Appendix C - Engineering Report

Rational Calculations ‐ Catchment 2
Reference ‐ Chapter 4 QUDM.




Job Name.            Triller Court                          CATCHMENT INFORMATION
Job No.              C6361                                LOCAL AUTHORITY                            NSC
Date                 9/05/2022                            IFD INFORMATION                           Noosa
Designed             BWM                                  10% AEP 60min                              65.2
Checked              MVC


   EXISTING TIME OF CONCENTRATION                                           DEVELOPED TIME OF CONCENTRATION                        COEFFICIENT OF RUNOFF
                                                                                                                               Sub‐Catchment Area (Ha) Fraction Impervious (%)      Runoff Coefficients
                     Std Inlet Time                                                           Std Inlet Time        CMT No.    Pre Catch    Post Catch      Existing   Developed    Existing        Developed
                                                                                                                      1          5.243        5.243             0          6          0.66            0.68
                                                                                                                      2
                     Slope (%)                6.0                                             Slope (%)               3
      SHEET FLOW




                                                                               SHEET FLOW
                     Flow Length (m)         50.0                                             Flow Length (m)         4
                     Horton's 'n'            0.035                                            Horton's 'n'            5
                     Flow Time (min)          10                                              Flow Time (min)        Total       5.243        5.243            0           6         0.66             0.68



                                                                                                                                                    PEAK DISCHARGE CALCULATIONS
      CHANNEL FLOW




                     Flow Length (m)         134.0                                            Flow Length (m)                    Rainfall (mm/hr)           Coefficient of Runoff   Peak Discharge (m³/s)
                                                                               PIPED FLOW




                     Fall (m)                19.0                                             Fall (m)                AEP       Existing    Developed       Existing   Developed    Existing        Developed   Difference (%)
                     Flow Time (min)          0.8                                             Flow Time (min)         63%         70           70            0.53        0.54        0.54             0.55          2.3%
                     Multiplier ∆              3                                              Multiplier ∆            39%        87.7         87.7           0.56        0.57        0.72             0.73          2.3%
                     Flow Time (min)          2.4                                             Flow Time (min)         18%        108          108            0.63        0.64        0.99             1.01          2.3%
                                                                                                                      10%        124          124            0.66        0.68        1.19             1.22          2.3%
                                                                                                                       5%        141          141            0.69        0.71        1.42             1.46          2.3%
      CHANNEL FLOW




                     Flow Length (m)         140.0                                            Flow Length (m)          2%        162          162            0.76        0.78        1.79             1.83          2.3%
                                                                               KERB FLOW




                     Fall (m)                15.0                                             Fall (m)                 1%        178          178            0.79        0.81        2.05             2.10          2.3%
                     Flow Time (min)          0.9                                             Flow Time (min)
                     Multiplier ∆              3                                              Multiplier ∆                                       MANNING'S CALCULATIONS ‐ Pre Developed
                     Flow Time (min)          2.7                                             Flow Time (min)       Scenario     Area       Perimeter   Radius        'n'          Slope            Velocity     Discharge
                                                                                                                      Pre        2.605        5.752      0.453       0.15           4.0              0.79           2.05
      CHANNEL FLOW




                                                                               CHANNEL FLOW




                     Flow Length (m)         170.0                                            Flow Length (m)
                     Fall (m)                 9.0                                             Fall (m)                                           MANNING'S CALCULATIONS ‐ Post Developed
                     Flow Time (min)          1.3                                             Flow Time (min)       Scenario     Area       Perimeter   Radius        'n'          Slope            Velocity     Discharge
                     Multiplier ∆              3                                              Multiplier ∆            Post       2.655        5.797      0.458       0.15            4.0             0.79           2.10
                     Flow Time (min)          3.9                                             Flow Time (min)
                                                                                                                                                 MANNING'S CALCULATIONS ‐ Max Depth
                                                                                                            Total   Scenario     Area       Perimeter   Radius        'n'         Slope             Velocity     Discharge
      CHANNEL FLOW




                     Flow Length (m)                                                                                  Post       9.102        9.731      0.935       0.15           4.0              1.28          11.61
                     Fall (m)
                     Flow Time (min)
                     Multiplier ∆              3
                     Flow Time (min)          0.0

                                     Total           19