RFI - Appendix G SWMP by MPN Consulting

 16 December 2021




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 on ground catchments to bioretention basins, where
Q1 flows will receive treatment while additional flows with discharge into the external stormwater
network.

Runoff from the existing landscape areas at the North and South East corner of the site will remain
generally as per pre-development conditions and will be treated by the existing grassed swale.

Approximately 260m2 of the access driveway and the carpark will bypass the bioretention basins.
This has been allowed for in the model so the overall net water quality objectives are achieved for
the development

Treated water will discharge off site via a proposed stormwater connection. The treatment plan for
the proposed development is depicted on MPN Plan 8293-CP.1.01 attached in Appendix 3, with
MUSIC excerpt below.




 Excellence with Economy in Engineering                                                                        12
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