Attachment 3 - Engineering Report · MCU23/0030

6.3     Stormwater Quantity Management


The site contains an existing dwelling and hardstand areas. The existing fraction of
impervious area is 50%. Proposed works over the site will result in 70% of the site
becoming impervious in the developed scenario. This figure falls within prescribed ranges
for residential developments outlined in Table 4.5.1 of QUDM.


The increase to impervious areas will result in a minor increase to peak stormwater
discharge leaving the site. It is expected that existing stormwater infrastructure available
to the site has been designed and constructed to QUDM and Council’s minimum
standards and will be sufficiently sized to convey stormwater runoff from the subject site
in a fully developed state.


Note, a proposed rainwater harvesting tank installed as part of the water quality
management scheme will reduce peak discharge to road reserve and will also reduce the
total volume of runoff from the development site.



6.4     Water Quality Management Plan


Refer to the attached Engineering Drawing No. C6398/23/D01 for details of stormwater
quality management for the development site. The total site area is 612m² and the
proposed land use is low density residential.


An assessment has been undertaken to determine if the proposed development is subject
to State Planning Policy (SPP) water quality objectives. Trigger Questions have been
applied to the development to determine if SPP compliance is required. Refer to Table
6.4a for details.




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