Briefing for Risk Analysis for Dam Safety Field Review Group

1
Probability of Failure for Gates, Equipment and
Early Warning Systems

• Briefing for Risk Analysis for Dam Safety Field
  Review Group
• 19 March 2002
• Stuart Foltz
• ERDC-CERL

2
Probability of Failure for Gates, Equipment and
Early Warning Systems

• Briefing Topics
• Dam Gate Risk Overview
• Activities
• Products
• Funding

3
Probability of Failure of Gates

• Risk analysis studies
• Gates were not part of Alamo Dam risk analysis
• Gates were not part of Hills Creek risk analysis

• Gates inspected in 2001

• Bureau of Reclamation doesnt focus on gates
• Corps (dam safety) focuses on seismic, PMF, and
  spillway erosion

• Huntington portfolio includes a gate focus
• Ft Worth portfolio includes a gate focus

4
Probability of Failure of Gates

• Common perception
• Failure of a gate presents a much smaller risk
  than dam failure.
• Based on risk analyses reported by Dr. David
  Bowles (Utah State University)
• Smaller, more frequent events can have greater
  cumulative consequences than large events

5
Probability of Failure of Gates

• Unknowns
• Anchorage deterioration
• LRL, NWD
• Trunnion friction
• Folsom
• ASCE, USCOLD,
• ICODS
• NWD (Omaha, Kansas City), Table Rock
• Untested gates
• No load
• Not operated under load
• Operational issues

6
Probability of Failure of Gates

• August 2001 gate inspections by Jack Lewin and
  Greg Ballard
• Hills Creek (Portland)
• Ft.Worth
• Huntington
• Inspection and thorough review of gate function,
  performance, and operations.

7
Probability of Failure of Gates

• Issues raised by Lewin and Ballard
• Emergency Preparedness of Project personnel
• Knowledge of flood charts
• Access to project by District personnel
• Gate exercising
• Maintenance of gates
• Incident records

8
Probability of Failure of Gates

• Consultant visits (continued)
• Many gates are in need of repairs and
  rehabilitation.
• Deterioration beyond what is deemed acceptable by
  the consultants
• Equipment below code and accepted standards
• Questioned readiness of backup power
• Consultants noted instances where small repairs
  necessary for reliable gate operation were
  delayed or not performed

9
Probability of Failure of Gates

• Consultant visits (continued)
• You may like to draw Stuart's attention to the
  methodology of creating a condition index as used
  by Scottish Hydro (now Scottish Southern
  Energy).

10
Probability of Failure of Gates
Huntington Portfolio Priorities
11
Probability of Failure of Gates

• FY02 milestones
• Identify critical components and generic events
  lists
• Assess gate incident databases
• Summarize EWS survey results

12
Probability of Failure of Gates

• Cal. State Univ. Fullerton (CSF) Research
  Effort
• Develop generic lists of gate related faults and
  events (phase III)
• Develop a criticality index to help identify the
  risk associated with those events

13
Spillway Condition Evaluation

• Hydro Quebec, Bureau of Reclamation, Manitoba
  Hydro, Ontario Hydro
• Condition evaluation procedures for
• Lift gates, Tainter gates
• Mechanical equipment
• Electrical equipment
• Operation
• Develop procedure to evaluate relative risk of
  gate related infrastructure components
• As of FY01, this effort is funded outside this
  work unit.

14
Failure of Electrical/Mechanical Gate Components

• http//www.mvr.usace.army.mil/failuredata
• Collecting data on performance of components that
  fail (Censored data)
• We need to determine how to uncensor the data to
  account for all the components that never failed
  or were replaced before failure.

15
Probability of Failure of Gates

• Failure data
• Rock Island web site
• NPDP data
• USACE tainter gate problems
• European data
• Inventory data
• EWS survey
• USBR

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Probability of Failure of Gates

• Early Warning Systems
• Components
• Flood prediction
• Flood management
• Emergency identification
• Emergency notification
• Evacuation

17
Probability of Failure of Gates

• Early Warning Systems
• What impact does EWS have on risk?
• Are there common deficiencies?
• What are the mitigation methods?
• Can EWS improvements be used to mitigate other
  risks?

18
Probability of Failure of Gates

• Three primary areas of concern for EWS
• 1 - Readiness of local authorities
• 2 - Testing of EWS
• 3 - Access vulnerabilities during flood events
• ? Are we over-confident in our abilities?
• Survey did not evaluate security or the impact of
  deferred maintenance on dam safety

19
Products FY02

• Conference presentations and paper
• ICODS Dam Safety Workshop (Feb 2002)
• Survey of USACE Early Warning Systems
• Portfolio assessment
• Review of gate assessment sub-contractor report
• Continuing process

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Products FY02(Incomplete)

• EWS Survey
• Combine with FY00 USBR survey report
• Publish report
• Criticality Analysis and Fault tree report
• Revise, expand, and improve draft report
• Draft inspection procedure for gate operational
  adequacy and electrical operating equipment
• (no longer funded by this work unit)

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Probability of Failure for Gates, Equipment and
Early Warning Systems

• Milestones FY03
• Complete framework for simplified comparison of
  relative risk
• Complete risk criteria for inspection
  maintenance scenarios
• Summarize and report existing gate failure data

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Funding