People are often surprised to find out that the most likely environmental damage caused by fire at a waste handling site is not a result of the blaze but the huge quantities of water discharged in a very short time to get the fire under control.
Waste and recycling sites are currently under obligation to reassess their fire accident plans, but could be overlooking the potential impact of the millions of litres of water likely to be discharged to fight a major fire.
Following a string of high-profile fires at waste handling premises last year, the Environment Agency (EA) has revised its technical guidance for sites storing combustible waste, instructing them to review their fire accident planning with a ‘must’ action to meet the standards.
As part of this, operators should review whether their sites are able to safely contain huge volumes of water. Not only could some sites unknowingly be in danger of causing serious environmental damage through fire water pollution, but there can be crippling fines and costs to pay to put right the damage – and most businesses are unlikely to be insured against the losses.
It is no longer enough for organisations to take a punt that it won’t happen to them. In the early stages of a fire, thousands of litres of water are discharged into the environment every minute. The surface water runoff created will pick up pollutants and contaminants from whatever burning or hazardous substances are present. If a site is not fully contained, they will escape into the local environment.
The 2013 fire at Jayplas in Smethwick needed 14 million litres of water simply to contain it, equivalent to six Olympic swimming pools, according to the West Midlands Fire Service. After the Buncefield disaster in 2005, the Health and Safety Executive found that the protective bunding had many flaws that caused large volumes of fuel, foam and fire-fighting water to leak out of the contained area.
The site’s last line of water pollution defence – so-called tertiary containment – was practically non-existent, amounting only to surface drainage systems which were not designed to cope with any large-scale releases.
The EA’s revised technical guidance includes a requirement to demonstrate the containment facilities and pollution prevention equipment in place for managing fire water. For this, operators are referred to another important industry guidance document: CIRIA C736 – Containment Systems for the Prevention of Pollution. CIRIA C736 was significantly revised in the light of lessons learned, particularly from Buncefield. The Waste Industry Safety and Health Forum has also issued helpful industry guidance: Reducing Fire Risk at Waste Management Sites.
To provide water pollution containment, most companies begin by installing isolation valves in the outlets to surface water drainage to prevent water escaping from the site, and then contain it until it can be safely removed and tankered away. In addition, bunds or physical barriers can sometimes be constructed, especially around hazardous areas.
Hydro International recommends using drop seal valve technology, which provides a watertight, failsafe solution that is already installed at more than 150 sites across the UK. The latest version is called the Hydro‑Brake Isolator pollution containment valve.
On more complex sites, operators will still need to be sure that, even with valves installed, in the case of a fire, the surface water drainage will not back up, overtop the bunds and storage measures and flow out of the site into the surrounding environment.
Hydraulic modelling techniques are a valuable way of mapping the surface water pathways on and off a site, then they can test and prove any valves, bunds or temporary storage measures that are proposed. A solution can be designed and constructed in the safe knowledge that any potential incident will be fully contained.
Phil Collins is national water pollution sales manager at Hydro International, a technology provider for the control and treatment of stormwater and wastewater
Image - Supplied by Hertfordshire Fire and Rescue Service