Step by Step Guide for Inspection of Spill Containment Bunds

What is a Spill Containment Bund?

A spill containment bund is a secondary containment system meant to collect any leaks or spills from a primary containment system, such as a storage tank. A spill containment bund consists of an impermeable bottom and impermeable walls to create a watertight region surrounding a storage tank. Any liquid that escapes the primary containment is contained in the bund and prevented from leaking onto the site or escaping into the environment. 

Inspection of Spill Containment Bunds

Inspection and maintenance of spill containment bunds is a crucial but frequently neglected aspect, especially in remote locations. To ensure the bund's integrity, a system of inspection should be in place. This can be achieved through a combination of regular visual inspections, formal detailed structural inspections, and water fill testing. Water fill testing is the primary method to test the integrity of spill containment bunds. 

Following these steps will allow you to inspect spill containment bunds correctly by water fill test.

1. The spill containment bund should be inspected for obvious signs of damage or cracking prior to initiating the water fill test.
2. Ideally, new spill containment bunds should be tested before installing any tanks or other equipment.
3. If tanks have already been installed, they must be securely bolted down to prevent floating during the test.
4. Any sensitive equipment inside the spill containment bund which may be damaged by being submerged should be removed.
5. Consideration should be given to damage to any thermal insulation which becomes submerged.
6. Ideally, the spill containment bund should be filled to the brim during the test. If this is not practical due to the location of sensitive equipment which cannot be removed, the bund should be filled to the highest practical level.
7. For the test period, the tank(s) within the spill containment bund must either be emptied or, as a minimum, all transfers to and from the tank(s) suspended.
8. Provision should be made for the safe release/removal of water from the bund on completion of the test.
9. A permit to work should be obtained for the test, and suitable safety precautions implemented, e.g., cordoning off the area and cessation of liquid transfers.
10. Testing should not be carried out during wet or icy weather.
11. Personnel must be in attendance at all times during the test.
12. The spill containment bund should be visually monitored during the fill to detect any gross leakage or signs of developing cracks or distortion. If any of these are observed, the test should be immediately abandoned and the water drained.
13. Once filled to the test level, the spill containment bund should be externally examined for water leakage, and the location of any leak points should be noted.
14. A suitable hold period should be used to detect any loss of water level due to gross leakage through the base.
15. Once the test is complete, the test water should be drained in a safe and controlled manner.
16. A final internal inspection of the spill containment bund should be carried out after the test water has been drained.
17. The spill containment bund and associated equipment should be returned to normal condition, including the bund drain valves.