE DIVISION A PLAN FOR EROSION CONTROL OF THE TEMPORARY COAL GULCH <br />DIVERSION ADEQUATE TO HANDLE THE VELOCITIES OF THE 10-YEAR, 24-HOUR <br />STORM. THIS PLAN MUST BE APPROVED PRIOR TO IMPLEMENTATION. <br />