Abstract:
A large part of the land south of Pretoria is underlain by dolomite from the Chuniespoort Group
of the Transvaal Supergroup. In South Africa, dolomite rock has a notorious reputation for the
formation of sinkholes and subsidences. Thousands of people reside and work in the Centurion
area, where numerous sinkholes have occurred, causing damage and in some instances loss
of property and even lives. Centurion has rapidly densified over the last 40 years, with an
increase not only in the number of people, but also in the density of waterborne services. This
paper proposes draft guidelines for the allocation of an Inherent Hazard Class for percussion
boreholes, referred to as the ‘Simplified Method of Scenario Supposition’. This method was then
used to classify the Centurion CBD and surrounding area.
