One big change with regard to dam safety in Canada is a push toward the use of a risk-informed approach that includes traditional deterministic standards-based analysis.
By Clare Raska
Clare Raska is senior engineer, operational safety with BC Hydro and president of the Canadian Dam Association.
Editor’s Note: Treatment of dam safety issues in Canada is unique, so we asked the Canadian Dam Association to indicate the hot dam safety topics in their country.
In Canada, there is no federal regulatory agency or dam safety program, and regulation of dams is the responsibility of the provinces and territories. However, only four of the 13 have in place legislation or guidelines governing dam safety, meaning dam safety in the country relies on an owner’s due diligence for the most part.
The Canadian Dam Association (CDA) is Canada’s representative to the International Commission on Large Dams (ICOLD) and provides a forum to discuss issues related to dam safety in Canada. CDA’s Dam Safety Guidelines have become the “go to” reference for dam owners, operators, consultants, suppliers and government agencies, providing a set of principles applicable to all dams and an outline of processes and criteria for management of dam safety. A companion series of technical bulletins suggest methodologies and procedures for use by qualified professionals as they carry out dam analyses and safety assessments.
In late 2013, a revision to the guidelines was published to provide clear endorsement of the use of a risk-informed approach to dam safety, which includes traditional deterministic standards-based analysis. This revision pointed out that suggested levels for flood and earthquake hazards should be treated as target levels for initial consideration and consultation between the dam owner and regulator. In addition, consideration must be given to other hazards relevant to dam safety assessments, such as internal erosion of embankment dams, human factors affecting operational decision-making, and reliability of spillway systems. Dam safety also needs to concern itself with the interdependency between hazards because some combinations of typically non-threatening events can lead to a dam failure.
Extensive discussions are needed at both a societal and governmental level to resolve the question of how safe a dam should be — a question that arises whenever major investment decisions include a dam safety component. The issues go beyond the realm of engineering analysis. CDA is encouraging open discussion at its 2014 annual conference, with its theme of “A Balance of Changing Priorities” and a session on how dam owners and regulators need to work together to reach the appropriate balance. This conference takes place Oct. 4-9 in Banff, Alberta.
Several Canadian dam-owning utilities are developing systems engineering and operational aspects of dam safety risks. The emerging methodologies address the interactions of multiple engineered components and consider human reliability, organizations, policies and procedures. The CDA conference will feature a workshop that presents the results of this work, “Second Generation Risk Assessment for Dam Safety — A Systems Approach.”
Other topics of interest include implementation of public safety programs and formation of a working group to address emergency management for dams and ongoing development of risk-informed processes for dam safety decisions. Periodic dam safety reviews are expected by provincial regulators, and the Association of Professional Engineers and Geoscientists of British Columbia have issued Professional Practice Guidelines for Legislated Dam Safety Reviews. CDA is working to develop guidance for broader application.
|Manitoba Hydro’s Pointe du Bois spillway replacement project is being completed to address dam safety concerns related to a requirement for additional spill capacity, as well as to provide a modern and safer working environment for staff.|