Responding to fires
Fire suppression means all actions or operations undertaken to contain, manage or control fire, from the time it is detected until it is declared out. Standard terminology is used by all fire authorities in NSW to describe the status of a fire.
- 'GOING' is used to describe a fire that is actively burning and spreading and before control lines have been established around it.
- 'BECON' is used to describe a fire as 'being contained' - when control lines are in the process of being constructed around a fire.
- 'CONT' is used to describe a fire as 'contained' - when firm control lines have been established around the entire perimeter of the fire and there is a low risk of the fire breaking these control lines.
- 'PATROL' is used when a fire has been blacked out (no active flame) to at least 50 m depth around its entire perimeter and it only needs occasional monitoring or patrol to ensure that it remains contained.
- 'OUT' is used when all active flames have been blacked out (extinguished) and there is a low risk of reignition.
Under the Rural Fires Act 1997, OEH has a statutory responsibility for fire management and control on its managed land and to protect human life, property, the environment, and natural and cultural heritage from the adverse effects of fire.
All fire suppression operations undertaken by OEH are done in accordance with an Incident Action Plan (IAP) specific top the fire and utilising the Australian Inter-Service Incident Management System (AIIMS) developed by the Australian Fire Authorities Council (AFAC).
OEH uses a broad range of strategies to respond to bushfires depending on:
prevailing seasonal conditions and forecast weather
predicted fire behaviour
fire fighter safety
assets and values at risk
the impact of strategies on biodiversity and cultural heritage.
Tactics for the suppression of bushfires include direct attack, backburning, use of earthmoving equipment and use of fire suppression chemicals.
Direct attack has proven to be most effective within the first 12 hours of a fire starting. Direct attack is usually done using ground crews often supported by aircraft. Depending on the size and intensity of the fire and the terrain, ground crews can contain and suppress the fire front directly using water and hand tools. OEH fire fighters are expert at using dry fire fighting methods of fire suppression so they do not rely on water being available. OEH also has specialist remote area fire fighters that are able to be deployed to inaccessible rugged terrain via helicopter. Remote Area Fire Teams (RAFT) can directly attack small fires such as spot-overs. As well as supporting ground crews aircraft are also able to undertake direct attack by water bombing the fire front. This often reduces the fire intensity allowing ground crews to direct attack.
Aircraft are used for a variety of purposes in fire management. Fixed-wing aircraft are used to detect fires, undertake reconnaissance of fire behaviour and boundaries (including via infra-red line scan), transport fire crews from various parts of NSW, provide a platform for airborne radio repeaters and undertake water bombing. Helicopters are used to transport fire crews onto the fire ground (including winching), provide operational support for crews on the fire ground, identify hotspots via infra-red sensors, undertake reconnaissance, perform as air attack supervision, command or observational platforms and undertake aerial ignition and water bombing.
Backburning is a tactic used in the control and containment of fires. It involves igniting another fire to consume fuel in the path of the main fire. Backburning has proven to be an effective fire suppression tactic that can be both cost effective and environmentally sustainable.
A backburn is generally lit from a secure control line and allowed to burn towards the main fire. The aim of the backburn is to gain sufficient depth so that the movement of the main fire will be stopped and spotting will not occur across the control line. Back burning operations can be assisted by the use of incendiaries to ‘deepen’ the burn, either from aircraft or with the use of incendiary launching devices.
A backburn is only conducted only when both fuel and weather conditions are suitable for the containment of the burn. This may be at night when it is cooler and more humid, after a wind shift or lull, or after a cool change.
Earthmoving equipment, including bulldozers, tractors and graders, can be the most effective means of rapidly constructing fire control lines. The use of earthmoving equipment however, can cause serious damage to the environment including soil erosion, damage to natural and cultural heritage and the translocation of weeds and pathogens. Conditions apply to use earthmoving equipment within OEH-managed lands to maintain conservation values and meet environmental legislative requirements.
Fire suppression chemicals
The two types of bushfire suppression chemicals used by OEH are retardants and foams. Retardants decrease the flammability of fuels whilst foams increase the effectiveness of water as an extinguishing agent for immediate use on active flame. Salt water is also classed as a fire suppression chemical due to the potential for environmental impacts if used in fire suppression.
Retardants (Long Term Suppression)
Retardant compounds are composed of either ammonium phosphate or ammonium sulphate. They are generally used for parallel and indirect attack and are applied aerially by agricultural fix wing aircraft and/or helicopters. They are useful in limiting the spread of low intensity sections of a fire.
Foams (Short Term Suppression)
The concentrate used to make foam surfactants is very similar to household detergent. Foam surfactants aid direct attack suppression operations by expanding water droplets, increasing insulation, remaining on fuel surface longer and penetrating deeper into the fuel layer.
The environmental impacts of fire suppression chemicals are minimal and OEH endeavours to minimise the use of chemicals near water courses. Salt water is occasionally used for water bombing operations in reserves along the coast and estuaries. The adverse impact of salt water on vegetation increases the further the location is from the coast. This is because the further vegetation communities are from the coast the less tolerant they are of salt.
Protecting natural heritage
Fire management operations, such as back burning, the construction of fire trails and breaks, use of fire suppression chemicals and the use of vehicles and aircraft for suppression activities, may compromise the conservation of native species, communities and the protection of landscape features. The implementation of these fire management operations needs to be evaluated to avoid or minimise adverse impacts on the conservation values of OEH-managed lands.
Features requiring special consideration include:
- vegetation communities and habitats of significance
- threatened species, populations and communities, and areas of critical habitat
- areas with high aesthetic value
- highly erodable areas
- scheduled water catchments.
Fire may also have positive impacts on native vegetation. Where a vegetation community has exceeded its fire regime threshold (has not burnt for a considerable period of time and plants are senescing) and where the risk to life and property permits, the Incident Management Team may decide to allow a wildfire in this area to burn up to defined control lines rather than invest significant effort to contain the fire to a smaller area.
Protecting cultural heritage
There are many aspects of Aboriginal heritage, including Aboriginal sites and artefacts, landscapes with physical evidence of Aboriginal cultural practices, natural landforms, sites of spiritual or ceremonial significance and native flora and fauna (totem species, bush foods and medicines).
OEH manages a broad range of cultural heritage including structures, works such as roads, dams, cultural landscapes, modified landscapes and archaeological sites. Cultural heritage often reflects evidence of a shared history between Aboriginal and non-Aboriginal people. Cultural sites of significance are identified in Reserve Fire Management Strategies which are used in fire suppression operations. During fires in reserves of high cultural significance, specialist OEH Cultural Heritage Conservation Officers are consulted to ensure the protection of these values from fire suppression operations. Post-fire rehabilitation is also undertaken where required.
Page last updated: 27 April 2012