20210153 - Maple Street 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 is captured internally and discharge into the Council
          stormwater infrastructure on Myall Street as the legal point of discharge.

     •    The existing and proposed development site have been modelled for the critical design
          storm events for the site, which found attenuation would be required. Provision of a 50kL
          attenuation tank with a 55mm low flow orifice 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.

     •    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 diverted to the attenuation tanks for flow mitigation. Run-
          off from the driveways will be treated using pit inserts within the driveway pits to provide
          filtration of gross pollutants. All run-off captured within the site will be conveyed to a
          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 20 of 26
Revision 0

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