While controlling fires at major accidents, fire control methods themselves can result in hazardous pollution. Fire prevention plans need strengthening to avoid environmental risks.
Major accidents
Incidents which have the potential to kill or seriously injure many people, or cause the environment to be poisoned severely, or for a long time (which ultimately may also affect human health) are defined as major accidents.
The Control of Major Accident Hazards (COMAH) Regulation SI 743/1999, as amended, is used to:
- identify industrial sites where major accidents may occur
- regulate how they are to be operated to prevent major accidents.
COMAH is the UK’s way of implementing the EU’s Seveso II directive, so named after the small Italian town of Seveso where a very serious accident released dioxins into the environment in 1976.
COMAH liability is based on the hazardous properties of one or more materials, combined with the inventory held on site at any one time.
COMAH typically covers:
- fires
- explosions (solids, liquids, gases)
- toxic gas releases
- releases of hazardous materials to the environment (a major accident to the environment is referred to as a MATTE).
COMAH does not cover:
- transport accidents for rail, road, air, sea (although a transport accident might trigger a major accident, for example a road tanker might crash into a fuel tank)
- offshore oil and gas incidents
- military incidents.
Significantly excluded from the scope of COMAH are grid-scale battery energy storage systems (BESS)
BESS are a fundamental part of the UK’s move towards sustainable energy. BESS accidents (such as lithium-ion battery fires and explosions) have the potential to release hazardous substances, such as hydrogen fluoride, toxic metals and explosive gases.
Fire control methods and the environment
During major accidents, fire control measures can themselves result in the release of hazardous pollutants to ground.
Buncefield oil storage depot, 2005
- The original major accident was a fire and associated vapour-cloud explosion, which spread to several other fuel storage tanks.
- Explosions resulted in injuries to more than 40 people and significant damage to the surrounding area and the environment.
- During the fire, some of the tanks and their bunds collapsed, which led to spillages of fuel which moved into nearby drains.
- One of the drainage manholes had an old forgotten borehole which had not been sealed, and this allowed fire-water runoff, foam and fuel to pollute the chalk bedrock aquifer, an important drinking water resource.
- The Health and Safety Executive also found that the protective bunding and containment system was not designed to cope with any large-scale releases.
Stanton-by-Dale recycling plant, 2012
- Several thousand tonnes of waste wood caught fire on the site.
- Fire-water runoff drained uncontrolled from the site into a local watercourse.
- Chemical processes during combustion resulted in an elevated biological and chemical oxygen demand, which reduced the amount of available dissolved oxygen in the water.
- Aquatic life was wiped out for several kilometres of the watercourse.
Current thinking on fire control at COMAH and BESS sites
COMAH-regulated sites are required by law to have plans in place to control water used to fight on-site fires.
Fire prevention plans might be required to control fire-water runoff in accordance with CIRIA 736 containment systems for the prevention of pollution.
Containment systems might include:
- bunds, lagoons and tanks
- emergency temporary containment (for example sacrificial areas)
- catch-pits and interceptors
- separators and booms
- drain seals and sandbags.
BESS sites lack standardised guidance and legislation on the management of fire-water runoff, drainage and surface-water management to prevent pollution.
Fire & Rescue Services encourage BESS developers to include mitigation measures for containing and managing fire water runoff, and control measures for potential impact on the environment in emergency response and fire prevention plans.
System capability/capacity should be based on anticipated water application rates, including the impact of water-based fixed suppression systems. Sites located in flood zones should have details of flood protection or mitigation measures.
Public concerns about the environmental risks of grid-scale battery energy storage systems are rising.
The last word
WHS provides environmental consultancy services for the full water cycle.
This includes drainage design and surface-water management as well as water runoff, flood risk and pollutant risk assessment.
We have detailed knowledge and understanding of catchment hydrology, hydrogeology, environmental impact assessment and, most importantly, we know how the regulators work.