Risk Analysis
[Paragraph here]
Potential Failure Modes Analysis
“Potential failure modes are mechanisms that can result in an uncontrolled release of the reservoir. A potential failure modes analysis is a critical first step in conducting a risk analysis. It requires a detailed records review and a review of dam performance (e.g., instrumentation, visual, and operational). Information is also needed on flood and earthquake frequencies in order to consider hydrologic and seismic potential failure modes. The perspective of local office personnel, including dam operators, inspectors, and dam tenders, is invaluable. The goal of a potential failure modes analysis is to: (1) identify the site-specific credible potential failure modes for a given dam; (2) provide complete descriptions of the potential failure modes, including the initiating event and the progression of steps leading to an uncontrolled release of the reservoir; and (3) provide a general description of the magnitude of the breach, including identifying and recording the factors that make the potential failure more likely and less likely and the consequences more severe or less severe”.[1]
“It is recognized that large controlled flood releases may result in significant downstream consequences, including loss of life, but these events have typically not been included as potential failure modes because they result from intended operation of the dam. Large controlled releases that may result in serious downstream consequences are typically made to prevent even greater consequences that would occur from dam failure. Agencies may elect to consider the risk from large controlled releases, and risk communications should occur when large releases are made”.[2]
Risk Estimation
- Loading Conditions
- [Paragraph here]
- Breach Estimation
- [Paragraph here]
- Structural Response
- [Paragraph here]
- Consequence Estimation
- “The next step in the process is to identify the consequences for each asset. The potential consequences of a dam failure include loss of life and injury, damage to structures and infrastructure, loss of services, and road closures resulting from flood damage, fallen trees, and debris”.[3]
Risk Communication
“Communication is important in all aspects of dam safety within an organization, with the public, and with the specific owners or stakeholders of a project. However, communication about the work associated with risk is particularly important because of the fears, sentiments, perceptions, and emotions surrounding the work risk and the use of risk analysis in engineering” (Federal Guidelines for Dam Safety Risk Management, FEMA, 2015).[2]
“Integrate risk communications early in the process of responding to dam safety issues. This is beneficial because by including individuals in the process and giving them the opportunity to provide input, and possibly, influence decisions, they are more likely to accept the decisions being made. Provide context for risk communications (i.e., compare with other risks). This is especially important for the public who may have trouble identifying the significance of dam safety risks”.[2]
“Risk estimates are inherently uncertain, with the nature and amount of uncertainty varying from dam to dam. It is important to acknowledge the uncertainty and put it into the proper context. The following aspects of uncertainty in risk estimates and the dam safety case should be discussed: what is certain; what is likely, but not certain; what is possible, but not likely”.[2]
Examples
Best Practices Resources
Federal Guidelines for Dam Safety Risk Management (FEMA P-1025)
Federal Guidelines for Dam Safety Risk Management
Assessing the Consequences of Dam Failure: A How-To Guide
Trainings
On-Demand Webinar: The History of Dam Safety Governance in the US Including Risk Analysis
Citations:
Revision ID: 2522
Revision Date: 09/08/2022