RFI - Attachment 3 - Stormwater Management Plan

 STORMWATER QUALITY MANAGEMENT

     4.1. Operational Stormwater Management
In accordance with the Noosa Plan 2020 Water Quality and Drainage Code, the proposed development site will be
required to achieve the design objectives for operational stormwater quality as outlined in Table 9.4.8.3 PO6, as
shown in Table 4.1 - Operational Water Quality Objectives below.


                                           Table 4.1 - Operational Water Quality Objectives

                                                 Pollutant                 Percentage Reduction
                                                                                Target (%)

                                    Total Suspended Solids (kg/yr)                  80

                                        Total Phosphorus (kg/yr)                    60

                                          Total Nitrogen (kg/yr)                    45

                                         Gross Pollutants (kg/yr)                   90



The proposed upgrade of Carpenters Road will convert a gravelled surface to sealed, which will immediately
reduce free sediment available to be transported during storm events and prevent the sediment loads impacting
upon the downstream waterways. Run-off from the proposed upgrade will be convyed in grassed tables drains
acting as swales, further reducing pollutant and nutrient loads generated by the development. Based on the
confined nature of the access easement, this is considered a best practice approach to providing stormwater
quality improvements to the access.

The following discussion will assess the quality management for the proposed development site within Lot 2 RP
200519 where the developed site will significantly alter existing conditions . MUSIC modelling has been carried out
to assess the proposed development treatment train against the above objectives as described in the following
sections.



          4.1.1 MUSIC Modelling
The proposed development and the above treatment train have been modelled in MUSIC (Model for Urban
Stormwater Improvement Conceptualisation) software in accordance with the Water by Design MUSIC Modelling
Guidelines (2018).

The climatic data has been modelled using the rainfall and PET data at station 40059 (Cooroy Composite) in 6-
minute timesteps. The rainfall run-off parameters have been set as defined for the Southeast Queensland region,
shown below in Figure 4.1 - Rainfall run-off parameters for SEQ




Project number 21020                                                                                           Page 17 of 36
File RECOR Concept Stormwater Management Report - 21020.docx, 2022-09-05
Revision 0


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