Appendix D- SWMP

 29 September 2023




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 3 below.


                                              WATER QUALITY OBJECTIVES


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

                                                                                                      No visible films
           80                          45                            60                       90
                                                                                                        or odours

                                            Table 3 – 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 natural treatment methods to treat the runoff prior to discharge from the site.

Stormwater runoff from the roof will be captured in a series of new gutters, downpipes and pits,
which will discharge along with the remaining suspended car park catchments to bioretention
basins, where Q1 flows will receive treatment while additional flows with discharge into the
external stormwater network.

The bioretention basins are located to pickup direct downpipe flows to ensure the basins remain
shallow when compared to the surrounding ground levels.

Runoff from the existing car park areas will continue to discharge through the existing bio basins
which will be retained as part of the Stage 2 development works.

Treated water and overflows will discharge into the new stormwater pipe networks constructed as
part of the Stage 2 retail developments.

The treatment plan for the proposed development is depicted on MPN Plans 9954 DA03-DA08
attached in Appendix 2, with MUSIC excerpt below.




 Excellence with Economy in Engineering                                                                                  12
 https://mpncnetau.sharepoint.com/sites/administration/shared             documents/9000-9999/9900-
 9999/9954/report/29-09-23 stormwater management plan_issue a.docx