FERC’S RISK-INFORMED DECISION MAKING

FERC’S RISK-INFORMED DECISION MAKING From PFMA to Risk Assessment Doug Johnson – Regional Engineer - Portland

834 High Hazard Potential 234 Significant Hazard Potential

In the Beginning… for FERC • Risk Assessments begin with a Potential Failure Mode Analysis (PFMA) • The FERC first began using risk in a dam safety context in 2003 when it documented the PFMA process into its dam safety guidelines (Chapter 14).

PFMA • A PFMA is an exercise to • identify all potential failure modes under static loading, normal operating water level, flood, and earthquake conditions including all external loading conditions for water retaining structure • assess those potential failure modes of enough significance to warrant continued awareness and attention to visual observation, monitoring and remediation as appropriate.

PFMA (cont.) • PFMs are developed by the core team • Likely and unlikely factors affecting the chances of occurrence are documented. • PFMs are categorized by level of seriousness.

PFMA Progress • Since the program was initiated all high hazard potential dams have been analyzed. • Significant and Low hazard potential dams are still in progress.

What is Risk-Informed Decision Making (RIDM) • Decision-making, which has as an input the results of a risk assessment. • Risk information will play a key role in decisions related to dam safety but will not be the only information to influence the final decisions. • RIDM involves a balancing of social and other benefits and the residual risks.

Extension of PFMA process • PFMAs detail how a dam might fail • PFMAs do not directly consider the scope of potential consequences • PFMAs do not estimate the likelihood of an adverse event • RIDM will consider these items

Why Risk?

Tolerable Risk • Risk society is willing to live with in order to secure certain benefits, • Risk society does not regard as negligible or something it might ignore, • Risk that society is confident that are being properly managed by the owner, and • Risk the owner keeps under review and reduces still further as practicable.

Joint Federal Risk Group • Includes Reclamation, Army Corps, TVA, FEMA • A common federal approach to Risk • Standards for risk reduction: Governance vs. Tolerance

RIDM Engineering Guidelines • Concrete Dams • Embankment Dams • Internal Erosion and Piping • Spillway Gates and Outlet Works • Operational Issues, SCADA • Hydrologic Hazard Analysis • Probable Seismic Hazard Analysis • Consequences • Risk Analysis • Risk Assessment

Benefits to Owners and FERC Provides a process to better understand and quantify potential failure modes; Identifies previously unidentified failure modes with high risk, in particular, non-traditional failure modes; Builds on the work completed in PFMAs Provides a means to compare the safety of different dams using a common basis - risk;

Benefits to Owners and FERC Improves understanding of the uncertainty and variability in traditional analyses; Provides a way to understand the risk associated with a single dam or an entire inventory of dams; Allows evaluation of risk reduction alternatives and effectively reduces the risk regulated dams pose to the public in quantifiable and defensible terms; Focuses resources on those structures that pose the greatest risk. (FERC Strategic Plan)

Final Thoughts • FERC RIDM program will proceed in parallel with deterministic methods for the near future. • Phased approach to implementation. • Dams requiring full quantitative risk will be few. • In longer run, PFMA process may be expanded to include Qualitative Risk Assessment

FERC’S RISK-INFORMED DECISION MAKING