Building Blocks for Practical Quantitative Risk Assessment

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The webinar will review the basic building blocks for performing quantitative risk analysis related to dam safety and how they fit into the spectrum of risk assessment.  Several potential failure modes will be discussed along the way to illustrate the concepts and how they fit together. 

 Topics will include:

• Brainstorming and initial screening of potential failure modes
• Potential Failure Mode Identification – This is the first vital step for any risk assessment.
• Semi-quantitative risk assessment for additional screening of potential failure modes.   Since there is a 3-day training class available through USSD for this, only a brief description will be presented, but criteria for deciding which potential failure modes to carry forward to quantitative risk analysis will be discussed.
• Event Trees – The rules for constructing event trees from potential failure mode descriptions and for estimating probabilities will be discussed.
• Load-Frequency Analysis – Determining load probabilities from seismic hazard curves, hydrologic hazard curves, and reservoir frequency curves will be discussed.
• Probabilistic Analyses and Models – The mechanics of performing probabilistic analyses will be discussed.
• Frequency Data – Sometimes statistical data can be used to make some judgments about probabilities.
• Subjective Probability and Expert Elicitation –The procedures for conducting expert elicitation to obtain probabilities, and some of the biases to be aware of, will be presented.
• Consequences – Consequences represent one third of the risk equation.  Estimating consequences, focusing primarily on life safety, will be briefly discussed.
• Tolerable Risk Guidelines and Building the Case – How the building blocks fit together and building the case for whether the estimates meet tolerable risk guidelines will be discussed.


The webinar is geared toward people of various disciplines and experience levels working in the area of dam safety.  A basic understanding of dams and appurtenant structures, as well as traditional dam safety evaluations will be useful in understanding the information presented.

2 CEUs

Gregg A Scott, P.E., F. ASCE

Scott Consulting, LLC

Mr. Scott received his B.S. and M.S. degrees in Civil Engineering from the University of Colorado, Boulder. He started his career with the Bureau of Reclamation in 1976, where he worked for 34 years before joining the U.S. Army Corps of Engineers Risk Management Center as Lead Civil Engineer, where he worked through 2018. He has been involved with design, analysis, and construction of dams and dam safety projects, as well as the development and application of potential failure mode analysis and risk analysis for dam safety. He served on several review panels for Bureau of Reclamation and Corps of Engineers dam construction and dam safety projects. He has authored over 35 technical papers in journals and conference proceedings related to dam safety and dam engineering. He is now retired from Federal service, but continues to consult on a limited basis. 

Bill Fiedler, P.E.

Senior Technical Advisor


Bill has 42 years’ experience in hydraulic and structural engineering designs for concrete dams and appurtenant structures, with the Bureau of Reclamation. While with Reclamation, he served as a technical specialist and design team leader for numerous water resource projects. In the later part of his career, he served as a member of Reclamation’s three-person Risk Advisory Team, which was responsible for developing additional risk analysis methodologies and providing training for Reclamation.

staff. Bill has particular expertise in concrete dam and spillway modifications, including: project planning and design coordination; analysis and design of structural modifications; review of design drawings and specifications; construction support; and risk analysis methodologies and facilitation. He has written numerous papers focused on dam safety evaluations and dam safety modifications. He was a lead author on a Reclamation manual focused on drains for dams and on a FEMA manual focused on flood overtopping protection for dams. For the past two years, he has worked as a consultant in the role of senior technical advisor.


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01/26/2023 at 10:00 AM (MST)  |  Recorded On: 01/31/2023
01/26/2023 at 10:00 AM (MST)  |  Recorded On: 01/31/2023 You will access the webinar through Zoom
2 Questions
PDH Certificate
2.00 PDH credits  |  Certificate available
2.00 PDH credits  |  Certificate available