Bunded Tanks FAQ

What is a Bunded Tank?
A bunded tank is quite simply a tank within a tank. The outer tank has the ability to hold 110% of the volume of the inner tank, so if the worst does happen and the tank is pierced or overfilled then the leaked product will all be contained in the outer tank. A single skin tank consists of a single rotationally moulded container, in which fuel is stored. Single Skin Tanks are suitable for most installations at single family dwellings in the United Kingdom – unless the installation is situated within an environmentally sensitive area. To determine whether or not the site can be described as environmentally sensitive, it is recommended that a Risk Assessment is undertaken prior to tank installation. In anticipation of possible future environmental legislation, consideration should be given to fitting a bunded tank – even where a single skin tank will currently suffice.

How close to a boundary can I place an oil storage tank?
If the tank is less than 3400 litres, it can be placed within 760mm of a boundary. This distance assumes that there are no flu outlets or buildings between the tank and the boundary. Where these clearances cannot be achieved, the protection measures noted in British Standard BS 5410 : Part 1 : 1997 must be provided by means of a 30 minutes fire-resistant wall which extends at least 300mm above and beyond the ends of the tank. For tanks with a capacity greater than 3400 litres, please contact OFTEC for advice.

How close to a building can I located an oil storage tank?
Tanks with a capacity not exceeding 3400 litres should not be fitted any closer than 1.8 metres to a building. Where these clearances cannot be achieved, the protection measures noted in BS 5410 : Part 1 : 1997 must be provided by means of a 30 minutes fire-resistant wall which extends at least 300mm above and beyond the ends of the tank. It will be necessary to protect exposed eaves forming part of a roof within 1.8 metres of the top of an oil storage tank to provide a 30 minute resistance to fire. Cladding should be applied to the eaves in order to prevent fire spreading to the roof. If the tank capacity is greater than 3400 litres, please contact OFTEC.

What are the Building Regulations?
Both Oil Storage Regulations and Building Regulations apply to domestic storage. Oil Storage Regulations state that if you are storing below 3500 litres you are exempt. If you are considering storing more than 3500 litres any new installation must be bunded. For existing installations all commercial tanks must comply by sept 2005. All new domestic installations must comply now and agricultural tanks over 1500ltr must have been bunded since 1991. Building Regulations state that if you are installing a new tank or changing an old one, any tank with a capacity of more than 2500 litre's MUST be bunded. However, tanks with less than 2500 litre capacity must be bunded if the tank is:-
- Within 10 metres of controlled water
- Located where spillage could run into an open drain or to a loose manhole cover
- Within 50 metres of a borehole or spring
- Over hard ground or hard surface ground that could enable spillage run-off to reach controlled water
- Located in a position where the vent pipe outlet is not visible from the fill point
- Supplying heating oil to a building other than a single family dwelling

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