Appendix B- SWMP

                                                              Rational Method Peak Flow Calculations
Job No:              23098                                                                                                                                                  MORGAN CONSULTING
Job Type:            Proposed Townhouse Development                                                                                                                          ENGINEERS PTY LTD
Address:             5 Pearl Street, Cooroy                                                                                                                              1 GREAT GEORGE STREET
Council:             NSC                                                                                                                                                   PADDINGTON QLD 4064


IFD Data:            26.4125 (S),152.9125 (E)                               Minor Storm:      Q10                                                                            Designed:      RC
1
    I10              70mm/hr                                                Major Storm:     Q100                                                                            Checked:       HM

Pre Development                                                                                          Post Development

Time of Concentration

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

Sheet Flow (Friends Equation)
     Sheet flow length (L)                    64      m                                                  Pipe Flow
           roughness (n)                    0.03             short grass                                               Flow distance        68.26        m      Pipe
              Fall of NSL                   2.21     m                                                                Fall of channel                    m
     Slope of Surface (S)                    3.5     %                                                                 Flow Velocity             2.5    m/s
                      total                 10.0    mins                                                                         total           0.5    mins
Concentrated Overland Flow                                                                               Concentrated Overland Flow
           Flow distance                        0    m                                                               Flow distance                       m
                 velocity                     0.7   m/s                                                                    velocity              0.7    m/s
                    mins                      0.0   mins                                                                      mins               0.0    mins
   Surface type multiplier                    3.0                                                            Surface type multiplier             4.0
                     total                    0.0   mins                                                                       total             0.0    mins

Total tc                                    10.0    mins                                                                  Total tc               5.5    mins



Runoff Volume Calculations

          Name        Area (ha)        tc              fi     C10                                            Name          Area (ha)        tc             fi    C10
                       0.227                         0.24     0.75                                                          0.227                        0.74    0.85

             Total      0.227         10.0                    0.75                                                Total      0.227         5.5                   0.85

                     Frequency                                                                                            Frequency
        ARI                            Cy             Iy                     Qy                               ARI                           Cy            Iy              Qy
                       Factor                                A (Ha)                                                         Factor                             A (Ha)
      (years)                       (Fy*C10)        (mm/h)                 (m3/s)                           (years)                      (Fy*C10)       (mm/h)          (m3/s)
                        (Fy)                                                                                                 (Fy)
          3 mth                                                            0.018                             3 mth                                                      0.025
            1           0.800        0.599           97       0.227        0.037                               1             0.800        0.679          118    0.227   0.051
            2           0.850        0.636           110      0.227        0.044                               2             0.850        0.721          133    0.227   0.060    37%
            5           0.950        0.711           148      0.227        0.066                               5             0.950        0.806          180    0.227   0.092    38%
           10           1.000        0.749           172      0.227        0.081                              10             1.000        0.848          211    0.227   0.113    39%
           20           1.050        0.786           196      0.227        0.097                              20             1.050        0.891          241    0.227   0.135    39%
           50           1.150        0.861           225      0.227        0.122                              50             1.150        0.975          280    0.227   0.172    41%
           100          1.200        0.898           247      0.227        0.140                              100            1.200        1.000          309    0.227   0.195    39%




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