Most sites storing hazardous chemicals have containment of some sort. A bund was built when the tank went in, there is a drain valve somewhere, and the arrangement has never been formally assessed against current guidance. It usually holds. The question an inspector will ask is whether you can demonstrate that it holds, for the chemicals you actually store now, in the volumes you actually store them.

CIRIA C736 is the recognised UK industry guidance on containment of hazardous chemicals at industrial and process sites. We assess existing containment against it, design and upgrade the arrangements that fall short, and produce the documentation that lets you show the Environment Agency, the HSE, an insurer or an auditor where you stand.

What the work involves

The starting point is what is actually there. We survey the existing secondary containment across the site, including bunds, sumps, tanks and drainage, and assess it against the substances being stored and the volumes involved. That includes the compatibility of construction materials with the chemicals in question, which is a common gap on sites where the stored product has changed since the bund was poured.

Where containment falls short we design the upgrade. That covers capacity, permeability and resistance of the containment structure, lining systems where they are needed, and the drainage and isolation arrangement: valve control, bund emptying procedure, and separation of clean water from potentially contaminated water. It also covers the practical side that gets forgotten at design stage, namely whether anyone can safely get in to inspect and clean the thing once it is built.

The work is coordinated across process, mechanical and civil disciplines in-house, because containment is one of those problems that sits between them. A bund designed without reference to the process is either an obstruction or an expensive box that does not suit the duty.

How it connects to your other obligations

Containment rarely sits on its own. The same substances that drive a containment assessment usually appear in your DSEAR assessment, your hazardous area classification and, on larger inventories, your COMAH safety report. Environmental permitting adds a further set of expectations about what leaves the site and under what circumstances.

Treating these as separate exercises produces four documents that disagree with each other, which is worse than having one. We work from a single view of what is stored, where, and in what quantity, so that the containment case, the DSEAR assessment and the zoning are built on the same inventory rather than three different snapshots taken in different years.

What you get

  • A survey and assessment of existing containment measured against CIRIA C736
  • Capacity and compatibility assessments for the substances actually stored on site
  • Bund sizing calculations and lining or material specifications where an upgrade is needed
  • Design of drainage, isolation and bund emptying arrangements, including clean and contaminated water separation
  • Access and maintenance provision designed in, so inspection and cleaning can be done safely
  • Civil and structural design of containment features, produced in-house
  • Risk assessments and supporting documentation demonstrating the compliance position
  • Reports, drawings and validation evidence suitable for regulators, insurers and auditors

When clients typically call us

  • An Environment Agency or HSE visit has raised the state of secondary containment
  • The chemicals stored in an existing bund have changed and compatibility has never been checked
  • A new tank, storage area or chemical is being introduced and containment needs designing
  • An environmental permit application or review requires evidence of containment adequacy
  • A spill, overflow or near miss has exposed a gap in the drainage or isolation arrangement
  • Nobody can produce a calculation showing the bund is sized for the inventory it serves

Frequently asked questions

Is CIRIA C736 a legal requirement?

It is guidance rather than legislation. The legal duties sit elsewhere, in environmental permitting, COMAH and general health and safety law. What C736 provides is the recognised benchmark for how those duties are met in practice, which is why regulators and insurers work to it and why demonstrating compliance with it is the practical route to demonstrating you have done enough.

Our bund was signed off when it was built. Is that not sufficient?

Only if nothing has changed. The common failure is not a bund that was built badly but one that was built for a different chemical, a smaller inventory or a different tank arrangement. Containment that is not reassessed under change control gradually stops matching the site it protects.

Can you do the assessment without shutting anything down?

In most cases yes. Survey and assessment work is largely non-intrusive. Where an upgrade is needed we plan the construction around your operations, and we design for a live site rather than assuming a clear field.

Do you carry out the inspection work as well?

Yes. Containment condition assessment is part of our vessel and containment inspection service, and the two are usually done together on an existing site.

Related: Part of our engineering consultancy services. See also vessel and containment inspection, DSEAR assessments and civil and structural design.

If your containment has not been assessed against current guidance, or the chemicals in it have changed since it was built, we can tell you where you stand and what it takes to close the gap. Talk to us about your site. Request a call