Good evening, I appreciate that there are many questions that you would need to ask in order to answer the following question suitably and sufficiently, however please take it with 'a pinch of salt' as I am just looking for general hazards and methods.

Please can you provide methods/hazards associated to the removal of an underground fuel tank? I would appreciate any advice/guidance on this please.

Many thanks,
Wayne.

I had some experience in this a good few years ago. The work was contracted out but the chosen company did need to be kept an aye on, RAMS wear good but working to them not so.

Foam fill inerting may be a better option if you really have to get the tank out. Nitrogen inerting is another possibility.
I take your talking about an old steel tank (as opposed to modern installations where the tank (steel or GRP) is usually strapped to a concrete base, infilled with pea gravel,with reinforced concrete cover over?

Older tanks are usually encased in concrete or (only ocassionally) installed in brick vaults and it is common that they remain in-situ when installations are abandoned.