RFI - SWMP Elands

65-67 Elanda Street, Sunshine Beach
Site Based Stormwater Management Plan
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In table 3.7, the sum of the peak flow represents the mitigated post-development peak flows.
In order to assess the efficiency of the proposed detention tank, flow results are further
compared, as shown in Table 3.8.

Table 3.8 Flow outcome assessment

            Storm Event      Unmitigated Post-       Mitigated Post-     Pre-development
                             development Peak    development peak flow   peak flow (m3/s)
                                 Flow (m3/s)               (m3/s)
        63% AEP, 25min                0.031                0.019              0.017
        39% AEP, 25min                0.036                0.022              0.022
        20% AEP, 25min                0.051                0.031              0.035
        10% AEP, 25min                0.061                0.039              0.046
        5% AEP, 25min                 0.070                0.044              0.054
        2% AEP, 25min                 0.074                0.054              0.059
        1% AEP, 25min                 0.082                0.062              0.069



In Table 3.8, it can be observed that after the mitigation of the detention tank the peak flows
are significantly reduced in comparison to the unmitigated post-development peak flows.
Moreover, through the comparison between the mitigated post-development peak flow and
the target flow of mitigation, it can be observed that the proposed stormwater system
achieves the target of “no-worsening”.




File Name:            WCD-22936 – 65-67 Elanda_SWMP.docx
Revision:             B                                                                     18