B. A. Cole
In October 2000 ANCOLD published a history of dam technology in Australia covering the 150 years in which large dams have been constructed in this country. The paper describes how this project began, the search for authors, the way the authors tackled their tasks, the peer reviews which resulted in additional chapters being written, and the archive searches for interesting photographs to illustrate the text. All this was accomplished by dam engineers including the editor. Then follows an account of the professional publication process: sub-editing, desktop publishing, proof-reading, the preparation of an index, the cover design and the printing process. Some conclusions are drawn from this first experience of book publishing.
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A. Ash, D. S. Bowles, S. Abbey and R. Herweynen
A preliminary risk assessment was undertaken of its three dams by the South East Queensland Water Board (SEQWB) in 1999. The risk assessment process used included a series of workshops that proved to be an important part of ensuring a worthwhile result. The combined expertise of the consultants together with that of staff from the Board and the Queensland’s Department of Natural Resources were used to improve the outcome. The results of the assessment showed that the process had both advantages as well as difficulties in comparison to a standards based approach for making dam safety decisions. Risk Assessment was seen to be a useful management tool for managing dam safety. It gave the owner the ability to quickly rank upgrade requirements or maintenance options on the basis of probability of failure, life safety risks and financial risks to the owner or economic risks to all stakeholders.
The entire historical record of rainfall archives held by the Bureau of Meteorology over the region of Australia affected by tropical storms has been examined and the extreme storms have been extracted. From this database, we account for site specific effects (moisture and topography) from each of the storms, allowing us to compare storms amongst each other. This then allows us to construct a theoretical maximum precipitation in a generalised sense. By then returning the site specific information for a particular region, we can infer the probable maximum precipitation at this location.
M. B. Barker and D. Holroyde
A detailed study was completed for the Stage 2 works of the Grahamstown Dam augmentation to investigate various alternatives for the slope protection of the Saddle Dam and Subsidiary Dam embankments, including a standards based and a risk management approach. The standards based approach required an evaluation of the slope protection level and least cost option based on the hazard rating of the dam. Due to the sand construction of the embankments, it was possible to apply a wave erosion model SBEACH to develop an economic risk model for optimising the slope protection alternatives. The erosion model included the effects of the wind direction, reservoir level and wind speed variation during flood events, embankment profile and material parameters. The risk management approach clearly showed that significant cost savings could be achieved by using the risk management approach. Furthermore, the cost curves indicated the sections of the embankments for which present capital works would not be economically justified and for which ongoing maintenance works would be economically advantageous.
Failure modes and effects analysis (FMEA) has been increasingly utilised to prioritise and investigate dam safety deficiencies. It can be used to enhance dam safety programmes. Dam Surveillance, O & M procedures, and emergency plans can all be evaluated for their effectiveness in detecting and mitigating the applicable failure modes for a dam. Experience with a workshop process to carry out this evaluation and some of the improvements that have been identified are described.
Richard R. Davidson, Roger Vreugdenhil and Mark Foster
Significant cracking was observed on the crest of the main embankment at Lake Eppalock for many years, but in recent years increasing movement upstream during low reservoir levels indicated a progressively deteriorating stability situation. Investigations also revealed cohesive filter material that would allow a crack to propagate. A fast-tracked remedial works program was completed in 1999 to rebuild the highly vulnerable upper rockfill shells and filters, both upstream and downstream. To manage construction risk, the works were carried out directly by G- MW with innovations in removal, protection and replacement of the downstream shoulders, and placement of a new multi-zone filter.