Callaghan and Toth IWMP Report revised

                                                                                Callaghan & Toth

4.       WATER QUALITY MANAGEMENT PLAN
4.1      Proposed On-Site Stormwater Treatment Process

The developed site was divided into MUSIC model sub-catchments as shown on Plan No.
1714-01. The proposed treatment train for the development site is also illustrated on Plan No.
1714-01 and listed below:

1. Rainwater Tanks will be required to collect water from the new roofs. Six tanks all of 14,000
   litre capacity will be above ground and have potable top-up supply when 80% empty with an
   overflow pipe discharging to the underground detention system. The tank capacity is to be
   adequate for the supply of toilets and some landscape watering.

2. Fox Gross Pollutant Traps will be used as field inlets to collect gross pollutants and
   sediment.

3. Detention System – The use of two ecoAID systems to manage peak rates of stormwater
   runoff to mitigate flows from pre to post development scenarios. The ecoAID system will
   also act as a GPT by removing sediments as per the manufacturers specifications.

4. The Biopods – two bioretention basins will treat the stormwater runoff from the new
   buildings, pathways, landscaped areas and car parks, and rainwater tank overflows, etc.
   The treated runoff will then be directed to an existing storm water pipe within the property.
   The bio-retention component will remove the nutrients and retard flow.


4.2      MUSIC Model
4.2.1 Source Nodes

Catchment areas of source nodes within the proposed development have been identified as
sub-catchments such as roofs, carparks, road and verge areas. MUSIC allows for the
characteristics of these source nodes to be amended to ensure that accurate pollution
generation and hydraulic characteristics are used to generate stormwater runoff within the
model. Table 4.1 below details the sub-catchments used in the MUSIC model, land use,
percent imperviousness and area of each sub-catchment. The MUSIC Modelling Guidelines for
South-East Queensland – Version 1 December 2010 have been used to set levels of
imperviousness. The site has been related to a “Commercial” land use and pollutant export
parameters detailed in the Guidelines for this land use have been used for each node.




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1714-Cartwrigth Village Extension_IWMP_Revision 3.doc                           April 2019