Appendix D_Engineering Report

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5.4.9 Downstream Stormwater Infrastructure
An assessment of the existing downstream stormwater infrastructure within Resort Drive and
through Precinct E1 to the Golf Course has been provided. The capacity of the downstream
pipes within Resort Drive and Precinct E1 and the flows from their corresponding contributing
catchments are summarised in Table 5-4 below. Refer to Appendix E for the Concept Siteworks
and Drainage Plans which outline the location of the existing stormwater pipes and their
proposed contributing catchments.

                                Table 5-4 – Pre and Post-Development Peak Flows
                            Pipe                        Contributing         Q10 Flow       Pipe Capacity
                                       Pipe Grade
       Pipe Number       Diameter                       Catchments            (m3/s)           (m3/s)
                                           (%)
                           (mm)
             1              675              1.1               C2             0.396             0.841
             2              375              1.4               C1             0.134             0.208
             3              535            0.34                C1             0.134             0.261
             4              800              5.0        C1+C2+Road            0.692             2.957
             5              800              4.7        C1+C2+Road            0.692             2.886
             6              800              7.8        C1+C2+Road            0.692             3.668



It has been demonstrated that the existing pipe system within Resort Drive and within Precinct
E1 has sufficient capacity cater for the Q10 flows from the ultimate development of Precinct
E2. Therefore, on-site detention is not deemed necessary for the proposed development on
Precinct E2.


5.5 Stormwater Quality Management
The proposed development will involve an increase in impervious surfaces and a change in land
use. Potential sources of contaminants and stormwater quality improvement devices identified
for the operational phase of the development are outlined in Table 5-5

                                      Table 5-5 - Sources of Contaminants

                                                   Pollutant
              Target Pollutant Type                                   Acceptable Treatment Examples
                                                     Size

        Primary         Screening of gross                          Litter baskets, swales, buffer strips,
                                                   >5000um
       Pollutants           pollutants                                              GPT’s
                        Sedimentation of
       Secondary                                   125um -
                        coarse to medium                            Swales, sedimentation basins, ponds
       Pollutants                                  5000um
                            sediment
                           Enhanced                                  Bio-retention basins, constructed
                                                    10um –
                      sedimentation of fine                         wetland macrophyte zones, other bio
                                                    125um
                          particulates                                         technologies
        Tertiary     Adhesion and filtration
                                                   0.45um –     Constructed wetland macrophyte zones,
       Pollutants    of very fine / colloidal
                                                     10um               other bio technologies
                            sediment

                       Biological uptake of                     Constructed wetland macrophyte zones,
                                                   <0.45um
                        dissolved particles                             other bio technologies



Engineering Services Assessment
Residential Development at Precinct E2, Noosa Springs, Noosa Heads