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5 <br />SUN COAL COMPANY <br />MEADOWS N0. 1 <br />IMPOUNDMENT CERTIFICATION <br />"As-Built" Design <br />Impoundment No. 1 (Upper Pond) <br />Ten year 24 hour storm event 1.6 inches <br />Twenty-five year 24 hour storm event 2.0 inches <br />One hundred year 24 hour storm event 2.3 inches <br />Ten year 24 hour runoff 9.6 cfs-Total flow 0.72 acre feet <br />Twenty flue year 24 hour runoff 18.2 cfs-Total flow 1.36 acre feet <br />One hundred year 24 hour runoff 25.9 cfs-Total flow 1.9 acre feet <br />Soil Conservation Service Curve Number 75 <br />Drainage Area 43.1 acres <br />Vegetative Type Grasslands <br />Principal Spillway <br />Drop Structure 36 inch-Capacity 28 cfs <br />Drop Structure Embankment Discharge Pipe= 18 inch CMP <br />Capacity with Head approximately 22 cfs <br />Emergency Spillway Design <br />Trapezoidal <br />Spillway Depth 2.0 feet <br />Spillway Width 10 Peet <br />Spillway Sideslopes 2:1 <br />Riprap D-50= 6 inches <br />Riprap Channel Length 75 feet <br />Spillway Flow Characteristics 100 year storm <br />Peak Pluw 26 cfs <br />Depth of Plow .727 feet <br />Flow Velocity 3.12 fps slope @ 1 percent <br />Embankment Height 9 Peet <br />Embankment Width 180 feet <br />Impoundment Storage Capacity 1.0 acre Peet <br />Impoundment Sediment Storage Capacity (See Pigure 5A) <br />Topsoil Depth 6 inches <br />Vegetative Type Grass <br />