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Dead Storage Calculations <br />MPCA Requirements: <br />Minimum Dead Storage Volume Required <br />1800 cubic feet per acre draining to the basin <br />On-site area draining to basin = 16.123 acres <br />Off-site area draining to basin = 0.000 acres <br />Total acres draining to basin = 5.573 acres <br />req'd acres vol req'd <br />1800 * 5.573 10031.4 <br />NWL = 894.5 <br />From HydroCAD stage storage, volume below elevation <br />894.5 = <br />2.109 > 0.230 <br />Storage provided > Min Storage, design is OK <br />Water Quality Volume Required <br />Existing Impervious = 1.926 acres <br />Proposed Impervious = 9.611 acres <br />Added Impervious 7.685 acres <br />Required Volume = 1.1" * added impervious <br />TP Factor = 0.500 <br />Required Volume = 1.409 acre feet <br />Volume @ NWL = 2.109 Acre Feet <br />Water Quality Volume = 3.518 Acre Feet <br />2.11 > 1.41 <br />Storage provided > Min Storage, design is OK <br />Elevation at water quality volume = 896.90 <br />Surface Area at Elev 896.90 = 0.685 acres <br />From HydroCAD, flow at elevation 896.90 = 1.510 cfs <br />Max outflow = 5.66 cfs per acre of surface acre of pond: <br />Max outflow = 3.877 cfs <br />1.51 < 3.88 <br />Outflow < max outflow, design is OK <br />NURP Dead Storage Requirements <br />Volume provided in pond shall be greater than or equal runoff from a 2.5 inch event <br />Volume from 2.5" event - HydroCAD:1.583 acre feet <br />Volume provided at pond:2.109 acre feet <br />2.109 > 1.583 <br />Storage provided > Min Storage, design is OK <br />DEAD STORAGE CALCULATIONS <br />acre-ft equiv. <br />0.230 <br />2.109 acre feet