Firefighting tactics to mitigate impacts on people and the environment
Fires in waste stacks can be difficult to extinguish. Applying large volumes of water or foam is often ineffective, particularly if the fire is deep seated and the stack is made up of fine or densely packed waste such as tyre crumb or wood chip and an ash layer develops which make water penetration difficult. It may also generate large volumes of polluted firewater and smoke.
Incident commanders and Waste Fire Tactical Advisors may need to consider other firefighting tactics to extinguish a large waste fire to minimise impacts on the public and environment. One or more of these may be employed and the tactics may need to change during the course of the fire, particularly if the fire is likely to burn for an extended period or the hazards change. For example, during the initial stages of a fire which is burning fiercely with a buoyant plume and smoke travelling away from vulnerable people due to the wind direction a well ventilated controlled burn may be suitable, when combined with actions to stop fire spread such as:
- Removing unburnt waste from a burning stack
- Creating fire breaks
- Cooling nearby building
As the fire begins to die down and smoulder tactics may need to change to include more active firefighting, such as the removal of burning material with heavy machinery and then dousing it in a bunded area.
Some tactics may require sufficient time for the necessary resources and equipment to arrive. Tactics may need to be changed due to a change in climatic conditions such as wind direction.
Active firefighting tactics for waste fires include:
- Separating burning material from the fire and quenching it with water jets in an area with sealed drainage. Alternatively burning material can be extinguished by placing it in a sealed bunded area, tank or vehicle containing a pool of water. The benefits of this approach include:
- Reducing the amount of contaminated firewater produced
- Reducing or preventing the risk of water pollution
- Reduced costs
- Water jets may still be used initially to knock down flames in a burning pile to allow machinery and equipment to get close enough to remove burning waste. These jets should be stopped once surface material has reached saturation point and the allocation of more water serves no purpose and poses an additional risk of pollution. Excessive water runoff will indicate when saturation has occurred.
- Removing unburnt waste using heavy machinery and other equipment to reduce fuel load and create fire breaks
- Using a fine spray or mist to reduce pollutant levels in the smoke plume and the volume of firewater run-off produced
- Extinguish using water or fire foam or a wetting agent. This may need to be directed to a specific area of the burning waste to be effective. For example, the Chimney technique where the firefighting agent is applied to the base of a burning stack of baled material.
- Burial with the approval of the appropriate environment agency
- An accelerated well ventilated burn, see Controlled burn
- Recirculating firewater if safe to do so
When determining tactics FRS incident commander should wherever possible consider advice from other agencies including public health agencies and environment agencies on the likely environmental and human health impact of any proposed cause of actions as well as any measure that can be taken to mitigate their impacts.
FRS incident commander may also wish to seek advice from the National Waste Fire Tactical Advisor capability, they can provide specialist knowledge of waste fire tactics including how to mitigate the impact of waste fires on people and the environment.
The final decision on the tactics chosen will however rest with the incident commander. See also Controlled burn.
Environment agencies may also be able to provide equipment on request, such as heavy machinery, and additional containment facilities. For example, the EA Temporary Barriers used for protecting communities from flooding, can also be used to contain clean water for firefighting or contaminated firewater.
Wetting agents have been used successfully at several large combustible waste site fires as well as during trials carried out by WISH on how waste burns and can be extinguished. More work is required before any decisions are made about their widespread use. This includes consideration of their environment impacts. See Foam for current guidance on mitigating their environmental impact.
For more information FRS see Fires in Waste Sites National Operational Guidance