USACE Levee Safety Risk Analysis Process and Methodology Overview

1. USACE Levee Safety Risk AnalysisProcess and Methodology Overview Jason Needham, P.E. Consequence Specialist USACE Risk Management Center 09 December 2011

2. Levees pose risk to people and property Inherent risk associated with living near rivers and oceans Degradation of existing structures Changing construction techniques Increase in population, climate change, etc Increase in public awareness Katrina and other recent events Congress points to USACE Large portfolio - limited funds How do you decide what to fix first? Problem

3. Previous Situation HQ

4. Assess the integrity and viability of levees and recommend actions to assure they do not present unacceptable risks to the public, property, and the environment. Hold public safety paramount Reduce economic damage Maximize cost effectiveness Develop reliable and accurate information (decision driven) Build and maintain public trust USACE Levee Safety Program

5. Levee Safety Portfolio Risk Management Process

6. Levee Safety Portfolio Risk Management Process Routine Activities

7. Levee Safety Action Classification System • Transition from Routine to Non-routine • Reflects urgency of action • Depicts range of risk • combination of • likelihood of inundation • consequences of inundation • with an emphasis on life-safety • Provides consistent and systematic guidelines for actions commensurate with the risk

9. Levee Safety Portfolio Risk Management Process Non-Routine Activities

10. Levee Screening Tool • Developed to quickly assess the condition and consequences of levees in the Corps of Engineers portfolio • Combines information from: • National Levee Database; • Levee inspection process; • Limited Engineering Assessment of project features. • Relative Risk Index • Philosophy • Data consistency • Conservativejudgements • Largo portfolio • Simplify!

11. Plotting – Prior to Overtopping

12. Initial Results – New Orleans • System levees designed to reduce flooding from Mississippi River and Lake Pontchartrain FOR OFFICIAL USE ONLY

13. Segment Screenings Vicinity/Segment Map East Jefferson LD Orleans LD Pontchartrain LD 5 4 6 2 1 3

14. Plotting – Overtopping

15. Initial Results – New Orleans • Recommended LSAC Rating = LSAC 2 • Combination of life, economic, or environmental consequences with the probability of inundation due to overtopping with subsequent breach, is very high. • Justification: • Performance concern: Breach during overtopping • Evidence: • Good performance expected for events up to 100% loading • Incipient overtopping frequency estimated at 200-year return period • Studies show breach likely for event at or about 200-500 yr event • Breach during overtopping would significantly increase consequences • Critical infrastructure includes numerous hospitals, oil & gas refineries, and chemical industry facilities that could lead to major impacts well beyond the protected area

16. Relative Levee Safety Portfolio Risk Management Process When We Use Risk Analysis Risk Analysis Approach isDecision Driven Absolute