The Dam Safety Program in South Africa

Dam safety in South Africa was implemented by means of Section 9c of the Water Act in 1984; as of 31 March 1997, the national registry included over 3500 dams. Dam owners are legally responsible for compliance, which is based on dam size and hazard classification. Dam owners of Category II and III dams are compelled to have dam safety inspections every 5 years by an Approved Professional Engineer (APE), and, in the case of a Category III dam, by an approved professional team, guided by an APE. Progress with inspections has been slow because of restricted financial resources and the reluctance of owners. Of 582 dams inspected, 31% have inadequate spillway capacity; other major deficiencies include trees and vegetation on embankments; inadequate monitoring and contingency planning; and geotechnically related problems such as seepage, settlements affecting foundation stability within embankment dams, slope stability, erosion at the toe of the dam wall or downstream, erosion of unlined spillway channels, and surface drainage/erosion problems. This paper discusses these major geotechnical problems and presents statistical analysis and case studies that illustrate the severity of the lack of appreciation for proper geotechnical site investigations, quality control during construction (compaction and moisture content) and maintenance-related problems. 12 pp., 10 references.