BBNE00529_0002_0001-REP-001-1-73 Eumundi-Noosa Rd SMP

•     Detention Tank Summary:

      –   Size = 50m3

      –   Outlet 1 = 2 x 225mm at RL0.0m.

      –   Outlet 2 = 3m weir at RL1.30 (this allows for surcharge of the tank back to the driveway in events larger than the 1% AEP).

      –   Flow Depth in 10% AEP = RL1.0m

TABLE 4.9: PEAK DISCHARGE COMPARISON – EXISTING VS MITIGATED SCENARIOS


    Scenario              10% AEP

    Existing (m3/s)       0.261

    Developed (m3/s)      0.314

    Mitigated (m3/s)      0.258

    Difference (m3/s)     -0.03



4.3            Flows South to Starboard Avenue
From the development site there is approximately 0.8 ha of catchment (refer Figure 2.4) would report south down Starboard Avenue in
events where the design capacity of the drainage network has been exceeded (i.e. minor design storm of 10% AEP). From this it is considered
that the gap flow (difference between minor (10% AEP) and major storm (1% AEP)) would report south down Starboard Avenue. The pre-
development flow reporting from this catchment south down Starboard Avenue in the 1% AEP is approximately 0.25m 3/s. The gap flow in
the post-development scenario is 0.11m3/s, which is less than the pre-development scenario. This assessment aligns with the design of the
downstream network which estimates approx. 0.95m3/s in the 1% Ato surcharge are report south with the updated IFD’s the pre-
development peak in the 1% AEP is 0.31m3/s and the gap flow the post-development scenario being 0.19m3/s, which is less than the pre-
development scenario. As such, it is considered the non-worsening conditions are achieved south to Starboard Avenue.




                                                                    0.8ha

                                                                                                                Gap Flow
                                                                                                                Report South




Figure 2.4: Catchment of Gap Flow Reporting South down Starboard Avenue




73 EUMUNDI - NOOSA ROAD, NOOSAVILLE I BBNE00529_0002_0001-REP-001-1                                                                     18