Judgment - PECA 24.25 - 19.06.2026

 STORMWATER QUALITY

     5.1. Operational Stormwater Quality Management

 5.1.1 Water Quality Objectives and Requirements
As the proposed development site is greater than 2,500m2 in area, the development will be required to meet water
quality design objectives outlined in the State Planning Policy (2017) and Council’s Water Quality and Drainage Code
(2020). The proposed development site will be required to achieve the following design objectives for operational
stormwater quality.

                                           Table 5-1 - Operational Water Quality Objectives

                                           Pollutant                       Percentage Reduction Target (%)
                              Total Suspended Solids (kg/yr)                             80
                                 Total Phosphorus (kg/yr)                                60
                                  Total Nitrogen (kg/yr)                                 45
                                  Gross Pollutants (kg/yr)                               90



 5.1.2 Water Quality Modelling
Details of the proposed treatment train are provided in Section 3.1 above and shown on preliminary drawings
attached in Appendix C. Further details of the proposed devices and preliminary sizing are provided below.


 5.1.3 Bioretention Basin
Table B in Appendix 2 of the State Planning Policy (2017) states that “In lieu of modelling, the default bio-retention
treatment area to comply with load reduction targets for all Queensland regions is 1.5 per cent of the contributing
catchment area”. MUSIC modelling has not been undertaken for sizing of the proposed bioretention basin. The
proposed bioretention basin has been sized at 1.5% of the contributing catchment area in lieu of MUSIC
modelling.

It is proposed to provide a bioretention basin design for this project generally in accordance with the following
typical section.




                                       Figure 5-1 -Typical Cross Section of a Bioretention Basin


The bioretention basins will be designed in accordance with Water By Design’s Bioretention Technical Design
Guidelines (2014). Planting will be provided in accordance with Council’s requirements.



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