Tailing Dams in Peru: Ways to Resolve Technical and Social Problems Based on Brazil and Canada’s Case Studies

By Serena Chiang and Kasei Oma

“We build infrastructure like a building or a bridge relatively quickly, and people might imagine that it will last forever, but it usually won’t.  Mining infrastructure such as a tailings dam is constructed progressively and, post-closure, is expected to remain stable in perpetuity.  But will it?  For it to remain stable in perpetuity, the mining company would need to undertake effective stewardship during the design, construction, operation, closure and post-closure phases.  This would require commitments from the mining company, governments and affected communities to do the right thing.”

——Professor David Williams,  Director of Civil Engineering at University of Queensland

The establishment of mining communities in nations have always been a controversial issue. Associated with mining, are tailing dams (structures to store mine wastes), in which adequate ways to prevent failures are not mature yet. This article will evaluate tailing dams from the technical and social aspect.

The technique aspect will provide information about the mechanisms of tailing dams. The social implications will be addressed from an environmental aspect (mainly focusing on water pollution) and local aspect which involves the disputes between mining companies and local community.


The article will explore how different approaches to tailing dam management are in Peru, compared with countries such as Brazil and Canada in which major tailing dam failures have already occurred.

This section will be background information about the mining industry in Peru. The current relationship between mining communities and local communities will be addressed, along with the introduction of mining companies that are essential to the case studies.

Peru is a country located in the West Central Coast of South America where the geography is very diverse: including the desert (Costa) on the west, Highlands(Sierra)on the center and the Amazon (Selva) on the east. It is important to understand the geography of Peru, because it can show the distribution of mining companies (figure 1.1), along with understanding how essential it is for mining companies to be located at a region that is stable and not prone to earthquakes (figure 1.2).

Figure 1.1 Most of Peru’s mining industry is located in the highlands because the area contains the country’s major mineral deposits which is critical for extracting natural. Source: Maps Peru
Figure 1.2 Peru consisted of tectonic plates Naza and South American plate where the subduction makes the Peru Chile trench prone to earthquakes. The highlands are relatively more stable. Source: LimaEasy

Peru is the third largest producer of copper in the world following Chile and China. The mining industry is important to Peru where Mineral Commodities alone account for 60% of the country’s exports.

Reasons for social conflict

There has been rising tension between the mining community and the local community: The mining community includes the investors, the mining companies and the board of directors; the local community involves mine workers, local people who provide resources to the mining community, and local people who are affected directly by leakages of tailing dams.

A major reason for conflict is deterioration in water quality and quantity. These concerns are especially raised by local inhabitants where polluted water poses threats and inconvenience. Other reasons for conflict include foreign companies being unable to successfully integrate in the society. The Government is working on social license (the acceptance of the company’s standard practice actions by the community and stakeholders) and communicating shared value to incorporate social responsibility.

Conflicts within/between mining companies

Other than dispute from the local communities, there are arisen conflict between and within mining companies. Conflicts within the company includes the consistent changing of engineers. This leads to knowledge not being passed on and the lack of communication leads to problems such as making the design of tailing dam structures less stable.

Another identified conflict between companies is with regards to the transitioning process such as the legal responsibility. Which company should be held responsible-whether the old company or the new company-is ambiguous.

Introduction of crucial mining companies

Chinese mining companies play a big role in the Peruvian Mining industry. One of the biggest mining communities in Peru is Las Bambas, which is a copper mine that is located in Cotabambas of Southern Peru. Las Bambas consists of MMG (China Minmetals, 74% of share) accounting for 62.5% as a joint venture project.

There are also countries like Brazil who have major mining companies like Vale and Samarco. Vale is headquartered in Brazil and is the largest producer of Iron ore and nickel unlike Samarco which is a privately held company. In Canada, the Mount Polley Mining Coporation’s line of business includes mining of gold ores from lode deposits.

Tailing Dams

This section will be explaining what tailing dams are, the variety in the location of tailing dams and also case studies regarding tailing dam failures.

What tailing dams are

In Las Bambas, Minas Gerais (Brazil) and British Columbia(Canada), the establishment of mines create waste that are consisted of ground rock particles, and minerals which are sometimes stored in Tailing Dams. Tailing dams (generally made out of rock or earth), are also known as Wet processing because the dams store the combination of water and waste.

There are multiple reasons why a tailings dam may collapse: excessive amounts of heavy rain or poor foundations of the dams, or tailings liquefaction, which can also lead to leakages into surface and groundwater and are a threat to wildlife.

The variety in the location of tailing dams

The location of tailing dams varies. Upstream tailing dams are the most common because it aims to make disposal of tailings cheaper. Upstream tailing dams are at the top of the slurry and the dam crest will be moving upstream. However, earthquake or nearby mine blasting can make upstream dams susceptible to liquefaction and the upstream dams work poorly in seismic areas compared to downstream and centerline dams. 

Centreline tailing dams have moderate cost, but restrictions to the dam include not being able to maintain a permanent storage and having height restrictions for raising rate. 

Figure 2.1 Types of sequentially raised tailings dams Source:

Reasons for choosing case studies

The significance of exploring Peru involves taking precautions methods before the failure occurs. Even though there are no major dam failures in Peru’s status quo, it doesn’t indicate that the fundamental problems in tailing dams should be ignored. Brazil, and Canada’s dam failure cases are analyzed because Brazil is a country in Latin America, therefore similar aspects can be inferred. However, for Brazil, there have already been two major dam failures in the past few years and it is important to see how preventive methods are developed.

The reason Canada was chosen to be a comparison for Peru is because Canada is one of the More Developed Nations. Canada, despite having access to the best technologies for preventing failures, could not prevent the Mount Polley failure from occuring.

The selected three case studies represent a developing nation and a developed nation, in order to display contrast on the different actions conducted by the various mining companies.

Case Studies

With tailing dams being susceptible for failure, there have been recorded failure cases all over the world. Among the various examples, the three most famous recent and famous cases are the Brumadinho Failure, Fundao Failure and the Mount Polley failure.

Vale was responsible for The Brumadinho failure case which was recorded on 2019.  The dam released around 12 million cubic metres of mining waste and the slurry was carried downstream, killing all living things in the river and making water undrinkable. The failure also resulted in 259 deaths where 11 people were reported missing.

Figure 3.1 The aftermath of the dam burst in Brumadinho. Photo: EPA-EFE/Antonio Lacerda

Prior to the Brumadinho failure, was the Fundao failure which took place in Minas Gerais, Brazil on 2015. There were 43 million cubic of tailings that flowed into the Atlantic Ocean. Other than polluting water, it also disrupted the ecosystem which affected the Brazilian Atlantic Forest (one of the world’s biodiversity hotspots).

Figure 3.2 The Fundão Tailings Dam on the 7 July 2016, approximately eight months after failure occurred. Photo: Ibama

Another infamous case was recorded in British Columbia, Canada, known as “Mount Polley Failure, which was breached on 2014. It was a four square kilometer sized tailing pond and spilled an estimate of 25 billion litres into Polley Lake, Hazeltine Creek and Quesnel Lake, heavily affecting the salmon population.

Figure 3.3 The tailing wastes flood into the river of Mount Polley. Photo: Jonathan Hayward/Canadian Press

Two Alternatives for Tailing Dams

In this section, the alternatives for failures such as dry processing and sand dams will be explained.

As conventional building process increases the risks that the structure could fail, alternatives to dams will undoubtedly receive renewed interest from mining companies following the recent tragedies.

Figure 4.1 Conventional Tailing Dam Photo: 3BL Media

Dry Stacking of Tailings (Filtered Tailings)

Dry Stack Tailings systems are particularly suited to mining operations operating in areas where water conservation is critical, and they also ensure safety. Dry stacking is one of the most sustainable methods used to store filtered tailings.

The process can be analyzed several steps:

  1. Large rocks crushed in the underground mine
  2. Minerals from the mines are separated into concentrates
  3. Tailings are dewatered
  4. Water is recycled in the stacking plant
  5. Filtered tailings are transported to the facility adjacent to the stacking plant
  6. Tailings are compacted into a mound that is engineered for stability
Figure 4.2 Mobile Stacking Bridge (MSB) as part of a dry stacking solution for iron ore tailings in Mauritania. Photo: Tenova
Figure 4.3 Depicting the advantages and disadvantages for dry stacking

Sand Dams

The design of a sand dam needs to have significant stability against extreme events. This means that the dam can maintain the containment function of the deposited tailings even under much worse seismic event. The production of sand is a daily task that has to be adjusted to the features of the tailings provided by the flotation plant.

Figure 5.1 Basic structure of sand dams Source: KrackenScape

This condition does not exist in civil construction where the construction material is selected and processed until the required quality is obtained and then is transported by trucks and placed on the dam.

The social aspect will be introduced in the following three case studies. The method will be using stakeholder analysis.

Stakeholder Analysis

Stakeholder analysis is part of stakeholder management and an important technique for stakeholder identification and the analysis of their needs. These stakeholder analyses explain how mining companies, local communities, NGOs and government interact with each other in the cases of social conflicts and tailing dams failure.

Peru’s Tailing Dams-Las Bambas

In this section, information will be provided about Las Bambas including the conflict associated with legal responsibilities, social conflicts, and the various stakeholders.

Figure 6.1 Mining facility of Las Bambas, Peru Photo: GyM

Conflict during transitioning process

As previously identified, conflicts between companies includes the difficulty in transitioning and the claims to legal responsibility on whether it should be on the old company or the new company.

Las Bambas(Peru) is an example. It was originally owned by other company called Xstrata (Switzerland). However, in 2014 it was sold to MMG.

Unfortunately, the change of its owner still led to serious problems. Before the changing of Las Bambas’ owner, the state authority in Peru have already approved six modifications about the enviornment in Las Bambas. This has indeed raised concerns regarding lack of communication and consultation of the affected communities.

After MMG was in charge, the relationship between the communities and the company deteriorated, making local communities protest and asking for environmental protections in indigenous territories. These conflicts tend to escalate easily, and for many years, people were killed in protests against MMG.

 Figure 6.2 Recent years’ news reports about the indigenous people being killed:

Some of the problems exist due to the dust, noise and vibrations of mines which affects indigenous communities along with lacking measures of prevention or mitigation. Companies should be aware of the issue and take action instead of blaming the problem on the previous owner of the mine.

Stakeholder Analysis

Figure 6.3 Las Bambas Stakeholder Analysis

In Figure 6.4, communities are strongly dissatisfied. As compared to Developed Nations, Peru’s indigenous people’s voices are hardly to be heard in the society. Although Peru was officially part of EITI, companies rarely follow the standards and the goal of accomplishment.

Figure 6.4 Influence VS Attitude of stakeholders

Canada Tailing Dams-Mount Polley failure

This section will include the Canadian governments’ responses to the failure, stakeholder analysis and the reasons why Mount Polley’s investigations were more effective than Las Bambas will be addressed.

Following the Mount Polley disaster in British Columbia, Canada, a local state of emergency was declared for the Cariboo Regional District over drinking water contamination concerns.

Clean up efforts have led to a reconstructed creek. A drinking water ban was lifted within weeks of the spill and water testing is being conducted by the government. An investigation into the cause of the spill revealed engineers failed to account for glacial silt underneath the tailings containment pond, leading to structural insufficiencies that caused the collapse.

Figure 7.1 Satellite imagery before the collapse and after the collapse Source: The Commonsense Canadian

Stakeholder Analysis

Figure 7.2 Stakeholder analysis of Mount Polley, Canada

Canada has a relatively complete legal system. From Figure 7.2, many government departments are involved in the investigation of the disaster and restructure programs.

Differences displayed in Developing Nations and Developed nations

It should be emphasized that First Nations'(Indigenous communities in Canada) voices are easier to be heard as compared to the local communities in Peru. Through the media, communities’ dissatisfaction has created large impacts, which played a role in supervising enterprises and governments to some extent.

In the case of Mount Polley, First Nations like Xtasull communities hired independent scientists to investigate the water qualities of lake because stated that they could not believe the results published by the mining companies.

Figure 7.3

From figure 7.3, publics have a high influence because they are able to comment on the reports online. Public comments have resulted more extensive air monitoring program implemented around the mine site in response to concerns over dust generation from exposed material in the dams.

Multi-party suggestions and coordination have made Mount Polley’s investigations very effective. The rights and interests of local people are well protected, and the reflections reported by the public are also highly respected. This is currently not possible in countries like Peru where the legal procedures for solving mineral problems are not complete, which usually creates long-term social conflicts.

Brazil’s Tailing Dams-Brumadinho and Fundao

This section is going to compare the Brazilian governments’ and the mining companies’ responses to the two consecutive failures, along with the stakeholders involved.

Responses by the two companies

Minas Gerais is in the southeast of Brazil and according to National Mining Agency of Brazil, among the 221 tailing dams in the region, 42 were classified to be high risk.

Mining company Samarco is responsible for the Fundao Failure. Responses to the failure includes Samarco signing an Conduct Adjustment Agreement with the federal and state government, focusing on ways to repair the devastating effects.  Samarco is trying to implement dry stacking disposal and further seeks to have a Corrective Operating License in order to resume operations.

Brumadinho Failure lead in sudden halt of the project and resulted in the Brazilian government having outlawed the construction of “upstream dams”. The tailings which reached the Paraopeba River were further tracked by National Water Agency and the Geological Survey of Brazil.

Brumadinho Failure stake holder analysis

Figure 8.1 Stakholder analysis for Brumadinho Failure
Figure 8.2 Locals A referring to workers for mine, locals b are people affected by tailings

The government’s creation of the National Dams security policy failed to prevent the Brumadinho failure. Further responses include the International Council on Mining and Metals creating a panel that aims to develop an international standard for reviewing the world’s best practices for managing tailings.

Fundao failure stakeholder analysis

Figure 8.3 Stakeholder analysis for Fundao Failure
Figure 8.3


This section will include: Ways of resolving the technical and social problems, standards to mining companies, conclusion of the findings.

Ways to solve technical problems

The technical problems of tailing dams can be addressed through banning upstream dams and also setting restrictions upon the height of small medium sized dams (below 45 metres) which are more prone to failures. There should be proper evaluations of the geological and environmental factors before establishing a dam.

Ways to solve social problems

Companies need to take full responsibility after a spillage. It is necessary for mining companies to provide monetary compensation to the locals affected and they should also have legal responsibility towards their workers who have passed away during the incidents. To guarantee mutual understanding, periodic meetings and training should be conducted between representatives of locals and those in the mining industry. Also, it is important that mandatory emergency practices should be established in order to make workers understand the necessary responses to failures.

To prevent conflicts between companies, the transitioning process should include the creation of legal documents between the old and new company to clarify legal responsibilities. To prevent conflicts within companies, the board of directors need to make sure that the consistent changing of engineers will not lead to inconsistency in knowledge, therefore clear monitoring of dams is required.

Figure 9.1 Protest in Peru against Tia Maria mining project

Standards on companies

Figure 9.2


Overall, our society still does not fully appreciate the long-term implications of building a dam to store billions of tons of potentially-harmful waste in large impoundments. Advances to the technology for designing and identifying the long-term threats to these structures have usually been researched and prompted after the occurrence of tailing dam failures.

Just as Professor Williams mentioned, “Mining companies need to maintain their financial and social licenses to operate.  Associated tailings dams that store the fine-grained wastes of mineral processing, must be made more resilient, responsive to technical and social issues, and responsive to their multiple stakeholders.”

Therefore, it is suggested that instead of only trying to bring advanced technology to the conventional dams, companies should always take the responsibility of the long-term risks of the society by inheriting the dam and take responsibility for waste management. Peru need to combine the best approaches taken by the Brazilian and Canadian Government to prevent future disaster. It is crucial to note that long term risks should be clearly assessed in order to prevent failures.

*Tianshu Zhang contributed to the story.

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