7. Attachment F - Bushfire Hazard Assessment

                                                              Bushfire Hazard Assessment and Management Plan




                                                                             62,193   Very High   Very High
        SW          8.1       Remnant       9.5      Downslope        48
                                                                              kW/m


The results of the potential fireline intensity calculation for bushfire-prone vegetation within the
assessment area show that vegetation within the site (VHC 8.1) has a potential bushfire hazard class
of ‘High’ or ‘Very High’. Section 5 outlines the requirements for management and mitigation of bushfire
hazard for the bushfire-prone vegetation within the site.

3.2 Radiant Heat Exposure and Bushfire Attack Levels

Bushfire attack levels (BALs) are used to quantify the levels of attack (radiant heat exposures/flux) that
built structures may experience during a fire event. The BAL is defined as ‘a means of measuring the
severity of a building’s potential exposure to ember attack, radiant heat and direct flame contact, using
increments of radiant heat expressed in kilowatts per metre squared, and the basis for establishing the
requirements for construction to improve protection of building elements from attack by bushfire’
(Standards Australia, 2018).

AS3959:2018 adopts six BAL categories, which are based on the level of radiant heat flux to which
buildings may be exposed to during a bushfire event. This level of heat flux generally relates to the type
of vegetation, effective slope and how far a building is from hazardous vegetation. BALs apply to
buildings and any attached or adjacent structure within 6 m of the building.

The BRC Technical Guide requires that radiant heat exposure/bushfire attack levels (BALs) are
calculated using either the SPP Bushfire APZ calculator (QFES, 2019b), which is the preferred method
or Method 2 of AS3959:2018. Where Method 2 is used, the following inputs are to be used:

    •    Site-specific values for FFDI (Step 1)

    •    Ground-truthed VHCs (Step 2) and their associated fuel loads (provided in Figure 14 of the BRC
         Technical Guide); and

    •    Site and effective slopes (Step 3).

The site is located within a large patch of remnant open forest. Given the extent of this patch, a potential
continuous fire run greater than 150m is highly likely to the north-east, but not to the east and south-
east. Accordingly, a short fire run methodology is relevant to this site for the east and south-east fire
runs. The following fuel loads have been used in the Method 2 assessment for all fire runs to the site–

    •    Understorey - potential fuel load of 31.0 t/ha;

    •    Total fuel load – potential fuel load of 35.0 t/ha

The Flamesol Method 2 Minimum Distance calculator has been used to calculate the minimum
separation distance required between the development and bushfire-prone vegetation for each BAL.
These results are provided in Appendix 2 and Figure 6 and summarised in Table 6.




                                                  PR22428_BHAMP_199 Beddington Road, Doonan          Page 18