RFI - 20210153 Maple St SWMP

 CONCLUSION
This Concept 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.

     •    The existing site surface run-off drains overland as well as within a drainage network
          discharging to the verge on Myall Street as the lawful point of discharge. The proposed
          development will maintain Myall Street as the lawful point of discharge, with run-off from the
          site discharged into the existing drainage system on Myall Street.

     •    The existing and proposed development site have been modelled for the design storm
          events applicable to the site, which found attenuation would be required to ensure no
          increase to peak run-off generation rates. Provision of a 50kL attenuation tank with a 55mm
          low flow orifice, and the proposed bioretention garden was found to provide suitable
          mitigation to the development to ensure that there will be no increase to existing peak flow
          discharges from the site for any of the storm events. Including the upstream external
          catchment, the results demonstrate and improvement will be achieved within the state
          controlled Myall Street.

     •    Rainwater reuse storage is provided at a minimum rate of 3,000L/unit. A total of 50kL of
          rainwater storage will be provided to meet the outcomes of the sustainable building code.
          Rainwater reuse is to be plumbed into non-potable demands throughout the site including
          in external irrigation and wash down areas, and internal toilets and laundries. The tank will
          be fitted with an automatic switching device to revert to town water supply where insufficient
          water is available for reuse.

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

     •    In the operational phase of the development, a stormwater treatment train will provide
          quality improvements as required by the Noosa Council Planning Scheme Policy. Roof run-
          off from the new buildings will be captured in rainwater tanks reuse in non-potable demands.
          Run-off from the ground surfaces will be captured by an internal drainage line to be conveyed
          through the site. All run-off from the site will be conveyed to an end of line bioretention
          garden along the southern boundary providing treatment for flows before they are
          discharged from the site.

          By implementing the proposed stormwater treatments, the development will reduce the
          quantity of stormwater pollutants by more than 90% of gross pollutants, 80% of total
          suspended solids, 60% total phosphorous and 45% total nitrogen, exceeding the pollutant
          reduction targets required for the site.

     •    The proposed stormwater solution is considered to minimise any adverse impacts to the
          downstream environment arising from the stormwater run-off while also meeting the
          stormwater quality targets required for the development.




Project number 20210153
File RECOR Preliminary Stormwater Management Report - 20210153.docx, 2022-03-31                                 Page 22 of 27
Revision 1

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