1. US Army Corps of Engineers BUILDING STRONG ® Overview of Risk Approach to Manage USACE Dam and Levee Safety Program The Reality of Risk: Dam Safety in the 21 st Century Session Douglas Boyer, PE, CEG Chief, Western Division Risk Management Center Institute for Water Resources February 19, 2013

2. BUILDING STRONG ® 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. BUILDING STRONG ® 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 3

4. BUILDING STRONG ® Investment Comparison

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

6. BUILDING STRONG ® The Question Which dams to work on first? 6

7. BUILDING STRONG ® 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 7

8. BUILDING STRONG ® Risk Assessment  What can go wrong?  How can it happen?  What is the likelihood?  What are the consequences? 8

9. BUILDING STRONG ® 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? 9

10. BUILDING STRONG ® 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? 10

11. BUILDING STRONG ® Answers Other Questions  Urgency of modification  What to modify  Extent/magnitude of modification 11

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

13. BUILDING STRONG ® Internal Erosion PFM Event Tree 13

14. BUILDING STRONG ®

15. Risk Reduction

16. BUILDING STRONG ® Cumulative Risk Reduction

17. BUILDING STRONG ® Change in Dam Safety Focus 17

18. BUILDING STRONG ® Change in Dam Safety Focus 18

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

21. BUILDING STRONG ® Benefits of PFMA/Risk Approach  Instills a culture of creative thinking  Why is this important? 21

22. BUILDING STRONG ® Benefits of Risk-Informed Decision-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 22

23. BUILDING STRONG ® 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 23

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