Today, slope heights are pushing limits that miners were only thinking about conceptually 10 to 20 years ago.
(Photo: Carly Leonida)

The question is: what strengths can the industry leverage to ensure that operational excellence continues to prevail? E&MJ asked three world-leading experts for their thoughts.

Toolbox Talk
Mark Hawley is executive director at Piteau Associates and Chair of the Large Open Pit (LOP) project, an industry- sponsored, international research and technology transfer project, which aims to improve knowledge of rock slope failures in open-pit mines. What are some of the most pressing geotechnical challenges that large scale open-pit mines face today? E&MJ asked Hawley. “First, slope heights are pushing limits today that we were only thinking about conceptually 10 to 20 years ago,” he replied. “Then, there’s a greater emphasis on social licensing and the potential for large open pits to impact nearby communities. There’s also increased awareness that geotechnical teams are a key component for the overall success of a mine. And there’s a greater focus on mine closure, and the need to engage early with multiple stakeholders.”

He added that meeting current and future staffing needs is a big challenge. Geotechnical credentials are easily transported from mining to other industries, and talent attrition is a significant problem. “We’re not doing a good enough job at attracting new professionals into the business, and training and retaining them,” added Hawley.

The Geotechnical Center of Excellence (GCE) at the University of Arizona is another industry-funded and member-led organization dedicated to bridging gaps that exist between academia, industry, and fields of study through a collaborative approach to research and education.

Founder, Dr. Brad Ross, explained: “Pit depth is a huge risk today. Ore grades are decreasing, strip ratios are increasing, and the sheer volume of material that needs to be moved means that we’re mining faster. All these factors affect rock stress and structures in different ways. And the truth is, we don’t know what the full effects of these changes will be yet.

“Take the Manefay landslide that happened at Bingham Canyon in 2013, for example. We knew that failure was going to occur thanks to really good monitoring. But when it happened, it acted differently than anything we’d experienced. It was a black swan event and a really important learning opportunity for the industry. But it also proved that there’s a lot we don’t know about how slopes of this scale will behave during failures.”

The increasing probability of failures both large and small is pushing the limits, not just of the industry’s geotechnical understanding, but also of the technologies designed to monitor and model open pits today.

“The monitoring tools we have now are very sophisticated compared to 10 or 20 years ago,” Hawley told E&MJ. “Technologies such as slope stability radar and time domain reflectometry (TDR) systems and accelerometer arrays, even remote satellite monitoring technologies, like In- SAR, were just starting to emerge 10 or 20 years ago, and only the largest mines could afford to use them. But today, virtually every moderate to large mine has access to these technologies and prices have come down significantly.”

Today, many mines use multiple stability radars rather than just a single one, and these routinely include InSAR and TDR. However, the data streams these systems produce are also massive and can easily overwhelm geotechnical teams with limited resources; managing this data and extracting useful insights is a job in and of itself.

“We are seeing a shift towards automated data collection systems and centralized data management,” said Hawley. “Many mines now have centralized geotechnical monitoring groups, located on site or remotely, which handle the data produced by several mines. The aim is to leverage economies of scale, generate efficiencies and bridge skills gaps.”

A blasthole drill rig at work at Freeport McMoRan’s Sierrita copper mine in Arizona, US.
(Photo: Carly Leonida)

Potter added that one of the biggest challenges for GCE members and stakeholders is that they have lots of tools to monitor slope movement on different scales, from a single drill hole all the way to InSAR, which can gather swathes of data about an entire site. But fitting that data together to understand what movement on one scale means in relation to another is a challenge.

“There are lot of different tools available that can integrate pieces of information relevant to slope monitoring,” she explained. “But there is progress to be made in terms of cross-platform tools that provide meaningful insights into the relationship between various data sets (surface and subsurface). A more holistic picture of a slope allows geotechnical engineers to be more proactive and take preventative actions based on small movements well ahead of time.”

Knowledge is Powerful
Managing surface deformations using radars, sensors and prisms has been a big focus in mining over the past decade. However, Hawley believes that going forward, leveraging subsurface monitoring systems (i.e., those commonly used in underground mining for cave advancements and undercut mining) for surface operations too, could unlock new insights.

“We don’t know enough about what’s happening at depth within slopes,” he said. “Technologies, like smart markers, which are placed in boreholes to measure real-time deformation at depth could give us a better understanding. That’s one emerging trend. Another would be the replacement of prisms with GPS monitoring systems that don’t require a total station system to monitor. They’re monitored instead using satellites and offer very high accuracy. We’re also seeing refinements in how we monitor using radars, and the balance between the different types of radar, and how that data can be visualized.”

Rockfall detection using technologies like Doppler radar is another key area for research and development. At the GCE, Potter and her team are exploring the use of thermal infrared cameras to detect when rocks dislodge from a slope and alert nearby workers/equipment operators.

“Over the past four years, we’ve been looking at the tactical applications of thermal imaging,” she said. “We’ve developed an algorithm that can automatically detect rockfalls using thermal imaging and have created a preliminary software that alarms for rockfalls and stores that information in a database. Now, we’re looking at understanding the long-term trends in that data and how rockfalls can inform larger slope movements and bench design evaluations. The industry hasn’t had a tool like this before that can systematically and reliably detect and record rockfalls.”

The project will also feed into the highwall safety project that’s being led by the U.S. National Institute of Occupational Safety and Health (NIOSH) which is looking to redefine catch bench guidelines. Part of this effort is the development of a slope incident database.

“Going forward, I think there’s an opportunity for miners to leverage AI and machine learning to better understand and manage their data,” added Potter. “By pooling data, as we’re doing in the slope incident database, the goal is to provide practitioners and researchers with access to a more comprehensive data set and to advance efforts to develop predictive models / algorithms and identify trends and risk factors.”

She added: “Gathering information from different sources, and helping companies work together to learn from each other and leverage these tools to make better decisions is an important part of our work.”

Educating Engineers, Today and Tomorrow
Collecting data is one thing but, as Potter, Ross and Hawley all eluded to, understanding what it shows and being able to take appropriate actions based upon it still requires people. Given the industry-wide shortage of geotechnical professionals, this means that elevating engineers from mundane data management tasks to more complex, problem solving-type tasks via high-quality, accessible and affordable training, is more important than ever.

In fact, all three experts interviewed for this article agreed that education and training should be the industry’s number one priority in pit slope management, and more broadly, over the next decade. Without that, the industry will not be able to meet its overarching productivity, safety and environmental goals.

Organizations like the GCE and LOP, and also the Australian Center for Geomechanics, which straddle industry, research and academia, have an important role to play in providing ongoing development and training opportunities that speak directly to the industry’s needs. Potter explained: “The GCE has upwards of 20 members, six of which are major mining companies, who also hold board positions,” she said. “They help us make decisions about which professional development topics to pursue, and which topics to research. I feel that structure keeps us closely connected to the industry.”

The GCE has a unique model for professional development. The team teaches certain courses and modules that are within their own areas of expertise, but the majority of course content is presented by subject matter experts from companies and organizations across the globe. The whole program is hosted online and reasonably priced.

Rockfalls are a major hazard for workers and equipment working close to highwalls. (Photo: Carly Leonida)

The majority of these courses were developed in partnership with the LOP which has underwritten course development since 2021, and purchased registrations upfront for its members to help support the development. “All of our courses, except for the geotechnical radar monitoring course, are based on books or texts by the LOP,” said Potter. “We work closely with their authors to ensure we’ve got the most up to date knowledge and subject matter expertise. We feel really strongly that there’s a need to bring people together to help solve these problems collectively and contribute to a better industry overall.”

Co-crafting Future Excellence
Hawley agreed: “The problems that we’re facing in slope stability are industry-wide, and they need to be tackled collaboratively for maximum impact. We’ll be kicking off the fourth phase of the LOP – LOPIV – later this year. Accelerating innovation and the development of technical skills and capabilities are key objectives of LOPIV. We want to encourage broader scale collaboration across the industry, not just among the top 10 or 20 multinational companies, but the next tier as well.”

LOPIV will have three core components. First, is the continued development of industry texts and guidelines for which the organization is well known. The team is currently preparing a refreshed version of its Guideline for Open Pit Slope Design which is a cornerstone for engineers the world over. “There’s been so much change in the industry since the original publication in 2009,” Hawley said. “It’s time for an update, and we’re hoping to publish that in late 2025. We’re also about to release a guideline on the closure of mine of open pit mines. That covers things like waste dumps, pits, water management facilities — everything but tailings. That’s been in development for five years.”

Another pending guideline details interactions between open pit and underground mine workings, and the final one covers the design and operation of heap leach facilities. “There have been a couple of large heap leach failures this year,” Hawley said. “We started developing this guideline in 2023, so we were a little ahead of the game. But this topic is very much front of mind for the industry now.”

Applied research is the second component of the LOP’s work, and the third is education. “As an industry, we’re not doing enough through the traditional university pathways to attract and educate engineers and geologists,” said Hawley. “Meeting the increasing need for qualified people will be key to maintaining a healthy and safe industry, and in reducing the incidence of slope failures. We need to find other ways to fill that need, and so the LOP is working with groups like the GCE to produce webinars and online courses that are accessible to students and professionals.”

Hawley believes organizations like the LOP will play an increasingly important role in the future of mining, given the multifaceted nature of the challenges that the industry faces. “Universities aren’t set up to deliver practical training,” he explained. “Their focus is more on education fundamentals, and pure and applied research. Also, funding for post-secondary education and mining focused career paths in universities continues to erode. Groups like the LOP can help to bridge those gaps and advance best practice across the industry. Ultimately, we’re stronger when we work together and share our resources.”