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The amount of disturbed area draining into Taylor Gulch sedimentation pond will <br />build up gradually as the Taylor Gulch area is mined. This will allow time for reclama- <br />tion of mine area so that the early fill areas will be well vegetated by the time later areas <br />are .added to the disturbed drainage area. <br />SEDIMENTATION PONDS <br />Three sedimentation ponds have been built, and two sedimentation ponds are <br />planned for construction. Drainage from ali disturbed areas are directed to these ponds <br />through mine fill terraces and contour ditches, mine fill collection ditches, and roadway <br />ditches. Whereever practical, drainage from undisturbed areas has been diverted away <br />from these ponds so that the pond sizes need not be prohibitively large and that maximum <br />detention time may be achieved for runoff from disturbed areas. Data on the five ponds <br />is given in Tab{es 7 and 8, and illustrations of the ponds are shown on Figures 7 thru 12. <br />Descriptions of each of the ponds are given in the following subsections. <br />Taylor Gulch Tributary Sedimentation Pond <br />This pond i Ilustrated on Figure 3 is a prcposed ;oral planned for construction on a • <br />tributary of Taylor Gulch. Its purpose will be for sedimentation of the runoff from the <br />Taylor Gulch mine area. This is the lost area planned for mining, and construction of <br />this pond wi II take place at the time that mining is being finished in the Section 11 area in <br />preparation for collecting runoff from the new area to be mined in the Taylor Gulch area. <br />This pond has been designed to provide sedimentation and flood detention capacity <br />in accordance with Colorado Mined Land Reclamation Board's regulations, and is patterned <br />after designs used for the constructed Streeter Gvlch pond. Sufficient sediment capacity <br />is provided for 3 years of collection of sediment, and the elevations of the principal spillway <br />and emergency spi Ilway are set to provide an average of slightly more than 24 hours of <br />flood detention fora 10-year flood occurrence. The maximum water surface for the 10- <br />year flood occurrence will be elevation 69d3.0 or about 2 feet under the emergency <br />spillway elevation, thus providing a good margin of safety for this occurrence. The spillway <br />has been designed to safely pass a 25-year flood occurrence with a freeboard in excess of <br />1.0 foot to the top of the embankment. <br />r <br />7 <br />