Engineering_Integrated Water Management Plan

2.4 Treatment Measures

The various treatment measures proposed to be implemented within this
development are outlined below. They are made up of rainwater tanks, EnviroPods,
StormFilters and bioretention systems. The localities of the measures are detailed in
Figure 6.

2.4.1 Rainwater Tanks




Through appropriate design of rainwater tanks it has been found that significant
reductions in run-off can be achieved. Rainwater tanks not only provide temporary
detention of stormwater run-off, but also provide a significant alternative for water
supply uses. Collected roof water is suitable for garden irrigation or toilet flushing
with no additional treatment.
Rainwater tanks have been modeled as a lumped tank to represent the entire
development. Sizing of each tank volume has been modeled in MUSIC using
estimated demands for each use to achieve a minimum 80% reliability. The
demands of each use on the site are highlighted in below in Table 7. Irrigation of the
site landscape will be sourced from the Tavern tank. Landscaping area has been
estimated as 10% of the carpark area, irrigating at a rate of 548mm/yr. The annual
irrigation demand scaled by daily PET was calculated as 270KL/yr.

Table 7: MUSIC Rainwater Tank Demands

                                  Units      Average         Demand         Daily
      Use           Usage                    Persons         (L/P/D)       Demand
 A1-Residential      Toilet         6            1.2            26          187.2
                    Laundry         6            1.2            35           252
  Commercial         Toilet         10            2             25           500
 A2-Residential      Toilet         18           1.2            26          561.6
                    Laundry         18           1.2            35           756
    C-Tavern         Toilet         1              -             -          1,800
    E-Shops          Toilet         3             2             25           150
    F-Shops          Toilet         5             2             25           250

Based on the roof catchment areas and the demands estimated for each use, the
rainwater tank modeling parameters are detailed in Table 8.




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