Attachment G - Stormwater Quality Management plan

                                                                                Callaghan & Toth



4.4      MUSIC Modelling Results

The MUSIC modelling program has been used to investigate the performance of various
treatment options in the treatment train. MUSIC version 6.2.1 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.


4.4.1 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 6.2.1 Summary Report.

The information above indicates that the new hardstand playground areas 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                                2%
             Total Suspended Solids             84%                  80%
             Total Phosphorous                  60%                  60%
             Total Nitrogen                     42%                  45%
             Gross Pollutants >5mm              98%                  90%

4.4.2 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 2001-02 shows
the treatment systems of Tree pits, biopods, vegetated swale and rainwater tanks.

This treatment train is able to achieve reductions as per the pollutant load reduction targets
(See Table 4.2) which complies with Council’s requirements. It is noted that the Total Nitrogen
(TN) percentage reduction achieved is 42%, which is close to the required 45% reduction
target. This preliminary design details that the nutrient reductions are achievable and following
detailed design, sufficient bioretention systems will be incorporated to show that the TN
reduction target is achieved.




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2001 Hinterland Playground SWMP                                              February 2020