Regulations for Bunded Oil Tanks

What is a bunded tank?

A Bunded Oil Tank is simply a tank within a tank. The fuel is stored in the inner tank and the outer tank acts as a failsafe so that in the event of a spillage, excess fuel will collect in the bund. They are a requirement at commercial, industrial and institutional premises.  In some circumstances in domestic situations it is still possible to use a single skin tank.

How do I know if I need a bunded tank?

All non-domestic oil storage tanks over 200 litres need to be bunded.

For domestic premises you need to carry out an oil storage risk assessment (this can be obtained from OFTEC - form TI/133D). In brief a Bund is required in domestic situations if...

• • You are storing over 2500 litres.
  • Your tank is near an open drain or loose fitting manhole.
  • Your tank is within 10m of controlled water such as a river, stream etc.
  • Your tank is located where any spillage could travel over hard ground to reach controlled water.
  • Your tank is located within 50m of a borehole, spring or well.
  • Your tank vent is not visible from the fill point. (Such as an extended fill point)
  • Your oil use is for a building other than a single family dwelling.
  • Any other unique hazards to your site.
  • Please refer to the Oftec information guide: https://www.oftec.co.uk/consumers/off-gas-grid-guides/home-guide-to-domestic-liquid-fuel-storage-up-to-3500-litres

How close to a boundary can I put my oil tank?

If the oil tank has a nominal capacity of less than 3,500 litres, it should not be placed any closer than 760mm to a boundary. This assumes that there are no flue outlets or buildings between the tank and the boundary. Where these distances cannot be achieved, the protection measures noted in OFTEC Technical Instruction Book 3 and British Standard BS5410 must be provided by means of a 30-minute fire resistant wall which extends a minimum of 300mm above and beyond the ends of the oil tank. For oil tanks with a nominal capacity of 3,500 litres or greater please contact your local Building Control Officer or OFTEC.

How close to a Building can I put my oil tank?

Oil tanks with a nominal capacity not exceeding 3,500 litres should not be fitted any closer than 1.8 metres to a non fire-rated (30-minute minimum fire resistance) wall or eaves. Where these clearances cannot be achieved, the measures noted in British Standard BS5410 and OFTEC Technical Instruction Book 3 must be provided i.e. the provision of a 30 minutes (minimum) fire resistant wall which extends at least 300mm above and beyond the ends of the oil tank. It will be necessary to protect exposed eaves forming part of a roof within 1.8 metres of the top of an oil tank to provide a minimum of 30 minutes fire resistance. Cladding can be applied to the eaves in order to prevent fire from spreading to the roof. For oil tanks with a capacity of 3,500 litres or greater, please contact your local Building Control Officer or OFTEC.

What are the base requirements for plastic oil tanks?

All oil tanks must be installed on a flat, level and fire resistant base capable of supporting the weight of the tank when fully laden. If concrete slabs are used they should be a minimum of 50mm thick. The base should extend at least 300mm beyond the widest points of the tank and fully support the base of the tank in its entirety. Piers or pillars are not suitable for this purpose and can cause irreparable damage to the tank.

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