RFI - Attachment E - SWMP Callaghan and Toth

                                                                               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 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                              1.4%
             Total Suspended Solids            83.7%                 80%
             Total Phosphorous                 59.3%                 60%
             Total Nitrogen                    44.6%                 45%
             Gross Pollutants >5mm             99.4%                 90%



4.4.2 Assessment of Results

The developed site has been modelled as a series of Industrial sub-catchments, which
incorporate Water Sensitive Urban Design (WSUD) treatment trains. Plan No 2001-01 shows
the existing treatment systems Biobasin 1 and 2, with the two existing grass swales and one
new swale location.

This treatment train (once the existing Biobasin systems are refurbished) is able to achieve
reductions as per the pollutant load reduction targets (See Table 4.2) which complies with
Council’s requirements. Please note that the 59.3% reduction in TP is considered to be
equivalent to 60% required reduction. As well as the MUSIC model result of 44.6% reduction in
TN, is considered to be equivalent to the required 45% reduction.




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2001 Lower Mill Carpark Extension SWMP                                             July 2020