‘When Is It Necessary To Fit A Bunded Tank?’ Asks Steve Beech

9th March 2014

One of the most frequent questions we’re asked by heating oil users at Tank Depot UK, is ‘Must I fit a bunded heating oil tank?’

Unfortunately, the answer is neither simple nor straightforward. Instead a risk assessment must first be completed, to ascertain whether a more expensive bunded heating oil tank is required, or whether a less expensive single skin tank will suffice. Any such assessment must obviously be undertaken only by a suitably competent person e.g. an OFTEC Registered Technician, or in England and Wales, an appropriately qualified technician registered with the Association of Plumbing & Heating Contractors (APHC).

For those unfamiliar with storage tank terminology, a bunded heating oil tank simply consists of a tank within a tank. The inner tank is the primary storage container, whilst the outer tank (or ‘bund’), acts as a failsafe. In the event of a spill arising from the inner tank surplus fuel will be safely and securely contained within the bund – and a potential environmental pollution incident will be avoided. By contrast, a single skin tank does not incorporate any secondary containment whatsoever. In the event of a spill and dependent upon where the tank is installed, a pollution incident may result.

The risk assessment to determine whether or not a bunded tank is required, consists of eight questions:

  1. Is the total installed on-site capacity greater than 2,500 litres? It’s important to note the capacity threshold applies to the total on-site storage capacity. So if there will be let’s say a 2,000 litres capacity tank supplying a heating system and a separate 1,000 litres capacity tank supplying an oil-fired stove, the total capacity will be 3,000 litres and both tanks will need to be bunded;
  2. Is the tank within 10 metres of controlled water? Controlled water includes lakes, reservoirs, rivers, streams, the sea, lagoons and even drainage ditches whether or not water is physically present. If it’s not a garden pond and it might have water in it, then it’s almost certainly controlled water;
  3. Is the tank located in a position where a spill could run into an open drain or loose fitting manhole cover? The definition of an open drain includes domestic drains and storm drains. And unless you’re certain that any manhole in close proximity to the tank is sealed, then legally it will almost certainly be defined as ‘loose fitting’. In all such instances, a bunded tank will be required;
  4. Is the tank located within 50 metres of a well, borehole or spring? And additionally, can you be absolutely certain that it isn’t? Fifty metres is a significant distance and not all wells, boreholes and springs are visible. So unless you can be absolutely certain that there are no wells, boreholes or springs within 50 metres… it’s best to be safe and opt for a bunded tank;
  5. Is the tank located over hard ground, which would allow spillage run off to reach controlled water?
  6. Is the tank located in a position where the vent pipe outlet is not visible from the fill point? Such installations include those, which incorporate a remote or offset fill point, as well as many underground oil tank installations too;
  7. Is the tank supplying a building other than a single-family dwelling? Simply put, if the tank supplying fuel to agricultural, commercial, industrial or institutional premises, or premises other than a house occupied by one family, then the tank must be bunded;
  8. Is there any other site specific hazard? Site specific hazards can take many forms. And it’s important to remember in England, all tanks installed within a Groundwater Source Protection Zone 1 must be bunded… no if’s, no buts and no maybes.

If the answer to any of the above questions is ‘Yes’ then ordinarily, a bunded tank must be installed.

However, if you’re on a budget, then it may still be possible to quite legally install a single skin tank. For example, if the tank is within 10 metres of controlled water but not situated where spillage run off could reach control water… then relocating the tank further away from its proposed position, might enable a single skin tank to be installed. Or if the tank is within 50 metres of a well, borehole or spring, then by again repositioning it might be possible to quite legitimately install a single skin tank.

At Tank Depot UK, we always recommend that even if a bunded tank is not legally required, serious consideration should always be given to fitting one. However, we also realise that competent, professional, installers and technicians are ultimately the best people to determine the right tank for any installation. That’s why as well as supplying a wide range of bunded tanks from leading manufacturers including Atlas, Carbery, J Seed and Kingspan Environmental, we also supply a wide range of single skin tanks too.

If you’ve a query on the right tank for the job… feel free to call us for advice on 01332 834 141, e-mail info@tankdepot.co.uk or visit us online.

Important Information: This article was originally published by OilFiredUp Rural Energy News and is reproduced by TankDepot.co.uk with permission.

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Article Last Updated 9th March 2014
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