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Table Of Contents
Chapter 2 Working with Ponds
132
Calculating the Required Storage Volume for a
Detention Basin
The Detention Basin Storage method is a quick method for performing
stormwater detention design. For smaller sites, you could use this method for
sizing the detention pond. For large sites it is good idea to use this method
before designing your pond to get an approximate idea of the pond size that
will be required.
The Detention Basin Storage method is explained in Chapter 6 of the TR-55
manual. The resulting value from this method is the estimated required storage
volume. When using this method you should calculate your peak discharge
using TR-55.
Data input required for the Detention Basin Storage method includes the
following values:
n
Allowable peak discharge
n
The peak inflow (cfs)
n
The runoff from the drainage area in inches
n
The type of storm disribution
n
The size of the drainage areas
To calculate the required storage volume for a detention basin
1 You can calculate runoff and save the calculations to a file. This is not required,
but if you do not save the data to a file, then you have to manually enter much
of the data for calculating the required storage volume.
n
Use the TR-55 Tabular Hydrograph Method to create an inflow hydrograph
file (.tab file, an .hdc file, or a .wk1 file).
n
Use the TR-20 Method to create and save an inflow hydrograph file (.hdc or
.wk1 file).
n
Use the TR-55 Graphical Peak Discharge Method to create an inflow
hydrograph file (gpd file).
n
Use the Combine Hydrographs command to create a composite inflow
hydrograph (.hdc file).
2 You can create a rough design of the detention pond, and calculate the stage-
storage-curve for the pond. Save the stage-storage-curve as an .ssc file. You can
load this data into the Detention Basin Storage dialog box to compare the
calculated storage volume with the pond elevation.
3 From the Hydrology menu, choose Routing
ä
Detention Basin Storage to
display the Detention Basin Storage dialog box.