Laserfiche WebLink
September 2%, 1979 <br />File ido, �9-470 <br />STORM DRAINAGE <br />Bvergreen Business Park <br />Site Location - West of Evergreen Way along north side of 100th St. S.W. <br />Area of Site - 4.21 Acres <br />Existing Site Coqdition - Covered with small alders. Slopes 1qo toward 100th SL'.S.W. <br />(to southl. <br />- Assume runoff coefficient - CU = 0.2 <br />� Developed Site <br />Buildings 1.12 Acres <br />Paving 2.13 Acres <br />Total 3.25 Acres <br />C = 0.9(3.25) + 0.35(0.96) = 0.77 <br />.21 <br />Using Return Frequency of 10 years <br />F'or East Portion <br />Pre-development <br />VE = 0.2(0,43 x 2.12 x 43,560) = 0.2(2.12?(1561) = 663 cf. <br />12 <br />Post-development <br />VD = 0.77(2.121;1561) = <br />2553 <br />Run-off Differential = 1890 cf. <br />Additional Storage due tc Lag Time <br />Tc = 5 min. <br />� = CiA = 0.2(1.3)(2.12) = 0.55 <br />Mean Rate of Discharge - 0.28 <br />