Item 11 Appendix E - Stormwater Management Plan-1.0 · MCU22/0094

 20 May 2022


Stormwater runoff from the new roof, carpark and landscaped areas will be directed to a
bioretention basin for stormwater quality treatment. High flow bypasses will be constructed
around the bioretention basins for flows exceeding the treatment flows.

Approximately 58m2 of the access driveway, pavement and landscaped areas will bypass the
bioretention basins to allow the driveways to join neatly into the existing road system. The treated
areas will be over treated so the overall net water quality objectives are achieved for the
development.

Stormwater treatment will be implemented to remove sediments, nutrients, gross pollutants and
hydrocarbons in accordance with the requirements of Noosa Council and the State Planning Policy.

This development sits within a lot that has been allowed for in previous stormwater calculations,
therefore no detention is proposed for this development.

The proposed conceptual stormwater drainage layout is depicted on MPN Plan 9307-CP.1.01,
attached in Appendix 3.

5.4.2 Stormwater Quantity Management Strategy

The proposed development site will connect into the existing drainage system for the Noosa Civic
Subdivision. The sites minor flows will run through the existing pipe system whilst the major
overflows will overland flow down the internal roads prior to discharging to the Creek to the south
of the site. There will be no impacts to external properties as a result of the development flows
through the internal site system.

5.4.3 Stormwater Quality Management Strategy

In order to satisfy the requirements of the State Planning Policy July 2017 for the adequate
treatment of stormwater runoff, natural treatment solutions have been provided to remove
hydrocarbons, suspended solids and nutrients prior to being discharged from site.

5.4.3.1 Potential Pollutants Generated
The pollutants that could be potentially generated as a result of the development use are as
follows:
     • Litter
     • Sediment
     • Nutrients (Nitrogen and Phosphorous)
     • Hydrocarbons (oils and grease)
     • Surfactants
     • Pathogens/Faecal Coliforms (bacteria and viruses)

The MUSIC computer modelling program developed by the Co-operative Research Centre for
Catchment Hydrology was used to predict the performance of the proposed stormwater treatment
train.

At this stage the pollutants modelled in MUSIC are Total Suspended Solids (TSS), Total
Phosphorous (TP) and Total Nitrogen (TN).




 Excellence with Economy in Engineering                                                                8
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