Hazard of sinkhole formation in the Centurion CBD using the simplified method of Scenario Supposition

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.