Fire water – a critical issue in pollution containment
29 March 2016
People are often surprised to learn the most likely environmental damage caused by fire at an industrial site is not a result of the fire itself, but the water that is used to fight it. In this article, Phil Collins, National Sales Manager at Hydro International, looks at some of the effects the huge quantities of water discharged to get a fire under control can have, and suggests ways to contain pollution and mitigate possible damage.
When a fire breaks out at an industrial site, the water has a habit of finding routes to flow across the site in directions no-one originally expected, let alone mapped, before ending up in a river or sewer.
Such a pollution incident can lead to crippling costs to pay for the cleanup and to put right the environmental damage, and many companies will not be insured against these losses.
To give an idea of the quantities of fire water involved, a fire at a plastics recycling operation in Smethwick in 2013, notoriously thought to have been started by a Chinese lantern, needed 14 million litres of water simply to contain it, equivalent to six Olympic swimming pools, according to the West Midlands Fire Service.
And after the Buncefield disaster in 2005, the Health and Safety Executive found that protective bunding had many flaws that caused large volumes of fuel, foam and fire water to escape the site.
The site’s last line of water pollution defence – so-called tertiary containment – was practically non-existent, amounting only to the site’s surface drainage systems which were not designed to cope with any large-scale releases.
In July 2010, five companies were fined a total of £9.5 million for their part in the Buncefield disaster.
Catastrophes of this magnitude are unlikely ever to happen, but given the financial and reputational risks, it is clear that taking steps to avoid these scenarios will often be commercially advisable.
Furthermore, 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. If they cannot provide such proof, then they may be forced down the route of expensive remediation that might otherwise have been avoided.
As government funding is cut back, environmental authorities are being forced to relinquish their advisory role and are increasingly enforcing regulations through prosecution. Fines can be significant. In the worst cases, a pollution conviction can even include the option of custodial sentences for company directors.
Sites that store or use hazardous or polluting substances, in particular, need to take steps to ensure they 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 compliant Environmental Management System (EMS) – or for those companies working to IS0 14001.
These kinds of regulations are not restricted to the UK, of course; 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 a fire, thousands of litres of water can be discharged into the environment every minute. The surface water runoff created 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 for sites where the substances stored are not hazardous in themselves, fire water can still be a concern. Vehicle and loading movements on- and off-site can also be a flashpoint for pollution spills.
Fires at waste handling and recycling sites have been a particular focus for concern in recent years, for example where metals or plastics are handled. There is even the potential worst-case scenario of fire water and heavy rainfall combining to overwhelm a containment area.
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 for water pollution containment.
To provide water pollution containment, most companies begin by installing isolation valves in the outlets to surface water drainage to prevent flood or fire water escaping from the site and contain it until it can be safely removed and tankered away. In addition, sometimes bunds or physical barriers can be constructed, especially around hazardous areas such as oil or chemical tanks, to contain spills.
Drop Seal Valves
Drop Seal Valves are a great start – as long as the valves are of the correct design. Often I see sites where a penstock valve is installed, but the word ‘penstock’ covers some types of valves that do not have the ability to drop seal low pressure flows fully and if a site is looking to contain pollution, then the valve must contain the entire flow.
Penstocks are closed by the force of the head of water rising in the drain. That means that if the pressure is insufficient, then polluted water could still trickle through the opening and out into the environment.
Given that the latest Drop Seal Valve technology provides a watertight, failsafe solution, the type of valve currently in use around a site should be of immediate concern.
Rectifying this should be sufficient for most small incidents. However, how do you know that in a serious incident, when flood or fire water starts to fill up your containment area, it does not overwhelm the surface water drainage, overtop your bunds and flow out of those pathways you didn’t know were there?
In its 224 pages, CIRIA C736 recommends that companies begin with a full assessment based on the source-pathway-receptor model to aid in a holistic containment strategy.
Hydraulic modelling techniques can be used to map the surface water pathways on and off a site. The beauty of this technique is that it can be used to test and prove any valves, bunds or temporary storages measures that are designed to ensure full containment of the site. A solution can then be designed and constructed in the safe knowledge that any potential incident will be fully contained.
For many companies, both large and small, finding the time and expertise in-house to complete the necessary steps can be a challenge. This is where calling in a water control specialist can reap dividends.
Operators end up with a professional, consultative document that can be presented to the Environment Agency, Fire Service and other regulators to provide evidence of robust pollution containment. In some circumstances, an insurance underwriter could also be persuaded to discount premiums based on the evidence provided.
Now, you can really say “job done”.
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