Every major tailings facility failure leaves behind a trail of devastation—lost lives, damaged communities, environmental harm, and shattered trust in the mining industry. Each time, we engineers pore over the investigations, publish lessons learned, and issue new guidelines. And yet, decades into my career, I’m struck by how often the same themes repeat themselves.
We’ve advanced tremendously in tailings management since the 1980s, but here’s what I believe we still haven’t fully learned from past failures.
1. Water Is Still Underestimated
If you read the post-mortems of most tailings dam failures, water shows up as the root cause: excess pore pressures, uncontrolled seepage, insufficient drainage, liquefaction triggered by saturation, or overtopping. We know water is the single most important factor in stability. And yet, water balance models are often optimistic, drainage features underperform, and extreme climate events overwhelm systems.
What we haven’t learned: Water is unforgiving. Every facility should be designed and operated with conservative assumptions, redundancy, and contingency plans. Hoping the water will behave is not a strategy.
2. Foundations Matter More Than We Admit
Several high-profile failures, including Mount Polley (2014), were driven by foundation conditions rather than embankment design. Weak layers, undetected shear zones, or collapsible soils undermine even the most carefully engineered structures. Despite this, I still see projects where foundation investigations are limited by cost or schedule pressures. Too often, we treat the ground as uniform when it rarely is.
What we haven’t learned: You can’t “engineer out” a bad foundation. Thorough geotechnical characterization is non-negotiable, and designs must adapt to what the ground actually gives us. I often say that you pay for a proper site investigation whether you have one or not.
3. Human Factors Are Overlooked
Failures are frequently attributed to “design flaws” or “unexpected conditions,” but in reality, operational decisions are often the trigger: raising faster than planned, neglecting instrumentation, mismanaging pond location, or cutting corners in construction. We still tend to separate design from operation, as if the two exist independently. But the safest design can be compromised by poor execution, and the best operators can’t save a design that isn’t practical in the field.
What we haven’t learned: Tailings facilities require a culture of responsibility, not just compliance. Engineers, operators, and management must stay aligned from design through closure.
4. Closure Is Still Treated as Tomorrow’s Problem
We’ve been talking for decades about “designing for closure,” but too often it’s still deferred. Facilities are built to meet production needs, with closure left to be figured out later, sometimes decades later. This mindset creates long-term liabilities that are costly, complex, and in some cases, unmanageable.
What we haven’t learned: A tailings facility isn’t temporary. It will outlast the mine itself. If closure isn’t part of the design from day one, we are setting ourselves and future generations up for failure.
5. We Keep Forgetting That Models Aren’t Reality
Modern software can produce beautiful, convincing analyses: slope stability, seepage, dynamic response. But as every failure investigation shows, the ground doesn’t read our reports. Failure modes are more complex than circles on a slope or neat finite element meshes. We continue to put too much faith in models and too little in observation and judgment.
What we haven’t learned: Analyses are guides, not guarantees. Real-world monitoring, regular inspections, and conservative assumptions are still the best defense.
6. We Still Struggle with Transparency
Finally, there’s a cultural lesson we haven’t fully absorbed: transparency. Many past failures were preceded by warning signs (rising pore pressures, unusual movements, inadequate designs) that were known but not widely shared. While the Global Industry Standard on Tailings Management (GISTM) is a big step forward, there is still hesitation in parts of the industry to openly share risks, data, and lessons.
What we haven’t learned: Tailings failures don’t just damage one company, they damage the credibility of the entire industry. Openness and accountability aren’t optional; they’re essential.
Closing Thoughts
Looking back at four decades in tailings management, I’m proud of the progress we’ve made. Facilities today are safer, better monitored, and more thoughtfully designed than they were in the 1980s. But the repetition of familiar themes in failure after failure tells me we still have more to learn, not just technically, but culturally. Until we truly embrace humility in the face of uncertainty, prioritize water management above all else, and design with future generations in mind, we risk repeating history.
And history has shown us the cost of forgetting.