What are the best practices, tips, and tools to prepare for your Semi-Quantitative Risk Analyses Workshop?

By Nick Paull, Project Engineer; Kerri Puckett, Water Resources Engineer, and Chris Krage, Senior Engineer

The Federal Energy Regulatory Commissions (FERC) has updated its Part 12D inspection process. It now incorporates a Semi-Quantitative Risk Analysis (SQRA) as part of the Comprehensive Assessment (CA) process for high hazard, FERC-licensed dams in the Unites States. While other entities in the dam safety community have used SQRAs for many years, the updated FERC regulations have a wide-ranging impact on moving the dam industry toward using risk-based approaches.

In a SQRA, a team is assembled who will develop a broad understanding of the likelihood of failure for various potential failure modes (PFMs) for the dam and the associated financial or life-loss consequences. As part of the SQRA process, the SQRA team will be required to perform an in-depth review of background information prior to holding a SQRA workshop. Because many dam owners have never been through a SQRA, we’re going to shed some light on the process. Between 2021 and 2023, GEI’s dam safety team performed 16 SQRAs in six different states.

In this blog, we’re sharing a few of our insights on the process; we’ll look at good practices, tips, tools, and lessons learned from preparing for SQRA workshops.

Why SQRAs?

SQRAs provide a useful framework to illustrate the risk associated with PFMs and the total risk for each dam (i.e., aggregate risk associated with all PFMs). For individual dams, the risk results can be used by owners to identify the risk-driving PFMs and help prioritize funding and studies focused on these PFMs.  For owners with multiple dams in their portfolio, performing SQRAs for each dam can also help prioritize the dams that are risk drivers, to better understand which dam facilities have the highest risk, and how to best spend your dam safety funds.

Choose Your Team

Your SQRA team is generally comprised of:

• The Independent Consultant(s) (ICs)
• Facilitators
• Subject Matter Experts (SMEs)
• Owners Representatives

To assemble the right team, consider the strengths and weaknesses of each member, including their technical discipline, availability, and personality. Your SQRA team should be “right-sized” for the size and type of dam being evaluated. Larger teams will likely be less efficient. If possible, try to find ways to streamline the SQRA team by having a single participant serve multiple, non-conflicting roles.

Prepare Your Team

Practicing the SQRA process with core team members ahead of time can save time within the workshop. Practice creating and estimating PFMs with a probability estimating tool prior to the workshop to familiarize participants with the entire process. There are often pieces of background documentation that have not been digitized or are not included in the documents provided for the team’s review. Practicing ahead of time can also remind participants of the kinds of information they will need.

New Analyses Required for your SQRA

In advance of the SQRA workshop, you will need to complete a Hydrologic Hazard Analysis, Probabilistic Seismic Hazard Analysis, and Consequence Evaluations. In 2022 and 2023, timing of the rollout of the new FERC guidelines dictated that these studies be performed in the same year as the Comprehensive Assessment. Going forward, these studies can be separated and performed in advance of the Comprehensive Assessment, which can allow owners an opportunity to spread funds and staff resources over multiple years. Depending on the sensitivity of the dam to hydrologic and seismic hazards, simplified approaches can also be applied to lessen the burden.

Reduce Sources of Uncertainty ahead of your Workshop

Uncertainty is embedded throughout the SQRA process. Your SQRA team will be required to estimate failure likelihood with an incomplete dataset, so it’s critical that your team includes appropriately experienced Subject Matter Experts. In the FERC process, these SMEs must demonstrate sufficient experience in their field of expertise and be approved in advance to serve on the team.

While we cannot eliminate uncertainty, there are strategies that can help reduce the uncertainty where possible.

The more data that is available the better. Digitizing old reservoir level or precipitation data can be helpful to augment data sources available online. The SQRA team often needs to extrapolate previous studies to consider the impact of hydrologic or seismic loads larger than those that had been previously considered. By including a larger database of previous conditions, these extrapolations can be better anchored to past conditions and the structure’s response to the broader range of loads can be better estimated.

Some additional analyses can also be helpful to perform in advance of your SQRA:

• Stability Analyses
  • Free body diagrams for overturning or sliding of rigid structures, and
  • Limit equilibrium analyses for embankments or slopes
• Seismic Analyses
  • Probabilistic liquefaction triggering analyses
  • Empirical crest settlement or cracking estimates, and
  • Seismic slope displacement analyses
• Internal Erosion
  • Filter compatibility checks, and
  • Nodal estimates of internal erosion probabilities based on soil type
• Geologic Analyses
  • Erosion rate estimates, and
  • Geologic mapping

Keys to a Successful SQRA Workshop

Most SQRA workshops that our team has facilitated required about 10 days to complete, which means the workshop takes hundreds of person-hours by the SQRA team.  With the potential for hundreds of brainstormed failure modes to work through, it’s almost impossible to escape redundant procedures. But, based on our experience, we recommend the following strategies to help make the workshop a positive experience:

• Plan to be Gone
  • SQRA workshops require experienced senior staff to be mostly unavailable for two to three weeks. Work with staff and other clients ahead of time to prepare for this absence.
• Have a Singular Focus
  • Avoid multitasking or looking ahead so you can focus on the current workshop task.
• Communicate Absences
  • If you have an unavoidable conflict during the workshop, notify other participants including FERC, several days in advance.

• Leave Time for Others
  • Rather than scheduling full-day workshops, consider adjusting workshop hours into blocks with a two-hour break in the middle to allow participants to step away and check in on other projects.
• It’s a Marathon, not a Sprint
  • You may be tempted to push through the workshop as quickly as possible. But this can lead to missing critical information that could impact risk estimates. Create a positive, “slow and steady” mindset for all participants.
• Listen to the Room
  • Adjust the planned times if participants are worn out and inject 5-10 minute breaks to help relax the room.
• Screen with Care (But Still be Quick)
  • Screening out PFMs can be helpful to reduce workshop time, but be careful not to screen out PFMs just to “make it go away”.
• Be Aware of Biases
  • Providing an overview of potential biases can help prevent their potential impacts.
• Know your Limit and Estimate Within it
  • Only make likelihood of failure estimates within your area of expertise and engineering judgement.
• Different Roles, Same Goal
  • Different parties have different perspectives, but everyone has the goal of dam safety.

Conclusion

While FERC’s new updated 12D inspection process is still in its infancy, the preliminary results from the process have been informative and have helped owners, consultants, and regulators to better understand a given dam’s risk drivers.

The SQRA process can be long, labor intensive, and expensive. This blog has provided a general overview of good practices, tips, tools, and lessons learned from preparing for SQRA workshops. For a deeper dive into the process, or to begin preparing for your own SQRA, contact Nick Paull, Kerri Puckett, or Chris Krage.