F. G. Bell

Environmental impacts associated with an abandoned mine in the Witbank Coalfield, South Africa

Abstract Mining at Middelburg Colliery in the Witbank Coalfield commenced at the turn of the last century. Initially, there was little environmental degradation associated with mining activities; however, in the late 1930s, a pillar-robbing programme commenced. This has had a marked effect on the environment. Some of the most notable primary effects include subsidence, the appearance of tension cracks at the surface and crownhole development. Secondary effects include spontaneous combustion of the coal worked, as air has been provided with ready access to the mine, accelerated subsidence due to the strength of many pillars being reduced by burning, and a marked deterioration of groundwater quality in the area due to the seepage of acid mine drainage from the mine. Spoil heaps also form blemishes on the landscape. These contain significant amounts of coal and have undergone spontaneous combustion. The deterioration in the quality of water has led to the decimation of vegetation in some areas and the eradication of aquatic flora and fauna in a nearby stream.

A survey of contaminated ground with illustrative case histories

Contaminated ground represents a problem in all the industrialized countries of the world. Contaminated ground may give rise to hazards and that implies a degree of risk which also involves a problem of definition. The investigation of a site which is suspected of being contaminated differs somewhat from a routine site investigation. Sampling of soils, groundwater and gas producing material may be required. Various precautions may be necessary in doing this and operatives may have to wear protective clothing. The first case history considered involves a site investigation for a relief sewer in Glasgow, Scotland. As the site investigation progressed it ran into made-ground which contained chemical waste. The presence of this waste meant that the nature of the investigation changed and much more stringent safety precautions had to be taken. It also meant that the initial location of the sewer tunnel had to be repositioned at greater depth in uncontaminated sandstone rather than in the superficial deposits above. Two further case histories associated with coal mining in the Ruhr district of Germany are included. The methods involved in investigating these two sites are described, as is their rehabilitation. Copyright