5179SQMP_2 PearsonsRd_Feb2021_Rev2_

                                                                                   Callaghan & Toth



4.3      MUSIC Modelling Results

The MUSIC modelling program has been used to investigate the performance of various
treatment options in the treatment train. MUSIC version 6.3 is the current version and capable
of incorporating rainwater re-use in the model. These features have been used in making
comparisons between different stormwater management systems for this report.


4.3.1 Water Quality Objectives

This model meets the pollution load reduction target as detailed in the State Planning Policy
2017 (Appendix 2: Table B). The following have been included in Appendix A.

                The treatment train effectiveness for the system.
                The MUSIC Version 6.3 Summary Report.

The information above indicates that the new carpark, sealing, footpaths, and associated
landscaping with the proposed stormwater treatment train will achieve reductions in pollutant
loads as detailed in Table 4.2 below.

         TABLE 4.2:          COMPARISON OF LOAD REDUCTIONS

              Parameter                      MUSIC            POLLUTANT LOAD
                                           REDUCTION             REDUCTION
                                            RESULT                TARGETS
                                                              (Source: SPP 2017)
              Flow                             3.5%
              Total Suspended Solids           83%                    80%
              Total Phosphorus                 57%                    60%
              Total Nitrogen                   50%                    45%
              Gross Pollutants >5mm            100%                   90%



4.3.2 Assessment of Results

The developed site has been modelled as a series of Urban Residential sub-catchments, which
incorporate Water Sensitive Urban Design (WSUD) treatment trains. Plan No 2035-01 to 03
Revision C shows the proposed location of the treatment system - BB4, BB1, BB2, BB3,TP1,
TP2 and TP3.
The reductions listed in Table 4.2 above generally comply with Council’s requirements, Water
by Design Deemed to Comply Solutions and the State Planning Policy December 2013 –
Appendix 2, Table B. except for Total Phosphorus being 3% lower than the pollutant load
reduction target of 60%. Total Phosphorus result for the site discharging into the tributary is
57% - which is considered suitable as the target is 60% and the result is within acceptable
model error. Further polishing can be expected from overland flow thru densely vegetated
buffer.

Therefore, it is considered that the proposed stormwater treatment system is currently sufficient
to reduce the pollutants prior to exiting the site and entering the tributaries of the Six Mile Creek.

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2035 2 Pearsons Road IWMP – Revision 2                                          February 2021