Appendix C - Engineering Report

Rational Calculations ‐ Catchment 1
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         99.908        99.908           2.7         2.8       0.6668           0.6670
                                                                                                                          2
                     Slope (%)               24.0                                             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)           7                                              Flow Time (min)            Total      99.908        99.908           2.7        2.8         0.67             0.67



                                                                                                                                                         PEAK DISCHARGE CALCULATIONS
      CHANNEL FLOW




                     Flow Length (m)         148.0                             PIPED FLOW     Flow Length (m)                         Rainfall (mm/hr)           Coefficient of Runoff   Peak Discharge (m³/s)
                     Fall (m)                26.0                                             Fall (m)                    AEP       Existing     Developed       Existing   Developed    Existing        Developed   Difference (%)
                     Flow Time (min)          1.0                                             Flow Time (min)             63%        41.5          41.5           0.53        0.53        6.14             6.15         0.04%
                     Multiplier ∆              3                                              Multiplier ∆                39%         52            52            0.57        0.57        8.18             8.18         0.04%
                     Flow Time (min)          3.0                                             Flow Time (min)             18%        64.7          64.7           0.63        0.63        11.37            11.38        0.04%
                                                                                                                          10%        74.5          74.5           0.67        0.67        13.79            13.79        0.04%
                                                                                                                          5%         85.3          85.3           0.70        0.70        16.57            16.58        0.04%
      CHANNEL FLOW




                     Flow Length (m)         203.0                                            Flow Length (m)             2%         99.5          99.5           0.77        0.77        21.17            21.18        0.04%
                                                                               KERB FLOW




                     Fall (m)                15.0                                             Fall (m)                    1%         110           110            0.80        0.80       24.425           24.434        0.04%
                     Flow Time (min)          1.3                                             Flow Time (min)
                     Multiplier ∆              3                                              Multiplier ∆                                           MANNING'S CALCULATIONS ‐ Pre Developed
                     Flow Time (min)          3.9                                             Flow Time (min)           Scenario     Area       Perimeter   Radius        'n'          Slope             Velocity     Discharge
                                                                                                                          Pre       33.581       49.559      0.678       0.15           2.0               0.73         24.425
      CHANNEL FLOW




                                                                               CHANNEL FLOW




                     Flow Length (m)         250.0                                            Flow Length (m)
                     Fall (m)                13.0                                             Fall (m)                                               MANNING'S CALCULATIONS ‐ Post Developed
                     Flow Time (min)          1.8                                             Flow Time (min)           Scenario     Area       Perimeter   Radius        'n'          Slope             Velocity     Discharge
                     Multiplier ∆              3                                              Multiplier ∆                Post      33.591       49.571      0.678       0.15           2.0               0.73         24.433
                     Flow Time (min)          5.4                                             Flow Time (min)
                                                                                                                                                     MANNING'S CALCULATIONS ‐ Max Depth
                                                                                                            Total   0   Scenario     Area       Perimeter   Radius        'n'         Slope              Velocity     Discharge
      CHANNEL FLOW




                     Flow Length (m)         575.0                                                                        Post      64.492       93.314      0.691       0.15          2.0                0.74          47.53
                     Fall (m)                12.0
                     Flow Time (min)          5.0
                     Multiplier ∆              3
                     Flow Time (min)         15.0
      CHANNEL FLOW




                     Flow Length (m)         865.0
                     Fall (m)                13.0
                     Flow Time (min)          7.0
                     Multiplier ∆              3
                     Flow Time (min)         21.0

                                     Total           48