5:30 PM17:30

AEG Mile High Chapter October Meeting

Trying again! Talks by members presenting at the AEG Annual Meeting in Asheville:

(unconfirmed) Rebekah Bieber, ERM and Martin Marietta Materials
The Danger of Silos: Three Case Studies That Illustrate Why Professions Working in Different Areas Need to Talk

Casey Dowling, BGC Engineering Inc. (tentative, subject to field work)
Landslide Susceptibility Mapping for Large Landslides in Saskatchewan

Kevin Mininger, RJH Consultants, Inc. (tentative, subject to field work)
”Where to Focus” – Using the PFMA/SQRA Process to Manage Risk at a Single Dam or an Entire Portfolio

Social hour begins at 5:30, announcements and introductions at about 6:45, talks begin at about 7pm


The Danger of Silos: Three Case Studies That Illustrate Why Professions Working in Different Areas Need to Talk
Rebekah Bieber, ERM and Martin Marietta Materials; David Bieber

As professionals, we generally communicate with other professionals who do what we do. Three events illustrate why actively seeking out professionals working on related problems can potentially save lives and/or reduce property damage. The 1980 eruption of Mount Saint Helens in Washington killed 57 people and caused an estimated $870-million in damage. One of the takeaways of the event was that better communication between seismologists, volcanologists, and slope stability experts might have reduced the death toll. The 1994 Northridge earthquake in California, which killed 57 people and resulted in an estimated $20-billion in damage, occurred on a fault that was well documented by petroleum geologists working in the area, but was relatively unknown to engineering geologists and seismologists. Pre-event knowledge regarding the fault by engineering geologists in Southern California might have led to changes in seismic hazard zonation in the area. The 2013 Manefay slide at the Bingham Canyon Mine in Utah did not result in any deaths or injuries because mining engineers recognized the slope failure hazard potential before the event. However, the slide did result in several million dollars in damage to equipment. The size of the slide was not anticipated, which resulted in considerable property damage. In post-event analysis, mining engineers realized that had they had better knowledge of research into natural landslides they would have been better able to predict the magnitude of the event and moved vulnerable equipment out of harm’s way.

Landslide Susceptibility Mapping for Large Landslides in Saskatchewan
Casey Dowling, BGC Engineering Inc.; Pete Quinn; Matthew Lloyd; Matt Dipple

Large landslides are widespread in the Western Canada Sedimentary Basin, which extends across the southern two thirds of the province of Saskatchewan. A novel approach was taken with the application of a standard bivariate statistical method (weights of evidence) for development of a landslide susceptibility map for large, deep-seated landslides at a nominal scale of about 1:50,000. Large landslides were inventoried within a 500 m buffer of every community in the province, and this inventory of communities plus buffers served as the basis for analysis. This approach is novel in that the landslide inventory and study area cover a very small proportion of the whole study area but comprise a relatively unbiased and statistically significant representation of the whole, as confirmed through validation by landslide identification in randomly selected locations outside the communities study area. A map like this needs to have its continuous range subdivided into meaningful bins to result in a useful product that presents information in a way suitable to support decisions. The end users of the map were closely involved in establishing thresholds for use in subdividing the map into four bins of Very Low, Low, Moderate, and High Susceptibility—each with different intended use in planning for future linear infrastructure.

“Where to Focus” – Using the PFMA/SQRA Process to Manage Risk at a Single Dam or an Entire Portfolio
Mininger, Kevin, RJH Consultants, Inc.; Edwin Friend, Erin Gleason, Ryan Schoolmeesters, John Hunyadi

Where best to use limited resources is a key decision for dam owners and regulators, whether focused on a single facility or an entire portfolio. Risk informed decision-making (RIDM) was developed by large Federal agencies such as the Bureau of Reclamation and Army Corp of Engineers to address this problem. However, use of RIDM by smaller agencies and dam owners has been less common; perhaps because of a perception that a large commitment of resources is required. The Dam Safety Section of the Colorado Office of the State Engineer has developed a Comprehensive Dam Safety Evaluations (CDSE) process to effectively implement a potential failure modes analysis (PFMA) and Semi-Quantitative Risk Analysis (SQRA) of high hazard dams under their jurisdiction. A SQRA is much less resource intensive than a traditional Quantitative Risk Assessment, yet provides an economical and beneficial process for RIDM. RJH Consultants and Denver Water have successfully used the CDSE process at several dams to economically identify risk-driving potential failure modes (PFMs) and recommend mitigations and investigation activities to address the risk-driving PFMs. Geo-professionals are an important part of the PFMA and SQRA process because many PFMs are based on impacts from geologic materials and because we are practiced in the big picture thinking that is critical to identifying PFMs, evaluating how PFMs impact a dam and its foundation, and quantifying the likelihood of PFMs resulting in dam failure. This presentation will present our experiences with the SQRA process and case histories highlighting how the SQRA process effectively prioritized PFMs.

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