PR-102995-10 IRR to Council_FINAL_27May14

     Existing Upstream Catchment Detention Volume Calculations

Initial Sizing of a Detention Basin (QUDM Section 5.05.1)

                                                (QUDM EQN 5.04)

                                                (QUDM EQN 5.05)

                                                (QUDM EQN 4.13)

                                                (QUDM EQN 4.02)

                Pre-developed Flow, Qo

      Time of Concentration, t c =         11 mins
     Coefficient of Discharge, C =         0.7           (QUDM Tb 4.05.3)
                  Intensity, 11I10 =    166.6 mm/hr      (IFD Data)
                         Area, A =      0.504 ha

                                                 3
                               Qo =     0.163 m /s       (QUDM EQN 4.02)

                Post-developed Flow, Qi

      Time of Concentration, t c =          6 mins
     Coefficient of Discharge, C =       0.86            (QUDM Tb 4.05.3)
                   Intensity, 6I10 =      210 mm/hr      (IFD Data)
                         Area, A =      0.504 ha

                                                 3
                                Qi =    0.253 m /s       (QUDM EQN 4.02)

                                 r=     0.354            (QUDM EQN 5.05)

                                Vi =   121.46            (QUDM EQN 4.13)

                            Vs/Vi =     0.278            (QUDM EQN 5.04)

                                                  3
                               Vs =      33.8 m