South Africa has a long history of mining extending beyond 100 years. Over time, many mines had not implemented closure plans once resources were depleted. This has resulted in between 5,000 – 6,000 ownerless and derelict mines across the country, which are now the responsibility of the South African government. These mines include almost every mineral commodity that has ever been exploited in South Africa.
As many of these operations often represent a significant health, safety and environmental risk, authorities have instituted a program to address the risks at these operations by implementing rehabilitation activities to effect closure. Given the health risks, such as asbestosis, mesothelioma, lung cancer and pleural plaques of communities exposed to asbestos fibres, the authority has initially focused its attention on rehabilitating asbestos mines.
In the last quarter of 2013, SRK was appointed to provide engineering and design services for the rehabilitation and ultimately the closure of several abandoned and derelict mines throughout South Africa. In undertaking the activities, SRK deployed a multidisciplinary team to assist with identifying site specific risks for which remedial measures are required.
Mitigation of risks was then utilised as the basis of the conceptual design and ultimately the final design for the remedial measures. A phased approach was adopted where various possible conceptual closure designs were considered and then assessed against practicality, cost, and ability to mitigate risk and achieve the desired closure objective. Closure measures included limiting mobilisation of loose fibres present over the surfaces where mining and processing activities took place, as well as limiting mobilisation of fibres in the rock matrix in which asbestos was contained, which are now stored in various residue disposal facilities. The closure activities also included sealing the means of ingress and egress from the workings. The majority of these ownerless and derelict mines are located in steep terrain, where protection from erosion and other water related damage had to be incorporated into the closure design. The integration of the disciplines, which included geotechnical and civil engineers, hydrologists, geologists and scientists, is undertaken within the context of our internationally recognised experience in all aspects of mining and waste management.
In total, SRK has overseen design-to-construction monitoring phases of 13 derelict operations since 2013. Since mine closures are becoming more of a reality worldwide due to operations depleting mineral resources, SRK believes that the integrated approach focusing on risk mitigation created for this project, is adaptable for rehabilitation on many other mines.
Raymond Mayne: rmayne@srk.co.za
