BAL report 56 Reserve St Pomona - Bushfire Attack Level - Minimum Distance Assessment

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              Wollemi Eco-Logical
                Environmental Project Management | Bushfire Assessment | Vegetation Management




Proviso
This report has been prepared for the sole use of Leif Obrien for the purposes for which it is
provided. No part of this report, its attachments or appendices may be reproduced or distributed
to third parties, not connected with the delivery of the purpose, by or on behalf of the client,
without the express written consent of Wollemi Eco-Logical.




DISCLAIMER

To the extent permitted by Law, Wollemi Eco-Logical Pty Ltd (incl. its director/s employees and consultants)
accepts no responsibility or liability to any person or entity for any consequence, including but not limited to all
losses, damages, costs, expenses or inconveniences, arising directly or indirectly from any information and
advice in this report.




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         Wollemi Eco-Logical
          Environmental Project Management | Bushfire Assessment | Vegetation Management




Introduction
Wollemi Eco-Logical has been engaged to undertake a Minimum Distance, Bushfire Attack Level
(BAL) assessment, consistent with the Australian Standard – Construction of Buildings in Bushfire
Prone Areas (AS3959-2018), for a proposed development on the subject site.

This assessment utilised a Method 2 BAL assessment, to provide setback requirements for a
proposed development, in order to achieve specified BAL ratings. This assessment is based on the
classification of potentially hazardous vegetation, slope and separation distances to the
development, and informs the required construction standards to be applied.

Subject Site
The subject site is located at 56 Reserve St Pomona and is formally described as Lot 188 on MCH1261.
The subject site covers an area of 12,141sqm and is represented in Figure 1.




                                                           Figure 1: Subject Site

Proposed Development
It is understood a new residential dwelling is to be constructed on the subject site. The proposed
development layout is represented (informally) in Figure 2.




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                                         Figure 2: Proposed Development Location

Current Bushfire Hazard Mapping
A review of State Bushfire Hazard Overlay Mapping, as maintained by the Department of State
Development, Manufacturing, Infrastructure and Planning (DSDMIP), revealed the site is within a
potential bushfire hazard area (Figure 3).




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                                        Figure 3: Bushfire Hazard Overlay Mapping

Potentially Hazardous Vegetation
A site assessment was undertaken on the 14th April 2022 to classify vegetation within 100m of the
proposed development.

As represented in Figure 1, assessable vegetation within 100m of the proposed development is
present to the east through south to west. Regulated Vegetation as maintained by Qld Department of
Natural Resources & Mines (DNRM), maps this vegetation as containing an assemblage of Regional
Ecosystems (RE’s): 12.3.2 (dominant) described as ‘Eucalyptus grandis tall open forest on alluvial
plains; RE:12.3.1 described as ‘Gallery rainforest (notophyll vine forest) on alluvial plains’; and RE
12.3.11, described as ‘Eucalyptus tereticornis +/- Eucalyptus siderophloia, Corymbia intermedia open
forest on alluvial plains usually near coast’.

Site assessment confirmed the presence of vegetation communities consistent with the mapped
Regional Ecosystem composition and structure. Immediately adjacent the proposed dwelling location
contains an assemblage of Eucalypt open forest more consistent with RE 12.3.11.

Bushfire Attack Level – Minimum Distance Assessment
The Building Code of Australia (BCA) requires all Class 1-3 and Class 10a buildings associated with a
dwelling, to be constructed in accordance with the Australian Standard 3959 (2018) - Construction of
buildings in bushfire-prone areas (AS 3959-2018). This standard provides minimum construction
standards for new dwellings in designated Bushfire Prone Areas.

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         Wollemi Eco-Logical
          Environmental Project Management | Bushfire Assessment | Vegetation Management



The construction standards are intended to improve the performance of buildings subjected to
burning debris, radiant heat or flame contact. The AS3959- 2018 methodology prescribes Bushfire
Attack Levels (BAL’s) to the facades of proposed buildings to which corresponding construction safety
standards are applied. AS3959-2018 defines Bushfire Attack Levels 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, which is the basis for establishing the requirements for construction to improve
        protection of building elements from attack by bushfire.’

In accordance with the Australian Standard – Construction of Buildings in Bushfire-prone Areas (AS
3959, 2018), an assessment of the Minimum Distance Setback Requirements for individual BAL ratings,
has been undertaken to inform construction standards for the proposed development based on the
potential Bushfire Hazard adjacent the proposed development location (Table 1).

This assessment has been based on the following assumptions:
     ▪  A Fire Danger Index (FDI) of 47 (QFES 2022);
    ▪   Proposed development will be located in the layout as represented in Figure 2.
    ▪   Fuel load calculations (Method 2 BAL) for potentially hazardous vegetation to the south and
        east has been determined as reflective of ‘Class 16.1 Eucalyptus dominated forest on drainage
        lines and alluvial plains’ with 18t/ha fuel load potential.
    ▪   Setbacks distances for the proposed development from adjacent potentially hazardous
        vegetation, are understood to be determined based on this and other assessments.
    Additional parameters, including slope, used to determine the minimum distances for relative
    BAL ratings are detailed in the following Tables.
        Table 1: BAL Minimum Distance - Hazardous Vegetation to the East through South to West




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In accordance with AS 3959 (2018), the required setbacks to achieve specific Bushfire Attack Level
ratings for the proposed development on the subject site has been determined. Based on this
assessment, a setback of ≥9m to the east through south to west is required in order to achieve a BAL
29 rating for the proposed dwelling. The above setback requirements for each elevation has been
provided to inform design of the proposed development. Final BAL Rating is dependent on the
setbacks to potentially hazardous vegetation able to be achieved, and can be finalised once detailed
design and known vegetation setbacks are determined. Recommendations for vegetation
management within the APZ are detailed in the following section.

N.B. It is important to note that this report is not to be considered approval to undertake vegetation
clearing to achieve the above identified BAL ratings. Vegetation clearing will require approval from
Council and/or State prior to being undertaken, unless existing approvals or exemptions are
applicable.

Recommendations for Vegetation Management
The landscaping and ongoing management of vegetation in areas susceptible to Bushfire Hazard is an
important tool to mitigate bushfire risk. Previously detailed setbacks to hazardous vegetation should
prevent buildings from being subjected to direct contact from flames, and reduced levels of radiant
heat in the event of a bushfire.

Landscaping and vegetation retention within the identified setbacks to hazardous vegetation should
consider the following guidelines:
    ▪  Immediately adjacent proposed buildings should either be fully cleared and regularly
       maintained (i.e. lawn) with managed ground based fuel loads and ladder fuels.
    ▪   Where retaining trees, ensure they are isolated individuals, small isolated clumps or islands
        and provide a tree canopy cover of less than 15% within the setbacks to hazardous vegetation,
        with clear separation of retained trees and vegetation outside the APZ by >10m canopy
        separation. Tree canopies within this setback should be located greater than 2 metres from
        any part of the roofline of a building. Any trees should have lower limbs removed up to a
        height of 2 metres above the ground.
    ▪   Any landscaping performed on site shall maintain the setbacks to hazardous vegetation
        effectively free of available fuel. Landscaping plants may be used in this area so long as they
        are selected for their low combustibility, by virtue of high moisture content, low volatile oil
        content, high leaf mineral levels, large fleshy leaves, and absence of shedding bark. They
        should be placed so as to not provide either vertical or horizontal connectedness of plant
        material, and avoid overhanging rooflines or contact with flammable parts of buildings. Any
        planted trees should be of species which grow to over 2m, to maintain separation between
        lower canopy and the ground.
    ▪   Turf is to be maintained regularly to reduce the potential for long grass to fuel an advancing
        fire toward buildings.




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         Wollemi Eco-Logical
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Important Note:
It should be noted that this Method 2 Bushfire Attack Level Assessment (BAL) and Minimum Distance
Calculation has been determined based on site conditions at the time of writing, and utilising current
best-practice assessment methodologies as detailed. This information has been provided to inform
detailed design, as the site layout and setbacks able to be achieved have yet to be determined. This
report should not be considered a final Bushfire Attack Level rating, nor a Bushfire Management Plan
for the purpose of planning approval of the proposed development. These reports, where applicable,
are to be finalised/prepared once detailed design of the proposed development is complete.

Bushfire Assessment methodologies are not able to factor in and predict catastrophic bushfire events.,
Bushfires are an intrinsic part of Australia's environment, are often unpredictable, and have
potentially extremely serious consequences, and no guarantee is able to be provided or should be
assumed that the area will not be affected by bushfire at some time.

Regardless of the results of this assessment, owners should be aware of the unpredictability of
Bushfire in the landscape, and the need to be bushfire aware and prepared for extreme events.

All Queenslanders should be familiar with the official Bushfire Warnings system and have a completed
Bushfire Survival Plan. Print ready guides for preparing a Bushfire Survival Plan and to assist in the
interpretation of the official Bushfire Warnings system are available for download from the Rural Fire
Service Queensland website – https://ruralfire.qld.gov.au/bushfires/.

There are three formal Bushfire Warning levels:

         Advice

         Monitor conditions and review your bushfire survival plan.

         Watch and act

        Conditions are changing. Start taking action and follow your bushfire survival plan.

         Emergency Warnings

        You are in danger. Act on your bushfire survival plan now.




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