Douglas Boyer, PE, CEG Chief, Western Division Risk Management Center

1. Overview of Risk Approach to Manage USACE Dam and Levee Safety ProgramThe Reality of Risk: Dam Safety in the 21st Century Session Douglas Boyer, PE, CEG Chief, Western Division Risk Management Center Institute for Water Resources February 19, 2013

2. Corps Dam Safety Portfolio • Corps owns 704 dams, Nationwide and in P.R. • embankment = 86 % • concrete = 7 % • combination = 7 % • Project purposes include: flood control, navigation, hydropower, water supply, fish & wildlife conservation, recreation • Median height: 93 feet • Mean height: 112 feet • Average age: 53 years • High Hazard dams: 77 % • Total storage capacity: 331 Million Ac-ft

3. Traditional Dam Safety Approach • Standard engineering analyses • Conservative inputs • Factor of safety • “check the box” • Standard design criteria • Probable Maximum Flood (PMF) • Maximum Credible Earthquake (MCE) • Expensive designs and repairs

4. Investment Comparison

5. Given • Dams needing repair – approx. 300 • Annual budget - $500 M • Public trust responsibility, accountability, and transparency • Range of project benefits and value

6. The Question Which dams to work on first?

7. Risk Analysis Provides a systematic approach to decision-making that enhances the scientific basis of USACE decisions and comprises three tasks: • Risk assessment • Risk management • Risk communication

8. Risk Assessment • What can go wrong? • How can it happen? • What is the likelihood? • What are the consequences?

9. Risk Management • What is the problem? • What can be done to reduce the likelihood or severity of the risk described? • What are the tradeoffs in terms of costs, benefits, and risks among the available options both now and in the future? • What is the best way to address the described risk?

10. Risk Communication • Why are we communicating? • Who is our audience? • What do we want to learn from our audience? • What do they want to know? • What do we want to get across? • How will we communicate? • How will we listen? • How will we respond?

11. Answers Other Questions • Urgency of modification • What to modify • Extent/magnitude of modification

12. Risk • Identification of potential failure modes • Decomposition of failure process • Qualitative or quantitative estimates of likelihood of events • Comparison of result to a standard

13. Internal Erosion PFM Event Tree

15. Risk Reduction

16. Cumulative Risk Reduction

17. Change in Dam Safety Focus

18. Change in Dam Safety Focus

19. Principles of Risk Informed Approaches No simple numerical solutions – decisions are informed, not based, on risk Risk compliments, does not replace, traditional engineering standards or experience Credible way to treat uncertainty Periodic and Continuing Risk is integral, not “bolt on”, to our profession

20. Benefits of PFMA/Risk Approach • Multidisciplinary Team • Civil Engineers • Other Engineers • Geologists • O&M personnel Wow, I never thought about it that way before!

21. Benefits of PFMA/Risk Approach • Instills a culture of creative thinking • Why is this important?

22. Benefits of Risk-InformedDecision-Making • Better Understanding of Potential Failure Modes • Identifying Previously Unidentified Potential Failure Modes • Considering the Probability of Failure & Consequences • Comparing the Risk of Different Dams • Understanding the Uncertainty in Analyses • Comparing the Contribution of All Failure Modes to the Overall Risk

23. Challenges • Same/similar engineering knowledge – just a different approach and focus • Training in risk concepts and principles • A tendency to focus on the “number” rather than ‘building the case’ • Lack of risk experience

24. Photograph from inundated area downstream of Teton Dam, Idaho (1976)