Technical Workshop TW1Survey of International Dam Safety

Risk Approaches and Practices:KEYNOTE – INTERNATIONAL OVERVIEW

David S. BowlesRAC Engineers and Economists, LLC

and Utah State UniversityRACEngineers and Economists, LLC

TW1: Survey of International Dam Safety Risk Approaches and Practices

• France• Australia• United States• The Netherlands• Canada• Spain• United Kingdom• South Africa

1. The context and history of using dam safety risk assessment.

2. The range of purposes and approaches, including sources of guidance on procedures.

3. The use in decision making. including guidance on the tolerability or acceptability of risk.

4. Future trends in the practice of risk assessment and advice for countries who are                    considering starting to use risk assessment.

Traditional Standards Risk‐informed• Safety judged by compliance with 

engineering standards and good practice

• Focus on design loading cases

• Engineers are prime safety “decision makers” through conservative assumptions, severity of load cases and defense in depth

• Consequences of failure usually limited to potential “hazard” classification

• Compliance sometimes interpreted as “zero risk”

• Generally not well integrated with owner’s business processes

• In addition make “the case” for actions with reference to understanding of failure modes and demonstrating tolerable risk (life‐safety)

• Considers entire range of loading events and all significant failure modes

• Non‐technical decision makers are informed by engineers through characterization of failure risk

• Understanding and estimation of potential consequences of failure

• Understanding and managing non‐zero residual risk (understanding, options, probability and consequences)

• Can be well integrated with owner’s business processes

Why are some using risk assessment? • Better identification & understanding of dam safety issues

– Standards more likely to miss important risk drivers/failure modes• Backlog of dam safety work – need to prioritize• Reasons related to business

– Justify capital and O&M expenditures and timing– Enterprise risk management– Corporate governance – corporatization, privatization– Due diligence, liability management, business sustainability

• Reasons related to regulation – Economic (rate case), environment, health and safety regulators

• Because of growing acceptance in dam safety community– Increasingly becoming accepted good practice

• Better communication of risks to public and non‐technical decision makers

Define PURPOSE and OUTCOME TARGETS – VARY WITH PURPOSE, OWNER & CULTURE

1)Dam Safety Outcomes Failure modes/understanding Needed investigations/priority‐urgency Risk reduction options/priority‐urgency Monitoring & surveillance improvements

2)Business/Stakeholder Outcomes Potential liabilities/consequences Insurance/loss financing implications Capital budget and financing/justifications Rate case License to operate/safety case

1. Index (points/weights assigned to deficiencies)• Limited insights into failure mechanisms• Often distorts “risk estimates” including relative risks (“risk metric”)• Often leads to working on the wrong issues• Reclamation & USACE no longer use

2. Semi‐Quantitative Risk Analysis (SQRA)• Preliminary RA – Periodic Inspections/Portfolio• Not suitable for complex projects or                                                      

supporting costly or sensitive decisions3. Quantitative Risk Analysis (QRA)

• Issue evaluations• Risk reduction alternatives evaluation• Portfolio RA for complex projects• Uncertainty

Levels of Risk Analysis: “Decision Driven”

Consequences

Individual Dam Risk Assessment- One dam

Portfolio Risk Assessment- Many dams

Portfolio Risk Management- Should be integrated across dam safety program & owner’s business 7

Integration of Dam Safety Risk Management 

Process

Recurring Activities

Non-Recurring Activities

Risk‐Informed Decision Making(RIDM)

• New decision paradigm• Some concerned that RIDM will lead to lower safety

• If RIDM used properly it can lead to better decisions and lower risk

• Ironically a strictly standards‐based regulator can slow progress towards lower risk

• Should be coherencebetween

OK Not OKOK Agree ??

Not OK ?? AgreeRisk

Standards

Understanding of the Dam safety issues

Risk Estimates

the numbers

Planned Actions –O&M, Monitoring and Surveillance, Inspections and Risk Reduction

RIDM provides an Opportunity to Change the Regulation Paradigm

• FROM: standards‐setting by regulator AND compliance by the owner

• TO: goal‐setting by owner WITH oversight by regulator

• Mature Example: Victoria, Australia:– Statement of obligations of owner– Annual update of PRA submitted to regulator

• USA: opportunity for hydro‐dam owners to take the safety initiative with FERC RIDM Program

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Trends in Owner Governance• USACE

• Eric Halpin ‐ USA

• United Utilities, UK• PRA and updates to justify rate case to Economic Regulator

– Completed three 5‐year cycles

• Developed corporate tolerable risk guidelines ~ HSE• Some fixes not required by “regulator” but implemented to meet safety corporate tolerable risk goals

• In‐house dam safety coordination committee – better integration with owner’s business

Trends in PRA & PRM• Level of detail

– Use of SQRA/risk matrices for periodic inspections– Scaling QRA throughout PRM process

• Technical approach– Improved guidance for probability estimation– Simulation to replace empirical life‐loss estimation(HEC‐LifeSim, LSM)

• Involving community emergency managers– Software designed for dam safety risk assessment (DAMRAE)– Simulation approaches to replace event trees especially for river systems

• Dam safety decisions– Interim risk reduction measures –> “immediate” risk reduction– Improving recurrent activities– Staged/phased risk reduction and investigations

• Updating PRA– Up to three cycles in Australia and UK

Closing• RA

– Risk‐informed not Risk‐based– Important to use proper risk metric – caution about index approaches– Level of detail “decision driven”

• PRA– More than just Prioritization– “Work on the right things”– Urgency and priority are different– Include staged/phased investigations and risk reduction– Must update – living document – flexible software/decision support – scalable RA

• PRM– Improved approach to the owner's entire dam safety management program – Not simply an additional activity– Target desired types of outcomes– Integrate into owner’s business context

• Regulatory compliance is not sufficient– Owners have many other considerations– Important that the regulator allows a portfolio risk perspective– Owners should take the initiative with oversight from regulators

E‐mail:David_S_Bowles@hotmail.com

Home Page (including links to selected papers):http://www.racengecon.com/davidbowles.html