Detention Pond by Rational Method

[EngrSTR]

Hi,

Can someone please provide a good go-by or design reference for sizing a detention pond by rational method. its for a small 4 acre development.

 

[fel3]

A Google search for rational method detention basin turned up quite a few resources. This one looks like a good explanation:

https://pdfs.semanticscholar.org/18ea/979294010250508a6783f50f39b935273b90.pdf

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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[gbam]

Just an FYI, that does not exist. Rational Method computes peak discharge and does not provide hydrograph which is needed for routing. There is a "Modified" Rational Method that is out there that tries to accomplish the hydrograph issue.

 

[bgo84]

While I would switch over to using SCS instead of rational, there is a crude way to get close.

Rv = 0.05 + 0.9 * IA
Where: Rv = Runoff coefficient (unitless)
IA = Impervious fraction (unitless)

DV = 3630 * RD * RV * A
DV = Design volume (cu ft)
RD = Design storm depth (in)
A = Drainage area (ac)

Again, I would strongly suggest using another method if you are trying to design a detention pond.