Join us at MINEXCHANGE on February 25–28!
Russ Sheets is a senior geotechnical engineer in Barr’s Bismarck, North Dakota, office. Russ has nearly 20 years of experience using geological information to understand site conditions and make recommendations for mining projects. Having worked on projects from the pre-feasibility stage through mining, he interprets and analyses geologic data to develop practical solutions for stable designs that mitigate geohazard risks. Here, we chat with Russ about the many factors that come into play when developing inventive solutions to the complex mining challenges you’ll encounter in the field.
Russ will present more on this topic at the upcoming Society for Mining, Metallurgy, and Exploration (SME) MINEXCHANGE 2024. Check out his presentation, “A Surface Geotechnical In-Pit Underground Portal Relocation: An Operations-Based Case Study,” on Wednesday, February 28, at 3:45 p.m. The case study investigates a past project in which competing operational site needs resulted in a safely managed slope failure.
You studied geological engineering in college. What challenges did you face applying this knowledge once in the field?
I discovered that the general model or design inputs for mining, geological, or hydrology analysis that I learned in college were simplified and uniformly applied across a geologic formation or area. The intention is for students to learn the concepts and how to solve the problem, as learning every possible site-specific geological scenario is impossible. Then real life hits when we get into the field. For example, laboratory results are not necessarily clean enough to provide a clear strength criterion. Or groundwater data identifies multiple compartments and flow paths at depth that must be considered, rather than a clean “water table.” This is when a new graduate engineer begins to understand there is more “how to” information needed to solve the problem, including site conditions, observations, and engineering judgement.
I had to learn myself that the “best” mining geotechnical solution on paper or computer may not be practical on site.
Once on site at a mining operation, a young engineer begins to understand that any solution must consider the non-geotechnical factors. I had to learn myself (and later mentor my junior staff) that the “best” mining geotechnical solution on paper or computer may not be practical on site.
What if the available equipment cannot construct the design? What if the geotechnical-only solution negatively impacts the business needs of ore production and cash flow? What if you’re unable to sway the preconceived notions of others? In these scenarios, it’s important for young engineers to learn that this is not an indication of their technical skills but rather an indication of a more complicated decision-making process outside of their control or influence. The solution may indeed be perfect—if geotechnical engineers ruled the world! (For more on this concept, see my article in SME’s Mining Engineering magazine.)
British mathematician George Box once said: “All models are wrong, but some are useful.” How do you apply this quote to your work in the field?
Early in my career, I was fortunate to have mentors who helped guide geological-based support in the context of this familiar quote. At some point, all models are going to be limited by the amount of data available, ability to organize and process, and then compute through an analysis. Depending on project site conditions, the intent is that you have enough information to develop a model that is accurate and precise for your situation.
You then must question whether your model is useful enough to guide recommendations. This is when the human-factor of engineering judgement must be leveraged. Ideally, your team is comfortable with discussing the opportunities and limitations using open and honest communication.
There are frequently competing priorities on a project site. How do you find a path forward?
One of my early mentors explained it this way: My responsibility is to “tell him what I know, when I know it, and then—to the best of my abilities with the information available—determine the extent of the risk and my thoughts on mitigating that risk.” Depending on the situation, we may not always be right, but it’s our responsibility to keep sharing updates or changes in opinion as they happen. And, even with my feedback, there will be competing priorities that may ultimately drive any decisions.
There will be competing priorities that may ultimately drive any decisions.
Consider these competing priorities: The timing to fully implement a geotechnical-driven design change may mean that ore production targets will not be met for the month, or quarter, or year. But, if the safety of personnel can be maintained during project implementation, is there a practical way to continue mining for production while using monitoring and more operational controls? Or, can the geotechnical solution be phased or completed at a slower pace concurrent with mining? Safety is always the overarching priority and, if people can be kept safe with various geotechnical solutions, then they can be considered viable solutions.
In my upcoming presentation at MINEXCHANGE 2024, one competing priority I address is the interaction between surface and underground mine operations in the same area. What is the driver for decisions? Underground mine production, or surface operation equipment availability to remediate the access? And what about weather impacts? If a slope failure is precipitation sensitive, can we wait until the weather improves when risks will minimize without added effort or cost? The question will get asked, “What are the chances of a catastrophic slope failure actually occurring?”
Where does operational experience come in? How do you balance this with your engineering training?
As a rookie engineer, there is not a silver bullet to quickly understand project risks and solutions—although that would be nice! These skills come with time as engineers gain the operational experience needed to make decisions that require sound engineering judgement. Spending time in the field inspecting, monitoring, and simply observing open-pit slope behavior to understand the geological or geotechnical aspects is one key component—but learning the mine and business plan drivers is another.
Is the solution achievable with the resources available, based on input from mining operations and engineers? While a computer-designed model of an ideal slope design or failure remediation plan may appear to be a sound solution, if it cannot meet business plan needs or be executed in the field, is it really a solution? And if mining operations staff and engineers do not understand the solution as presented, the chances of it being implemented are slim to none.
Determining when to use internal resources and when to reach out to external resources is another critical factor to consider.
Determining when to use internal resources and when to reach out to external resources (i.e., consultants) is another critical factor to consider. Has an on-site mine operations team been carrying out a ground control monitoring plan? If yes, has there been consistency over time, or substantial staff turnover? Does the team understand both the technical and operational challenges at the site?
If not, how frequently has a consistent, external geotechnical engineer been brought in to observe conditions as an open pit slope is established? What value and experience would external geotechnical engineers provide? Does the execution schedule support additional time and costs to bring someone potentially unfamiliar with the site up to speed?
Who is best suited to evaluate your mine operation for any geotechnical risk? While theoretical, technical-based knowledge is essential, understanding geotechnical risk from an operational experience standpoint is paramount.
Contact our team to learn more about our approach to developing safe, practical, achievable solutions customized to your mine’s needs.
About Russ Sheets
Russ Sheets, senior geotechnical engineer, has nearly 20 years of experience using geological information to understand site conditions and provide recommendations for geotechnical projects. His experience includes planning and executing investigations for new development, existing sites, and ground failures, as well as interpreting and analyzing geologic data to develop practical solutions for stable designs that mitigate geohazard risks. Additionally, Russ has implemented inspection and monitoring systems to investigate soil and rock behavior. Prior to joining Barr, Russ developed his geological and geotechnical skill set in the gold fields of northern Nevada.
Related projects
A local area within a highwall at Bald Mountain had an existing instability and rock fall hazard in the upper open-pit slope. This instability was potentially jeopardizing mining operations due to its location above a primary haul ramp for active mining. To study the instability, Barr conducted a geological and geotechnical analysis and reviewed previously collected slope monitoring data with respect to precipitation before delivering our assessment of the highwall condition and geotechnical approach for slope instability. Additionally, Barr reviewed all aspects related to risk mitigation, including geotechnical and operational controls and practices, development of threshold movement rates, and industry best practices for mitigating geotechnical risk.
Open-pit mining operations bear a degree of risk related to slope stability due to factors such as geology type, weather, seismic activity, and mining practices. Record rainfall levels in Nevada caused a pit wall to fail at a client’s open-pit hard-rock mine, forcing the closure of pit haul roads and two active mining areas. Barr worked with the client to adjust site access and implement a monitoring program to allow operations to resume while a long-term remediation plan was developed. Barr’s remediation plans were successfully implemented, and the facility returned to normal operations with its primary haul roads less than four months after the slope failure.