Risk-informed decision making (RIDM) offers a new approach to the Federal Energy Regulatory Commission (FERC) dam safety program, and it is here to stay. Because the engineering industry abounds with initialisms and acronyms, let me provide some insight on RIDM in the context of the FERC dam safety program.
1. What is RIDM?
The FERC defines RIDM as “the process of making safety decisions by evaluating if existing risks are tolerable and present risk measures are adequate, and if not, whether alternative risk reduction measures are justified.”
My own interpretation of RIDM is that it is a framework for guiding dam safety planning decisions that considers whether the estimated likelihood of an adverse outcome and its associated consequences can be tolerated from a societal, economic, and environmental context.
2. How is risk defined in dam safety?
The International Commission on Large Dams (ICOLD)’s definition of risk is that it is a measure of the probability and severity of an adverse effect to life, health, property, or the environment.
My understanding of risk is that it is the likelihood of realizing an adverse outcome for a given loading condition multiplied by the consequences resulting from that adverse outcome. The adverse outcome can be attributed to a breach scenario, a component malfunction, or mis-operation.
3. Why is RIDM important?
The FERC’s take is that a RIDM approach for safety assessments of dams complements the more traditional standards-based approach where “safety is assessed by following established rules for design events and loads, structural capacity, safety coefficients, and defensive design measures.” Furthermore, “those that analyze, evaluate, and manage risks have found that integrating risk approaches provides a rigorous, systematic, and thorough process that improves the quality of, and support for, safety decisions.”
My opinion is that RIDM provides an alternative approach for planning of dam safety improvements that evaluates and prioritizes upgrades based on their relative contribution to the overall risk profile of the project.
The benefits of RIDM include:
- It greatly improves the understanding of the dam through the systematic analysis of failure mechanisms;
- It offers a means of analyzing and assessing risks where no widely-accepted, standards-based approach has been established;
- It provides an understanding of the potential liabilities of dam ownership and an appreciation of the residual risks.
4. How is RIDM used?
Applying RIDM involves three components: risk analysis, risk assessment, and risk management.
The key activities of dam safety risk analysis are system identification and risk estimation. Risk analysis, as defined by FERC, is “a structured process aimed at estimating both the probability of failure of the dam or dam components and the consequences of failure.” It is also the portion of the RIDM process where “potential failure modes, structural performance, and adverse consequences are identified” and “a quantitative or qualitative estimate of the likelihood of occurrence and magnitude of consequence of these potential events is made.”
The key activity of dam safety risk assessment is risk evaluation, which is where “values (societal, regulatory, legal, and owners) and value judgments enter the decision process, explicitly or implicitly, by including consideration of the importance of the estimated risks and the associated social, environmental, economic, and other consequences, in order to identify and evaluate a range of alternatives for managing the risks.”
The key activity of risk management is risk reduction, which typically encompasses avoiding the risk, reducing the probability of occurrence, reducing the consequences, or transferring the risk.
5. What now?
Has this dialog on risk analysis, assessment, and management left you confused, overwhelmed, and feeling at a loss for informed decision making? If so, you are not alone. RIDM is a relatively new approach in the FERC dam safety program intended to complement the standards-based approach, and it is not going anywhere. As with most things in life, experience feeds confidence, so I suggest you embrace the RIDM approach to dam safety and take the opportunity to immerse yourself in the application and benefits. If you need assistance, we at Mead & Hunt are available to help.
