# Detention Basin Volume



## jeb6294 (Jul 26, 2006)

Not sure if my brain hasn't started working or what (I just got back from vacation)....

How can I determine what size detention basin I need with a calculated Qin and a specified Qout *using the rational method*. I can do it using TR55, but all my other calcs are based on rational so I'd rather not switch back and forth.

i.e. I have detention basin with ~25 cfs coming into it and I want to limit the discharge to, let's say 10 cfs irregardless of what the governing body's requirements are (the basin is going to be on a ridge so really there is no predeveloped runoff).


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## DVINNY (Jul 26, 2006)

You'll need an infinitely big basin, cause 25 in and 10 out don't add up.

The 25 in must be varied at some point, and a medium derived from that variation. correct?


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