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SHANON HEIGHTS 6/9197 <br />BRL <br />Storm Drainage Calculations (Per City of Everett <br />Site Area = 2.76 Ac within the 36th Street combined sewer drainage basin <br />Existing ground cover - Light forested land with light grass and sparse trees. THe <br />proposed land use will be apartment complex with 80% <br />impervious and 20% landscaping @ 10% slopes. <br />Table 1 10 year pre -development - 10 year post -development <br />Table 2 Allowable RR = 0.265 cfs/Ac <br />Therefore total allowable RR = 2.76(0.265) _ � cfs Or 0.265 cfs/Ac <br />Table 6 Landscape detention storage required 101 cu.ft./Ac (by interpulation) <br />Therefore 2.76(.2)(101) = 55.75 cu.ft. <br />Impervious detention storage required 2,080 cu.ft./Ac <br />Therefore 2.76(.8)(2080) = 4,592.64 cu.ft. <br />Total storage required = 55.75 + 4,592.64 = 4.646.39 cu.ft. VT <br />