Bushfire Hazard Assessment Management Plan v2 - 434 Lake Cooroibah Rd Lake Cooroibah v1 · RAL26/0015

Bushfire Hazard Assessment & Management Plan v2                                      NCES REF: J001445
434 Lake Cooroibah Rd Lake Cooroibah, QLD



      •    Unlikely - Could occur but doubtful
The determination of whether a bushfire event is likely or unlikely to impact the site has been
based on the relative position of hazardous vegetation to the site and its connectivity with
hazardous bushland areas. A fire burning in hazardous vegetation located upwind of the site
under typical south-east Queensland seasonal fire winds from the north to north-west to west
to south-west is considered to represent a ‘likely’ probability of impact to the site. A fire burning
in hazardous vegetation located downwind of the site under typical south-east Queensland
seasonal fire winds is considered to represent an ‘unlikely’ probability of impact, albeit
acknowledged that the back head of a fire may nonetheless impact the site however the
intensity of the back head is not considered to be significant for the risk assessment at hand.
Hazardous vegetation has been confirmed to the north and west of the development footprint.
The likelihood of a fire positioned to the north and west of the site approaching toward the site
is considered likely as seasonal fire winds would be expected to drive the fire front toward the
site. A forest fire burning toward the Lot 7 building area from the north and west would however
be expected to revert to a low intensity grassfire upon interception of the cleared low threat
VHC 41.4 conditions to the north and west of the proposed building footprint in Lot 7.

5.3       Consequences of Impact
The consequences of a fire front positioned to the north and west of the site would be expected
to include radiant heat impact and ember attack which can lead to damage to property and or
injury or loss of life.
The Flamesol results infer direct flame contact to the Lot 7 boundaries from SU1b (Lf =
11.15m) to the north would not occur by virtue of the 60m available separation. Similarly, the
Flamesol results infer direct flame contact to the Lot 7 boundaries from SU2 (Lf = 12.59m) to
the west would not occur by virtue of the 67m available separation.
Spotting across the low threat conditions would remain an inherent risk and could impact the
site and surrounding land.
Radiant heat exposure risk primarily affects the northern and western facades of the future
dwelling/s in Lot 7.
The BRC 2019 identifies that exposure to 1 kW/m² RHF represents the maximum for indefinite
skin exposure and at 2 kW/m²:
      •    Pain is felt on bare skin after 1 minute exposure (non-fatal); and
      •    Firefighters with protective clothing can withstand this exposure level for a          few
           minutes however, they are likely to experience rise in core body temperature.
The above impacts are therefore possible within Lot 7 given it is located <100m from the
identified hazardous vegetation.
Assessment Benchmark 4 of the Department of Infrastructure, Local Government and
Planning’s Natural Hazards, Risk and Resilience –– Bushfire (December 2019) State Planning
Policy – state interest guidance material, references radiant heat flux (RHF) exposure of
<29 kW/m² on a Reconfiguration of a Lot development footprint plan as generating an
Acceptable to Tolerable level of risk for non-vulnerable uses. Exposure to <29 kW/m² RHF:

      •    reduces potential exposure to bushfire attack, particularly direct flame contact;
      •    reduces the likelihood of piloted ignition due to radiant heat exposure;
      •    improves consistency between planning and building outcomes;
      •    reduces potential for conflicts between planning and building approvals; and
      •    avoids duplication and regulatory burden on home owners.
Note, building exposure of <29 kW/m² RHF is not to be misrepresented to infer acceptable
protection of human life in exposed conditions.
A building envelope is identified on the plan of development hence the exposure risk is to be
assessed from the proposed building envelope boundaries.
Table 1 confirms the following setbacks are required to achieve <29 kW/m² RHF exposure to


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