“ Building Strong “ Delivering Integrated, Sustainable, Water Resources Solutions Background on Engineering Risk Assessments (ERA) for USACE Civil Works Infrastructure Robert C. Patev North Atlantic Division – Regional Technical Specialist (978)

“ Building Strong “ Delivering Integrated, Sustainable, Water Resources Solutions Engineering Risk Assessments

“ Building Strong “ Delivering Integrated, Sustainable, Water Resources Solutions Risk

“ Building Strong “ Delivering Integrated, Sustainable, Water Resources Solutions Background on ERA –Major Rehabilitation Program (MR) ERA process started in USACE in early 1990’s ERA process for MR still in use today by many USACE Districts –Develop ERA Framework for MR »ER – Assist MR reports for planning studies (Section 6 and Enc 2) »Developed ETLs on ERA »Developed ERA specific models and examples - Gates, Sheet piles, Piles, Gravity monolith stability »Develop computer software - Piles (RCPGA) and monolith stability (RCSLIDE)

“ Building Strong “ Delivering Integrated, Sustainable, Water Resources Solutions Background on ERA –System Studies Upper Mississippi River Illinois Waterway (1993) –Development of more advanced reliability models –Structural models – limited geotechnical Ohio River Main Stem ( ) –Development of state-of-the-art reliability models »Using finite elements, advanced reliability techniques –Development of hazard rate models –System models feed back into MR reports Great Lakes and Saint Lawrence Seaway Study (2006 – Present) –Continued development of new ERA models –Extensive use of Expert Opinion Elicitation Panama Canal Study (2009-Present) –Bi-national studies to set prioritization of investment decisions for navigation lock maintenance.

“ Building Strong “ Delivering Integrated, Sustainable, Water Resources Solutions Background on ERA –Interagency Performance Evaluation Task (IPET) Katrina – Operational Risk and Reliability (2005 – 2009) Examine risks the conditions of levees and flood walls prior to, after 1 June repairs, and 100-yr design levels –Estimation of reliability for over 135 reaches and 197 gates and transitions –Full risk and reliability analysis –152 hurricanes, 37 sub basins –Examine economic and loss of life

“ Building Strong “ Delivering Integrated, Sustainable, Water Resources Solutions Background on ERA Advanced Development of Time-Dependent Models and Response Surface Models –Structural – Chickamauga Lock and Dam MRR – Alkali Aggregate Reaction (AAR) growth (2000) –Geotechnical - Wolf Creek Dam and Center Hill Dam MRR – karst seepage (2003/2004) Screening Portfolio Risk Assessment (SPRA) for Dam Safety (2005) –Rank USACE inventory of 600+ dams »Base rate adjustment »Adjustment to rating – Adequate, Probably Adequate, Probably Inadequate and Inadequate »Relative ranking procedure »DSAC Class (I-V) ranking »Completed in 2009

“ Building Strong “ Delivering Integrated, Sustainable, Water Resources Solutions Background on ERA –Dam Safety Risk Assessments Complete risk assessment procedure for site-specific dams with high DSAC ratings –Potential Failure Mode Analysis (PFMA) –Issue Evaluation Studies (IES) – more formalized ERA than SPRA –Dam Safety Modification (DSM) Report – a higher level MR ERA required –Levee Safety Risk Assessments Risk assessment procedure for USACE inventory of levees and flood walls –Levee Screening Tool (LST) – similar to SPRA, to develop inventory and LSAC rating –Potential Failure Mode Analysis (PFMA) –Issue Evaluation Study (IES) – currently under development –Levee Safety Modification???

“ Building Strong “ Delivering Integrated, Sustainable, Water Resources Solutions Where is ERA going in USACE Engineering? –Future of ERA in USACE? Increased usage and development –More major rehab studies –More system wide studies –More dam safety studies –More levee safety studies –Use in asset management (O&M) –Use in design of civil works infrastructure