Appendix J - Civil Engineering Report and SBSMP

                                                                               Noosa Residential Development
                                                                        Ref: 24553 C R002 REV03 10.08.21.docx
                                                                                                 August 2021


Contents
EXECUTIVE SUMMARY                                                                                          5
1     INTRODUCTION                                                                                         6
      1.1   Background                                                                                     6
      1.2   Background Information                                                                         6
      1.3   Property Detail                                                                                6
2     EXISTING SITE                                                                                        8
      2.1   Existing Site Features                                                                         8
3     FLOODING                                                                                             9
      3.1   Flooding Considerations                                                                        9
4     PROPOSED DEVELOPMENT                                                                                10
5     STORMWATER INFRASTRUCTURE                                                                           11
      5.1   Existing Infrastructure                                                                       11
      5.2   Lawful Point of Discharge (LPD)                                                               11
            5.2.1    Existing LPD                                                                         11
      5.3   External Catchment                                                                            11
6     STORMWATER QUANTITY ASSESSMENT                                                                      12
      6.1   Proposed Development and Associated Issues                                                    12
      6.2   Stormwater Quantity Modelling – XP-STORM                                                      12
      6.3   XP- Modelling Assumptions and Methodology                                                     12
            6.3.1    Pre-Development Case Model                                                           13
            6.3.2    Post-Development Case Model                                                          13
      6.4   Peak Storm Results                                                                            14
      6.5   Recommendation                                                                                14
      6.6   Onsite Detention Lifecycle Costs                                                              14
7     STORMWATER QUALITY ASSESSMENT                                                                       15
      7.1   Treatment Objectives                                                                          15
      7.2   Site Analysis and Design Strategy                                                             16
            7.2.1    Pre-Development Phase                                                                16
            7.2.2    Bulk Earthworks Phase                                                                16
            7.2.3    Construction Phase                                                                   17
            7.2.4    Maintenance                                                                          17
      7.3   Stormwater Quality Improvement Devices (SQIDs)                                                17
      7.4   Operational Phase Treatment                                                                   17
            7.4.1    Bioretention Basin                                                                   18
            7.4.2    Swale drains                                                                         18
      7.5   MUSIC Model                                                                                   18
      7.6   On-site Treatment Lifecycle Costs                                                             19
      7.7   Water Quality Monitoring                                                                      19
      7.8   Maintenance                                                                                   19
8     CONCLUSION                                                                                          20


BRISBANE / SYDNEY / MELBOURNE / GOLD COAST / SUNSHINE COAST / DARWIN / PERTH                          Page 3