SWMP Technical Memo Climate Change as submitted with Further Advice response

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                                                                                           Sunshine Coast | Brisbane
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TECHNICAL MEMORANDUM
Response to RFI Item 4 - Climate Change Allowance

   To                        Development Assessment, Noosa Shire Council

   From                      Eoin Whitmore, RPEQ 31423 - RECOR Pty Ltd

   Date                      12 August 2026

   Project                   Cooroy Social Housing - 45 Maple Street and 9 Myall Street, Cooroy

   RECOR reference           P0478-26-001

   Subject                   Supplement to the Stormwater Management Plan dated 24 June 2026




1. Purpose and response summary
This technical memorandum supplements the Stormwater Management Plan (SWMP) dated 24 June 2026
and responds to Council's RFI Item 4 concerning the climate-change allowance. The DRAINS model has
been revised and rerun for the 1% AEP event with rainfall depths increased by 20%. The updated model
confirms that the current civil design achieves a non-worsening discharge outcome without increasing the
nominated 75 kL main detention tank.




2. Council requirement and applicable guideline
Council's RFI refers specifically to section SC6.7.6(1)(d)(i) of Planning Scheme Policy 6 - Engineering Design
Standards. Under the 'Climate Change' heading, the Noosa Plan 2020 requires drainage design and flood
impact assessments to use the latest Bureau of Meteorology IFD data for the study location. It identifies the
major drainage design event and defined flood event as the BoM 1% AEP IFD with a 20% increase in rainfall
intensity for future climate change.
Accordingly, the climate-change verification undertaken for this response applies the 20% uplift to the
complete 1% AEP rainfall-depth series used by DRAINS. The other AEP events remain as assessed in the
submitted SWMP. The adjoining 800 mm tidal-tailwater allowance is not applicable because the site
discharges to Council's inland stormwater network in Myall Street rather than directly to a tidal waterway.
Guideline source: Noosa Plan 2020 - Schedule 6 Planning Scheme Policies, PSP6, SC6.7.6(1)(d)(i), PDF page 54




P0478-26-001 | Cooroy Social Housing | RFI Item 4     Page 1 of 6