06-09-22 Stormwater Management Plan_Issue F · MCU21/0175

 6 September 2022


The Stormwater Management Plan outlines the site in two sections, the operational phase and the
construction phase. The operational phase addresses treatment of contaminated runoff from the
developed site by natural methods before discharging into receiving waters whilst the construction
phase of the Stormwater Management Plan addresses erosion and sediment control to prevent
contamination of water sources by stormwater runoff during construction of the site.

5.4       Operational Phase

5.4.1 Proposed Site Drainage

Stormwater runoff from the proposed development will be collected and conveyed in a new
stormwater pit and pipe network to the existing internal infrastructure.

Stormwater runoff from the new roof, carpark, internal road and servicing areas will be directed to
6 bioretention basins for stormwater quality treatment. High flow bypasses will be constructed
around the bioretention basins for flows exceeding the treatment flows.

Stormwater runoff from the landscape areas at the North and South East boundaries will remain
generally as per pre-developed conditions, with some re-shaping required to ensure stormwater
infrastructure remains clear of the proposed building works.

The west and central parts of the development will sheet flow toward a narrow bioretention basin
fitted in the middle of the carpark, adjacent to the arbour link. Surrounding runoff will fall toward
the southern bioretention basin via kerb and crossfall. Similarly, the eastern section of the
development will sheet flow toward two bioretention basins on the south-east corner of the site.
Once sheet flow is conveyed within the basins, stormwater will be piped toward the lawful point of
discharge.

Approximately 310m2 of the access driveway, carpark and footpaths will bypass the bioretention
basins to allow the driveways to join neatly into the existing internal road system. The treated
areas will be over treated so the overall net water quality objectives are achieved for the
development.

Stormwater treatment will be implemented to remove sediments, nutrients, gross pollutants and
hydrocarbons in accordance with the requirements of Noosa Council and the State Planning Policy.

Stormwater discharged from site is proposed to be consistent with the existing Emporium
showroom discharge. This development sits within a lot that has been allowed for in previous
stormwater calculations, therefore no detention is proposed for this development.

The proposed conceptual stormwater drainage layout is depicted on MPN Plan 8293-CP.1.01
attached in Appendix 3.

5.4.2 Stormwater Quantity Management Strategy

The proposed development site will connect into the existing drainage system for the Noosa Civic
Shopping Centre. The sites minor flows will run through the existing pipe system whilst the major
overflows will overland flow down the internal roads prior to discharging to the Creek to the South
of the site. There will be no impacts to external properties as a result of the development flows
through the internal site system.




 Excellence with Economy in Engineering                                                                 8
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