Bushfire Hazard Assessment & Management Plan v1 - 60 Glenridge Drive COOROIBAH

Bushfire Hazard Assessment & Management Plan v1                                  NCES REF: J001001
Lot 47 on RP860577 – 60 Glenridge Drive, Cooroibah



                  society will not accept this risk and measures are to be put in place to reduce
                  risks to at least a tolerable level.
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 Plan of Development depicts building envelopes within the proposed Lots which will be
primarily flanked by hazardous on all sides, precluding Lots 1 and 2. The likelihood of a fire
approaching from the northwest, west, and southwest is considered likely, given dominant
regional fire weather winds are derived from the north-west to south-west.
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
during the modelled bushfire conditions resulting in total structure loss.

The Plan of Development depicts a minimum 25m setback between the proposed building
envelopes and the onsite revegetation works and/or off-site hazardous vegetation (VHC 22.1
forest). A minimum of 20.1m is the minimum separation required to ensure the proposed
building envelopes on the Lots 1-8 are exposed to <29kW/m² radiant heat flux as per the
Flamesol modelling presented herein. The extent of proposed separation therefore facilitates
an acceptable risk of radiant heat impact thereby satisfying Assessment Benchmark 4 of the
SPP Bushfire 2019.




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