Bushfire Risk Assmt & Risk Mngt Plan for house at 297 Lawnville Rd, Black Mountain Revision 1 December 2020 ENAM

                         Ecological Natural Area Management

The actual fuel loads of the impacting vegetation were not assessed, however, based on the above
published potential fuel accumulations from the published literature shown above, this report will
use the next highest acceptable fuel load from AS3959 which is the “Rainforest” fuel loads which
are 10 t/ha surface fuel load and 12 t/ha total fuel.
7.4       Forest Fire Danger Index
This report will use the specified Forest Fire Danger Index of FFDI 40. as required by Australian
Standard AS3959.
7.5       Parameters used in the bushfire behaviour modelling
West bushfire attack
This modelled fire burns up-slope through Notophyll vine forest (rainforest) to attack the house
from the west.
    • Fuel loads used are the “Rainforest” fuel loads of Australian Standard AS3959 of 10t/ha
       surface fuel & 12t/ha total fuel.
    • Separation of the house from the hazard: 18m
    • Slope in the vegetation = 7.90
    • Site slope = 7.00


7.6       Results of bushfire attack modelling
Table 4: Assessed Bushfire Attack Levels for the modelled bushfire attack
                                                       Modelled bushfire attack
Modelled bushfire parameter                               West bushfire attack
Separation from the hazard                                       18 m
Vegetation                                               Rainforest
Modelled surface fuel load                                       10 t/ha
Modelled total fuel load                                         12 t/ha
Vegetation slope (degrees)                                      7.9 0
Site slope (degrees)                                            7.0 0
Modelled rate of spread                                        0.83 km/h
Flame width                                                     100 m
Radiant heat                                                  11.69 kW/m2
Modelled fire line intensity                                   5133 kW/m
Modelled flame length                                          6.82 m
Level of construction (BAL)                                BAL 12.5

From Table 4 above the worst case Bushfire Attack Level from the bushfire modelling is BAL 12.5
See Appendix 2 for a detailed software reports from which the above table was generated.
7.7       Bushfire Attack Levels for each building elevation
Australian Standard AS3959 Construction of buildings in bushfire-prone areas specifies that the
building elevation opposite the assessed bushfire attack direction can be reduced on BAL level due
to shielding by the building but BAL 12.5 cannot be reduced further so the Bushfire Attack Levels
for each of the building elevations are:
      •    BAL 12.5 for all building elevations.


Bushfire Risk Assessment and Management Plan for a house at 297 Lawnville Rd, Black Mountain   December 2020

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