Swmp

The modelling results show the pollutant reduction objectives are met for all contaminants listed in Table
5.1. Details of the proposed bio-retention basin are provided in the Stormwater Management Plan
drawing no: SCG 33132 - SW1.1 thru to SW1.2 (Appendix D.)




6.0       STORMWATER QUANTITY


Noosa Shire Council’s Planning Scheme – Noosa Plan 2020, requires post development peak flows
leaving the development site will not exceed the pre-development peak flow rates for the required design
storms.

A Stormwater Quantity Analysis has been undertaken of the existing and developed site conditions in
accordance with the following guidelines.

                       −     QUDM 2017
                       −     Noosa Planning Scheme 2020
                       −     Australian Rainfall and Runoff (ARR 2019)

The following section of this report discusses the proposed developments impact on peak stormwater
discharge from the site and the proposed mitigation measures to ensure a non-worsening effect is
achieved to downstream properties.

6.1       Drains Analysis
To calculate the peak discharges for the site under existing (pre-development) and proposed (post-
development) conditions. Hydraulic modelling has been undertaken for the site using the software
package PC DRAINS, to determine peak flows. We have modelled the site to establish existing and
proposed stormwater drainage characteristics.

Rainfall patterns accompanied with Initial Loss (IL) and Continuing Loss (CL) was sourced from the
Australian Rainfall and Runoff 2019 (ARR 2019) data hub for Noosaville.

Initial Losses (IL) and Continuing Loss (CL) were approximated based on the storm losses from the
ARR Data Hub, Table 6.1 below states the adopted values: -




SCG Consulting Engineers                    Page 14                                SCG Ref: 33132(SWMP)