US Army Corps of Engineers Dam Safety

Transcription

1 US Army Corps of Engineers General Program Overview & Impacts of Issues on Project Regulation Charles Pearre, PE Program Manager,, Emeritus June 2011 US Army Corps of Engineers BUILDING STRONG

2 Defined Dam safety is the art and science of ensuring the integrity and viability of dams such that they do not present unacceptable risks to the public, property, and the environment. It requires the collective application of engineering principles and experience, and a philosophy of risk management that recognizes that a dam is a structure whose safe function is not explicitly determined by its original design and construction. It also includes all actions taken to identify or predict deficiencies and consequences related to failure, and to document, publicize, and reduce, eliminate, or remediate to the extent reasonably possible, any unacceptable risks Federal Guidelines for, Glossary of Terms (FEMA 148), April

3 Transition to a Risk Informed Program Moving from a solely standards based approach to a dam safety portfolio risk management approach. Standards based or essential guidelines approach is included in the risk informed approach. One element of a risk informed decision is compliance with tolerable risk guidelines Other non-quantitative factors will influence risk management decisions. 3

4 Risk Framework 4

5 Guiding Principles Portfolio Risk Management Life safety is paramount. Do No Harm Risk-informed corporate approach. Urgency of dam safety actions. Risk communication. Prioritization of studies and investigations. Formulation and prioritization of risk management measures. Level of detail of risk assessments. Routine dam safety activities. Risk Reporting 5

6 USACE Portfolio Management Reassess Risk & Revise DSAC Implement Risk Reduction Measures Modification Study Yes Monitoring, Instrumentation, and Evaluation Classification (DSAC) DSAC I, II, III,, & IV Dam safety issue Identified that requires further evaluation? Yes IRRM Issue Evaluation Study Remedial Action Justified? Training NO No NO All Dams Routine O&M Routine/Annual Inspections Periodic Inspections Periodic Assessment Incident or inspection finding triggers DSAC review? YES Outside Loop: Routine Activities Inside Loop: Non-Routine Activities Centrally Managed Processes: Queues Priorities Classifications Policy Decentrally Executed Processes: IRRMs Routine Activities Implementation of Risk Reduction Measures Jointly Executed: Risk Assessments IES & DSM Studies

7 Routine Activities Reassess Risk & Revise DSAC Implement Risk Reduction Measures Modification Study Yes Monitoring, Instrumentation, and Evaluation Classification (DSAC) DSAC I, II, III,, & IV Dam safety issue Identified that requires further evaluation? Yes IRRM (DSAC I, II, III Only) Issue Evaluation Study Remedial Action Justified? Training NO No NO All Dams Routine O&M Routine/Annual Inspections Periodic Inspections Periodic Assessment Incident or inspection finding triggers DSAC review? YES Monitoring, Instrumentation, and Evaluation Routine O&M Routine/Annual Inspections Periodic Inspection (5 years) Periodic Assessments(10 years) Training & Emergency Exercises Emergency Action Plans Budgeting ( Program and Maintenance)

8 Non- Routine Activities Classification (DSAC) DSAC I, II, III,, & IV All Dams Interim Risk Reduction Measures Reassess Risk & Revise DSAC Dam safety issue Identified that requires further evaluation? No Routine O&M Issue Evaluation Study Implement Risk Reduction Measures Modification Study Yes Yes IRRM (DSAC I, II, III Only) Issue Evaluation Study Remedial Action Justified? NO Routine/Annual Inspections Periodic Inspections Periodic Assessment YES Modification Study Implement permanent risk reduction measures Re-assess risk & review DSAC Monitoring, Instrumentation, and Evaluation Training NO Incident or inspection finding triggers DSAC review?

9 Action Classification I URGENT AND COMPELLING (Unsafe) Action Class General Description II URGENT (Unsafe or Potentially Unsafe) III HIGH PRIORITY (Conditionally Unsafe) IV PRIORITY (Marginally Safe) USACE Action Classification Table* Characteristics of this class CRITICALLY NEAR FAILURE Progression toward failure is confirmed to be taking place under normal operations. Almost certain to fail under normal operations from immediately to within a few years without intervention. OR EXTREMELY HIGH RISK Combination of life or economic consequences with probability of failure is extremely high. FAILURE INITIATION FORESEEN For confirmed (unsafe) and unconfirmed (potentially unsafe) dam safety issues, failure could begin during normal operations or be initiated as the consequence of an event. The likelihood of failure from one of these occurrences, prior to remediation, is too high to assure public safety. OR VERY HIGH RISK The combination of life or economic consequences with probability of failure is very high. Urgency & Risk Description SIGNIFICANTLY INADEQUATE OR MODERATE TO HIGH RISK For confirmed and unconfirmed dam safety issues, the combination of life, economic, or environmental consequences with probability of failure is moderate to high. INADEQUATE WITH LOW RISK For confirmed and unconfirmed dam safety issues, the combination of life, economic, or environmental consequences with probability of failure is low and may not meet all essential USACE guidelines. Actions for dams in this class Take immediate action to avoid failure. Validate classification through an external peer review for dams with life loss concerns. Implement interim risk reduction measures, including operational restrictions, ensure that emergency action plan is current, and functionally tested for initiating event. Conduct heightened monitoring and evaluation. Expedite investigations to support justification for remediation using all resources and funding necessary. Initiate intensive management and situation reports. Implement interim risk reduction measures, including operational restrictions as justified, and ensure that emergency action plan is current, and functionally tested for initiating event. Conduct heightened monitoring and evaluation. Expedite confirmation of classification. Give very high priority for investigations to support justification for remediation. Actions Required Description Implement interim risk reduction measures, including operational restrictions as justified, ensure that emergency action plan is current, and functionally tested for initiating event. Conduct heightened monitoring and evaluation. Prioritize for investigations to support justification for remediation considering consequences and other factors. Conduct elevated monitoring and evaluation. Give normal priority to investigations to validate classification, but no plan for risk reduction measures at this time. V (Adequately Safe) ADEQUATELY SAFE Dam is considered adequately safe, meeting all essential USACE guidelines with no unconfirmed dam safety issues, AND RESIDUAL RISK IS CONSIDERED TOLERABLE. Continue routine dam safety activities, normal operation, and maintenance. * At any time for specific events a dam, from any action class, can become an emergency requiring activation of the emergency plan

10 USACE Investment Plan Multi- Billion Dollar Investment to Repair over 300 Structures Includes all Moderate to Extremely High Risk Structures Time to Complete Investment -18 to 55 years depending on annual funding levels Population at Risk: +15 Million Avoids $236 Billion in Direct Damages

11 Prioritize Investment By Risk DSAC I DSAC III DSAC II

12 Interim Risk Reduction Measures (IRRMs) Classification (DSAC) DSAC I, II, III,, & IV All Dams Reassess Risk & Revise DSAC Implement Risk Reduction Measures Modification Study Yes Dam safety issue Identified that requires further evaluation? Yes IRRM (DSAC I, II, III Only) Issue Evaluation Study Remedial Action Justified? No NO Routine O&M Routine/Annual Inspections Periodic Inspections Periodic Assessment YES While the study, design, and construction of longterm solutions are pursued, IRRM are the most responsible way to manage the risk to public safety. Monitoring, Instrumentation, and Evaluation Training NO Incident or inspection finding triggers DSAC review?

13 Principles for Implementing IRRM at High Risk Dams The IRRM Plan sets the sideboards for decision making, decision points, and actions required. General public safety responsibility informs all of our statutory responsibilities. It is after public safety guidelines are met that other purposes and objectives will be considered. Decisions should be risk-informed, not risk-based. We manage risks of flood waters, we do not control them. Advanced planning and execution of mitigating measures is far more effective with planned, controlled release of the pool than with the case of unplanned, uncontrolled release resulting from failure of the project. 13

14 Non-Structural IRRM Examples Reservoir pool restrictions / operational changes Stockpile materials Improve/increase inspection and monitoring Pre-placed emergency contracts Establish pool levels for increased surveillance Update Emergency Action Plans Emergency exercises and coordination with stakeholders (includes communication) Warning systems Preventative Maintenance

15 Structural IRRM Examples Improve seepage collection system Install shallow cut-off trench Fill voids in embankment or foundation Grout/Seal conduit joints Grout curtain Downstream stability berm and/or inverted filter.

16 Issue Evaluation Studies Classification (DSAC) DSAC I, II, III,, & IV All Dams IES The study findings Reassess Risk & Revise DSAC Dam safety issue Identified that requires further evaluation? No Routine O&M YES determine the nature of the dam safety issue, Implement Risk Reduction Measures Yes IRRM (DSAC I, II, III Only) NO Routine/Annual Inspections the degree of urgency for action Modification Study Yes Issue Evaluation Study Remedial Action Justified? Periodic Inspections Periodic Assessment Report presents risk documentation justification for conducting a Modification Study Monitoring, Instrumentation, and Evaluation Training NO Incident or inspection finding triggers DSAC review?

17 Modification Studies Classification (DSAC) DSAC I, II, III,, & IV All Dams DSM Reports Reassess Risk & Revise DSAC Implement Risk Reduction Measures Modification Study Dam safety issue Identified that requires further evaluation? Yes IRRM (DSAC I, II, III Only) Issue Evaluation Study No NO Routine O&M Routine/Annual Inspections Periodic Inspections YES Decision documents to obtain approval to implement permanent risk reduction measures DSM Report replaces: Yes Remedial Action Justified? Periodic Assessment Major Rehabilitation Evaluation Reports Monitoring, Instrumentation, and Evaluation Training NO Incident or inspection finding triggers DSAC review? Assurance Evaluation Reports

18 Potential Impacts on Projects Short term impacts due to IRRM, i.e. pool restrictions Hydropower Water supply Navigation Flood Damage Reduction Recreation Planning for reallocation to Municipal & Industrial water supply Sponsor incurs costs related to dam safety and related RR&R actions Increases long term ability to operate as authorized

19 Reallocation Policy EC , Water Supply Storage and Risk Reduction Measures for Dam Safety, 15 March DSAC I, II, and III Projects A reallocation that would require raising the conservation pool is not permitted while a project is classified DSAC I, II or III. DSAC IV Projects: Recommendations for reallocations that would require raising the conservation pool will be considered by Headquarters USACE on a caseby-case basis. Reallocation reports that recommend pool raises must include a review of the Potential Failure Mode Analysis (PFMA) for the dam and an analysis of the effect of a higher pool elevation on the probable failure due to seismic or hydrologic conditions. Cost Sharing The non-federal entity will be required to share in the costs of IRRM and other remediation.

20 Cost Sharing Section 1203, WRDA 1986 Hydrologic and Seismic Deficiencies Major Rehabilitation or Operations and Maintenance: Older (pre-1986) agreements may allow for amortization Current model water storage agreement terms Seepage and Stability Deficiencies

21 Communication USACE will maintain public trust through effective, transparent, and continuous communication and stakeholder involvement. Public Meetings News Releases Agency Web Sites Hot Topics button at Facebook, Twitter, YouTube, etc. Updating Specific Stakeholders Water Supply Navigation Recreation Hydropower Emergency Management Preparedness Exercises Downstream Notification Chain You are always welcome to call the Public Affairs Office.

22 Modifications Some modifications can adversely effect water supply infrastructure Cut off wall Changes to outlet conduit Cost sharing of modifications Prorated by project purposes Seepage/Stability modifications Full cost sharing by purpose Section 1203 (Seismic & Hydraulic) 15% of standard cost sharing Slide 22

23 EC Restrictions Total number of Dams = 652 Includes saddle dams and levees around upstream towns and villages Number of Projects = 557 Dams authorized and constructed Corps O&M Number of DSAC I, II, & III Dams = 288 Dams/Projects available for water supply studies = 269 (48% of Projects) Dry Dams = 62 Less Than 100 acre feet of normal storage Navigation Dams = 138 Slide 23

24 Summary Observations of Dam Safety Program Geotechnical Issues Dominate Portfolio DSAC ratings can change with events, study, or remediation DSAC IV is a combination of low consequences and low risk Balancing Water Supply with other purposes is important Slide 24

25 Questions? Please continue to keep dam safety in mind New Delhi Dam Failure in Iowa (non-fed) July 2010