Rehabilitation of Osborne Dam outlets

Abstract

Purpose The purpose of this paper is to communicate and share experiences with other dam designers, operators and maintenance officers arising from the rehabilitation of the Osborne Dam outlets, pursuant to informing future dam outlet designs and rehabilitation of similar dam outlets. Design/methodology/approach This paper documents and utilizes actual events that occurred before and during the rehabilitation of the outlets. Some solutions applied were unique, with resultant innovative engineering designs being decided on site. Realizing that a descriptive research format would best serve the sharing of experiences of the outlets’ rehabilitation, the case study approach was selected. Before commencement of the rehabilitation works, the different operational problems that had been identified, photographed and documented by the dam’s operating staff were verified by the dam owner’s engineers, technicians and consultants. Visual and photographic verification was done using divers for areas under water. Literature review was conducted so as to learn from solutions employed elsewhere. A physical model of the solution considered the best way to keep the intake tower dry was made and tested. Findings The outlets’ rehabilitation works, taking 12 months to complete at a total cost of US$5 million, involved installation of new service gates, replacement of the sleeve valves, refurbishment of the butterfly valves and provision of dewatering pumps. Originality/value This paper offers unique experiences and lessons for dam designers and other dam operation and maintenance officers while contributing to the body of knowledge of outlet works rehabilitation.