Appendix D - Bushfire Assessment · RAL26/0026

3.0     LOCAL HAZARD MAP
3.1     GENERAL
The SPP reference documentation sets out the following methodology for preparing a Local Hazard Area
Map:
     Categorising the vegetation within the site in accordance with the vegetation hazard classes
        derived from BRC (refer to Figure 1)
     Using the patch and corridor filtering process to remove narrow corridors and small patches of
        hazardous vegetation (refer to Figure 1)
     Subdividing the identified vegetation hazard classes into bushfire hazard sub-units based on
        slope differences and vegetation hazard classes (refer to Figure 2)
     Assigning SPP Potential Bushfire Intensity classes to the sub-units (refer to Figure 2)
     Application of 100m Potential Impact Buffers to the amended sub-units to derive an overall Local
        Hazard Map (refer to Figure 3)

3.2     PATCH AND CORRIDOR FILTERING
The bushfire hazard assessment process adapts the method used to generate the SPP Bushfire mapping,
described in Leonard et. al. (2014), with further refinement to allow for the downgrade and/or filtering of
small patches and narrow corridors where needed in accordance with contemporary mapping rules
outlined in the BRC and Leonard and Opie (2017).

Section 4.2.6 of BRC outlines the patch and corridor filtering process to modify potential intensity of small
patches and corridors (based on Leonard et. al. 2017). The process involves the following three stages:
       Remove small, isolated patches of a single Vegetation Hazard Class less than 1ha if they are
          further than 100m from any other continuous fuel greater than 2 hectares in size
       Downgrade the intensity of small patches (0.5 to 3 ha). This process downgrades the effective
          fuel load of continuous vegetation patches 0.5 to 2ha by 66%, and 2 to 3ha by 50% if they are
          completely surrounded by either no fuel or by discontinuous fuel further than 100m from any
          other continuous-fuel vegetation patch greater than 2 hectares in size
       Removing narrow corridors of vegetation less than 50m wide and less than 0.5ha through a
          process of patch erosion and dilation. These small patches are merged with surrounding
          vegetation by allocating a patch to the Vegetation Hazard Class that is most common to the patch
          boundary.
In this assessment, narrow bands of VHC 22.1 and VHC 9.1 occur which are less than 50m in width and
are surrounded by low hazard VHC 39.2 vegetation or VHC 43.6. BRC states that narrow corridors and
areas of continuous fuel <50 metres in width are not sufficiently wide to support a fully developed flame
front. These areas are less likely to ignite due to their disconnection with fuels that can carry running fire
fronts. If ignited by a point or line ignition, these areas will limit the fire head width and, as a result, the
fireline intensity. The combined effect of lower ignition likelihood and lower intensity is likely to result in
fireline intensity of less than 4,000 kW/m, and this presents a low hazard to land use planning and
development assessment. Therefore, the identified narrow bands of vegetation have been merged into
the adjoining vegetation hazard class for the purposes of the bushfire hazard assessment (refer to Figure
1).

AUGUST 2026                   BUSHFIRE HAZARD ASSESSMENT & MANAGEMENT PLAN                              Page: 13
                                      380 MCKINNON DRIVE, COOROIBAH