080623 BlueCare Bushfire Assessment Report_Iss B_screen version.pdf [As Published] · 132008.1128

                                                                                             Bushfire Protection Assessment
                                                                                                                   BlueCare
                                                                                            Grass Tree Court, Sunrise Beach

2.4      Bushfire Modelling

Bushfires may be modelled using mathematical modelling techniques.

For heathland vegetation wind speed is a dominant factor in determining fire behaviour characteristics. For planning
purposes a wind speed of 45km/h is generally considered the appropriate (worst case) wind speed for inputting into
empirical models and has therefore been adopted for this assessment. There are two types of heathland on the site – tall
heath to approx 3m in height and low closed heath to 1.5m in height. The tall heath has a higher fuel load and therefore
contributes to higher fire intensities.

The results of the modelling for a credible worst case fire scenario on the property ‘Design Fire’ are summarised below.
The result could be equated to a 1 in 50 year event which is the recognised level of planning recognised as being by the
Australian Bushfire Council. The majority of fires occurring within a 50 year timeframe would not reach the intensity
predicted in this worst case scenario.

Fire behaviour was modelled as potentially being very intense during a credible worst case bushfire weather scenario
and based on the existing topography and vegetation type and extent. The intensity of the modelled fires is such that the
worst case fires could not be directly attacked by fire suppression authorities and a defensive strategy would need to be
adopted. It is therefore important that the proposed development include design attributes which make the development
more easily defendable.

Based on the proposed 15m setbacks from the predominant vegetation the modelled radiant heat for the worst case
scenario is such that direct flame contact with the proposed buildings would not occur. Copies of the modelling results
are included below. Calculation equations and assumptions are included in Appendix 1.




                                                                                                     Tall Heath Results




Low Heath Results




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                                                   © 23 June 2008
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