8. Volume 5 - Stormwater Management Plan

                                            LAMBERT & REHBEIN
                                              ENGINEERS • MANAGERS • SCIENTISTS


3.3     PRE DEVELOPMENT SCENARIO
Table 2 below outlines the calculations, methodology and inputs used to undertake the pre
development hydrologic modelling in XPStorm.
                           Table 2 Pre Development XPStorm Inputs
                    Item                       Value        Units      Source / Comment

IFD Chart                                      Noosa         N/A     Bureau of Meteorology

IFD Coefficients                               Noosa         N/A     Bureau of Meteorology

Zone                                              3          N/A    AR&R, Volume 1, Book 2

Impervious Initial Loss / Continuing Loss *    2.5 / 0       mm     AR&R, Volume 1, Book 5

Pervious Initial Loss / Continuing Loss *      20 / 2.5      mm     AR&R, Volume 1, Book 5

Impervious Catchment Mannings                   0.015        N/A       Roof and Pavement

Pervious Catchment Mannings                     0.035        N/A             Grass

Impervious Catchment Area                      0.0990         ha    Contour and Detail Survey

Pervious Catchment Area                        0.1438         ha    Contour and Detail Survey

Vectored Slope Impervious                        0.5          %           Survey Plans

Vectored Slope Pervious                           7           %           Survey Plans

* The Initial and Continuing Loss models are within the specified Australian Rainfall and Runoff
(AR&R) ranges and have been calibrated to the results obtained from rational method
calculations.

To check the order of accuracy of the XPStorm model, rational method calculations were
completed for each storm event. The peak event was assumed to be equal to the time of
concentration for the catchment.

Table 3 overleaf shows the results of the hydrological modelling and the rational method
calculations. For further details, the XPStorm outputs are enclosed in Appendix D and the
rational method calculations are enclosed in Appendix E.




 Ref: B16239CR002                                         - 4 -                    Stormwater Management Plan
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