6521 EVERGREEN WAY 2016-01-01 MF Import

m SWALE CALCS. 14-Ju1-94 EVERETT DAIRY QUEEN--EVERGREEN WAY, LSA 3146 16:14 ------------------ -----------------------------------� -----------� ------------ Contributory ares = 1.01 acres Tima of Concentration: Flow len. Vert. Ground T. Toi.al �pe Runoff Time of Time ft Drop Slope Cover Vel. Travel 10.0 _____________________________________________________ --------------- 360 7.0 1.94� paved 2.81 2.1 12.14 Tinie of Concentration, T(c) minutes = 12.14 Des. storm: 2 year recurrence, Itc in/hr = 0.945 Des. storm: 25 year recurrence, Itc i.n/hr = 2.050 Area, A acres = 1.015 A sf 44200 ------------------------------- � ------------•------------- landscaping 0.25 x 4400 sf Driveway/parking 0.90 x 39800 C - --0.835 Flow, � cfs= (Itc x A x C) = 2 year O.d01 Flow, Q cfs= (Itc x A x C) = 25 year 1.738 -------------------------------------------------------- Calculating flow through a swale: Friction far.tor = 0.200 Side slope = 3.000 H: 1V Channel s].ope = 0.0134 ft/ft Bottom wi'th = 3.000 ft Swale lenc;th = 160 ft Depth Top Area Wetted feet Width SF Perim ft ---------------------------- ------- 2 year storm: 0.45 5.70 1.96 5.85 HYDR Q RADIUS cfs R ------- ---------- 0.33 0.82 need Q = 0.80 Vel. Resid. fps Time min. 0.42 6.4 25 year storm: 0.67 7.02 3.36 7.24 0.46 1.74 0.!i2 need Q = 1.74 - --------------------------------- ------------------------ If the ��weighted average" 'residence time is considered, roug•hly computed as follows (for the 2-year storm only): Area of site draining through l00 feet of swale as a oercent of total = Residence time for 100 feet of swale = Weighted average residence time = 5.2 � 9000 sf 20.4% 4.0 minutes 5.9 minutes