HomeMy WebLinkAboutSW6201003_Calcs (SCM Size)_20210118
VAR Ph IV Required Storm Volume
Pond #1
Drainage Area:
16.17 acres 704,557 sf
Impervious Area: 288,473 sf (6.62 ac)
% Impervious: 40.9%
1 inch Storm Event:
Rv = 0.05+0.009 I
Rv = runoff coefficient
I= percent impervious
Rv=0.05+0.009*40.9%
= 0.4181
For volume that must be controlled:
Volume=3,630*Rd*Rv*A
Volume required = 3,630*(1 inch)*(0.4181)*16.17 acres = 24,541 cf
Volume provided = 84,269 cf
Forebay vol = 14,765 cf (17.5% of main pond)
SA/DA ratio is 1.65 for a depth of 3 feet
Required surface area = 16.17 ac * (.0165) = 0.2668 ac or 11,622 sf
Surface area provided = 22,676 sf