Volume 2-05, Chapter 3 - City of Wichita
Volume 2-05, Chapter 3 - City of Wichita
Volume 2-05, Chapter 3 - City of Wichita
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Section 3.2.5 - Enhanced Swale<br />
Side Slopes = 2:1<br />
Channel Slope = 0.015 ft/ft<br />
Then:<br />
1.49 2 1<br />
3 2<br />
Q wq<br />
= Q = VA = D S DW<br />
n<br />
where:<br />
Q = peak flow (cfs)<br />
V = velocity (ft/sec)<br />
A = flow area (ft 2 ) = WD<br />
W = channel bottom width (ft)<br />
D = flow depth (ft)<br />
S = slope (ft/ft)<br />
A minimum width can be calculated.<br />
nQ 0.15*1.23<br />
W =<br />
=<br />
1<br />
5<br />
1<br />
3 2<br />
3<br />
2<br />
1.49D<br />
S 1.49*1 *0.015<br />
5<br />
=<br />
Q 1.23<br />
V = = = 1.23 fps ( > 1fps)<br />
WD (1')(1')<br />
1ft<br />
Increase width to 4’.<br />
Q 1.23<br />
V = = = 0.31fps<br />
(OK)<br />
WD (4')(1')<br />
Check Dams<br />
Compute the number <strong>of</strong> check dams required to detain the WQ v . With where:<br />
• Dam height = 1.5 feet<br />
• Spacing <strong>of</strong> check dams will be 60 feet (based on top <strong>of</strong> downstream dam same<br />
elevation as upstream dam’s toe).<br />
The total volume need to be storage behind dams equals:<br />
WQ v<br />
= ( 0.84inches)(1acre) = 3<strong>05</strong>0ft<br />
3<br />
Each dam stores: <strong>Volume</strong> = (length behind dam)(width <strong>of</strong> dam)(water depth behind dam)<br />
= (60’)(1.5’)(4’) = 360 ft 3<br />
A total <strong>of</strong> (3<strong>05</strong>0)/(360) = 8 check dams will be needed to capture the water quality<br />
volume.<br />
<strong>Volume</strong> 2, Technical Guidance Page 3 - 77
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