Appendix C - Stormwater Management Plan

 CONCLUSION
This Stormwater Management Report has outlined how the stormwater run-off from the site is to be managed to
comply with the relevant requirements and minimise any adverse impacts to the downstream catchments.

     •    Run-off from the proposed development will continue to make use of the existing stormwater drainage line
          from the site which connects to Council stormwater infrastructure in Station Street to the east as the lawful
          point of discharge.

     •    The peak flow conditions for the existing and proposed development were analysed in DRAINS to determine
          the impacts of the proposed development. As the development will increase the peak flows from the site,
          stormwater attenuation is required to be provided to the new roof area to ensure developed flows do not
          exceed existing conditions. A 3kL slimline attenuation tank, with a 50mm low flow orifice and 150mm
          overflow outlet was found to provide the required reduction.

     •    The existing stormwater pipe discharging from the site was analysed under the peak 1% AEP storm
          conditions for the developed (attenuated) site, and it was found that the peak run-off was able to be carried
          without exceeding the required freeboard in the pit. The infrastructure has therefore been deemed
          adequate to convey the proposed development discharges.

     •    During construction, erosion and sediment control measures are to be implemented to minimise potential
          contaminants impacting the downstream receiving environment in line with the objectives of Appendix 2 of
          the SPP. An erosion and sediment control plan shall be developed as part of a submission for Operational
          Works approvals.

     •    As the development will result only in a relatively small roof area that is not expected to contribute
          significantly to the pollutant generating characteristics of the site, stormwater quality treatment is not
          proposed for the development. Instead, first flush diversion of roof run-off will provide nominal water quality
          improvements that are suitable for the scale and nature of the proposed development.

     •    The proposed stormwater solution manages run-off generated by the proposed development without
          resulting in significant impacts to water quality or quantity and is therefore considered to meet the Water
          Quality and Drainage objectives of the Noosa Plan.




Project number 20220213
File 20220213 Reserve St SWMP.docx, 2022-09-19 Revision 1                                               Page 13 of 16

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