A bund wall is a special type of retaining wall, specifically used with the storage of substances that are potentially harmful to the environment/atmosphere. Bund walls can be made to various different specifications, depending on the requirements of the company. Because bund wall construction involves hazardous materials, it is essential that the company undertaking the project is experienced and understands what is at stake. That means making the correct calculations and carrying out appropriate testing to ensure safety standards are met. It is crucial that the bund wall stops the held material from escaping.
At an industrial scale, large companies who use large amounts of liquid, whether chemical or neutral, need to keep said liquid stored. Huge tanks are needed to contain these liquids, but of course there is an ever-present danger of tanks failing. Whether this is due to poor workmanship, an accident (such as a collision), or simply failure due to stresses over time, hazardous substances need to be contained to prevent excessive damage. This is where a bund wall comes in. They typically surround clusters of storage tanks so that in the event of catastrophic failure, any harmful substances are contained within the bund wall.
Bunding should be designed to hold an entire tank’s worth, but are often made to be slightly larger, for added security. They should have the strength to match. Where bunding is shared by more than one tank, the bund should be designed in relation to the contents of the largest tank. Most typically, bund walls are made from concrete, both the wall itself and the floor. This is a situation where the poor drainage qualities of concrete are very useful. Assuming it has been constructed properly, the bunding should be completely impermeable, making it an excellent material.
Smaller tanks require smaller bund walls, naturally, which can often be made of plastic or steel. Material selection depends on a number of factors, from the type of substance and the cost involved.
Rainwater and the Elements
This is one of the main reasons why bund walls are often built to contain more liquid than the largest tank. Rainwater will of course start to fill the space which poses a problem. Systems can be installed to help remove the build-up of water which otherwise wouldn’t be able to drain. Alternatively, some sort of roof can be installed to stop rain from getting in in the first place, but this is not always suitable. For example, if the hazardous liquid is flammable, a roof may prevent it from receiving adequate ventilation.
Depending on what’s required, a bund wall can be very large. Regardless of whether the liquid contained is hazardous or not, bund wall failure can cause extensive damage. In order to avoid failures occurring, testing at regular intervals is required. Small cracks quickly develop into leaks if not dealt with quickly. Regulations dictate how often your bund wall needs assessing. Mostly, it’ll be required that a bund wall is assessed annually, but this is simply a rough benchmark and depends on the type of site and what’s involved.
The most common test involved is simply a visual inspection. Of course, this requires a qualified engineer to know what to look for. The most common structural issues occur where the walls join together and where they join with the floor. Cracks and defects that can potentially lead to leaks need to be identified before they have a chance to develop.
Another bund integrity testing could be a Hydrostatic test which involves filling the bund with water, up to the capacity it is designed to hold. The water is left for some time to check how much water gets absorbed by the walls, or if any water permeates into cracks. Then the test itself is carried out, assessed and said water is disposed of. This is a great way to analyse a bund wall’s integrity.
Of course, for new bunds, they need to be tested before being put to use. This typically happens on the site they’re constructed. If successful, they are given a test certificate and can be taken to be installed.
Particularly for very large containers, it is imperative that bund wall construction is given the appropriate care and consideration from the design process through to installation. Make sure you choose a company who has experience with construction and installation of bund walls. KDS Construction have installed a number of bund walls over the years and are fully licensed and comply with regulations. Experience counts for a lot when it comes to dealing with hazardous chemicals, so don’t take any chances! If you’d like to talk to us about your requirements, get in touch today.
B5 Taylors Cl, Parkgate,
Tel: 01709 845765