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sediment oloa y. The SEDCAD computer program was also utilized to calculate the sediment <br />• flowing into end through the principal spillway using the DEPOSITS portion of the program. <br /> The results show no sediment flowing out of the pond as a result of the 10-year, 24-hour <br /> storm (100X Basin Trap Efficiency). <br />The Revised Universal Soil loss Equation (RUSLE) was used to determine the sediment <br />loading to the pond to estimate frequency of cleanou t. <br />Tons/AC/ <br />Condition Area (ac.) R K LS C P Year Tons/Year <br />Undisxurbed 389.2 30 0.26 8.1 0.003 1.0 0.190 73.9 <br />Disturbed 346.9 30 0.20 8.1 0.561 1.0 27.3 9470.4 <br />Topsoil Stockpiles 16.46 30 O.i2 8.1 9.05 1.0 3.88 63.6 <br />10,549.9 tons x 60X delivery ratio = 5764.7 tons/year <br />Includes roads, topsoil removed areas, facilities, end pit/spoil areas. <br />• Based on sediment density of 80 lbs/cu ft this amounts to 144,120 cu ft/yr or 5,338 cu <br />yds/yr or 3.31 ac-ft per year. The amount of initial sediment storage is 13.9 ac•ft. The <br />cleanaut level is 60X of capacity. Therefore when the sediment volume reaches 8.3 ac-ft. <br />the pond will be cleaned out. This should take approximately three years to reach this <br />level. Peabody surveyed Pond 006 after construction to determine the initial sediment <br />storage capacity. Pond 006 will be resurveyed in 1994 to determine the amount of sediment <br />accumulation and remaining sediment storage rapacity. At that time, the actual sediment <br />loading will be determined and if the pond requires cleanout. <br />Particle Size Distributions. The particle size distribution for this sediment pond was <br />based on sieve end hydrometer analysis of various soil types in the Seneca II-W permit <br />area. This distribution is representative of the watershed for Pond 006 and based on a <br />weighted average. <br />• <br />13 <br />