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• Highway 160 by a culvert passing underneath the highway. The entire length of <br />Ditch No. 2 is placed in bedrock. The channel follows the contour of the land <br />and varies in depth. Construction will utilize the largest channel size along <br />the entire length to ensure adequate sizing of the structure. <br />Peerless may investigate the retention of Ditch No. 2 as a permanent drainage <br />feature. This will be beneficial both in terms of establishing drainage on <br />the light use road and diverting flows away from reclaimed areas. The design <br />submitted meets the requirements for permanent diversions. Assuming the ditch <br />will be retained, the drainage area intercepted by the ditch was not included <br />in the runoff calculation for the permanent Coal Gulch channel design. <br />Diversion Ditch No. 3 <br />r~ <br />U <br />Ditch No. 3 (West Ditch) is located above the planned portal entries. The <br />ditch is designed to intercept undisturbed drainage and divert this runoff to <br />an existing drainage which is tributary to Coal Gulch above Ditch No. 1. The <br />section of the natural drainage will be monitored and protected with riprap as <br />appropriate should any increased erosion occur due to the discharge of Ditch <br />No. 3. The cross section of Ditch No. 3 is similar to Ditch No. 2 (Figure 3). <br />Collection Ditch No. 4 <br />Ditch No. 4 (East Ditch) is located in the eastern part of the previously <br />disturbed area. The ditch is designed to collect runoff from the disturbed <br />• Revised 9/12/86 <br />7 <br />