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Supporting ISO14001 COMPLIANCE
If you store hazardous liquids at your site, bunding is a legal requirement. And yet, bunding failures remain one of the most common reasons businesses find themselves non-compliant, facing Environment Agency enforcement action, or dealing with a containment incident that could have been avoided.
What is bunded storage? In simple terms, it’s a secondary containment system, typically a wall, tray, or enclosure, surrounding a primary storage container. Its job is to catch any leaks, spills, or overflows before they reach drains, soil, or watercourses. The rules governing it in the UK draw on several pieces of legislation, including the Control of Pollution (Oil Storage) Regulations 2001, COSHH, and HSE guidance, including HS(G)71 and HS(G)176. The bottom line is that if you’re storing hazardous chemicals, your bunding needs to work correctly and be properly maintained.
Here are five of the most common mistakes that put businesses in breach of chemical storage room requirements, and what to do about each one.
Getting the maths wrong on bund capacity is more common than you’d think, and it’s one of the most straightforward ways to fall foul of hazardous chemical storage requirements.
According to the HSE, bunds should have a capacity of at least 110% of the largest container or 25% of the total volume of all containers, whichever is greater. That means if you’re storing a 1,000-litre tank, your bund must hold a minimum of 1,100 litres.
Where businesses go wrong is by calculating based on the volume they typically use rather than the maximum storage capacity, or by failing to account for all containers within the bund. If you’ve added containers since the bund was originally sized, it may no longer meet the legal minimum.
A bund is only as good as its physical condition. Cracked walls, deteriorating joints, or degraded base surfaces can all compromise containment, turning what looks like a compliant installation into one that’ll fail the moment it’s needed most.
Bund materials need to be compatible with the chemicals being stored. Polypropylene and LDPE work well for most chemical applications, but some aggressive solvents or acids can degrade certain materials over time.
Visual inspections should be built into your maintenance schedule. Look for hairline cracks, signs of chemical staining or corrosion, and any pooling around the base that might suggest the seal is compromised. Don’t assume that because a bund was compliant when installed that it’s still compliant today.
This one’s surprisingly common in busy warehouses and workshops: the bunded area gradually accumulates non-hazardous items because it’s a convenient space. Pallets, empty drums, tools, and other equipment all get stored inside the bund until there’s barely room for the hazardous containers it was designed to protect.
The problem is straightforward. Every non-liquid item taking up space inside the bund is reducing its available containment capacity. If a spill or leak occurs, the liquid has less room to collect, and if the volume exceeds what’s left, containment fails. This directly undermines what bunded storage is designed to achieve, and it’s a breach of hazardous chemical storage requirements.
Bunds can collect rainwater, especially in outdoor storage areas, but this water should not simply be released through open drainage valves or outlets. By the time it has accumulated in the bund, it may be contaminated by residues, leaks or small spills from the stored containers.
Leaving a valve or drain open effectively removes the bund’s ability to contain a spill. Any escaped liquid can pass straight through the containment area and into the wider site drainage system or environment. Instead, accumulated water should usually be removed safely, often by being sucked out and disposed of appropriately, depending on the level and type of contamination.
Open outlets, unsealed drains or poorly managed bund water are easy issues for inspectors to identify. Where hazardous liquids are stored, bunded areas should be checked regularly to make sure they remain intact, closed and capable of containing a spill.
The HSE and Environment Agency both expect businesses to demonstrate that their hazardous chemical storage requirements are being actively managed, not just installed and forgotten. That means written inspection logs, records of any defects identified and what was done about them, and evidence that checks are taking place at regular, defined intervals.
A simple inspection checklist covering bund capacity, wall and base integrity, valve status, drainage condition, and general housekeeping will cover most bases. It doesn’t need to be complicated, but it does need to exist and to be completed consistently.
Meeting hazardous chemical storage requirements isn’t a one-time task. Storage arrangements change, containers are added or swapped, and bunds age. What was compliant three years ago may not be now.
If you’re not confident that your bunding is up to scratch, getting an independent eye on it before an incident or inspection is far preferable to finding out the hard way. Get in touch with a member of our team and we’ll talk you through what compliant bunded storage looks like for your site.
We want our customers to understand the spill hazards on site and the solutions to resolve these hazards, protecting people and the environment. Our spill survey highlights spill potential on site, and options to mitigate any risks posed by liquid use, storage or transportation
