Tailings

Primary reference(s)

GISTM, 2020. Global Industry Standard on Tailings Management. Accessed 21 May 2025

Annotations

Key relevant UN convention / multilateral treaty

Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (1972), also referred as the ‘London Convention’ prevents dumping of waste at sea. At the time of writing, there were 87 parties to the London Convention (IMO, 2019).

UNECE Convention on the Transboundary Effects of Industrial Accidents (1992) at the time of writing had 41 Parties (UN Treaty Collection, 1992a).

Convention on the Protection and Use of Transboundary Watercourses and International Lakes (1992) also referred as the ‘Water Convention’, applies as industrial accidents at tailings management facilities may lead to water pollution (UNECE, 2014). Serviced by the United Nations Economic Commission for Europe (UNECE), it started as a regional convention but was opened up to countries outside the UNECE region in 2016. At the time of writing, it had 43 parties (UN Treaty Collection, 1992b).

Directive 2006/21/EC on the management of waste from the extractive industries also referred as the Extractive Waste Directive (2006) (European Commission, 2019).

Directive 2012/18/EU on the control of major-accident hazards involving dangerous substances, amending and subsequently repealing Council Directive 96/82/EC Text with EEA relevance also referred as the Seveso III Directive includes in its scope operational tailings disposal facilities, including tailing ponds or dams, containing dangerous substances (European Commission, 2019).

Drivers

TSF failures are occasionally associated with seismic activity but for rarely as seismicity is typically a critical aspect of the design considerations. One example where this occurred was in 2011 following the 9.0 magnitude earthquake off the coast of Japan's main island, Honshu, that led to the Fukushima Daiichi nuclear disaster.

As extreme rainfall events have become more prevalent due to climate change, this is a complicating factor in the management of water levels within TSFs. Some TSF failures have coincided with periods of heavy rainfall (e.g. the September 2024 failure of a TSF at Lanjigarh in Kalahandi district of Odisha - see here).

Impacts

Tailings may contain heavy metals, arsenic, string acids and strong bases and release them in the environment. 

Multi-hazard context

The figure below summarises common interactions between tailings and other hazards. This information should be used with caution and not be solely relied upon in Disaster Risk Management, particularly as some interactions may not have been included. Note that hazardous events occurring together or locally in space or time may not necessarily cause, amplify, or be otherwise related to each other. Specific examples of multi-hazard context can be found in the ‘Hazard drivers’ and ‘Impacts’ sections above. 

Multi-hazard diagram

Risk Management

The most commonly used approach to the handling and storage of tailings is within dammed impoundments referred to as ‘tailings storage facilities (TSFs)’ (Oberle et al, 2020; World Bank, 2021). TSFs are engineered structures that comprise the confining embankments (commonly referred to as tailings dams) and are designed to contain tailings and to manage associated water. A They contain mixed waste material from mining processes in liquid or slurry form and must be responsibly managed to prevent impacts on human health and safety, the environment, and other infrastructure. Other less commonly used approaches for tailings disposal include riverine disposal, submarine disposal, lacustrine disposal (in lakes), backfilling underground workings, and dry stacking (some of which are dependent on prevailing conditions and regulations and some no longer considered to be good practice). 

Tailings are usually stored within TSFs under water to prevent the formation of surface dusts and acid mine drainage (by forestalling oxidation), especially when large amounts of acid-generating pyrite and pyrrhotite are present (Kossoff et al., 2014; Koomsona et al., 2021). This requires careful management of water levels within storage facilities to prevent erosion and related problems. 

TSFs require particularly careful management for preventing and minimising air, water, and soil contamination. The rate of failure has been estimated as one in 700 to one in 1750 which is significantly higher than for water-retaining dams – one in 10,000 (David, 2003). Causes of failure include overtopping, poor maintenance, breach following heavy rain, breach following earthquake, foundation failure, and retention wall failure (Kossoff et al., 2014). Furthermore, abandoned mining sites and mining waste storage facilities may contain chemicals and other elements which may be dangerous to human and animal health and to the wider environment. 

Effective legal and institutional frameworks for dam safety and environmental protection, implementation and enforcement of relevant laws and safety standards, adequate tailing dam designs based on accurate risk assessments, regular inspections and special monitoring systems are of critical importance for sound tailings management (Centre for Economic Development, Transport and the Environment, 2012). 

Application of technology-driven solutions such as remote sensing methods has shown significant development for tailing dam monitoring and early warning systems to prevent their failure. More attention needs to be given to monitoring of the leachate coming out of the ponds/dams.

Monitoring

The section and the table below offer an overview of monitoring tailings. This information can be used for forecasting within a national early warning system (EWS). Since EWS capacities and processes differ across countries, the most current and specific information regarding EWS should be obtained from the appropriate national or regional agency/authority responsible for disaster management.

Surveillance programmes comprising instrument monitoring and visual inspections are important risk management practices for TSFs, and include internal monitoring (e.g. of deformations, pore pressures, etc.) and external monitoring (e.g. for deformation and leakage). A site-specific operations, maintenance, and surveillance (OMS) manual should be developed that describes OMS requirements based on the TSF consequence classification, current engineering design standards, and site considerations. The OMS manual should include: a description of all monitoring procedures for inspections and instrumentation monitoring; alert and alarm levels for monitored parameters; procedures for reporting on noncompliance, incidents, and failures; corrective actions; emergency plan.  (Oberle et al., 2020; World Bank, 2021).  

The surveillance programmes should also focus on identifying the conditions that would result in an emergency being declared. Operators should develop and (where necessary) implement a site-specific Emergency Preparedness and Response Plane (EPRP) for such circumstances, in particular for any conditions that could lead to catastrophic failures (ICMM, 2021; ICMM, 2005).