Underground oil storage

From the perspective of a domestic oil user, the thought of being able to hide their heating oil tank underground can seem an attractive option. However, digging a little deeper into the standards for installation and oil delivery could be enough for your customer to reconsider such a solution.

In the last 12 months, OFTEC has noted that owners of new and existing underground oil storage tanks are continuing to experience difficulties in obtaining oil deliveries. OFTEC is aware that a prominent independent oil distributor in the UK made a change to their delivery standards in late 2012, which prescribed a need for underground oil tanks to be accompanied by a report from an OFTEC registered technician, confirming the tank’s condition prior to a delivery of oil taking place.

The delivery procedure highlighted findings of Environment Agency research that showed that a large percentage of groundwater pollution incidents originated from the failure of underground oil storage tanks. Whilst OFTEC supports a move for increased vigilance when it comes to underground tanks, the inspection of underground tanks should only be undertaken by someone with specialist knowledge of the equipment they are inspecting and the appropriate equipment to safely perform the work.

OFTEC has pointed this out to the distributor concerned and requested that reference to the use of OFTEC registered technicians for this work be removed from their delivery standards.

Moving forward, OFTEC advises tank installers considering underground storage options to select above ground solutions where possible. This is consistent with regional building regulations that state that below ground oil storage is not recommended.

In exceptional circumstances where underground tanks are specified, two essential features of the tank design are: 1) that it is of the double skin type (not to be confused with an integrally bunded tank type); and 2) it is provided with an interstitial leak detection monitoring system between the inner tank and outer skin to provide a warning if the inner tank leaks.

Further information can be gained from OFTEC Technical Book 3, section 1.7.3, and Environment Agency publication PPG 27, which can be downloaded here.

OFTEC notes that whilst the document is watermarked “This document is out of date and was withdrawn 14/12/2015”, it should still be applied as best practice in the absence of alternative guidance at this time.

In addition, technicians should advise the prospective owner of an underground tank of the need to contact their local planning office before the installation commences, as planning permission may be required, and to contact their building insurers to enquire whether such an installation would be covered in the event of a pollution incident.