Before the effective disappearance of responsible British coal mining there was a Research Station at Bretby which published numerous articles on gaseous products from coal piles. You might be able to trace them through the British Library, British Council or the British Standards Institute. Serious luck.■

My only serious issue was where the methane from the inside of a dougnut pile would descend through the yard hopper and settle at the base of the reclaim tunnel. It is a similar issue with emergency reclaim hoppers and it is never recognised by designers. I once had a Chief Draughtsman of a once large UK Contractor who proudly boasted that he had never been underground even though he was presenting designs for extensive coal handling and storage. Neeedless to say his designs were easily rejected.

If you validly mention methane build up, in writing, before a Health and Safety official you will get all the support you need. ■