24-7-19 Attachment F Rev Stormwater Mgmt Plan

18 July 2019



5         STORMWATER
5.1       Flooding

Based on Noosa Shire Council flood mapping, the site is not subject to flooding from any sources.


5.2       Site Based Stormwater Management Plan

The aim of the Stormwater Management Plan outlined below is to:

          Prevent or minimise adverse social or environmental impacts from stormwater runoff
           originating from the proposed development.
          Achieve acceptable levels of stormwater runoff quality and quantity.

The Stormwater Management Plan aims to identify Stormwater Quantity and Quality Best
Management Practice for the site and demonstrate that water quantity and quality impacts will be
minimised in receiving waters.

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.


5.3       Operational Phase

5.3.1 Proposed Site Drainage

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

The new building and carparks will be constructed over a basement car park. The stormwater from
the roof and suspended car park will be directed to a new combined bioretention/detention basin
located along the Northern boundary of the site. Detained and treated water from the combined
bioretention/detention basin will discharge to an additional detention tank located under the drop
off area at the front of the building.

Stormwater runoff from the landscape areas at the front of the site will be conveyed along grassed
swales and discharge to the detention tank, via the new pit and pipe network.

Runoff from the courtyard area at the centre of the site will be collected and conveyed in the new
internal pit and pipe network to the detention tank.

Stormwater runoff from the car park access driveway at the South East corner of the site will
bypass treatment and detention and connect to the stormwater infrastructure constructed as part
of the masterplan ROL development.




Excellence with Economy in Engineering                                                               8
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