A bunded tank is essentially a tank within a tank, the idea being that if the oil tank is overfilled or splits, the oil that escapes, as a result, will be contained within the outer skin rather than spilling onto the ground and finding it’s way into the water courses. Once it gets into water or drains, the oil will leave your property and be widely dispersed, invariably leading to contamination and resulting in clean up charges which it is likely you will be liable for. The Environment Agency investigate this sort of situation very thoroughly and will trace the oil loss back to its source. In order to avoid all this, regulations have been put in place with regard to the storage of your oil.
Although in some parts of the UK – such as Scotland, Wales and the Channel Islands, bunded tanks are already the only permitted way of storing fuel. You should seek advice based upon your individual location before looking any further as it is likely that at some stage this requirement will be made compulsory for everyone.
Any oil tank in a domestic situation which has a capacity of more than 2500 litres has to be bunded regardless of location so as to minimise any potential oil loss.
A tank of any size will need to be bunded if, when filling, the delivery man is not able to see the vent pipe from the fill point. This is known as a “blind fill” and as it is far from ideal, this is designed to make a fuel delivery as safe as possible.
Remember, the whole idea is to avoid fuel getting into the watercourses and so if your tank is within 50m of a well, borehole or spring or if it is less than 10m from “controlled water” – typically a ditch, soakaway, stream, river or even a septic tank, it must be bunded. This is not negotiable.
Common sense is the order of the day and so generally you need to be considering whether any fuel from your tank could get where it shouldn’t in the event of an accident. Your tank may be 20m from a stream but if it is on concrete and the concrete slopes downhill to the water, the oil will have no-one else to go especially in the event of a dramatic split or if it is raining hard. It would not, therefore, be sensible in this scenario to try to persuade anyone that a single skinned tank is acceptable.
Imagine a scenario where you have lost 1000 litres of oil; it has gone down the drain and been tracked back to you. You need to be able to show that you did the maximum possible within the regulations to avoid a contamination issue caused by your stored heating oil. If you can demonstrate this, you will be looked on more with more sympathy by the bodies who police these matters and it could go some way to mitigating heavy fines for negligence.
If none of this concerns you, it is also worth considering that single skinned tanks tend to be warrantied for only 2-years these days whilst the manufacturers are happy to guarantee the bunded models for 10-years.
This is notifiable work and needs to be signed off by your installer as such or during a visit from Building Control. If you do not do this, you will not have the required paperwork in place if you try to sell your house.
If in any doubt, check with an OFTEC engineer who will advise whether you can still put in a single skinned tank - but the bottom line is that if you install a bunded tank, you cannot be wrong.