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3.3.4 Reclaimed Ephemeral Channels <br />Lower Road Channels <br />The reclamation of the mine site and road will include establishing stable <br />ephemeral channels across the reclaimed area. Two major channels cross the lower <br />portion of mine road, Munger Creek near the topsoil stockpile and the channel draining <br />the major canyon south of the road near where the waste rock disposal area was <br />proposed. Both channels are now diverted under the road with culverts. When the <br />culverts are removed, dry fords will replace the culverts. The reclaimed configuration of <br />each is shown on Figure 2.2-7C. <br />Calculations for the size of the reclaimed channels on the lower road are <br />contained on Table 3.9-5. These calculations are based upon previous surface water <br />hydrology studies for the two lower channels. The calculations are shown in Appendix <br />• M(v) for the 100 year event at the 72" culvert and Appendix M(i) for the 10 year event at <br />the 42" culvert. Pages 3 and 4 of Table 3.9-5 show the drainage area, flow calculations <br />and channel design for the 18" culvert near the topsoil stockpile. <br />Although the channels have been designed for non erosive water velocities, rip rap will <br />be installed in the channels to protect the fords and gravel on the road surface will <br />minimize rutting of the channel with wheeled traffic and the ensuing erosion. Rip-rap <br />keys will be installed at the upstream and downstream edges of the ford. The rip-rap <br />keys will be a two foot wide by two foot deep slot dug into the channel bottom on both <br />sides of the reconstructed channel. The keys will be filled with one foot top size rip - <br />rap. These rip rap keys will ensure that the fords will not be washed out during high <br />flow. The gravel will be reclaimed from the existing road where the road base is <br />excavated in the process of building the ford. The gravel is a coarse "pit-run" gravel with <br />a top size of about 10 inches and wi{I protect the channel bottom between the rip rap <br />keys. The gravel recovered from the existing road will be placed upon the road surface <br />for the ford to help maintain a firm road base that will not erode or wash out. <br />TR-22 3-14 OS/23I07 <br />