Guidelines on the Consequence Categories for Dams (October 2012)
ANCOLD has prepared these important Guidelines to provide a consistent method of categorising the consequences of dam failure so that resources can be allocated according to the potential effects of failure on the general community.
These Guidelines replace the ANCOLD Guidelines on the Assessment of the Consequences of Dam Failure issued in May 2000 and follow a similar approach. However, they include quite significant changes aimed at providing enhanced description of Consequence Categories and making them easier and more consistent to use.
The Technical Working Group has made every effort to make these Guidelines straightforward to use by professional engineers and consistent with other ANCOLD guidelines.
However the complexity of determining the various parameters that make up each Consequence Category means that only experienced dam engineering professionals should interpret and use these Guidelines when making decisions that could impact on community safety, community cost and services, infrastructure, natural environment, heritage, and the owner’s and other businesses.
ANCOLD published its first Guidelines for Design of Dams for Earthquake in 1998. The Guidelines were prepared to bring together knowledge about earthquakes in Australia following the devastating
Newcastle (1989 magnitude Mw 5.4) and the Tennant Creek (1988 magnitude Mw 6.6) earthquakes, and improved analytical methods to predict the behaviour of dams subject to earthquake.
When the 1998 Guidelines were issued, it was recognised that over time there would be improved data and tools to help the designer. This has indeed been the case and ANCOLD decided that it would be timely to update its Guidelines to incorporate the significant advances made in the understanding of earthquakes, seismic hazard assessments, analysis and design.
The Working Group convened to produce these updated Guidelines, replacing the 1998 Guidelines, was composed of representatives from dam owners, State dam safety regulatory agencies and private consulting practices. The draft Guidelines were made available for comment by ANCOLD members and international review of the Guidelines was undertaken by eminent practitioners in the subject matter from the United States, New Zealand and Switzerland.
Because of the seismic hazard uncertainty and the associated structural response, these Guidelines
encourage the use of risk-based methods for assessing existing dams and for the design of new dams. However, the deterministic approach is also covered for those owners who prefer to use it.
This guideline is the culmination of a great deal of voluntary work by convenor, Mr Steve O’Brien and his working group. It is a significant development for dam engineering in Australia and will be a valuable resource.
As with all ANCOLD Guidelines, this guideline is not a design code or standard and has been produced for the guidance of experienced practitioners who are required to apply their own professional skill and judgement in its application. Users must keep abreast of developments in the design of dams and appurtenant structures for earthquake and take those developments into account when using these Guidelines.
The Guidelines will again be reviewed when knowledge and practice have developed to a point when an update is required. Accordingly, ANCOLD welcomes comments from users and other interested parties.
Shane McGrathLearn more
Chairman of ANCOLD Inc.
This document has been prepared as a companion to the 2001 ANCOLD Guidelines on the Environmental Management of Dams. Since the 2001 guidelines were published much has been learnt about the critical issues that drive environmental concerns for both dam practitioners and the broader community arising from the construction of new dams, dam upgrades or altered operational strategies. The objective of this companion volume to the 2001 Environmental Guideline is to increase environmental awareness by encouraging more sustainable planning, design, construction and operation inputs to large dams. As such this companion volume complements rather than replaces the existing 2001 guideline. This companion volume focuses on:
Describing the complex Commonwealth and individual State regulatory environments that must be dealt with in all dam projects;
Discussing key issues surrounding the practices for effective stakeholder and community consultation;
Considering risk assessment for environmental matters associated directly with construction and operation, as well as the broader and more complex regulatory concerns of cumulative and consequential impacts; and
Providing a series of technical Practice Notes on a range of environmental issues that dam owners/ operators need to be aware of in all dam projects
A series of Practice Notes has been presented in Part B setting out a brief overview of current knowledge on a range of technical and operational matters of interest to dam owners/operators. These are not exhaustive reviews of current knowledge but rather serve to raise a level of awareness on a range of issues that need to be considered at the various stages of planning, constructing, operating and decommissioning a storage with respect to environmental concerns.
The 2014 Guidelines are intended to be regularly updated to reflect the changing regulatory environment as well as increasing technical knowledge about environmental management.
The two guidelines should be regarded as companion volumes for reference, with the 2014 Guidelines providing a targeted and practical environmental perspective.
The Technical Working Group set out to make these Guidelines simple and straightforward, avoiding scientific and technical jargon so as to appeal to the broader audience it targets. I take this opportunity to thank the members of the working group for their efforts in bringing this document to fruition.
The Guidelines are not a ‘rule book’ but rather a document to raise awareness of significant environmental matters to be considered by all dam owners/operators. ANCOLD welcomes comments on these Guidelines for inclusion in future editions.Learn more
The Watching Brief Guidelines for Dam Instrumentation and Monitoring Systems (1983), established following the Dam Instrumentation Workshop in Sydney, continues to scan for information and topical developments related to the monitoring of dams using a range of instrumentation techniques. A position paper outlining the current status for the Executive is planned for 2013 and will provide a mechanism to move forward on the need for an updated guideline.
Members wishing to contribute papers, views, or information to the watching brief should contact Chris Topham via the ANCOLD secretariat [email protected]ancold.org.auLearn more
Within about ten years of the 1991 edition of the ANCOLD Guidelines on Design Criteria for Concrete Gravity Dams being published the Limit State design approach it proposed fell out of favour with Australian dam engineers. The ANCOLD Executive recognised this situation and resolved that the Guidelines be revised to reflect the preferred design approach amongst Australian dam engineers. A Working Group and a separate Expert Review Panel were formed in 2005 to review the Guidelines with the intention of preparing a document that was not only more in line with the current thinking but would also be widely adopted and used by practicing dam engineers.
It has not been an easy task for the Working Group and the Expert Review Panel. Although the working stress method, with associated Factors of Safety, approach was agreed amongst the team, it took considerable time and effort to reach consensus on the details, in particular chapters four through to six. The issue that took most effort to resolve was how the Factors of Safety relate to the level of certainty of the inputs, including knowledge of the foundations, loads, strength of materials and assumed mechanically feasible failure surfaces. The notes to Table 6.4.1 and the discussion in Appendix A highlight this issue.
One thing the drafting team agreed on early, and unanimously, was the importance of the concrete gravity dam design team having a thorough understanding of the foundation conditions, the development of a detailed geological model of the foundations and an understanding of the kinematically feasible failure mechanisms. In keeping with this principle, this revision of the guidelines has the section on foundations at the front of the document. There is a strong recommendation that the design team has expertise covering foundation geology and rock mechanics as well as the dam engineer.
These Guidelines provide a basis for design of concrete gravity dams in most situations. However, they require that the user will be a professional dam engineer with significant experience who is able to use sound engineering judgement in the application of the guidelines. It is recommended that less experienced dam engineers using these guidelines do so under the advice and guidance of an experienced dam engineer. It is the dam engineer who is responsible for the design.
On behalf of ANCOLD I would like to thank the members of the working group and all the other contributors that persevered in developing and bringing these Guidelines to fruition. They will be of great assistance to dam engineering professionals both within Australia and internationally.Ian Landon-Jones Chairman, ANCOLD Learn more