Apdx 4 - SWMP

Rational Method Calculations

    Project        221304

   Address         28 Banksia Avenue                                                           By           DK


            Pre - Development                                                                       Post - Development
               Catchment Details                                                                        Catchment Details
     Area            0.0647            ha                                                     Area               0.0647        ha
       fi             0.00                                                                      fi                0.75
     C10               0.7                                                                    C10                 0.85
      I10             74.9           mm/hr                                                     I10                74.9       mm/hr

              Standard Inlet Time                                                                     Standard Inlet Time
     Time               5             mins                                                    Time                 5          mins

    Overland Sheet Flow (Friend's Eqn)                                                       Overland Sheet Flow (Friend's Eqn)
    Length                         m                                                         Length                         m
     Slope                         %                                                          Slope                         %

  Surface 'n'                                                                              Surface 'n'

     Time               0             mins                                                    Time                 0          mins

           Pipe Flow Travel Time                                                                    Pipe Flow Travel Time
Flow Distance                          m                                                 Flow Distance                         m
Fall of Channel                        m                                                 Fall of Channel                       m
      Time                            mins                                                     Time                           mins

                   Kerb Flow                                                                                Kerb Flow
    Length                             m                                                     Length                            m
     Slope                             %                                                      Slope                            %
     Time              0.0            mins                                                    Time                0.0         mins

    Channel Flow (Figure 4.8 QUDM, or                                                        Channel Flow (Figure 4.8 QUDM, or
          Manning's Equation)                                                                      Manning's Equation)
Flow Distance                          m                                                 Flow Distance                         m
Fall of Channel                        m                                                 Fall of Channel                       m
      Time                            mins                                                     Time                           mins


 Adopted Time of                                                                          Adopted Time of
  Concentration
                        5             mins                                                 Concentration
                                                                                                                   5          mins



      Pre-Development Peak Discharges                                                         Post-Development Peak Discharges
                                                            Design Storm   Frequency
   Area (ha)           Cy           Iy (mm/h)   Qy (m3/s)      (AEP)       Factor (Fy)
                                                                                            Area (ha)             Cy        Iy (mm/h)   Qy (m3/s)

    0.0647            0.56             125       0.013       63.20%          0.80            0.0647               0.68        125        0.015
    0.0647            0.595            157       0.017       39.35%          0.85            0.0647              0.7225       157        0.02
    0.0647            0.665            196       0.023       18.14%          0.95            0.0647              0.8075       196        0.028
    0.0647             0.7             226       0.028        10%            1.00            0.0647               0.85        226        0.034
    0.0647            0.735            258       0.034         5%            1.05            0.0647              0.8925       258        0.041
    0.0647            0.805            300       0.043         2%            1.15            0.0647              0.9775       300        0.053
    0.0647            0.84             331       0.05          1%            1.20            0.0647                 1         331        0.06

                                                            Discharge Comparison
                      AEP           63.20%       39.35%     18.14%            10%             5%                  2%          1%
                   Difference        0.002        0.003      0.005           0.006           0.007                0.01        0.01
                   Percentage       15.4%        17.6%      21.7%            21.4%           20.6%               23.3%       20.0%