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• 1986. The pond will be utilized for approximately one year while Sedimentation Pond 008 <br />is being constructed. Upon completion, Pond 008 will replace Pond 007. <br />Based on the up tlraina ge watershed characteristics, one 10-year, 24-hour precipitation <br />event would generate 3.54 ac-ft of sediment using H.U.S. L. E. <br />With the principal spillway elevation at 7049.35, Pond 007 can store approximately 6,61 <br />ac-ft, or the equivalent of the sediment generated from approximately 1.9 10-year, 24-hour <br />precipitation events. This will be adequate sediment storage until Pond 008 is completed <br />in 1987, <br />1987 Annual Hydrology Report <br />Following are the results of the sediment survey in the 7987 Annual Hydrology Report: <br />Sedimentation Pond OD2. Design information and calculations for this pond were submitted <br />in the Seneca II Permit Renewal Application (8/27/86), and subsequently approved by CHLRD. <br />• Based on this design; <br />(1) 10-year, 24-hour precipitation event generated a MUSLE sediment volume equal to <br />5.07 ac-ft. <br />With the principal spillway elevation at 6611.2, the pond could store approximately 267.36 <br />ac-ft or the equivalent sediment generated from approximately 53 10-year, 24-hour <br />precipitation events. Based on the 1987 sediment survey, the pond has approximately <br />187.18 ac-f t., or the equivalent sediment generated from approximately 37 10-year, 24-hour <br />precipitation events. <br />Following is a comparison of the 8/27/86 design and the 1987 sediment survey volume <br />calculations: <br /> (8/27/86) Design 1987 Survey <br /> Capacity Cumulative Capacity Capacity Cumulative Capacity <br />Elevation (Ac-ft) (Ac-ft) (Ac-ft) (Ac-ft) <br />6614 11,55 298.68 11,55 218.50 <br />6613 11.15 287.13 11.15 206.95 <br />• <br />7-11A-5 <br />