Dolomite is such a diverse rock! It is an exceptional aquifer for groundwater supply (which we often explore), a superior construction material (for aggregate and cement), a playground for tourism due to the beauty of its natural habitat, but, also the host of karst landscapes with sinkholes and subsidences.
Development on dolomite poses a risk due to the possible formation of catastrophic instability features such as sinkholes which could result in the loss of assets, injury or loss of life. Most of these features are, however, man-induced, and the risk associated with development on dolomite areas can be mitigated to a large extent through correct management.
Damage to structures on dolomite land far exceeds that of other geological formations in southern Africa, and to date, 39 people have died due to dolomite-related incidents. The first and most infamous event in the recorded history in the world dates back to 1962 when a crusher plant and 29 employees were engulfed in a sinkhole due to dewatering for gold mining in South Africa.
Recent studies indicate that property damage estimated at R15 billion and the average cost of sinkhole or subsidence repair between R500 000 and R6 million based on a selected study area of 3 700 ha south of Pretoria over a 20-year period. Although difficult to quantify, indirect losses are often higher than direct damage. The impact on the economy caused by a loss of serviceability and delays are rarely accounted for.
The amount of sinkhole-related damage shows an overall rising trend in recent years, despite the fact that the scientific community has substantially improved the ability to assess sinkhole hazards and manage the associated risks. This trend may be attributed to an increase of the number of people and human structures in karst regions, and a progressively higher impact due to the human-induced activities, such as leaking infrastructure, poor stormwater management, and groundwater abstraction.
One of our TA associates, AGES, developed a comprehensive method to manage the risks on dolomites over the last 10 years. This managing process adheres to all legislation, meets industry standards and pro-actively manages risks associated with development on dolomite. AGES developed an in-house multi-disciplinary team of competent engineering geologists, geohydrologists, town planners, social scientists, engineers, GIS consultants, and lawyers. A Rapid Response Team is in place to mobilise within minutes to the affected area, guiding all affected parties on how to handle the situation going forward.
Sinkholes are a reality in South Africa. The communities affected are most often most vulnerable, least resilient and never recover from personal losses due to disasters such as sinkholes. The vision of AGES is to implement dolomite risk programs in each local authority affected by dolomite land in order to prevent losses due to sinkholes as far as possible. This is our contribution to “touch Africa!”
