Heating Oil Tanks: Environmental Risk Assessment

Photograph of Carbery, Diamond and Bunded Oil Tanks on an orange background

Heating Oil Tanks: Single Skin Tank Environmental Risk Assessment

Before installing a Single Skin Heating Oil Tank, a Risk Assessment must first be completed by your Oil Tank Installer to determine whether or not a Bunded Tank is instead required.

What is a Bunded Tank?

A Bunded Tank consists of a ‘tank within a tank’. The inner tank is the primary storage container, whilst the outer tank has a volume equivalent to at least 110% of the capacity of the inner tank. It’s designed to act as a failsafe in the event of a spill. Bunded Tanks are a requirement at most Heating Oil storage installations in the UK, Republic of Ireland, Channel Islands and Isle of Man today.

How do I know whether I need a Bunded Oil Tank?

From an environmental perspective, the Risk Assessment will consider whether any spill from the tank could pose a threat to the environment. It asks a series of questions, to determine whether it’s permissible to install a Single Skin Tank or whether a Bunded Heating Oil Tank should instead be installed. Your Storage Tank Installer will frequently complete an Environmental Risk Assessment at the same time as a Fire Safety Risk Assessment.

A typical Environmental Risk Assessment is shown below. If the answer to any of the questions is ‘Yes’, ‘Maybe’, ‘Possibly’, ‘Probably Not’ or ‘Unsure’, then a bunded tank must be fitted. However, if the answer to every question is a definite ‘No’, then in some, very limited circumstances, it may still be possible to fit a Single-Skin Tank.

  • Is the total installed storage capacity on-site greater than 2,500 litres?
  • Will the Oil Tank be positioned within 10 metres of controlled water?
  • In the event of a spill from the tank, could fuel enter a drain or unsealed manhole cover?
  • Is the Oil Tank located within 50 metres of a well, borehole or spring
  • Will the Oil Tank be positioned over hard or hard surfaced ground that would allow a spill to reach controlled water?
  • Is the Oil Tank located in a position where the vent pipe is not visible from the fill point?
  • Will the Oil Tank be supplying fuel to a building other than a dwelling occupied by a single family?
  • Is the Oil Tank located in a Groundwater Special Protection Zone?
  • Are there any other site-specific risk or hazard, including but not limited to ditches (whether wet or dry), septic tanks, effluent treatment systems, soakaways and gullies?

At most installations in Ireland and Great Britain today, a Bunded Tank is now mandatory. If you're fitting a Single Skin Heating Oil Tank, in many instances you're almost certainly fitting the wrong tank. 

Can I complete a Risk Assessment myself?

No. Any risk assessment should only be completed by a competent and professionally trained fuel storage tank technician, such as a technician registered with The Oil Firing Technical Association (OFTEC). The Risk Assessment must be recorded and retained. To find your nearest OFTEC Registered Technician, visit the OFTEC website.

What is Controlled Water?

‘Controlled Water’ features prominently in most risk assessments. It’s a term used to describe streams, lakes, loughs, lochs, ponds, canals, coastal waters, estuaries and groundwater. It refers too, to all water which is below the surface of the ground in the saturation zone and in direct contact with the ground or subsoil.

Regional Variations

As well as the output of the risk assessment, regional variations also need to be considered. These may mandate the installation of a bunded oil tank, even if elsewhere a single skin oil tank might be permissible. As an example and since 15th. March, 2016, when the Control of Pollution (Oil Storage) (Wales) Regulations 2016 came into effect, virtually all new and replacement aboveground heating oil tanks installed in Wales must now be bunded.

Don’t forget to read the small print…

Some manufacturers of Single-Skin Oil Tanks also now specify their products are suitable for installation only within a suitably bunded area. Install the tank outside a bunded area and you’re installing the wrong tank, in the wrong place and using it for a purpose for which it was neither designed nor supplied. It will almost certainly void any product warranty and may also invalidate your home insurance. Be sure to read any small print associated with Single Skin Tanks very carefully.

Queries? Questions?

If you’ve any queries or questions, why not contact us? You can call us in the UK, Channel Islands and Isle of Man on 01789 632 151, on 01 5268 642 in the Republic of Ireland or e-mail hello@fueltank.store. We’re open from 9am to 5pm weekdays and our friendly, helpful team are on hand to answer your questions and queries.

Photograph of Carbery, Diamond and Harlequin Oil Tank on an orange background