Stormwater Management Report

8.3 MUSIC Model Results


The proposed treatment train modelled with MUSIC, includes the following water quality treatment measures:

A bio-retention basin will be constructed within landscaped areas to the south-east corner of the site adjacent the
                                                                           2                                  2
existing bushland. The bio-retention basin is to have a total area of 250m and a filter media area of 120m and is to
accept runoff for all roofs, hardstand and majority of landscaped areas prior to discharging into the existing drainage
infrastructure. The basin has been modelled with an extended detention depth of 300mm, a hydraulic conductivity of
200mm/hr and a filter media depth of 500mm.

The tabulated results are shown below:

                                          Table 4 – Treatment Train Effectiveness

                                                               Reduction         Target
                            Unmitigated       Mitigated                                      Compliance
              Pollutant                                        Achieved         Reduction
                              (kg/yr)          (kg/yr)                                         (Y/N)
                                                                  (%)              (%)
                 TSS            2350             234               90               80            Y
                 TP             3.80            0.776            79.6               60            Y
                 TN             28.0            11.4             59.4               45            Y
                 GP              283              0               100               90            Y


                                              Table 5 - Daily Pollutant Loads

                                 WQO’s         Pre-Development           Post-Development     Compliance
                Pollutant
                                 (mg/L)             (mg/L)                     (mg/L)           (Y/N)
                   TSS             6                 25.9                       2.73              Y
                   TP             0.05               0.236                      0.02              Y
                   TN             0.5                1.82                       0.47              Y


As demonstrated in Tables 4 and 5, the stormwater quality management strategies proposed for this development
exceed the taget reduction rates required by the NSC and the State Planning Policy (2014).




HR DESIGN                                         Reference No: 18-0165B                                    Page 9 of 15