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The storage and load -out sedimentation dam is an <br />existing structure and meets the requirements of <br />4.05.2., .5, .6, .7, and .17. It is located immediately <br />downstream of all storage and load -out facilities and <br />over the Farmer's Ditch, an irrigation canal that has <br />been piped beneath the load -out area. <br />The storage capacity of this pond is approximately 1.8 <br />acre-feet. Approximately 16 disturbed acres and no <br />undisturbed acres drain into the pond. Taking into <br />consideration the re -vegetation measures which will <br />help reduce sediment, this would require 16.0 acres x <br />0.035 acre-feet/acre = 0.56 acre-feet for sediment <br />storage capacity. The 10 -year, 24-hour precipitation <br />event would generate 16.0 acres x 0.04 acre-feet/acre <br />= 0.64 acre feet. The total required sedimentation <br />pond storage volume would be 0.56 acre-feet + 0.64 <br />acre-feet = 1.2 acre-feet. The existing sedimentation <br />pond volume is approximately 1.8 acre-feet which <br />exceeds required storage. <br />A sediment pond is provided for the stockpile area. <br />Details of this pond are found in Exhibit 8 Protection of <br />the Hydrologic Balance. This sedimentation pond is <br />located immediately west of the county road over the <br />railroad and south of State Highway 133. It is located <br />in the NW/4NW/4 of Section 32, T.13.S., R.91.W., 6t" <br />P.M. Drainage ditches have been installed to intercept <br />surface runoff from the coal stockpile and direct it to <br />the sedimentation pond. <br />The dam is constructed using compacted earth fill. <br />Plans and specifications are as shown in Exhibit 8. <br />The pond was constructed in 1979. <br />RN -07 2.05-18 02/18 <br />