Mining subsidence and its effect on the environment: some differing examples

The impact of mining subsidence on the environment can occasionally be very catastrophic, destroying property and even leading to the loss of life. Us ually, however, such subsidence gives rise to varying degrees of structural damage that can range from slight to very severe. Different types of miner al deposits have been mined in different ways and this determines the natur e of the associated subsidence. Some mining methods result in contemporaneo us subsidence whereas, with others, subsidence A number of different minera l deposits have been chosen to illustrate the different types of associated subsidence that result and the problems that arise. The examples provided are gold mining in the Johannesburg area; bord and pillar mining of coal in the Witbank Coalfield, South Africa; long-wall mining of coal in the Ruhr district; mining of chalk and limestone in Suffolk and the West Midlands, r espectively; and solution mining of salt in Cheshire. These mineral deposit s have often been worked for more than 100 years and, therefore, a major pr oblem results from abandoned mines, especially those at shallow depth, the presence of which is unrecorded. Abandoned mines at shallow depth can repre sent a serious problem in areas that are being developed or redevdoped. Abs traction of natural brine has given rise to subsidence with its own particu lar problems and cannot be predicted. Although such abstraction is now inco nsequential in Cheshire, dereliction associated with past subsidence still remains.