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Subject Protection of the Hydrologic <br />stem - Hubbard Canvon Ventilation Facilities <br />o. 2 - Somerset Coal Mine <br />Fill Slopes Below Yard Elev. <br />Data <br />CALCULATION NOTES <br />gy MOA <br />Checked <br />Acct <br />July 15 19 H1 <br />Sheet No. 1 of 4 Sheets <br />The outby slopes of the yard area dram into ditches along the edge of the Canyon <br />road and the toe of the yard fill slopes. These ditches drain into a culvert <br />under the road and into the creek, as shown. <br />The area is divided into three areas for computing soil loss and two areas for <br />ditch flow volumes. The slopes are 2:1 (2 rt. horizontal to 1 ft. vertical) and <br />vary from 8 to 13 ft. of vertical height. fhe slopes v,ill be planted to control <br />erosion. <br />Soil loss from the 2:1 slopes are not computed. The change of grade from thie slopes <br />to ditch will Cause the sediments to ~.ettle uut requiring periodic cleaning of <br />the ditch. The volume of transportable soil in the ditch is computed from the <br />total area run off for the average accwnulation of runoff in the ditch or from <br />the mid-point of the ditch. This transportable sediment will be controlled by <br />placing sedimentation barriers (straw bales or- sedimentation fences)in tfre ditches <br />at intervals and at the entrance into tfre culvert btisin. <br />• The two ditches are a triangular shapr~ and the cross-section near the culvert is <br />1 ft. deep x 4 ft. wide at 2:1 slopes. fora capacity of 1.95 cfs each. See <br />calculations for volume of peak flow for each ditch. The S.W. ditch has a <br />reduction in size as it approaches tt~~~ south yard access road, but i; adequate <br />to carry the reduced runoff accumulation. <br />f <br />i <br />E <br />i <br />i <br />i <br />i <br />I <br />t <br />h <br />f <br />I{k• <br />f <br />t <br />F <br />