210055 - 327 Kinmond Creek Road, COOTHARABA - Bushfire Risk Assessment

3. Bushfire Attack Level Assessment
To assess the bushfire hazard for the site and proposed development, the following tasks were
undertaken:

    •   Assessment of regional ecosystem (RE) mapping for the site and surrounding area
        (DNRME, 2020);

    •   Review of the proposed development layout;

    •   Review of high-resolution aerial imagery for the site;

    •   A site-based assessment undertaken on 16th July 2020 to:
        o   Verify the occurrence, extent, composition and structure of vegetation communities
            currently existing within and surrounding the site;
        o   Measure effective and site slope; and
        o   Assess adjacent bushland, existing fire breaks / trails and access roads.

    •   Identify potential bushfire hazards and risks. This includes an assessment of the bushfire
        risk and a BAL assessment for the proposed development. The BAL assessment
        outlines the AS3959:2018 requirements for the construction of future buildings.

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. In accordance with Sections 2.1 and 3.2.3 of AS3959:2018, the BAL applies to the
entire building and to any attached or adjacent structures within 6 metres of the building.

BALs are calculated in accordance with either Method 1 or 2 outlined in AS3959:2018. Given
that the proposed development shall require clearing to establish an appropriate separation
distance, Method 2 has been used to calculate the minimum separation distances for each BAL.
The following steps were undertaken to calculate these distances:

    •   Step 1: Determination of the relevant Fire Danger Index (FDI);

    •   Step 2: Assessment and classification of vegetation communities, fuel loads and
        vegetation height within and surrounding the proposed development;

    •   Step 3: Assessment of the effective slope beneath classified vegetation and the slope
        of the land between the site and classified vegetation;

    •   Step 5: Assessment of distance to the vegetation; and

    •   Step 6: Determination of Bushfire Attack Level (BAL).




PR20257_BAL_327 Kinmond Creek Rd, Cootharaba                                                    6