Malcolm Barker, Barry Vivian and David S. Bowles
Ross River Dam is located approximately 15 km upstream of Townsville and provides a dual role of water supply and flood mitigation. The dam comprises a 39.6m long concrete overflow spillway flanked by a central core rockfill embankment of 300 m in length with a 7,620 m long left bank earth fill embankment, which has inadequate internal filter zones for piping protection. Since completion, design rainfall predictions for the area have doubled, technical data has changed and so, too, have dam safety standards. Dam safety evaluations during 2000-2002 showed that the dam required upgrading in order to bring it up to international standards. As an interim measure, the spillway was cut down by 3.6m.
Upgrade design works were then completed using risk-based design criteria to validate the design, and construction is in progress. The upgrade works comprise spillway anchoring, installation of three radial gates on the spillway, stilling basin modifications, embankment filter protection, and dam crest raising.
This paper presents the options considered, the method of reliability analysis, and how the results influenced the spillway system design and overall risk evaluation for the upgrade design.
John D Smart
The paper presents the recent trends in the use of instrumentation and survey measurements at Bureau of Reclamation (Reclamation) dams. The underlying philosophy that has influenced those trends is presented and discussed. Based on experience at Reclamation, several factors that are considered key to the effective use of instrumentation and surveys are discussed. Several conclusions are offered.,
D.N.D. Hartford and P. A. Zielinski
With the notable exceptions of dyke safety in the Netherlands and dam safety in Australia, explicit consideration of the equity versus efficiency dilemma associated with dam safety decision-making has been virtually ignored in the past debates related to safety of dams thus leading to inconsistent judgments in the development of dam safety policies. The equity-efficiency dilemma is now being debated in Canada as part of the process of revising the Canadian Dam Safety Guidelines. This paper explains how the argument in favour of formulating the new Canadian Dam Safety Guidelines within the formal risk assessment and risk management framework is being presented. The paper then focuses on the difficulties involved in aligning the well tried and tested and generally successful traditional approach to dam safety with the relatively untried and untested risk assessment approach. While the paper does not provide a significantly different perspective (a made in Canada approach) to the role of risk assessment in dam safety management as established in Australia and as presented in ICOLD Bulletin 130 (ICOLD, 2005), it does challenge some aspects of the ways dams are classified in the emerging risk assessment frameworks for dam safety management.
Marius Jonker, Malcolm Barker and Gary Harper
This paper provides a framework for conducting an effective Failure Modes Analysis. It explains the fundamental principals and methods of Failure Modes Analysis. The current international state of practice on Failure Modes Analysis is discussed, and the objectives, benefits and limitations of Failure Modes Analysis assessed. Guidelines are given on how to apply the outcome of Failure Modes Analysis in dam safety management and surveillance.The effective application of Failure Modes Analysis is illustrated in a case study where the process was applied in the safety review and risk assessment of Rocklands Dam for Grampians Wimmera Mallee RegionWater Authority in Victoria.
David S. Bowles
Portfolio Risk Management is a risk-informed approach for improved management of dam safety for a portfolio of dams in the context of the owner’s business. It can be used to identify ways to strengthen technical and organisational aspects of a dam safety program, and to provide valuable inputs to various business processes. Portfolio Risk Assessment is a decision-support tool, which is incorporated in Portfolio Risk Management. It can combine engineering standards and risk assessment approaches to provide a systematic means for identifying, estimating and evaluating dam safety risks, including comparisons with other industries. It should be periodically updated to provide a basis for managing prioritised queues of investigations and risk-reduction measures to achieve more rapid and cost-effective reduction of both knowledge uncertainty and risk.
Portfolio Risk Assessment is a standard of practice in Australia and is being applied by the US Army Corps of Engineers and others. When properly conducted and used within its limitations, the Portfolio Risk Assessment process is generally considered to be robust, adaptive, defensible for corporate governance, and to justify its cost through such benefits as increased dam safety funding, identification of failure modes that were not previously recognised, identification of opportunities for improved risk management, and more rapid “knowledge uncertainty” and risk reduction.
Karen Soo Kee
Strategic resource management has never been more important than it is today with the aging of the “baby boomers” and their ongoing exodus from the workforce. The vacancies they leave in professions such as engineering are just beginning to be felt and will exponentially escalate over the next few years. Specialised professions such as dam engineering and related professions will be hit the hardest as the knowledge and skills learnt over decades are depleted.
The lack of skilled staff and in fact the lack of interest of young engineers in entering the dam industry is one of the critical challenges for today. How do we attract professional staff into the field of dam safety before the exodus creates a “black hole” that can never be filled? And how can we ensure the knowledge transfer from existing skilled staff to newer staff to retain expertise within the industry?
Another issue for resource management is that tomorrow’s workers, the “X &Y generations”, will be unlike the current and previous generations of workers. These workers will be less likely to have a mortgage, will have fewer children and be more interested in lifestyle, not career. They will be extremely confident, well educated and very mobile. The future will be a sellers market. The challenge here will not only be to attract and recruit talented workers but also to retain them.