RFI - SWMP Elands

65-67 Elanda Street, Sunshine Beach
Site Based Stormwater Management Plan
_____________________________________________________________________________________________




Table 3.3 Flow comparison between Pre- and Post- development

        Storm Event          Peak Flow Pre-       Peak Flow Post-   Difference   Difference
                               development          development       (m3/s)       (L/s)
                                        3                    3
                                      (m /s)               (m /s)
        63% AEP, 25min                0.017                0.031      0.014         14
        39% AEP, 25min                0.022                0.036      0.014         14
        20% AEP, 25min                0.035                0.051      0.016         16
        10% AEP, 25min                0.046                0.061      0.015         15
        5% AEP, 25min                 0.054                0.070      0.016         16
        2% AEP, 25min                 0.059                0.074      0.015         15
        1% AEP, 25min                 0.069                0.082      0.013         13



It can be observed that the proposed development shall produce a maximum of 16L/s
increase in flow discharge from storm events up to 1% AEP, which may cause actionable
nuisances to the vicinity of the development site. Hence, on-site stormwater detention
devices are necessary for the proposed development, so that the peak flow from the Post-
development scenario can be no greater than the Pre-development scenario.

To validate the modelling results above, Rational Method is also applied to estimate the
discharge, detailed calculation is presented in Appendix E. Table 3.4 summarises the peak
flows of various storm events.




File Name:            WCD-22936 – 65-67 Elanda_SWMP.docx
Revision:             B                                                                       12