RFI - Appendix B Civil Engineering Report · MCU22/0038

 12 May 2022




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.

The bioretention basins are located in the south west and along the western boundary of the site.

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

Treated water from Bio Basin 1 will connect into the basement drainage system for pump out to the
existing drainage network. Bio Basin 2 will connect directly to the external system for treatment
flows and overflows. The connection to the basin pump out for basin 1 is required due to the high
invert levels of the surrounding drainage network to the south. The treatment plan for the
proposed development is depicted on MPN Plan 8662-CP.1.01 attached in Appendix 3, with
MUSIC excerpt below.




 Excellence with Economy in Engineering                                                                                   12
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