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Tailings dam breaches (TDBs) and subsequent flows can pose significant risk to public safety, the environment, and the economy. Numerical runout models are used to simulate potential tailings flows and understand their downstream impacts. Due to the complex nature of the breach-runout processes, the mobility and downstream impacts of these types of failures are highly uncertain. We applied the first-order second-moment (FOSM) methodology to a database of 11 back-analyzed historical tailings flows to evaluate uncertainties in TDB runout modelling and conducted a sensitivity analysis to identify key factors contributing to the variability of the HEC-RAS model output, including at different locations along the runout path. The results indicate that prioritizing resources toward advancements in estimating the values of primary contributors to the sensitivity of the selected model outputs is necessary for more reliable model results. We found that the total released volume is among the top contributors to the sensitivity of modelled inundation area and maximum flow depth, while surface roughness is among the top contributors to the sensitivity of modelled maximum flow velocity and flow front arrival time. However, the primary contributors to the sensitivity of the model outputs varied depending on the case study; therefore, the selection of appropriate rheological models and consideration of site-specific conditions are crucial for accurate predictions. The study proposes and demonstrates the FOSM methodology as an approximate probabilistic approach to model-based tailings flow runout prediction, which can help improve the accuracy of risk assessments and emergency response plans. [ABSTRACT FROM AUTHOR]

Numerical models are used for detailed and site-specific tailings dam breach analyses (TDBAs) to estimate the downstream inundation and deposition resulting from a potential breach at a tailings dam. The results of TDBAs are key inputs into risk assessments, consequence classification, and emergency planning. This paper describes the research and development of a database of 12 tailings dam breach events with a specific focus on observations that are needed for numerical modelling, in conjunction with an assessment of existing dam breach conventions to improve consistency in reporting. The characteristics relevant to modelling include outflow volumes, breach processes, breach geometries, and runout observations local to the downstream area. This study and the new database shed light on the diversity of outflow materials, facility arrangements, breach processes, and downstream environments that affect the breach development and tailings runout. Familiarity with case studies is a crucial element of expert judgement for forward-analysis TDBAs, which this database supports. The database can also be used to define model inputs for back-analysis of additional tailings dam breach events, and simultaneously provides calibration or validation constraints with the runout observations. Continued review and critical assessments are needed to reduce uncertainties and to enhance case history data availability and quality in this database. [ABSTRACT FROM AUTHOR]

The rupture of the Córrego do Feijão iron mine Tailings Dam I killed at least 260 people and had major environmental and social impacts. We analyzed the chemical compounds dissolved in the surface water and the bottom sediments of Ferro-Carvão Creek, the watercourse directly affected by the disaster, and at points upstream and downstream of its confluence with Paraobeba River, the main watercourse of the region. We also analyzed samples of the released tailings and groundwater near the area directly affected. From an environmental geochemistry standpoint, the water analyses suggest that the water quality degradation was not as catastrophic as the human and material losses and damage to biota. The groundwater samples did not present disconformities according to the Brazilian Environmental Council (CONAMA). In fact, most of the surface water samples that exceeded the maximum allowed concentrations were upstream of the affected basin. This suggests that mining industry sources other than those associated with the disaster had damaged its water quality before the event. Thus, previous knowledge must be used to evaluate the real anthropic impact in events of this nature. It can also be an excellent tool to guide remediation in situations such as in the Córrego do Feijão Iron Mine disaster. [ABSTRACT FROM AUTHOR]

Both the tailings and associated leachates should be characterised to predict contaminant levels and identify suitable remediation strategies for appropriate closure planning of tailings management facilities (TMFs). Tailings and associated drainage waters from a modern Pb/Zn site were characterised to determine contaminants of possible concern for discharge. The potential for constructed wetlands to provide suitable treatment of tailings waters was assessed over a 10 month period. Tailings were slightly alkaline (pH 8.3), with high net neutralising capacity (578 kg CaCO3/t), very high level of neutralising carbonate minerals (ca. 60%), and low sulphide content (< 5%). Metal content was Zn (2430 mg/kg), Pb (1900 mg/kg), As (620 mg/kg), Sb (80 mg/kg), Ni (50 mg/kg), and Cr (30 mg/kg). The pH dependent leaching demonstrated the potential for higher amounts of metals to be released under acidic conditions (pH < 5), although this would be most unlikely given the very high NP/AP ratio. Drainage waters were net neutral (pH 7.7) but exceedance of surface water directive levels was observed for sulphate, Sb, and Zn. Constructed wetland treatment demonstrated effective Zn and Sb to achieve limit values. Sulphate levels remained high and exceeded the 250 mg/L limit values. Mn values in the wetland effluent exceeded influent levels. Further evaluation of the constructed wetland treatment option is warranted to achieve sufficient treatment of the neutral pH discharge to levels suitable for discharge. [ABSTRACT FROM AUTHOR]

Mine tailings pose environmental risks such as dust emission and acid mine drainage (AMD) and also present geotechnical risks, i.e. tailings dam failures. In-situ cementation of tailings has the potential to reduce the risks associated with such failures as well as the related environmental problems. In this paper, a new inorganic method of inducing tailings cementation is introduced using a naturally occurring mineral called trona (Na2CO3⋅NaHCO3⋅2H2O). Three methods of introducing dissolved trona, i.e. injection, slurry mixing, and infiltration, were tested and the results were compared. All methods proved successful on a laboratory scale but with different amounts of precipitated calcite at different sample depths. The precipitation profile distinctions could have applications in solving common problems associated with tailings including dust emission and liquefaction. Additionally, even distribution of precipitated calcite in the slurry mixing method shows potential for AMD prevention. [ABSTRACT FROM AUTHOR]

One of the Letšeng Diamond Mine's two tailings storage facilities has high volumes of toe seepage, which could be caused by internal erosion within the embankment, a major reason for many dam failures. A resistivity survey delineated two prominent anomalies associated with saturated spots within this embankment, which might have been due to free water in the tailings supernatant pond, water from the spigotting operation moving through the dam fill as wetting fronts, or embankment ponding due to rainfall. However, standpipe piezometers indicated that these anomalies were not associated with a phreatic surface in the embankment. Constructed entirely from coarse tailings with a saturated hydraulic conductivity of 2 × 10–05 m/s, the embankment is pervious, which inhibits development of a phreatic surface. Apart from toe seepage, there was no evidence of leaks at the embankment's downstream face. Steady state seepage was conservatively calculated as 15 L/s, which is periodically exceeded by almost threefold. A review of toe seepage vs. rainfall and groundwater levels suggests that these seepage fluctuations were due to increased precipitation-induced groundwater recharge and runoff. [ABSTRACT FROM AUTHOR]

Most mining operations produce waste material, or tailings, which is commonly stored within impoundments known as tailings storage facilities (TSFs). A common TSF design involves depositing slurry on tailings 'beaches' which are sloped towards a containing wall or central pond which collects excess water. A crucial aspect of safely operating TSFs is managing the residual moisture content of the deposited tailings, which requires an accurate understanding of the water balance of the TSF. However, evaporation from a TSF is particularly hard to quantify as the degree of surface wetness varies spatially and temporally, and moisture content depends on the time since tailings deposition and the prevailing climate. This study addresses these issues at an active TSF by combining field measurements, models, and satellite observations. Evaporation from open water was measured using a floating evaporation pan and evaporation from the tailings beaches was investigated using micro-lysimeter measurements. Evaporation rates for different moisture contents were expressed as a fraction of open water evaporation and a strong relationship was developed for use in satellite analysis. Spatial and temporal patterns of open water and moisture content were determined at 20 m resolution using moisture indices applied to Sentinel-2 satellite scenes. Continuous open water evaporation rates and spatial moisture content information were combined to estimate total TSF evaporation. Comparison of TSF evaporation rates to those derived using an existing site water balance model showed very good agreement. The methodology developed could be applied at other locations around the world. [ABSTRACT FROM AUTHOR]

Geochemical and geophysical investigations were performed in an area of the Darasun ore cyanidation tailings impoundment, which is located in a permafrost region. The tailings contain up to 40 wt% pyrite and 5.7 wt% arsenopyrite. The purpose of this work was to determine the composition and mechanisms of transformation of the tailings and species of As, Au, Ag, Be, and Tl in drainage waters and the Darasun River before and after mixing with technogenic flows from the mining area. When the waste is oxidized because of the repeated seasonal freezing and thawing of water, three groups of chemical elements are leached: typical ore metals and impurity elements (Pb–Co–Ni–Zn–Cd and Fe–Al–Tl–Be–In), noble metals, metalloids (Au–Ag–Cu–As–Sb–Se), and post-transition metals and metalloids (Bi–Sn–Te). Drainage waters with salinities up to 5 g/L form, with concentrations of sulfate ions up to 2 g/L and cyanide up to 4 g/L, high concentrations of Au (up to 130 µg/L), Ag (3.8 µg/L), As (up to 350 µg/L), and Sb (up to 1100 µg/L), and impurity elements (Tl, In, Be, and Bi). The drainage water flows into the Darasun River, resulting in hydrochemical anomalies tens of kilometers downstream. [ABSTRACT FROM AUTHOR]

La Parrilla is a tungsten and tin mine located in western Spain. The tailings facility has a total capacity for 3 Mm3 and will be executed in four different phases. The main constraint for the design and construction of the tailings dam is that it has been constructed over an existing one from the 1980s. The construction activities involved removal and substitution of the old tailings from the southern portion of the facility, ground improvement with gravel columns over an area of about 10,000 m2, and construction of the dyke's dam. This article describes the main design and construction aspects, including monitoring, until the dam's completion in June 2019. [ABSTRACT FROM AUTHOR]

An exploratory study demonstrated that subtle changes in solids and process water were caused by long-distance turbulent transport of tailings from the concentrator to the impoundment of a Cu (Mo) porphyry copper deposit. Slurry water chemical analysis was complemented by modelling potential phase precipitation or dissolution and speciation of dissolved metals. It was found that transport did not affect major insoluble mineral phases. However, the degrees of liberation of several phyllosilicates, as determined by automated mineralogy, were reduced close to the impoundment, which points to separation of clay particles from tectosilicate surfaces by the turbulence; this also was observed by SEM examination of micro-aggregate specimens. Reduction of maximum particle sizes, increased N2 monolayer adsorption, and resultant specific surface areas indicate that transport modified the micro-aggregates. Major element water chemistry is controlled by the presence of soluble mineral phases, such as gypsum, and reagents, such as lime, in the flotation process. Changes in the dissolved concentrations of some elements could potentially affect tailings deportment in the impoundment. Increased concentrations of Al may affect the clay settling behaviour, while Mo and As levels will require treatment prior to the discharge of water from the tailings impoundment. This study demonstrated that systematic scrutiny of tailings slurries leaving the concentrator and before entering the impoundment can be potentially useful, though care will have to be exercised to replicate sample handling and analytical conditions, during any long-term monitoring. [ABSTRACT FROM AUTHOR]

This paper describes a stepwise method for assessing lead hazards associated with mining. The procedural framework was constructed in a decision-tree format to facilitate a reliability estimate in the watershed. A sigmoid fuzzy membership function was proposed for measuring risks. Using the α-cut technique, seven areas of risk in the region were provided for all types of water use. The suggested model was validated at the Emarat lead mine, Iran. Samples were taken from the mine face, entrance tunnel, and drainage waters at the entrance and exit point of the processing plant and tailings dam. All of the samples were located in a very high risk zone (reliability = 0) for animal drinking water, but some could be used for crop irrigation (mine site's samples reliability > 0.77 and processing plant's samples reliability > 80). [ABSTRACT FROM AUTHOR]

We evaluated the potential use of a geomembrane-laminated geosynthetic clay liner (GCL) along the slopes of a boric acid tailings dam in Emet, Turkey. Even though a compacted clay liner (CCL) had been used at the bottom of the tailings dam, it was not possible to place a CCL along the slopes of the dam due to their steepness. Triaxial permeability tests were conducted on the base GCL without a geomembrane and the results indicated that although the volumetric flow through a cross section of the GCL was measured to be very low initially, it increased after a while due to the interaction of the bentonite in the GCL and the mine leachate. For this reason, using a geomembrane-laminated GCL along the steep slopes was found to be an appropriate solution. The mechanical properties of the barrier material were evaluated by performing a parametric study, including a slope stability analysis and an anchorage design for the geomembrane-laminated GCL. Based on the results, a geomembrane-laminated GCL with appropriate mechanical and hydraulic properties was chosen. [ABSTRACT FROM AUTHOR]

The disastrous impact of a tailings dam failure is more far-reaching than that of a water retention dam failure. This paper analyzes the movement characteristics of mudflow during a tailings dam failure using physical models based on the Wadugou tailings impoundment. The physical models were built according to the similarity laws to investigate an overtopping dam failure under natural conditions and when additional protective measures were used. Based on the experimental results, the dam breach size, the breach flow discharge, flow velocity, downstream inundated area, and tailings deposition volume are all reduced by preferably protecting and maintaining the tailings dam embankment to mitigate the destructive effects of a potential dam failure. Finally, the time required for safe evacuation for the Wadugou tailings impoundment area is given. [ABSTRACT FROM AUTHOR]

The article presents a study of the metal sorption and desorption behavior of the soil aimed at assessing the potential efficiency of a tailings dam and the risk of release of metal contaminants to groundwater, following dam construction at the Golgohar Iron Ore Mine in southern Iran. Results showed that the adsorption of elements in the soil profile is generally strong, suggesting that the soil in the study site can control some of the elements from entering the groundwater.

A 20 month long column study was conducted to evaluate the surface application of waste glycerol (WG) to reduce release of acid mine drainage constituents from mine tailings. Beneficial characteristics of the WG include high aqueous solubility, high organic content, and high alkalinity. Four columns were packed with fine-grained sulfide rich tailings and incubated in the field under ambient temperature and precipitation conditions. In the two replicate untreated control columns, diffusion of oxygen into the tailings resulted in large increases in dissolved iron, sulfate, manganese, magnesium, aluminum, zinc, and hot acidity with an associated drop in pH. In the two replicate treated columns, WG was blended into the top 0.18 m of tailings 7 months after the columns were established, resulting in large reductions in iron, sulfate, hot acidity, aluminum, copper, and manganese. Observed pollutant reductions resulted from a combination of processes including: (a) neutralization of acidity by the KOH present in the WG (b) reduction of SO to HS with subsequent precipitation of dissolved metals, and potentially (c) consumption of oxygen, slowing oxidation of the tailings. [ABSTRACT FROM AUTHOR]

Damage caused by accidents at hydraulic structures, due to natural hazards or human causes (e.g. terrorist sabotage) can be comparable to those caused by natural disasters. The paper identifies the major advantages of a common methodology for risk identification and quantification regarding the potential impact of accidents at tailings dams on the environment. Relevant Romanian and EU legislation and regulations enacted following the “Baia Mare” accident in 2000 are reviewed, along with a common risk evaluation methodology that can be applied by the mining sector to tailings dams. [ABSTRACT FROM AUTHOR]

There are other technical journals staffed entirely by unpaid volunteers, and I am undoubtedly biased, but I know of none that are as professional and highly regarded in their field as this one. I should also mention that three of these individuals are serving as guest editors for upcoming special issues of this journal, which will appear in print in 2020 (though of course many these papers are already published in the on-line version of our journal, which all IMWA members can easily access for free). Finally, I thank Christian Wolkersdorfer, who in addition to serving as IMWA's president, serves as this journal's managing editor - which means that he worries about the non-textual aspects of the journal, such as how figures should be formatted, and generally oversees our interactions with our publisher, Springer Nature. [Extracted from the article]

Alternatively, if the issue arrived in your mailbox later than usual, this means that we were able to have the publication delayed a little in an attempt to get a few more papers into this issue. Our impact factor is now better than over half of the world's water resource journals in Clarivate Analytics' science citation index! Such papers may not be highly cited, but they are key components of this journal and generally, are of more practical benefit than most of the other papers we publish. [Extracted from the article]

A correction to this paper has been published: https://doi.org/10.1007/s10230-021-00776-0 [ABSTRACT FROM AUTHOR]