Town Planning Report_Bunnings Trade Centre_v3.3

REPORT

4.9          Stormwater
There is existing underground stormwater infrastructure within Gateway Drive. The existing Bunnings site
has an internal stormwater network consisting of bioretention and detention basin which discharges into the
existing stormwater infrastructure within Gateway Drive. They are considered as the lawful point of discharge
for the proposed development.

4.9.1        Quantity
A new internal stormwater pit and pipe drainage system within a detention basin is proposed for the
development area. The proposed system will discharge to the existing stormwater infrastructure within the
development area and the existing Bunnings site.
Piped flows from the external catchment area will be captured, and will bypass the detention basin, and
discharge to the existing infrastructure.
Further refinement of the detention system location, layout, sizing and outlet configuration will need to be
undertaken as part of detailed design after a revised detail survey has been received. Modelling illustrating
pre and post-development (mitigated) design flows, shows that after mitigation, compared to the existing
condition, there is no increase in post-development design flow rates off the development area.

4.9.2        Quality
A stormwater quality treatment train consisting of one conventional bioretention system is proposed for the
development. The proposed bioretention system is proposed to be installed within the detention basin.
Modelling for the proposed treatment train shows that it will achieve the required water quality objectives.
During the construction phase of the development, an Erosion and Sediment Control Program will be
implemented to minimise water quality impacts. This program will be developed by the contractor engaged to
design and construct the plan and, will hence not be available until closer to the start of construction.
A Site Based Stormwater Management Plan prepared by Accor is provided in Appendix F.




102995-10 | Bunnings Trade Centre | 3.3 | 30 March 2022
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