Att 1 - RFI Amended SWMP

                                                                                             23098 - SBSMP/3
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                                            Table of Contents
1     INTRODUCTION ............................................................................................ 3
2     EXISTING SITE.............................................................................................. 4
  2.1    The Site ................................................................................................ 4
  2.2    Surrounding Area ...................................................................................... 4
3     PROPOSED DEVELOPMENT ............................................................................... 5
4     EXISTING DRAINAGE PATTERNS ......................................................................... 6
  4.1    Existing Infrastructure ............................................................................... 6
  4.2    Existing Drainage Patterns ........................................................................... 7
  4.3    Lawful Point of Discharge............................................................................ 7
5     STORMWATER QUANTITY................................................................................. 8
  5.1    Rational Method Assessment ........................................................................ 8
    5.1.1     Design Storms ....................................................................................8
    5.1.2     Rainfall Intensity ................................................................................8
    5.1.3     Times of Concentration .........................................................................8
    5.1.4     Runoff Coefficients ..............................................................................8
    5.1.5     Peak Flows ........................................................................................9
  5.2    Proposed Development Drainage ................................................................... 9
  5.3    XPSTORM Modelling ................................................................................... 9
    5.3.1     Intensity Frequency Distribution ..............................................................9
    5.3.2     Initial and Continuing Losses ................................................................. 10
    5.3.3     On-site Detention.............................................................................. 10
    5.3.4     Comparison of Peak Flows at Lawful Point of Discharge ................................. 10
6     STORMWATER QUALITY ................................................................................ 12
  6.1    State Planning Policy Assessment ................................................................ 12
  6.2    Construction Phase ................................................................................. 12
  6.3    Operational Phase .................................................................................. 14
    6.3.1     Sources of Contaminants ..................................................................... 14
    6.3.2     Proposed Treatment Train ................................................................... 15
    6.3.3     Pollutant Export Modelling ................................................................... 15
    6.3.4     MUSIC Modelling Parameters ................................................................. 15
    6.3.5     MUSIC Modelling Results ...................................................................... 16
7     FLOODING ................................................................................................ 18
8     CONCLUSION ............................................................................................. 19
Appendix A DETAILED SITE SURVEY ........................................................................ 20
Appendix B PROPOSED DEVELOPMENT PLANS ............................................................ 21
Appendix C NSC INTERACTIVE MAPPING PLANS .......................................................... 22
Appendix D NSC WATER QUALITY AND DRAINAGE CODE ................................................ 23
Appendix E RATIONAL METHOD CALCULATIONS ......................................................... 24
Appendix F CONCEPT SITE LEVELS AND DRAINAGE PLANS .............................................. 25
Appendix G BOM IFD ......................................................................................... 26
Appendix H XPSTORM PRE DEVELOPMENT RESULTS ..................................................... 27
Appendix I XPSTORM POST DEVELOPMENT RESULTS .................................................... 28
Appendix J XPSTORM POST DEVELOPMENT MITIGATED RESULTS ...................................... 29
Appendix K STORMWATER QUALITY OPERATION AND MAINTENANCE GUIDELINES .................. 30
Appendix L NSC FLOOD HAZARD OVERLAY MAP .......................................................... 31




Site Based Stormwater Management Plan
Proposed Townhouse Development at 5 Pearl Street, Cooroy