Reference Document - Flood & Stormwater Management Plan 28_8_2025

                        f)           The 10% AEP capacity of the road is as per the approved matches the approved SMP for the
                                     adjacent developments at 25 Pavilion St, which states:
                                     “Existing drainage capacity of Pavilion Street is approximately equivalent to the 10% AEP storm event,
                                     with flow greater than this overtopping the verge and entering the site.”
                                     This has intentionally been kept consistent between SMPs, and demonstrates that the proposed
                                     augmented basin achieves greater storage and improved freeboard in comparison to the
                                     approved SMP for 25 Pavilion St.
                                     A road capacity calculation was completed to confirm this assumption using a cross section of the
                                     road based on LIDAR data. Refer to Table 1-2 and Figure 1-5. Manning’s equation indicates that the
                                     road has a road capacity (1.16 m3/s) greater than the 10% AEP flow rate from the external
                                     catchments (0.437 m3/s for EX1 and 0.165 m3/s for EX2). Therefore, the assumption that Pavilion St has
                                     capacity for 10% AEP flows is conservative, and freeboard within the basin is expected to be greater
                                     than modelled.

                 Table 1-2: Pavilion St Road capacity calculation using Manning’s’ equation
                                            Parameter                                Value                            Unit
                                     Cross sectional area                            1.24                              m2
                                        Channel slope                                0.026                            m/m
                                      Wetter perimeter                               11.21                             m
                                        Manning's (n)                                0.04
                                     Hydraulic radius (R)                             0.1                              m
                                             Velocity                                0.93                             m/s
                                       Froude Number                                 0.73
                                        Flow rate (Q)                                1.16                             m3/s




                                                                             Road Cross Section
                                      0.2
                                     0.18
                                     0.16
                                     0.14
                                     0.12
                     Elevation (m)




                                      0.1
                                     0.08
                                     0.06
                                     0.04
                                     0.02
                                        0
                                             0              2            4                  6          8             10                12
                                                                                                                       Ground Level
                                                                      Distance (m)
                                                                                                                       Water level


                 Figure 1-5: Pavilion St Road Cross-Section



                 1.5.                 DA Approval Conditions 3 June 2025
                 DA approval was received from Noosa Council, dated 3 June 2025, for the development application
                 (RAL23/0013.02). Conditions of approval require Condition 22 and 23 to be addressed on submission of
                 operational works.



                 23-0167SMP01-V4 | Stormwater Management Plan | 33 Pavilion Street, Pomona                                            Page 17

Document Set ID: 24092538
Version: 1, Version Date: 02/09/2025