Mining Dam Research Articles

Challenges of environmental impact assessment in addressing environmental risk: insights from Brazilian practice in mining dams

ABSTRACT Environmental Impact Assessment (EIA) and Risk Assessment (RA) are critical tools for assessing and managing environmental impacts and risks of projects. However, their integration remains a challenge. This study examines how EIA practices account for risks in evaluating the environmental feasibility of mining dam projects in the state of Minas Gerais, Brazil. We analyzed licensing processes for projects approved between 2004 and 2022, using data from the state’s environmental agency. Methods included documentary and content analysis of Environmental Impact Statements (EIS) and review reports. Among the 25 cases analyzed, most focused solely on risk control without performing RA. Only two cases included RA, and two others lacked any risk-related information. Review reports revealed that only two went beyond considering risk control when assessing environmental feasibility. This suggests decision-making relies on a narrow focus on risk control. Furthermore, there is a misalignment between the EIS content and the criteria for project acceptability in review reports. Finally, we explore how politicization may undermine the EIA’s role in objective, and evidence-based decision-making. These findings underscore the superficial and fragmented approach to addressing environmental risk in mining dam assessments in Minas Gerais.

Marine mesocosm system: A reliable tool for testing bioaccumulation and effects of seawater enrichment with dissolved iron in reef organisms

In 2015, a marine mesocosm facility was designed and implemented by the Coral Vivo Project in its research station (Porto Seguro, Bahia State, Brazil) to initially study the effects of global impacts, especially ocean warming and acidification, on coral reefs. However, local impacts, including seawater contamination with metal(loid)s, are considered as a major threat to coral reefs. Also, in 2015, the largest disaster involving a mining dam occurred in Brazil. Iron (Fe) mining tailings originated from the dam failure affected not only freshwater ecosystems (rivers, lakes and lagoons), but also adjacent beaches, mangroves, restingas, reefs and other marine systems. Seawater, sediments and biota were contaminated with metal(loid)s, especially Fe, arsenic (As), mercury (Hg) and manganese (Mn). Therefore, we aimed to adapt the marine mesocosm facility of the Coral Vivo Project to evaluate the bioaccumulation and biological impacts of increasing concentrations of dissolved Fe on a diversity of reef organisms. Results obtained indicate a great versatility and reliability of the marine mesocosm system for application in biological and ecological studies on the isolated effect of seawater dissolved Fe on reef organisms of different functional groups simultaneously.•Studies involving seawater enrichment with dissolved Fe can be performed using a marine mesocosm system.•The marine mesocosm is a reliable tool to study the isolated effects of metal(loid)s on reef organisms.

Changes in land use dynamics following the Fundão dam collapse in the Doce River Basin, Brazil

Although regarded as “unexpected,” the collapse of the Fundão tailings dam in 2015 resulted from the synergistic interplay between the capitalist logic of environmental resource exploitation and environmental degradation in the Doce River Basin (DRB). Our objective was to assess whether this disaster altered land-use dynamics in the DRB. To achieve this, we characterized land-use transitions by comparing changes over three years before (2012–2015) and after (2016–2019) the disaster. We differentiated municipalities adjoining the affected rivers from the remaining municipalities. We evaluated anthropogenic and natural driving forces as explanatory variables: farmland to natural vegetation (land abandonment) or natural vegetation to farmland (farmland expansion). We detected two main driving forces of land abandonment, precipitation and temperature, both before and after the dam collapse. Still, there was a shift between periods: before the dam collapse, the drivers of land abandonment differed between municipalities adjoining and those not adjoining the affected rivers. After the disaster, all municipalities shared the same drivers for land abandonment. For farmland expansion, we detected five drivers for the period before (temperature, precipitation, natural vegetation area, roads, and municipality area) and five drivers after (urban area, slope, natural vegetation area, roads, and municipality area) the dam collapse. Thus, we detected a change in the drivers but no distinction between municipalities adjoining and not adjoining the affected rivers. Our results evidenced a direct effect of the disaster on land abandonment but not farmland expansion, where the observed temporal changes may be related to temporal changes independent of the disaster. Our work shows that the collapse of the Fundão mining dam changed the drivers of “land abandonment,” which may be due to anthropic avoidance of using Doce River’s water for farmland or to a change in socio-economic drivers, such as those related to the monthly financial compensation of affected farmers.

Biochemical changes and bioaccumulation of manganese in Astyanax lacustris (Teleostei: Characidae).

Major tailings dam failures have occurred recently around the world and resulted in severe environmental impacts, such as metal contamination. Manganese is a metal highly associated with mining activities, largely detected in mining dam collapses. This metal is considered necessary for different organisms, but it can be toxic and cause oxidative stress and genetic damage in fishes. In this study, we investigated the toxic effects of manganese on Astyanax lacustris, by exposing the fish individually to different concentrations of this metal (2.11, 5.00, and 10.43 mg/L) for 96 h. To assess the effects of manganese, we used biochemical biomarkers (glutathione S-transferase, catalase, and acetylcholinesterase enzyme activity) and the manganese bioaccumulation in different tissues (liver and gills). The obtained data showed that only at concentrations of 5.00 mg/L and 10.43 mg/L the activity of glutathione S-transferase differed significantly. Additionally, the acetylcholinesterase activity in the brain tissue was inhibited. The highest level of manganese bioaccumulation was observed in the liver and branchial tissue. Overall, we concluded that high concentrations of manganese may cause physiological changes in Astyanax lacustris.

Presentation on the methodology used to calculate the self-rescuing index for communities downstream mining dams

This paper presents the methodology developed to calculate the Self-Rescuing Index for communities downstream of mining tailings dams. An initial calculation formula was developed based on consultations with specialists in engineering, safety, geotechnology, geotechnics, geography, social work, and social sciences. This formula consisted of twenty-two indicators and five indices that make up the final index. The initial results were revised after a new round of consultation using the Delphi method, as well as considering the data available from official sources, Dam Break studies, and primary data collection from communities located in risk areas. The results were georeferenced, enabling a detailed analysis of people's location, their vulnerabilities, as well as of the territory, making a consistent geostatistical tool available for decision-making in managing disaster risks related to mining dams.

Assessment of the influence of DTM quality on dam rupture simulation processes

Computer programs applied to disaster simulation are widely used and widespread today, taking as input various data types, from specific to the application area to DTMs (Digital Terrain Models). This need for data input and, in particular, data related to relief is very relevant in prediction procedures for forecasting catastrophes, such as the failure of tailings mining deposit dams. Therefore, it is of fundamental importance to know and quantify the quality of this input data in question, in order to effectively serve this application. To this end, in this research, several tests were carried out, using as a reference for best results those obtained with the introduction of DTM from a LIDAR (Light Detection and Ranging) flight survey, this data being used as one of the primary and input into HEC-RAS (Hydrologic Engineering Center-River Analysis System). Subsequently, these same data had their spatial resolution degraded, that is, the pixel size increased, generating models with worse quality for new inputs and obtaining new simulation results of mining dam failures. The test area of the B1 Dam, located in Brumadinho-MG, Brazil, was used as a laboratory, where one of the biggest mining disasters in the world recently occurred and, for which, there are real data from the area affected by the dam collapse. The results obtained demonstrated that the use of an DTM with a spatial resolution of at least 2.5 meters or better, with DTM class A cartographic quality compatible with the most recent Brazilian standard, would guarantee reliable results.

Tailings dams’ classification based on risk using data from SIGBM

The Brumadinho and Mariana tailings dam failures in Brazil tragically highlighted the critical need for robust risk management in the mining sector. Tailings dams, by their very nature, pose significant risks to downstream communities and the environment in the event of failure. To mitigate these risks, a comprehensive risk classification system is essential. This abstract emphasizes the real-world impact of dam failures and strengthens the importance of risk classification. Risk analysis plays a central role in identifying, quantifying, and ultimately mitigating the potential consequences of tailings dam failure. The classification process considers various factors that influence dam stability and safety, including dam geometry and construction methods — the design and construction techniques employed significantly impact a dam's stability; tailings characteristics — the physical and chemical properties of the stored tailings can influence factors like liquefaction potential; operating conditions — factors like the rate of tailings deposition and the presence of seismic activity need evaluation; drainage system effectiveness — a well-functioning drainage system is crucial for managing pore pressures within the dam. By analyzing these elements, risk classification aims to categorize tailings dams into distinct risk levels, typically ranging from low to very high. This categorization allows for targeted risk mitigation strategies to be implemented based on the specific vulnerabilities of each dam. This paper proposes a methodology for risk classification of tailings dams utilizing data from the Brazilian National Mining Agency's (ANM) Integrated Mining Dam Management System (SIGBM). The study focuses on 203 dams situated in Minas Gerais, a Brazilian state with a history of dam failures. Data was extracted from SIGBM in February 2023. This research not only presents a general risk classification for the assessed dams but also delves deeper, offering a quantitative measure of vulnerability, risk potential, and potential consequences of a failure event for each individual dam.

Tailing dams’ accidents and compliance failures: A study in Brazil and Canada

The mining is an activity of importance to the world economy moving billions of dollars/years and employing a network of people. After the tragedies observed in Brazil over mining dams, reflections have been raised about the safety of these environments and their impacts on the environment. This paper focused on compliance weakness on tailing dams' regulations in Brazil and the impacts of environmental accidents in Canada. Besides that, it did a bibliometric analysis with tailing dams’ strings/terms relationed and a comparative Brazil-Canada, a developed country where a similar accident with a tailing dam happened. It discussed the following topics: Salient keywords and Emerging themes, temporal and geographical distribution of publications; growth publication; word cloud, the federal legislation, and instruments for safety of dams, regulations, and the role of inspections agencies, tailing dam accidents and the Canadian scenario of mining regulations and make a comparison between these two countries.

Case studies of assessment of human health risks after the dam failures of the Córrego do Feijão Mine and Fundão in Brazil

ABSTRACT In recent years, there has been an increase in environmental catastrophes involving mining dam failures. This study assessed the potential risks of iron ore tailings in riparian soils to human health after the worst dam collapses recorded in Brazil: from Córrego do Feijão Mine-CFM and Fundão. Chemical monitoring data from the three-year time interval since the collapses were used to estimate human risk indexes for trace elements such as arsenic, cadmium, chromium, mercury, nickel, lead, and zinc. In both case studies, the adult group indicated a propensity for the development of non-carcinogenic diseases through ingestion, inhalation and dermal pathways for all contaminated areas. Overall, children showed an exacerbated sensitivity to possible cancerous and non-cancerous effects, especially in the areas surrounding the dams and in Barra Longa, São José do Goiabal, Córrego Novo, Veneza, Periquito, Governador Valadares, Tumiritinga, Conselheiro Pena, Honório Fraga and Linhares (from the Fundão dam) and in all study areas from the CFM dam. These assessments demonstrate that in regions with mining activities, the cumulative effects of trace elements over time are harmful and expected. Therefore, there is a need for greater supervision by competent government bodies of conservation practices that enable environmental recovery or mitigation of their impacts, ensuring appropriate health and well-being conditions for local residents and workers.

Potential toxicity of iron ore tailings after the overflow of a mining dam in Nova Lima (Minas Gerais State, Brazil)

In January 2022, the Pau Branco Mine dam in Nova Lima (MG), under the responsibility of Vallourec, overflowed after intense rainfall and iron ore tailings impacted surrounding soils and aquatic ecosystems. These tailings can alter the natural composition of soils and rivers, poising risks on soil biota. This study consists of a preliminary evaluation of potential toxicity of terrigenous materials impacted by tailings from the Pau Branco Mine, based on acute bioassays with earthworms (Eisenia andrei) and germination tests with lettuce (Lactuca sativa). The physical and chemical characterization and determination of toxic metals in the samples supported the interpretation of the ecotoxicological data. The results indicated that the tailing deposition induced the increase in particle density, due to the increase in iron concentrations in the samples. As a consequence, the water holding capacity (WHC) of the materials and organic matter concentrations were dramatically reduced. Given that the mining tailings exhibit fine texture, their depositions on soils increased the percentage of fines particles (silt) in the samples. Metal determination revealed geochemical anomalies for nickel, copper and chromium, whose concentrations exceeded the threshold limits defined by Brazilian law for soil and aquatic sediment quality. The bioassays with earthworms showed no significant earthworm mortality, indicating low acute toxicity. However, earthworm biomass was significantly reduced, suggesting that they were submitted to some stress induced by the exposure to contaminants and/or by the reduction of the organic matter contents (food scarcity) and WHC (water scarcity). The bioassays with lettuce showed no significant effects on germination levels. However, the seedling biomass was significantly reduced due, possibly, to the reduction of WHC and especially due to the increase of fines particles in the samples, which tends to inhibit the establishment of the root systems.

Integrating reverse osmosis to a conventional river water treatment plant as a strategy to produce drinking water after mining dam rupture events: a case study

ABSTRACT Incidents of mining dam failure have compromised the water quality, threatening the water supply. Different strategies are sought to restore the impacted area and to guarantee the water supply. One example is water treatment plants that treat high-polluted waters within the required limits for their multiple usages. The current study assesses the integration of reverse osmosis (RO) to a river water treatment plant (RWTP) installed in Brumadinho (Minas Gerais, Brazil) to treat the water from the Ferro-Carvão stream impacted by the B1 dam rupture in 2019. The RWTP started eleven months after the mining dam rupture and is equipped with eight coagulation-flocculation tanks followed by eight pressurised filters. A pilot RO plant was installed to polish the water treated by the RWTP. Water samples were collected at different points of the water treatment plant and were characterised by their physical, chemical, and biological parameters (160 in total). The results were compared with the historical data (1997–2022) to reveal the alterations in the water quality after the rupture event. The compliance with both parameters was only achieved after the RO treatment, which acted as an additional barrier to 30 contaminants. The water quality indexes (WQI) suggested that the raw surface water, even eleven months after the incident, was unfit for consumption (WQI: 133.9) whereas the reverse osmosis permeate was ranked as excellent in the rating grid (WQI: 23.7).

First as a tragedy, second as a norm: global standards and Brazilian policies on the safety of mine tailings

This article seeks to analyze the regulatory framework that supervises the safety of tailings dams on an international, national and state scale, with emphasis on the management of mining dams built in Minas Gerais using the upstream technique – considered the most critical for the risk of collapse. To do this, we carried out a deductive analysis based on a literature review, combined with an inductive analysis from secondary sources (news items, reports and standards). We argue that the standards which have gained the most support from the industry, by not expressly prohibiting the existence of upstream dams, present contradictions that reproduce rather than remedy the vulnerability of territories exposed to the social and environmental risks produced by mining in Brazil, and worldwide. Based on the analyses proposed herein, we aim to understand how the problem of tailings management has been addressed by institutions on both a national and international level, thus identifying the effectiveness of standards and policies related to the problem of upstream dams.

Numerical modeling for mining dam cover infiltration design with geosynthetics: A trade off study

In the mining dam closure project, depending on the classification of the tailings, cover systems are used to reduce precipitation infiltration over time, avoiding future environmental impacts associated with metal leaching. Furthermore, reduced infiltration promotes reservoir drainage and therefore improved geotechnical stability. The covering system can be built from different materials, natural or synthetic, or even using waste itself. The main objective of this study is to present the results as a trade-off study of a one-dimensional modeling performed considering 3 configurations of geosynthetic covers, using the SOFTWARE SEEP/W emphasizing the importance and impact of the presence of geosynthetics. Since numerical models constitute an essential tool in the development of engineering projects, computational numerical modeling was carried out using Brazilian climatic parameters from the National Institute of Meteorology in conventional and automatic stations, and historical geotechnical parameters for a structure located in the state of Minas Gerais. Gerais (Brazil). For the comparison of the cover configurations, the thickness and type of the geosynthetic were varied. The results emphasize the importance of studying numerical modeling in the pre-closure design phase, to define a viable, economical and sustainable coverage, and contribute to the use of geosynthetics in this type of application.

Strategies for legitimizing negative events: Mining dam collapse and disclosure

Strategies for legitimizing negative events: Mining dam collapse and disclosure

The effect of a mining dam failure on the genetic diversity and population resilience of marine fishes along the eastern Brazilian coast

We used microsatellite DNA markers to examine the impact of the Fundão Dam failure, one of the world’s worst mining-related environmental disasters, on the genetic diversity of four marine and estuarine fishes across the Brazilian east coast's continental shelf and estuarine ecosystems. The strong mud flow along the Doce River and nearby areas resulted in changes in genetic diversity, with all species exhibiting low genetic diversity indices, primarily in estuarine species, and particularly those with a greater association with the substrate. Furthermore, the low M-ratio values in all species tested indicated a recent decrease in the effective population size. Estuarine species, particularly the slipper sole Trinectes paulistanus, were more directly impacted by the mud plume than marine species. The loss of genetic variability due to population decline is concerning because it is ultimately an important component in determining the ability of marine fishes to adapt to environmental changes. Combining genetic data from four fish species with different behaviours, habitats, life histories, and economic values revealed that genetic diversity was a valuable tool for assessing the effects of the Fundão Dam failure.

Environmental vulnerability assessment of the Doce River basin, southeastern Brazil.

Environmental vulnerability is an important tool to understand the natural and anthropogenic impacts associated with the susceptibility to environmental damage. This study aims to assess the environmental vulnerability of the Doce River basin in Brazil through Multicriteria Decision Analysis based on Geographic Information Systems (GIS-MCDA). Natural factors (slope, elevation, relief dissection, rainfall, pedology, and geology) and anthropogenic factors (distance from urban centers, roads, mining dams, and land use) were used to determine the environmental vulnerability index (EVI). The EVI was classified into five classes, identifying associated land uses. Vulnerability was verified in water resource management units (UGRHs) and municipalities using hot spot analysis. The study employed the water quality index (WQI) to assess the EVI and global sensitivity analysis (GSA) to evaluate the model input parameters that most influence the basin's environmental vulnerability. The results showed that the regions near the middle Doce River were considered environmentally more vulnerable, especially the UGRHs Guandu, Manhuaçu, and Caratinga; and 35.9% of the basin has high and very high vulnerabilities. Hot spot analysis identified regions with low EVI values (cold spot) in the north and northwest, while areas with high values (hot spot) were concentrated mainly in the middle Doce region. Water monitoring stations with the worst WQI values were found in the most environmentally vulnerable areas. The GSA determined that land use and slope were the primary factors influencing the model's response. The results of this study provide valuable information for supporting environmental planning in the Doce River basin.

Desastre socioambiental: condições de saúde dos atingidos na perspectiva dos profissionais de saúde e gestores

Objective: to analyze the health conditions of the population affected by the mining dam collapse from the perspective of healthcare professionals and managers. Method: this is a qualitative case study, conducted using public domain documents and interviews with healthcare professionals and managers, from March to May 2022, totaling 14 participants. The data were analyzed according to the theoretical propositions strategy based on the Social Determinants of Health. Results: the health conditions of this population have worsened in terms of respiratory problems, gastroenteritis, obesity, arboviruses, increased use of alcohol and drugs, and mental illnesses. The loss of employment, home, and community belonging of those affected is highlighted. Conclusion: the socio-environmental disaster was a conditioning factor for changes in the health conditions of those affected, exposing them to new scenarios and overlapping risks capable of modifying their quality of life and aggravating their biopsychosocial health conditions.

Hydrochemistry, Elements Distribution and Their Potential Recoveries in Gold Metallurgical Treatment Tailings Dams

Wastewaters are valuable sources of metals and metalloids and can serve as essential resources for their recovery. Characterizing and understanding the occurrence of metals and other compounds, along with identifying the most effective recovery methods, are key steps in unlocking the potential for reusing these resources. The present study focused on analyzing waters from various mining dams in the Iron Quadrangle (IQ) region of Brazil, which contained metals such as Au, Cu, Ni, Zn, and sulfates resulting from the metallurgical treatment of Au. The results revealed a range of metal concentrations in the neutral zone in three tailings. Additionally, a 3D map was created, and a statistical analysis and an exploration of the processes governing mobility and partitioning were conducted to assess the potential for reuse. Notably, the study identified a high potential for Au recovery, particularly through the utilization of sustainable and cost-effective methods such as nanofibers with biosorbents. Overall, this research contributes to the understanding and exploration of potential reuse procedures for strategic metals in various industrial applications.

A conceptual model to establish preventive and corrective actions to guarantee water safety following scenarios of tailing dam failure

One of the impacts related to mining dam failures is the change in water quality downstream of the rupture and a knowledge gap is observed in terms of methodologies aimed at the prognosis of impact in water abstractions, a vulnerability that can be identified before a rupture event. Thus, the present work aims to describe a novel methodological proposal, not currently considered by control agencies, of a standard protocol that enables a comprehensive prognosis of the impacts on water quality impact in scenarios of dam failure. Initially, extensive bibliographic research was carried out on the main disruptions events since 1965 intended to better comprehend the impacts on water quality and to identify mitigatory actions proposed by the time. The information provided a framework to propose a conceptual model for the prognosis of water abstractions, with the suggestion of software and studies to comprehend the different scenarios in the event of dam failure. A protocol was prepared to obtain information on potentially affected inhabitants and a multicriteria analysis was developed using the Geographic Information System (GIS) to suggest the employment of preventive and corrective actions. The methodology was demonstrated in the Velhas River basin considering a hypothetical scenario of tailing dam failure. Changes in water quality would be observed in 274 km of its extension, mainly related to alterations in solids, metals, and metalloids’ concentration, in addition to the impact on important water treatment plants. The map algebra and the results suggest the need for structuring actions in cases where the water abstraction is intended for human supply and in populations greater than 100,000 inhabitants. Populations smaller than these, or usages other than human supply, could be supplied by water tank trucks or mixed alternatives. The methodology pointed out the necessity for structuring supply actions with due notice, with the potential to prevent water shortages in scenarios of tailing dam failure and to complement the enterprise resource planning of mining companies.

Marine and estuarine crustacean diversity and assemblage structure in eastern Brazil three years after the Fundão mining dam failure

The present study investigates the spatial and temporal patterns of species richness and assemblage structure of decapod and stomatopod crustaceans in the area impacted by the Fundão dam collapse (Rio Doce basin, Brazil) in November 2015. From October 2018 to September 2019, monthly bottom-trawl samples were collected in estuarine and marine waters of the Rio Doce (directly impacted area) and three other localities. Forty-one crustacean species were recorded, with the overall community structure dominated by six species. The seabob shrimp Xiphopenaeus kroyeri was the most common species, with the coastal marine area near to the Rio Doce mouth being an important fishery ground. Species composition changed significantly among localities, habitats, and seasons, with marine and estuarine assemblages shaped by freshwater discharge. Distribution patterns of species were significantly influenced by the environmental variables potentially altered by tailings, such as turbidity and pH. Species richness and abundance differed among localities; as expected, they were generally higher on the inner shelf than in estuaries and higher during the dry season than the rainy season. Due to the lack of information before the disaster, the low number of species found in the Rio Doce estuary cannot be solely attributed to the disaster but also its freshwater condition. This is the first broad study of the estuarine and coastal marine decapod and stomatopod crustaceans in the region, and we suggest the need for long-term monitoring considering that the effects of this disaster are not easy to detect and probably need multi-year study to be evidenced.