Detention Basin Design
Detention Basin Design
(OP)
I have a project where a municipality requires that a detention basin be able to store the 100-year, 2 hour rainfall event for the site without exceeding the pre-developed discharge rates.
The area in question is relatively small, under 2 acres of parking. I'm not sure if I should be using the modified rational formula using various intensities vs time to determine peak storage (using different C values for pre development allowed discharge vs post development peak flow, storing the difference)
Or if I should simply take the intensity given for a 2 hr storm where volume V= (Acreage)(C)(intensity 2.5 in/hr)(time of storm 2hrs) and get an acre-ft of post and pre development, and store the difference.
Any thoughts?
The area in question is relatively small, under 2 acres of parking. I'm not sure if I should be using the modified rational formula using various intensities vs time to determine peak storage (using different C values for pre development allowed discharge vs post development peak flow, storing the difference)
Or if I should simply take the intensity given for a 2 hr storm where volume V= (Acreage)(C)(intensity 2.5 in/hr)(time of storm 2hrs) and get an acre-ft of post and pre development, and store the difference.
Any thoughts?





RE: Detention Basin Design
RE: Detention Basin Design
If you can't find a manual just use SCS Unit Hydrograph as it's generally a safe bet.
RE: Detention Basin Design
RE: Detention Basin Design
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: Detention Basin Design
if i understood your description of the drainage regulation correctly, than use the total rainfall depth, not intensity. calculate the volume for the developed condition. now calculate the basin size required to hold that amount such that the overflow through the spillway or outlet pipe is no more than the pre-development runoff.