Using Ground Penetrating Radar to investigate spoil layers in rehabilitated minesoils

Opencast coal mining on the Highveld of Mpumalanga involves the disturbance of highly productive soils, which must then be rehabilitated on top of the mined spoil. Various problems in this process may occur, however, which may lead to water-logging, compaction and/or decreased soil volume. Ground penetrating radar (GPR) is a useful technique in the characterisation of the rehabilitated soil and in determining the depth contours of the spoil layer. Studies with GPR were conducted at three rehabilitated opencast coal mines. In most cases GPR was able to clearly detect the top of the spoil layer and thus identify the variations in soil depth covering the spoil. Three-dimensional imaging can be achieved by means of a grid system, thereby identifying basins which could cause waterlogging. Advantages in the use of GPR include its capacity for obtaining continuous imagery and penetration to greater depths than is possible by soil augering. Time, manpower and financial savings can be achieved, increasing the pote...