Bunding
[2] If built properly, bunding is large enough and strong enough to contain the contents of an entire tank, though regulations may require it to be up to a third larger.
Large, exposed bunding will need a sump pump or some other system to remove precipitation, though it may also be used to transfer spilled liquid into another container.
[4] The bund may have a roof to prevent precipitation from getting in, but steps must be taken to provide adequate ventilation when storing flammable liquids.
[5] When the risk of tank failure is not as likely or when it would not cause extensive damage, the bunding may be designed to merely contain small leaks from hoses and valves.
[citation needed] Bunding is a legal requirement in many countries, particularly around tanks, storage vessels and other plants that contain liquids which may be dangerous or hazardous to the environment.
In addition, further guidelines in some countries (e.g. the UK) recommend additional measures such as providing sufficient "freeboard" or height of wall above the maximum holding capacity to accommodate dynamic factors such as a surge in situations of major tank failure or storm-driven waves in larger bunds.
Unlike ordinary fuel storage tanks, these are complex structures, with a higher propensity for leakage of the oil.
[citation needed] Most area and national companies realised that they had several thousand transformers, many of which had been leaking into the ground below them for many years.
[citation needed] The companies embarked on an upgrading programme involving the construction of "water-tight" bunds to retain any oil leakage and to prevent further pollution and contamination.
However, in the UK at least, the latest regulations[10] require some formal method to be put in place for the removal of the rainwater.
[12] Allegedly bunds can be used to hold rainwater in lightly sloping plains that have lost vegetation due to drought and overgrazing.
According to this theory, semi-circular bunds will hold the rainwater giving it time to penetrate the soil and rehydrate the seeds in the ground.
A polypropylene tank holding about 30 tonnes of 40% aqueous caustic soda sprang a leak about halfway down the main wall.
[citation needed] The corrosive fluid jetted out over the bund wall, causing great damage to the surrounding factory and adjacent premises.
[14] Bunded containment is generally not designed for tank boilover, because this would require to cover an enormous footprint, as clearly demonstrated by accidents such as the Tacoa disaster.
[15] Bunds will deteriorate over time (e.g. cracks may develop in concrete walls or reinforcement bars may corrode) or suffer damage (e.g. vehicle strikes) or modifications may have been made.
The definition of a competent person may be defined in the permit but is generally considered to refer to a Chartered Engineer with appropriate experience [1] Where there is doubt as to the integrity, then the visual inspection may be supplemented by a low-level hydrostatic test.
