Bushfire Hazard Assessment & Management Plan v4 - 7 Triller Court, Pomona

Bushfire Hazard Assessment & Management Plan v4                                   NCES REF: J000841
Lot 4 on SP320405 – 7 Triller Court, Pomona



Assessment Benchmark 4 of the SPP Bushfire 2019 references radiant heat flux exposure of
<29kW/m² on any part of the building as generating an Acceptable to Tolerable level of risk.
AS/NZS ISO 31000:2018 defines ‘Likelihood’ as the chance that something might happen.
Likelihood can be defined, determined, or measured objectively or subjectively and can be
expressed either qualitatively or quantitatively (using mathematics ). The following ‘likelihood’
categories for the probability of the assessed bushfire attack mechanisms impacting the
assessment area have been adopted within this assessment:
      •    Likely - Will probably occur
      •    Unlikely - Could occur but doubtful
The determination of whether a bushfire event is likely or unlikely to occur (i.e. impact the site)
has been based on the relative position of hazardous vegetation to the site. Hazardous
vegetation located upwind of the site under typical south-east Queensland (SEQ) seasonal
fire winds from the north to north-west to west to south-west are deemed to be exposed to a
‘likely’ probability of impact. Hazardous vegetation located downwind of the site under typical
SEQ seasonal fire winds are deemed to be exposed to an ‘unlikely’ probability of impact.

4.2       Risk from Identified Hazardous Vegetation
The building envelopes within proposed Lots 4-6 are flanked by the identified hazardous
vegetation to the north and south of the site. The Lot 7 BLE is flanked by hazardous vegetation
to the north, south, and west. The likelihood of a fire approaching from the south-west to north-
west is considered likely, given dominant regional fire weather winds.
The degree of separation offered to the adjoining vegetation is the primary driver of the
assigned level of risk and was determined with consideration to the Flamesol modelling output
presented in Section 3.3. In the absence of an appropriate separation buffer to the adjacent
vegetation, and implementation of relevant AS3959-2018 construction standards, the future
dwellings on the site could be exposed to direct flame, severe radiant heat and ember attack
resulting in total structure loss.

The Plan of Development provides a dedicated Asset Protection Zone between the proposed
building envelopes on Lots 4-6 and their respective northern, southern, and western lot
boundaries which coincide with the edge of hazardous vegetation. The building envelopes
within Lots 4-6 are separated from the VHC 9.1 open eucalypt forest by a minimum of 24m to
the north and 26m to the south. >23.9m separation to the north and >25.7m separation to the
south are the minimum separations required to ensure the proposed building envelopes on
Lots 4-6 are exposed to <29kW/m² radiant heat flux, based on the Flamesol modelling
presented herein.

The building envelope within Lot 7 is separated from VHC 9.1 by a minimum of 24m to the
north, 26m to the south, and 18m to the west. >23.9m separation to the north, >25.7m
separation to the south, and >17.9m to the west are the minimum separations required to
ensure the proposed building envelope within Lot 7 is exposed to <29kW/m² radiant heat flux,
based on the Flamesol modelling presented herein.

The extent of proposed separation with Lots 4-7 therefore facilitates an acceptable risk of
radiant heat impact.




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