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Section 11 Mine Area and Fill <br />This fill will be drained by graudally sloping ditches to the Gulch A ditch, except <br />for about 30 acres which will be drained to the smaller supplemental ditch. Both the <br />Gulch A ditch and the supplemental ditch will convey drainage flow to the Gulch sedi- <br />mentation pond. Two alternatives for the gradually sloping ditches are being considered <br />and are illustrated on Figure 7. <br />The first alternative consists of constructing 20-foot wide terraces at every 100 feet <br />of elevation similar to the terraces constructed on the Streeter Gulch fill. These terraces <br />would be pitched at a 5% slope toward the hillside to allow none-foot depth of drainage <br />to flow along the terraces to the Gulch A ditch. Also, the ditches would be dug an addi- <br />tional foot deeper on north slopes or any other slopes where accumulation of snow and ice <br />might interfere with drainage along the terraces during the spring thaw. <br />The second alternative consists of a series of contour ditches in lieu of the con- <br />struction of terraces. Two spccings of ditches have been considered: ditches at intervals <br />of 25 feet in elevation, and ditches at intervals of 50 feet. The vertical interval of 50 feet <br />• was found to provide sufficient ditching to safely convey the runoff to the Gulch A ditch <br />and was selected. <br />In both alternatives, additional control of runoff on the mine fills will be achieved <br />by the use of small furrows about 4 or 5 inches deep constructed at intervals of about 20 <br />feet slope distance. As both alternatives offer satisfactory handling of the runoff from the <br />fills to the collector ditch, the choice between alternatives will be made based on which- <br />ever alternative is judged easiest for construction using construction trials. <br />Taylor Gulch Mine Area <br />This area will be the last area to be mined, and the drainage practices determined <br />to be the best from the experiences gained on Streeter Gulch mine area and fill and the <br />Section 11 mine area and fill will be utilized on this area. The drainage will be directed <br />by one of the alternative means, either the sloping terraces or contour ditches, to the <br />Taylor Gulch tributary which lies on the western edge of the area to be mined, and thence <br />in the Taylor Gulch tributary to the Taylor Gulch sedimentation pond. <br />6 <br />