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• <br /> <br />Elevation (6/27/86) Design <br />Capacity Cum. Capacity <br />(Ac-f t) (Ac-ft) (1986 Survey) <br />Capacity Cum. Capacity <br />(Ac-ft) (AC-ft) (1987 <br />Capacity <br />(AC-ft) Survey) <br />Cum. Capacity <br />(Ac-ft) <br />6936.0 0 0 0 0 0 0 <br />6937.0 0.05 0.05 0.05 0.05 0.05 0.05 <br />6938.0 0.20 0.25 0.14 0.19 9.23 0.28 <br />6939.0 0.44 0.69 0.33 0.52 0.44 0.72 <br />6940.0 0.73 1.42 0.62 1,14 0,65 1.37 <br />6941.0 1.04 2.46 0.88 2.02 0.85 2.22 <br />6942.0 1.33 3.79 1.11 3.13 1.05 3.27 <br />6943.0 1.62 5.41 1.37 4.50 1.29 4.56 <br />6944,0 1.91 7.32 1.66 6.16 1.61 6.17 <br />6945.2 2.63 9.95 2.49 8.65 2.50 8.67 <br />6946.0 2.07 12.02 2.07 10.72 2.07 10.74 <br />6947.0 2.99 15.01 2.99 13.71 2.99 13.73 <br />6948.0 3.30 18.31 3.30 17.01 3.30 17.03 <br />• At the principal spillway elevation of 6945.2, the design sediment storage capacity was <br />9.96 ac-ft; whereas, the 1986 and 1987 sediment survey are virtually the same: <br />Based on the design: <br />(1) 10-year, 24-hour precipitation event generated a MUSLE sediment volume equal to <br />4.28 ac-f t. <br />Based on the 1987 annual sediment survey, the equivalent sediment generated from <br />approximately two 10-year, 24-hour precipitation events could be stored beneath the <br />principal spillway elevation. <br />At this time, this is an adequate amount of sediment storage; therefore, no remedial <br />sediment clean-out work is scheduled during the next year. <br />Sedimentation Pond 007. Sedimentation Pond 007 was replaced by Sedimentation Pond 008 <br />which was constructed in August, 1987. Pond 007 is scheduled to be mined in 1988. Once <br />the coal is removed in this area, the pond site will be reclaimed during reclamation of <br />• the adjacent mine area. <br />7-11A-8 <br />