The simplied equation mentioned above has been used to determine storage times in extended detention basin, where the discharge is typically through a small orifice. Therefore I would use this as a starting point for the discharge rate needed and model/adjust the basin accordingly.
As far as...
If I understand the question correctly you are looking for the discharge rate needed to allow a storage time of 30 min.
In the past I have had to calculate detention times for basins, so this should work:
Vol / time = flow
142000 ft^3 x 1/30 min x 1 min/60 sec = 78.8 cfs
Hope that helps.
I have a situtaion where I may need to replace approx. 6000 lf of 15" Sanitary Sewer line. The authority seems to like the idea of placing a parallel pipe, 18", next to the existing line. I believe there are going to be some environmental issues along the alignment, wetlands etc. and was...
