Posted By Graham Bullough From experience of schools which have changed their heating boiler fuel from oil (fairly similar to vehicle diesel and sometimes known as "red diesel")to gas, there is no requirement to get any formal decommissioning certificate if the tanks are just being left nominally empty. Presumably the smell is only in the tank room/enclosure and the vicinity of the filling point. Just keep the tank room/compartment locked to exclude unauthorised people. Like paraffin and vehicle diesel, heating oil is flammable but not highly flammable and therefore does not give off a readily ignitable vapour under normal conditions - unless you heat it first! This leads to the question of whether anyone plans to have the tanks removed to create extra storage space in the basement. Unless the tank compartment can be opened up to enable the tanks to be dragged out complete (after simple unscrewing of pipe connections) and taken away on lorries, the tanks will need to be cut up in situ. This requires thorough cleaning (de-gassing) of the tanks by a specialist contractor to remove all fuel residues from inside - otherwise if heat is applied by hot cutting, the residues will rapidly emit an ignitable vapour which will also be ignited by the heat. As the igniting vapour is effectively enclosed within the tank, it will explode like a bomb and. (diesel engines are also started by the application of heat, but in a controlled way with a small amount of fuel in a chamber which is strong enough to contain the explosive energy which is harnessed to move the vehicle.) There's plenty of info. available from HSE, etc. about precautions for work on tanks. I've no time at present to look for and name some appropriate publications, but other respondents will probably be able to help in this respect.

Posted By Kevin West Annetta, For the legal requirements/best practice for the decommissioning of oil tanks I would recommend you look in the following publications:- Health and Safety Executives's HSG176: The storage of flammable liquids in Tanks, 1998 (ISBN 07176 1470 0) Appendix 2 of the Health and Safety Commission's Proposal for the Dangerous Substances and Explosive Atmosphere Regulations. Health and Safety Executive's guidance note CS15: The cleaning and Freeing of Tanks containing Flammable Residues (ISBN 07176 1365 8) Should you require any further advice concerning the decommissioning of oil tanks particularly in the situation yopu describe please contact me directly.