Multiply the amount of time ...

Multiply the amount of time each pump is on in each lift station in minutes by the pump rating for the respective pump in GPM.  Add these together for each lift station to get the total period flow for each Lift Station.  This can easily be done in a spread sheet.  I have attached an example to work with.  If I didn't ad this correct contact me and I will try again, if you are interested, of course.

Sincerely,

Hal Millegan, Ph.D., P.E.