A concrete bund is an enclosure that surrounds tanks to provide secondary containment in the event of a tank leak or spill. They are a common requirement on sites with large amounts of hazardous liquid storage, such as COMAH sites or oil storage facilities. Bunds are also sometimes required for other equipment such as pumps, heat exchangers and filters. In many cases the bund walls are constructed of concrete and a floor is laid, but in some instances other materials such as geotubes can be used.

The most important aspect of any bund is the design, sizing and construction. In general a bund should be sized to hold 110% of the largest tank volume or 25% of total site capacity, whichever is greater.

Exploring Concrete Bunds: Features and Applications

Wall heights of bunds can vary, but typically they are built to a maximum of 1.5 meters. Taller walls increase the capacity of a bund and help to protect against the ‘spigot flow’ effect (where a tank fails and liquid passes over the wall into the bund) or the ‘tidal wave’ effect that can occur during a catastrophic tank failure. However, high walls can restrict access and ventilation of a bund and are not always suitable where flammable chemicals are stored.

All bunds should be regularly inspected, with a system in place for the detection of minor problems such as cracking or leakage. In addition, it is usual to install a system for the draining of rainwater to prevent flooding or water immersion of tanks and other equipment. This is normally achieved by incorporating a drain at the lowest point of a sloping floor with a manual valve, normally kept closed. Operating schedules should include daily opening of the valve to remove accumulated rainwater, which will also aid in the identification of minor leaks.