Reference Document - MCU12/0133.04

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Noosa FLC Extension to Existing Gymnasium and Additional Pavements
19 February 2025                                                                                   Ref. No. 2025.0108




 KEY FEATURE                               DETAILS                              COMMENTS ON PROPOSED
                                                                                DEVELOPMENT
 Runoff Treatment &                        - Site runoff will enter the         The existing water tank and
 Environmental Protection                  stormwater drainage system           infiltration system will be
                                           along Girraween Court.               retained. A new MUSIC model,
                                           - The drainage system flows          incorporating both previous and
                                           through an existing                  proposed works, has been
                                           bioretention/infiltration system     provided. Refer to ‘MUSIC
                                           before reaching Noosa National       Modelling’ Section for details.
                                           Park, Girraween Nature Reserve,
                                           and Burgess Creek.
                                           - While not specifically designed
                                           for the site, the bioretention
                                           system provides additional
                                           environmental protection.
                                           - No significant pollutant loads
                                           are expected due to the site’s
                                           intended use.
 Peak Flow & Flood Management              - The small increase in             The peak flows for stormwater run-
                                           impervious areas will lead to a     off from the site is likely to
                                           minimal increase in peak flows      increase marginally. However, the
                                           during major storms.                run-off will be contained within the
                                           - Approximately 1 m³ of flood       road reserve of Girraween Court
                                           detention will be required and      which ultimately discharges into
                                           can be easily accommodated in       Burgess Creek at the end of the
                                           the final site design through       Girraween Court. It is unlikely to
                                           infiltration systems, landscape     cause any worsening to third party
                                           depressions, or additional          property. In addition, on-site
                                           rainwater tank airspace.            detention is likely to cause a
                                                                               coincidence with external
                                                                               hydrograph peaks at confluence
                                                                               locations.
                                                                               Therefore, no on-site detention is
                                                                               deemed required or desirable for
                                                                               the proposed works.
 Overland Flow Path                        - Overland flow paths will remain   The overland flow path is expected
 Considerations                            consistent with existing            to remain unchanged with the
                                           conditions.                         minimal increase to hardstand.
                                           - During major storm events,
                                           water will sheet flow across the
                                           southwestern boundary onto
                                           Girraween Court, then west
                                           towards Burgess Creek.

In summary, the proposed works align with the original stormwater management strategies.
Erosion and Sediment Control
This site is considered low risk based on the following erosion hazard assessment:
    •    Predicted Annual Soil loss (tonnes) = A x B x T
    •    Where A = R.K.LS.C.P (as per the Revised Universal Soil Loss Equation).