P0198-25-001_12_Gympie_Street_Tewantin_SWMP

4          Stormwater Quality

4.1        Introduction
A stormwater quality assessment was undertaken for the proposed development at Tewantin using MUSICX
(Model for Urban Stormwater Improvement Conceptualisation), in accordance with the Water by Design MUSIC
Modelling Guidelines. The model was designed to evaluate the pollutant load reductions achieved through the
proposed treatment train, ensuring compliance with the Urban Stormwater Quality Planning Guidelines 2010.

The stormwater treatment system consists of a bio-retention basin located on the northeastern side of the
development, sized to effectively mitigate pollutant loads generated from impervious surfaces. The filter area of
the basin is set at 45 m², with a filter media depth of 0.4 m, which ensures sufficient treatment capacity for the
anticipated runoff volumes.


4.2        Stormwater Quality Modelling (MUSIC) Methodology
Stormwater quality modelling for the site was conducted using the ‘Model for Urban Stormwater Improvement
Conceptualisation’ (MUSIC) Version 6.3. The model was built to assess the effectiveness of the proposed bio-
retention basin and to ensure that stormwater quality meets the development’s Water Quality Objectives. A
diagrammatic layout of the MUSIC model is presented in Figure 2-1 below.

The MUSICX model was configured in accordance with the Water by Design MUSIC Modelling Guidelines,
incorporating the following parameters:

    •    Catchment Delineation: Defined based on site hydrology and impervious areas.

    •    Source Nodes: Representing runoff from urbanized catchments with a mix of pervious and impervious
         surfaces.

    •    Treatment Node: A bio-retention basin serving as the primary stormwater treatment measure.




Figure 4-1 MUSIC Model




 12 GYMPIE STREET, TEWANTIN
 Stormwater Management Plan                                                                                   17
 Client Reference: P0198-25-001        4 November 2025
 Prepared for Novato Group