Storage Volume Required calculation in EPA SWMM 5.1


I am new member to this forum as well new to EPA SWMM. 

As per city of Calgary need to model storm detention in EPA SWMM 5.1 for the project area 3.3 ha and need to know how much volume of storage required, permissible release rate is 80 l/s/ha. 

Immediate help is required and appreciated.


You need to be a member of SWMM 5 or SWMM or EPASWMM - (not formally associated with EPA) to add comments!

Join SWMM 5 or SWMM or EPASWMM - (not formally associated with EPA)

Email me when people reply –


  • Hi Anug,

    You can built a simple SWMM model which has one sub catchment, drained to a storage unit, connecting to  an outfall through conduit and convert conduit to an outlet. Rating curve can be given on this outlet having a rating curve maximum release rate of 264 l/sec.Sub catchment will have properties of your model. Use an orifice equation for rating curve Q=CA(2gh)^2. Use a big storage, model will use  a portion and you will get storage requirement. One hour or 24 hour City of Calgary storm can be used.

    Alternatively use figure 4.3 of the 2011 Stormwater Management and Design Manual, City of Calgary. Or you can build a  SWMHYMO model,use two commands calib standhyd and compute duel hyd .

    If you need further help, please email at

    Best Regards,

    Raza Ali

  • Dear Anuj,

    Did you find any solution for this? I have the same question.

    Best regards


This reply was deleted.