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Development of greenfield sites

Development of greenfield sites

Bushfire protection measures for the development of greenfield sites – part 1

Where greenfield developments are proposed in bushfire hazard areas compliance with the Australian Standard for the construction of buildings in bushfire prone areas (AS 3959-2009) and bushfire planning and design principles are mandated by local government to reduce the vulnerability of buildings and people to bushfire risks.

Implementation of bushfire design and construction requirements can have serious implications for the development including constraining land from development, limiting building design and layout options and adding to construction costs. Therefore, it is preferable to make certain any recommended bushfire protection measures do not become redundant if future development occurs around the site.

In this regard, it is very important to gain an understanding of the future context of the site. Review of state government land use plans for priority development areas and/or council zoning plans will provide an indication of future land use around the site. Land uses such as commercial mixed use and medium and high density residential uses would likely result in the removal of hazardous vegetation adjacent the site and would negate any benefits from imposing setbacks between building and classified vegetation and/or construction requirements under AS 3959-2009.

Key issues such as timing of future development around the site and identifying a cost effective strategy and interim bushfire protection measures will be discussed in part 2 of this article.

Bushfire protection measures for the development of greenfield sites – part 2

Last month we highlighted the importance of seeking to understand the future context of a development site so as to avoid bushfire protection measures that become redundant over time as development occurs on adjacent land.

This situation is possible for greenfield development sites where council and/or state government plans support development in the surrounding area. As planned development occurs, vegetation in the area of the development site will be cleared and result in a reduction in bushfire hazard.

This paper provides developers with four bushfire planning strategies for greenfield development sites which seek to maximise the yield of the land and reduce building construction costs.

  1. Prepare a plan showing bushfire hazard areas on the development site. Bushfire hazard is likely to come from significant areas of vegetation which are to be retained on the development site and from vegetation on adjacent land. At this stage of planning, bushfire hazard areas should be identified on the plan based on providing a 100 m wide setback between building envelopes and vegetation. In most fire weather conditions, this setback will be sufficient to prevent injury to people in the event of a fire and provide a defendable space to allow fire-fighters to protect property and/or evacuate people.
  2. Plan construction stages to avoid the construction of buildings in bushfire hazard areas until the end of the construction program. This will provide an opportunity for bushfire hazard areas to be eliminated by adjacent development and seeks to avoid the imposition of bushfire protection measures that may become redundant once adjacent development occurs.
  3. If necessary, construct and maintain temporary setbacks and fire-fighter vehicle access between early construction stages and bushfire hazard areas. Temporary setbacks and fire-fighter vehicle access should meet the local fire authority’s standards for asset protection zones and fire trails.
  4. A bushfire attack level (BAL) assessment should be undertaken for construction stages in all or part of an area identified on the bushfire hazard area plan. The BAL assessment will confirm if proposed buildings remain subject to bushfire hazard and will propose mitigation measures for the construction stage (if required).

Buildings should be designed and constructed in accordance with the Building Code of Australia and Australian Standard for the Construction of Buildings in Bushfire Prone Areas (AS 3959-2009) if located within a bushfire hazard area. Notwithstanding, alternative solutions may be negotiated in consultation with council and the local fire authority. If development on adjacent land is imminent, alternative solutions may include interim emergency response procedures and transferring risk, ie insurance. If required, consultation with council and the local fire authority should occur during the BAL assessment and prior to the construction stage commencing.