Appendix C - Stormwater Management Plan

31 October 2018



Land Use – Commercial                    Log10 TSS (mg/L)                    Log10 TP (mg/L)             Log10 TN (mg/L)


                                                         Storm                           Storm                       Storm
                                    Base Flow                           Base Flow                     Base Flow
                                                         Flow                            Flow                         Flow

Roof               Mean                     0             1.30               0           -0.89           0            0.37

                   Std. Dev.                0             0.38               0           0.34            0            0.34

Roads              Mean                 0.78              2.43              -0.6         -0.30          0.32          0.37

                   Std. Dev.            0.39              0.38              0.5          0.34           0.30          0.34

Ground             Mean                 0.78              2.16              -0.6         -0.39          0.32          0.37
Level/Open
Space              Std. Dev.            0.39              0.38              0.5          0.34           0.30          0.34
                                 Table 3 – Pollutant Export Parameters (Commercial)

5.3.3.5 Water Quality Objectives
The Water Quality Objectives of the receiving waters for the proposed development have been
obtained from State Planning Policy July 2017. The State Planning Policy load reduction targets are
summarised in Table 4 below.


                                                 WATER QUALITY OBJECTIVES


 Total Suspended                                              Total                    Litter/Gross
                               Total Nitrogen
  Solids (TSS) %                                         Phosphorous (TP)              Pollutants %            Oils/Grease
                             (TN) % Reduction
    Reduction                                              % Reduction                  Reduction

                                                                                                          No visible films or
          80                           45                          60                      90
                                                                                                               odours

                                                Table 4 – Water Quality Objectives

5.3.3.6 Treatment Plan
In order to achieve the Water Quality Objectives for the proposed development, it is proposed to use
mechanical treatment method to treat the runoff prior to discharge from the site.

Stormwater runoff from the proposed development will be captured in a new underground pit and pipe
network which will discharge to the proposed combined treatment / detention tank located at the South
Western corner of the carpark.

Treated water and overflow from the proposed combined treatment / detention tank will discharge off
site via a proposed stormwater connection to the existing stormwater pits constructed as part of the
masterplan ROL.

The treatment plan for the proposed development is depicted on MPN Plan 7700-DA.01 attached in
Appendix 3, with MUSIC excerpt below.




Excellence with Economy in Engineering                                                                                          12
l:\7000-7999\7700-7799\7700\reports\31-10-18 stormwater management plan_issue b.docx