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<br />49 <br />unit CH-15. Presently this drainage is diverted along the vest side of the <br />existing mine pit. The diversion is represented by CH-15. As restoration of <br />the existing pit area takes place, use of Sediment Pond "D" will be required <br />to store the runoff from the reclaimed area. Use of Sediment Pond "D" will <br />require shaping the pond storage area above the embankment to provide the re- <br />quired storage volume. The required storage volume for Sediment Pond 'D" <br />depends upon the reclamation of the drainage channel CH-15. If the existing <br />diversion is reclaimed and the natural drainage channel (which originally <br />flowed into Sediment Pond "D") is restored, then the contributing drainage <br />area to Sediment Pond "D" becomes 456.4 acres. However, the present diversion <br />(CH-15) is approximately the same length as the natural drainage channel which <br />has been disturbed and is not a major change in the location of the natural <br />I' drainage channel. If the existing diversion is made a permanent diversion, the <br />r- contributing drainage area to Sediment Pond "D" would be reduced to 18.9 acres. <br />The alternative for converting tte existing diversion (CH-15) to a permanent <br />• diversion will enable more complete restoration of the existing pit area due <br />to the need for less pond storage volume above Sediment Pond "D". Both alter- <br />natives presented will require a small temporary diversion to the east from <br />the Sediment Pond "D" embankment to intercept runoff which does not flow io <br />Sediment Pond "C". Another small temporary diversion is required along the <br />tce of the reclaimed area vest side slope for the second alternative. Required <br />storage volumes and spillway capacities are estimated for both alternatives. <br />Location of the temporary diversions are shown on Hydrology Map 2, Appendix A. <br />Design of the temporary diversions is given in Section 6.4. <br />The proposed Sediment Pond "E" vas designed for a crontributing drainage area <br />o° 30 acres. The location of the proposed Sediment Pond "E" is on the drainage <br />channel to which Magpie Creek is diverted. At this location, the sediment pond <br />would intercept the Hagpie Creek drainage runoff from the upper undisturbed areas. <br />Passage of runoff from undisturbed areas through sediment ponds is not required. <br />Also, proposed Sediment Pond "E" design is not adequate because the upper Magpie <br />Creek drainage area is approximately 1388 acres. To store the runoff from this <br />large drainage area would require a pond storage area that would inundate some <br />of the area planned to be mined by G.E.C. Minerals, inc. Thus, a new location <br />• for Sediment Pond "E" is proposed and shown on Hydrology Map 2, Appendix A. <br />This location, along with a diversion paralleling the drainage channel which <br />receives the Magpie Creek runoff (CH-10), will provide adequate control of runoff <br />