RFI - Attachment F - Engineering Report

15 May 2019


Issue – Water Quality

This issue is in relation to the following three Specific Outcomes of the Water Sensitive Design
Code.
     O1 Downstream ecosystems, properties and infrastructure are not adversely impacted by either
        changes to flow, water quality or ecosystem health caused by development
     O10 Development design and operation facilitates nil increase in gross pollutants entering
        stormwater systems.
     O7 Natural treatment strategies, including grass swales and bio-retention systems, vegetated
        filtration strips and gross pollutant traps, are used wherever possible

The application proposes the use of a Stormwater 360 proprietary product to achieve the required
stormwater quality pollution reduction targets to achieve the Specific Outcomes.

No information has been provided as to whether the nodes for the proposed Stormwater 360
proprietary devices within the MUSIC model have been tested and verified against the Stormwater
Australia (2018) Stormwater Quality Improvement Device Evaluation Protocol. Version 1.2 December
2018. Propitiatory devices are currently only considered in lieu of vegetated stormwater
treatment strategies retain or allow enhancement of existing environmental values on the site. In
these situations, their performance must be verified prior to being considered for a trial within
Noosa Shire. Trials are only considered where:
     Peer Review from a stormwater professional, endorsed by Stormwater Australia, has been
      provided verifying that the device has been tested in accordance with the Stormwater Australia
      (2018) Stormwater Quality Improvement Device Evaluation Protocol. Version 1.2 December to
      generate accurate and reliable data used within the MUSIC node for the proprietary device,
      and retesting against the protocol under Noosa rainfall conditions and development site is
      agreed to; and
     a significant environmental benefit is demonstrated by allowing a trial of the proprietary
      device at the development site (i.e. an area with existing environmental value will be retained
      in lieu of installation of traditional stormwater quality improvement device such as bio
      retention basins); and
     Opportunity is retained within the developed property to retrofit of traditional stormwater
      quality improvement devices (i.e. bioretention basin) to achieve the required pollution
      reduction targets. This is necessary for the instance where testing of the nominated
      proprietary product under local conditions against the Stormwater Australia (2018) Stormwater
      Quality Improvement Device Evaluation Protocol. Version 1.2 December 2018 demonstrates that
      the proprietary device within the developments treatment train fails to achieve the required
      pollution reduction targets.


Information Required
29.     Information in regard water quality improvement must demonstrate how the runoff from the
        development will deliver water quality and quantities consistent with the requirements of
        downstream ecology, as detailed in relevant flora and fauna management plans developed
        for the Shire Business Centre.
30.     Provide MUSIC modelling consistent with the Water by Design Music Modelling Guidelines
        to also demonstrate that the pollution reduction targets of 80% reduction in Total
        Suspended Solids, 60% reduction in Total Phosphorous and 45% reduction in Total Nitrogen
        are achieved.



Excellence with Economy in Engineering                                                                  3
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