Dam safety specialists across the United States are increasingly serving as Subject Matter Experts (SMEs) in risk analyses, a role that continues to expand beyond federal agencies. While the demand for qualified SMEs has grown significantly, opportunities for structured training remain limited.

This interactive virtual workshop is designed to prepare dam owners' staff, consultants, regulators, and other technical professionals to effectively participate in Potential Failure Mode Analyses (PFMAs) and Risk Analyses (RAs). Participants will develop a foundational understanding of risk-informed decision making, the probabilistic framework used in modern dam safety practice, and the critical role SMEs play throughout the risk analysis process.

The course emphasizes practical application by helping participants:

• Understand the fundamentals of risk-informed decision making.
• Build confidence in providing technically defensible expert judgments.
• Learn techniques for supporting subjective opinions with engineering evidence.
• Navigate differing expert opinions during facilitated discussions.
• Understand how risk results are developed and used to support dam safety decisions.

As an introductory course, this workshop provides the knowledge base necessary for participants to continue developing their expertise through future training and project experience.

Learning Objectives

Upon completion, participants will be able to:

• Explain the principles of risk-informed decision making.
• Describe the role and responsibilities of SMEs during PFMAs and Risk Analyses.
• Apply probabilistic thinking when evaluating potential failure modes.
• Effectively communicate engineering judgment and uncertainty.
• Participate more confidently in facilitated risk analysis workshops.
• Understand how risk outcomes support dam safety decisions and prioritization. 

Two half-day sessions

• Day 1: February 2, 10:00 am MT- 2:00 pm MT 
  • 3.5 instructional hours
• Day 2: February 4, 10:00 am MT- 2:00 pm MT 
  • 3.5 instructional hours 

For over 50 years, Dr. Bowles has been one of the most significant contributors to advancing the practice of safety and risk management in the United States and the international dam, levee, and mining engineering communities. His roles have included educator, researcher, coach, mentor, expert witness, technology developer, consultant, advisor, risk assessor, and contributor to many dam owners, regulators, and associated non-governmental organizations.   

Some of his contributions to our industry include: 

• A primary author of ICOLD Bulletin 130, Risk Assessment in Dam Safety, A reconnaissance of benefits, methods, and current applications – one of the fundamental guiding documents for modern risk-informed dam safety 
• Software for risk analysis and portfolio risk management and decision support, including development of LifeSIM application for life loss and other consequences estimating and software for forecast-based reservoir operations 
• Contributing author of dam safety policies at Reclamation and USACE 
• Individual and portfolio risk assessment and management practices 
• Spillway evaluation flood determination and dam breach modeling 
• Engineering hydrology, hydraulics, and sedimentation engineering 

Copyright © 2026 U. S. Society on Dams Printed in the United States of America ISBN 979-8-9870559-4-6 

FOREWORD 

The importance of monitoring programs for dam safety is widely accepted.  There are many historical cases of dam failures where early warning signs of failure might have been detected if a well-designed, well-executed dam safety monitoring program had been in place.  A monitoring program can provide information that is needed for a good understanding of the on-going performance of a dam.  Monitoring programs, including instrumentation and visual inspection, provide dam owners with knowledge of whether a dam is performing as expected and the ability to detect changes in performance.  This knowledge and ability is critical because the dam owner is directly responsible for the consequences of a dam failure.  Therefore, a well-designed, well-executed dam safety monitoring program must be a key part of every dam owner’s risk management program. 

This paper is part of a series of white papers prepared by the United States Society on Dams (USSD) Monitoring of Dams and Their Foundations Committee (the Committee) to address important topics with respect to the development and successful implementation of dam safety monitoring programs.  White papers in this series include: 

• Why Include Instrumentation in Dam Monitoring Programs?
• Routine Instrumented and Visual Monitoring of Dams Based on Potential Failure Modes Analysis
• Development of a Dam Safety Instrumentation Program
• O&M of an Instrumentation Program
• Instrumentation Data Collection, Management and Analysis
• Dam Safety Monitoring Training for Dam Operating Personnel 

While each of the above white papers addresses its topic in a “stand-alone” manner, there are interrelationships between these papers.  Readers of this paper may find it beneficial to refer to one or more of the other white papers for a broader understanding and perspective with respect to dam safety monitoring programs.  Up to this point in time, the series of white papers has primarily addressed programmatic aspects of dam safety monitoring rather than technological advances.  These papers that are programmatic in nature should provide dam owners, large and small, with basic information to evaluate or implement an adequate dam safety monitoring program.  These programs become more and more critical as our nation’s dams (and other infrastructure) reach and extend beyond their design lives. 

This particular white paper moves away from the pattern of discussing more general, programmatic dam safety monitoring topics to address a specific technical matter.  Proposals for the use of fully-grouted piezometer installations, rather than traditional piezometer installations (e.g., VW transducers or Casagrande standpipes installed in boreholes using sandpacks and bentonite chip seals), have resulted in technical discussions where people and organizations have reached a variety of conclusions.  The intent of this white paper is to shed light concerning when the use of fully-grouted 2 piezometer installations may and may not be appropriate and provide current “state-ofthe-practice” guidance for this installation approach.     

This white paper resulted from the work of a Sub-Committee of the USSD Monitoring of Dams and Their Foundations Committee.  Principal contributors to the effort were:

Pierre Choquet, DrEng., PEng., RST Instruments, Lead Author
John Hynes, PE, Stantec
Scott Martens, MEng., PEng., Teck Resources
Rudy Saavedra, PE, Durham Geo Slope Indicator
Jay N. Stateler, PE, retired from U.S. Bureau of Reclamation
Georgette Hlepas, PhD, PE, U.S. Army Corps of Engineers
Gerald Robblee, PE, GE, Schnabel Engineering
Michael Davis, PE, PEng., Stantec/TransAlta
Doug Wahl, PE, Geo-Pentech
Gordon Anderlini, PEng., BC Hydro
John Murphy, PE, U.S. Army Engineer Research and Development Center 

The Sub-Committee members would like to thank Jay N. Stateler for initiating this project and for preparing the first detailed draft that has remained the framework of the final version of the white paper. 

A Publication Review Committee (PRC) was formed by the USSD to review this paper composed of:

Tim Truong, PE, PMP, Yuba Water Agency, USSD Board Member and PRC lead 
Members of the TC220 on Field Monitoring in Geomechanics of the(International Society on Soil Mechanics and Geotechnical Engineering (ISSMGE),with special thanks to Leen De Vos, PhD, Civil Engineer, Flemish Government
Gord McKenna, PhD, Peng, PGeol, McKenna Geotechnical
Brad Long, PE, HDR
Matthew Walker, PE, Barr Engineering
Bradley Forbes, PhD, Peng, BGC Engineering   

The work of all these individuals, as well as the other members of the USSD Monitoring Dams and Their Foundations Committee that provided input regarding this white paper, is acknowledged and appreciated.  

Nonlinear weirs are attractive to practitioners as in some cases they provide a hydro-economical solution for new and rehabilitation projects. To academia, they remain a topic of interest due to a combination of the complex flow patterns they generate and the wide range of relevant geometries and application scenarios in rivers, dams, and other water resources applications with research topics including discharge efficiency, aeration, energy dissipation, local scour, driftwood and ice, and flow instabilities. Following three editions held in Europe and Asia (Liège, Belgium in 2011; Paris, France in 2013 and Qui Nhon, Vietnam in 2017), the 4th international workshop on Labyrinth and PKW moves to the United States, where several labyrinth and PKW prototypes coexist. As for the three previous editions, the workshop aims at bringing together people with varied background (engineers, researchers,...) to present and summarize the latest knowledge and developments on these non conventional hydraulic structures. Special emphasis will be put on planned and existing projects, data from real structures operation but also latest research developments.

Papers:

R&D – Floating Objects and Sedimentation

Labyrinth and PKW spillways in the USA Paxson G., Crookston – USA/Belgium

Behavior of floating trees at coexisting Piano Key Weir and gated spillway Yang J., Helgesson – Sweden

Effect of driftwood on the hydraulic performance of A-type PKWs in-stream or at reservoirs Venetz P., Pfister – Switzerland

Impact of sedimentation on the discharge capacity of labyrinth weirs Belzner F., Gebhardt – Germany

R&D – Hydraulics

Remote sensing of the 3D water surface downstream of labyrinth weirs Langohr P., Bung – Germany

Interfacial velocity characteristics downstream of a PKW vs. linear weir Belay B.S., Oertel – Germany

Model-Prototype upscaling of discharge capacity of Piano Key Weir Yang J., Nilsen – Sweden

Physical model investigations on nappe instabilities at labyrinth weirs Gebhardt M., Belzner – Germany

R&D – Design and Application

Studies of non-rectilinear weirs – From labyrinth to PKW Ouamane A., Lempérière – Algeria

Enhancing the hydraulic efficiency of PKWs – Recent research Yang J., Li – Sweden

Innovative association of Fusegate® and PKW Lempérière F., Chapuis – France

Innovative use of PKWs or labyrinth weirs for long dams in plains Ho Ta Khanh M. – Vietnam

R&D – Numerical Modeling

Sensitivity analysis of PKWs using CFD and empirical methods Oukaili F., Bercovitz – France

Experimental and numerical investigation of A-type rectangular side PKW Hussain S., Ahmad – India

Key width ratio influence on PKW discharge via OpenFOAM simulations Lüddecke L., Oertel – Germany

Investigation on flow field near A-Type PKW Quamar S., Ahmad – India

Project Applications

Projects – Lessons Learned

Lessons from Prado Dam labyrinth spillway design Diaz Y., Philips M., Allen J.D., Crookston B. – USA

Research and application of PKWs in Vietnam (2025) Ho Ta Khanh M., Dau Xuan T. – Vietnam

Case study: Burton Pond Dam – “Honey, I Shrunk the PKW” Bisio D. – USA

PKWs with orifice sluice Dau Xuan T. – Vietnam

Projects – Design

Arced labyrinth spillway for Dog River Dam Kirksey B., Tuladhar R., Hudock G. – USA

Springton Spillway: Arced labyrinth weir research and application Thompson S., Tullis B., Crookston B., Marchisello M. – USA

La Laye Dam design approach Roy M., Derrien S., Schaguene J.D., Dautois G. – France

3D modeling for Lower Crow Dam rehabilitation Bartels J., Bernedo Sanchez C. – USA

Projects – Construction

PKWs around the world Erpicum S., Jamali T., Crookston B. – Belgium

Nachtigal dam: 4917 m long labyrinth spillway Magnan D., Blancher B., Chapuis A., Guillemot T., Erpicum – France

High-altitude labyrinth weir design & construction Miller N., Provencher M. – USA

Stainless steel PKW at Oule Dam spillway Fournié Y., Tralli H., Alende J.D., Erpicum S. – France

In this webinar, Katie from KF Consulting Services will share proven strategies to help engineers write with confidence and precision. Drawing on decades of experience in engineering, project management, and technical writing, Katie will guide participants through the fundamentals of effective technical communication—whether preparing proposals, developing procedures, or finalizing project reports.

Transient populations can have a significant influence on risks posed by a dam, especially in locations with frequent water recreation downstream of the project. A key operating objective of many dams is to provide safe conditions for recreation within the vicinity of the dam. Dam Safety professionals must consider recreational populations when assessing emergency management plans and downstream consequences. These transient populations can be difficult to capture with conventional consequences modeling techniques which represent transient populations within a structure point dataset. Modeling methods often involve aggregating average annual population data and defining a set of points with fixed locations in the hazard area, potentially biasing risk estimates depending on the location of the point in relation to the terrain and hydraulics. These points do not capture uncertainty related to the transient population’s freedom of movement in the hazard area and do not allow for spatial variability or the representation of varying recreation populations near and within the river channel. Alternative methodologies are presented here which involve random spatial sampling of transient population points within the hazard area, capturing the influence of population density and spatial variability. A population sampling grid is used to redistribute transient populations spatially within a study area hundreds of times, simulating the possibility of a range of population distributions and hazard exposures within a recreation area. Additional methods are also presented to randomly assign population at risk within a study area as well as the modeling of transient populations with the evacuation model in LifeSim. The development of methodologies to better assess impacts to transient populations during breach events will advance risk assessment theory and practice and lead to better decision-making for risk estimators and emergency management agencies.

Since the introduction of FERC’s revised Part 12D program in 2022, over sixty Level 2 Risk Analyses (L2RAs) have been completed and over fifty Comprehensive Assessment Reports have been submitted to FERC.  This three-hour webinar will provide a discussion of the observations and lessons learned from the L2RAs and will provide clarification of existing L2RA guidance.  The webinar will also include a discussion of observations and general comments regarding the initial reviews of the L2RA reports.

Speakers: Staff from FERC’s Risk-Informed Decision Making Branch will be delivering the presentations

The 2023 Turkey earthquakes impacted a large region with seismic hazards such as strong ground shaking, surface fault rupture, liquefaction, lateral spreading, rockfall, slides, etc.  GEER-EERI mobilized a joint team in concert with Turkish colleagues to collect perishable data so that lessons could be learned from these earthquakes.  In this talk Robb Moss will give an overview of our GEER efforts, bring the lessons learned back to the US, and will give specific attention to the many earthdams that exhibited different levels of performance.

The effects of subsurface heterogeneity on liquefaction phenomena during earthquakes are discussed using case histories and nonlinear dynamic analyses with different subsurface modeling approaches. The importance of geologic and anthropogenic controls and the effects of stratigraphic heterogeneity, lithological heterogeneity, and inherent soil variability at the project site scale are discussed. The results of these studies reinforce lessons regarding the importance of subsurface characterization and its representation in analyses for evaluating liquefaction-induced ground deformations and their impacts on civil infrastructure.

Seismic performance assessments for earth slopes and dams are based on evaluating the permanent displacements induced by earthquake shaking and more recently probabilistic approaches have been proposed to incorporate uncertainties into the analysis.  This presentation will describe newly developed predictive models for earthquake-induced slope displacements based on finite element simulations.  The models are developed using both classical regression techniques and artificial neural networks (ANN), and models for both the median displacement and its variability are provided.  A missing part of most seismic performance assessments for slopes and dams is the translation of a displacement level into a damage state.  This presentation will also outline a seismic fragility framework for earth dams and slopes that is modeled after the approaches used for other types of infrastructure, such as bridges.  The framework uses an engineering demand model to predict the permanent displacement as a function of ground motion intensity, and a seismic capacity model to predict the probability of a damage state given the permanent settlement.