Playing with firewater?

10th March 2016

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  • Pollution & Waste Management



David Cole believes that it is time to close in on pollution containment

What is the most likely cause of environmental damage during a fire at an industrial site? The blaze itself? Air pollution? How about the combusting materials? Surprisingly, perhaps, the answer is none of these but the huge quantities of water that must be discharged at speed to control the flames.

What is more, the water has a habit of finding routes to flow across a site in directions no one ever expected, let alone mapped, before spilling into a river or sewer. A pollution incident such as this can lead to astronomical costs to pay for the clean-up and repairing the environmental damage, and most companies are unlikely to be insured against the losses incurred.

The scale of the problem

To give an idea of the quantities involved, a blaze at a plastics recycling depot in Smethwick in 2013, thought to have been started by a Chinese lantern, needed 14 million litres of water to contain it, equivalent to six Olympic-size swimming pools, according to the West Midlands Fire Service.

After the Buncefield explosion and fire in 2005, the Health and Safety Executive (HSE) found that protective bunding had many flaws that caused large volumes of fuel, foam and fire-fighting water to leave the site. The last line of water pollution defence – so-called tertiary containment – amounted only to the oil depot’s surface drainage system, which was not designed to cope with large-scale releases. The HSE reported that pollutants from fuel and firefighting liquids leaked from the bund, flowed offsite and entered the groundwater. In July 2010, five companies were together fined £9.5m for their parts in the disaster.

The HSE found that pollutants from fuel and firefighting liquids flowed offsite and entered groundwater

Feeling lucky?

Of course, most organisations believe catastrophes such as these are unlikely ever to happen. Nevertheless, it is no longer enough to feel lucky and take a punt that firewater will not escape into watercourses if a huge blaze breaks out. Given the financial and reputational risks, it is clear that taking steps to avoid so serious an incident is commercially advisable. Also, regulatory authorities are now clamping down with big fines and stricter expectations on organisations to provide proof of the measures they have taken to protect themselves and the surrounding environment. A company that cannot show this evidence may be forced down the route of expensive remediation that might otherwise have been avoided.

As government funding is cut, environmental authorities are being forced to relinquish their advisory role and are enforcing regulations through the courts. And fines can be significant, as the Buncefield case illustrated.

Site operators must ensure that any hazardous or polluting substances they use or store do not escape into the environment. Pollution containment is critical for sites operating under the Control of Major Accidents and Hazards (COMAH) 2015 or Environmental Permitting (England and Wales) Regulations (EPR) 2010. It should also be integral to any 14001-certified environmental management systems. COMAH and the EPR are not restricted to the UK; California’s Industrial General Permit 2014-0057-DWQ, for example, places the state’s industrial sites under similarly stringent environmental regulatory conditions.

In the early stages of fighting a fire, thousands of litres of water are discharged into the environment every minute – overall, 53m litres of ‘clean water’ were applied to the Buncefield blaze. The surface water run-off will pick up the pollutants and contaminants of whatever burning or hazardous substances are present and, if a site is not fully contained, they will escape into the local environment. Even at sites where the substances stored are not in themselves hazardous, fire-fighting water can still be a concern. Vehicle and loading movements onsite and offsite can also be flashpoints for pollution spills. In recent years there has been a particular focus on incidents at waste handling and recycling sites, one being in January 2014 at a plant in North Yorkshire when 50,000 tonnes of scrap tyres, rubber waste, tyre wire and textile materials caught fire.

There is even the potential worst-case scenario of firewater and heavy rain mixing to overwhelm a containment area.

Industry guidance

The UK’s central industry guidance document for pollution containment was significantly revised in 2014 in the light of lessons learned, particularly from Buncefield. CIRIA 736 Containment Systems for the Prevention of Pollution sets out clear guidance on the steps to take.

First, isolation valves should be installed in the outlets to surface water drainage to prevent flood or firewater escaping from the site. It can then be contained until safe removal. In addition, bunds or physical barriers can be constructed, especially around hazardous areas, such as oil or chemical tanks.

This is a good start – as long as the valves are of the correct design. Many sites install a ‘penstock valve’. The word penstock represents many types of valves and they do not all have the ability to stop low pressure flows fully; if a site is looking to contain pollution the valve must contain the entire flow. Penstocks are closed by the force of the head of water rising in the drain. So if the pressure is too low, polluted water could still trickle through the opening and into the environment. By contrast, a new valve technology, developed in 2013, provides a watertight, failsafe solution. The technology has been installed at more than 150 sites in the UK.

Hydraulic modelling

With the right containment valves installed that should be job done, should it not? Probably yes, for most small incidents. However, how do you know that in a serious incident, when flood or firewater starts to fill your containment area, it will not overwhelm the surface water drainage, overtop the bunds and flow out of those pathways the site operator did know were there? In its 224 pages, CIRIA C736 recommends that companies begin with a full assessment based on the source-pathway-receptor model (below) to aid a holistic containment strategy.

For many companies, large and small, finding the time and expertise in-house to complete the steps can be a challenge. Hydraulic modelling techniques can be used to map the surface water pathways on and off a site. The beauty is that they can be used to test and prove any valves, bunds or temporary storage measures that are designed to ensure full containment. A solution can then be designed and constructed in the safe knowledge that any potential incident will be fully contained.

Source-pathway-receptor model


The cause or source of the pollution – such as combustion emissions, dust, effluent discharges, leaks and spills, dumped or poorly managed waste.


The route the source takes to reach a receptor. Pathways include atmosphere, water (rivers, lakes, aquifers, coasts, seas) and land (including surface and underground contamination and groundwater).


To cause harm, the source must reach a receptor. These include humans, neighbours, wider population, sensitive individuals/communities, natural and owned resources (including crops and livestock), wildlife (plants and animals), conservation/sensitive species and habitats, and buildings and structures.


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