SCG 31131(SWM).RevA.pdf

Table of Contents
1.0     INTRODUCTION ..................................................................................................................................3
2.0     EXISTING SITE DESCRIPTION.........................................................................................................4
3.0     PROPOSED DEVELOPMENT.............................................................................................................5
4.0     EXISTING DRAINAGE .........................................................................................................................5
  4.1         Existing Drainage and Infrastructure....................................................................................................5

  4.2         Lawful Point of Discharge..........................................................................................................................6

5.0     STORMWATER QUALITY..................................................................................................................8
  5.1         State Planning Policy and Water by Design Assessment ................................................................8

  5.2         Construction Phase......................................................................................................................................9

      5.2.1       Silt and Sediment Erosion ........................................................................................................................................9

  5.3         Completed Development.........................................................................................................................10

      5.3.1       Water Quality Objectives .......................................................................................................................................10

      5.3.2       Sources of Contaminants .......................................................................................................................................11

      5.3.3       Proposed Treatment Measures...........................................................................................................................13

      5.3.4       Pollutant Modelling ..................................................................................................................................................13

6.0     STORMWATER QUANTITY............................................................................................................15
  6.1         Rational Method.........................................................................................................................................16

      6.1.1       Design Storms.............................................................................................................................................................16

      6.1.2       Rainfall Intensity .......................................................................................................................................................16

      6.1.3       Time of Concentration ............................................................................................................................................16

      6.1.4       Runoff Coefficient (C10)...........................................................................................................................................17

      6.1.5       Peak Flows ...................................................................................................................................................................17

  6.2         Proposed Drainage....................................................................................................................................18

      6.2.1       Catchments...................................................................................................................................................................18

      6.2.2       Peak Flow Mitigation ...............................................................................................................................................18

  6.3         Hydraulic Modelling (PC Drains)..........................................................................................................19

      6.3.1       Rainfall Data ................................................................................................................................................................19



SCG Consulting Engineers                                                   Page 1                                                             SCG Ref: 31131(SWMP).RevA