A Bund Is Not a Bund Until Somebody Tests It

Secondary containment is one of the few safety measures that is built once and then expected to work for thirty years without anyone looking at it. A bund wall around a fuel tank is poured, signed off, and from that moment treated as a permanent property of the site rather than a control that can quietly stop working.

How containment actually fails

Bunds rarely fail dramatically. They fail through small, reversible things that nobody owns:

• The drain valve left open. Most bunds have a valve to release rainwater. It is opened after a storm and not closed, and the bund becomes a shape in the ground with no capacity at all.
• Rainwater occupying the volume. Containment is sized for the tank, not for the tank plus a season of standing water.
• Penetrations. Pipework, cable ducts and conduits pass through the wall and the seal around them degrades long before the concrete does.
• Stored items. Drums, pallets and a spare pump placed inside the bund consume the volume that exists to hold a spill.
• Surface deterioration. Fuel-degraded render, hairline cracking at the floor-to-wall joint, and coatings that were never renewed.

The capacity question nobody asks aloud

Containment is normally sized at the greater of the largest tank's volume or a proportion of the total where several tanks share a bund. Sites add a second tank inside an existing bund far more often than they recalculate the volume. If a tank was added after the bund was built, the arithmetic needs redoing, and it is rarely in anyone's job description.

What an inspection should produce

A containment inspection is not a glance from the gate. It should record measured capacity against current contents, the condition of the floor, walls and joints, the state of every penetration, whether the drain valve is closed and lockable, and what happens to displaced rainwater. It should end with a photograph of the valve.

A spill that stays inside a bund is an operational inconvenience. The same spill reaching ground or a watercourse becomes a regulatory matter, a remediation bill and a conversation with your insurer — and the difference between the two is often one open valve.