Mine gas hazards in the surface environment

Abstract

Problems of mine gas issuing at the surface that have been encountered in the North-East coalfield of England are outlined. The gases involved are firedamp (methane), which can be flammable or explosive in certain percentages in air, and blackdamp (sometimes called 'stythe'), which can asphyxiate. The mining term 'blackdamp' describes carbon dioxide-rich and oxygen-deficient air and of the two gases is arguably the more dangerous in a surface environment. Carbon monoxide is mentioned for the sake of completeness, although it does not occur naturally. A history of incidents is given from 1950 up to the present time, the majority of which were in the Tyneside area, and the remedial measures that were taken are discussed. The presence of old shafts, unrecorded and undetected, or abandoned shallow mine workings is a common factor in most incidents and the roles played by rising water levels and the 'breathing effect' are considered. Mention is also made of opencast and landfill sites and their possible involvement. Methods of detection and prevention are described and the potential size of the problem is assessed.