The Benefits of Understanding Soil Moisture for Tailings Stability

Tailings storage facilities (TSFs) are among the largest and most critical engineered structures in the mining industry. Designed to safely contain mine waste and process water over operational and post-closure timescales, their long-term performance depends on a thorough understanding of changing ground conditions, structural behaviour, and evolving geotechnical risk. 

Following several high-profile failures in recent years, the integrity, monitoring, and governance of these assets have become a global engineering priority.

For operators today, complying with strict frameworks like the Global Industry Standard on Tailings Management is no longer just a regulatory box to tick; it is a fundamental moral and operational imperative.

At the heart of structural integrity and compliance lies a seemingly simple yet profoundly complex factor: internal hydrology. 

Exploring the benefits of understanding soil moisture for tailings stability reveals just how closely a facility's safety is tied to how water moves, settles, and exerts pressure within its walls.

Traditionally, understanding moisture distribution across a tailings facility has relied on piezometers, inspections and localised sampling. While these remain essential, they only provide information at discrete locations.

Advances in satellite remote sensing now allow operators to monitor soil moisture behaviour continuously across entire facilities, providing valuable additional insight into changing hydraulic conditions and helping engineers identify areas that may warrant further investigation.

How does water content affect tailings impoundment safety?

The direct relationship between saturation levels vs shear strength of mine waste dictates exactly how much physical load the embankment can safely bear. Shear strength is essentially the friction and interlocking resistance between solid particles. 

As moisture within the embankment increases, the void ratio and degree of saturation begin to shift. When the tiny void spaces between soil particles become completely filled with fluid, it dramatically drives up the pore water pressure in tailings dams.

Elevated pore water pressures act as an invisible, internal wedge. This hydraulic pressure increases the buoyancy of solid soil particles, reducing their friction and fundamentally compromising overall slope stability. 

Relying on precise soil moisture analysis enables geotechnical engineers to monitor these internal mechanics continuously, spotting dangerous pressure trends long before visible cracks or slumping appear on the dam's surface.

The mechanics of failure: Liquefaction and suction

One of the most catastrophic events for a mine facility operator is static liquefaction—a sudden loss of soil strength that occurs without the shaking of an earthquake. 

Pockets of high moisture are notorious static liquefaction triggers in tailings deposits

When saturated, loosely packed tailings are subjected to even a minor shift in load, steepening of the slope, or rapid deposition of new material. As such, they can rapidly transition from a solid-acting mass into a fast-moving, destructive fluid.

Córrego do Feijão “upstream” tailings dam catastrophic failure in Brumadinho, Brazil (2019). Photo by BBC – EPA.

Conversely, understanding matric suction in unsaturated soil mechanics highlights a hidden structural strength. In unsaturated zones of the dam, capillary forces actually pull soil particles tightly together, adding significant integrity to the embankment. By carefully mapping moisture retention in soil, engineers can utilise these natural bonding forces. 

The key to unlocking these geotechnical advantages lies in dedicated soil moisture control, ensuring the materials within the embankment never cross the critical threshold from safely moist, to dangerously saturated.

Evolving technology: Moving to automated precision

In the past, mine operators relied heavily on periodic site visits and physical instrumentation to gather geotechnical data. 

However, manual checks are inherently time-consuming, labour-intensive, and fundamentally limited because they only provide a retroactive snapshot of a single moment in time.

Emerging technologies, such as satellite monitoring, are transforming the industry, supporting greater accountability, with broader and more reliable coverage, offering a more comprehensive view than conventional ground surveys.

A 2025 paper in Science Direct on Tailings dam failures highlights the importance of advanced monitoring technologies to prevent failures, revealing how the implementation of advanced monitoring technologies such as InSAR can provide early warnings up to two years before failures.

By delivering automated data directly to engineering dashboards, teams can track the exact movement of the internal wetting front. Furthermore, automation is vital for monitoring the ever-shifting climate impact on tailings dam seepage, allowing operators to see exactly how a sudden spike in moisture during heavy rainfall or rapid spring snowmelt affects the interior of the structure.

A proactive approach to risk management 

During research undertaken with the European Space Agency, Geofem identified elevated moisture conditions around a TSF prior to failure. While moisture alone does not indicate imminent failure, understanding these evolving conditions can provide valuable engineering insight when combined with geotechnical assessment.

Geofem combines its proprietary satellite derived soil moisture model (developed in partnership with the European Space Agency) with hyperspectral analysis to identify elevated moisture conditions and help differentiate surface moisture patterns that may be associated with natural water or tailings-related seepage, providing valuable insight into evolving geotechnical and environmental conditions. 

This enables you to: 

• Detect potential seepage earlier

• Prevent potential stability problems and erosion

• Improve understanding of changing ground conditions 

• Complement existing in-situ monitoring

• Support geotechnical investigations 

• Reduce environmental risk 

• Improve water management 

Geofem’s soil moisture model, developed using multi-source satellite data and in-situ observations, identified elevated soil moisture conditions prior to dam failure, highlighting the potential influence of moisture variations on TSF stability.  

Maintaining a mine waste facility is a complex, high-stakes responsibility. By prioritising continuous moisture monitoring and analysis, operators can gain a deeper understanding of the hydraulic conditions and processes influencing long-term stability.

The ultimate goal of integrating advanced monitoring practices is preservation — protecting human lives, safeguarding the surrounding environment, and securing the operational future of the mine.

By transforming moisture monitoring from a reactive approach into a proactive, data-driven science, operators can make informed decisions, identify emerging risks earlier, and strengthen the long-term resilience of their tailings management strategies.

Geofem’s mine-wide risk intelligence helps operators strengthen tailings storage facility management, improve geotechnical risk awareness, and support safer, more informed decision-making. 

By combining satellite-based monitoring with engineering interpretation, Geofem provides continuous visibility of ground behaviour, moisture-related risks, and changing environmental conditions across tailings facilities and surrounding mining infrastructure.

Get in touch with the Geofem team to discover how satellite-based monitoring can support proactive tailings management, enhance risk assessment, and provide the engineering insight needed to make confident operational decisions.