TSF Monitoring (Tailings Storage Facilities) and disaster prevention

Not just a legal requirement; but a life or death responsibility

With a whopping average volume of 17 million cubic meters; tailings dams store a mine’s primary waste stream. Consisting of large surface impoundments of pulverised rock, water and harmful processing chemicals; tailings dams – if mismanaged – brim with the disastrous potential of not only devastating the environment, but also destroying both lives and livelihoods.

It is thus of paramount importance that these areas of mine sites are constantly and meticulously monitored. Management protocol is thus an enormous responsibility that should not be taken lightly at all. The significance of what happened on January 25, 2019 at Vale’s Córrego do Feijão iron ore mine in Minas Gerais, Brazil still haunts our memories, and still affects the lives of thousands of its downstream communities today. The catastrophe serves as a reminder as to just how paramount this is. Due to the failure of the operation’s tailings facility; the deadly mudslide caused at least 270 people to lose their lives, while the surrounding environment and downstream communities were destroyed. Furthermore, it is horrifying to note that 9.7 million cubic meters of waste was violently deposited into the Paraopeba River ecosystem (Earthworks, 2021). Adriaan Meintjes, an international mining expert describes in Mining Journal (November, 2019) that the incident ‘triggered a major, industry-wide and cross-organisational response to tailings storage facility (TSF) best practice in a manner not dissimilar to the safety and security response to the 9/11 terror attacks in 2001.’

Hence, without proper management, tailings facilities may threaten catastrophic events such as collapse, contaminated water seepage or overwhelming dust pollution. A legal requirement therefore exists, where programmes need to align their management of tailings storage facilities with that of the Global Industry Standard on Tailings Management (GISTM), which was launched on 6 August 2020. In order to conform with the Standard, the document states that operators are to use measures as specified, which will prevent the catastrophic failure of tailings facilities. This includes the implementation of best practices in planning, design, construction, operation, maintenance, monitoring, closure and post closure activities.

                                                                 

Tailings failures: how mismanagement has lead to monumental, historical catastrophes in the past

  • In August 2014, a tailings dam breach at the Mount Polley Mine in British Columbia released 5 million cubic meters of toxic waste into a lake and nearby creeks. Mature trees were ripped from surrounding forests, sending thousands of trees miles downriver into Quesnel Lake.
  • Shortly thereafter, in November 2015 the Fundão tailings dam at the Samarco mine (owned by Vale & BHP) in Brazil failed. The disaster killed 20 people downstream, while 3 villages were destroyed and over 600km of waterways were polluted with toxic mine waste.
  • In January of 2019, Vale’s tailings dam at Córrego do Feijão iron ore mine in Minas Gerais, Brazil -as previously mentioned- collapsed- shortly after vowing ‘never again’  after the Samarco catastrophe. With devastating, long-term impacts to the environment, and 270 lives lost as a consequence; this event has changed thousands of lives for the worst. 

Tailings failures are increasing in frequency and degree

As if the fairly recent case studies are not alarming enough; according to earthworks.org; the rate of serious tailings dam failures is increasing. According to specialist researchers for the Washington-based NGO; half (33 of 67) of serious tailings dam failures in the last 70 years occurred in the 20 years between 1990 and 2009. It is suspected that the increasing rate of tailings dam failures is directly related to the increasing number of TSFs larger than 5 million cubic meter capacity, which is necessitated to allow the economic extraction of lower grades of ore. What is more; according to worldminetailingsfailures.org; 19 catastrophic failures are predicted globally from 2018 and 2027 if management is not brought to the forefront. 

Yet, inattentive management still seems to predominate

With all the standards in place; and with some of the most devastating precedent studies of tailings dams disasters yet to be seen; one would think efficient management systems for disaster management of tailings dams is a top priority for all mines, worldwide. However, it seems that the urgency of this is yet to be fully realized by a majority of mines worldwide. 

The Responsible Mining Foundation, an independent research organisation based in Switzerland, raises even more alarm bells concerning the Responsible Mining Index (RMI) conducted in 2018. This report revealed that many of the world’s largest mining companies were not able to communicate how effectively they had been addressing the risks of tailings dam failure and seepage. Out of 30 mining companies assessed; only 22% scored on tracking, reviewing and acting to improve their tailings risk management, with Vale scoring slightly above average. A shocking 50% of the mining companies showed evidence of risk monitoring.

Tailing Storage Facility (TSF) Monitoring: the path to best practice and disaster management 

The dynamic, ever changing nature of TSFs has made their monitoring crucial to safety and risk management. With ever increasing capacities, as well as the shifting nature of their contents; the chemistry, structure as well as movement of tailings are constantly altered with the orebody and processing evolutions through time.

Michael Breetzke, a director for Swift Geospatial says that the importance of the monitoring of this ‘living, breathing’ system therefore cannot be more emphasized. After all, it is in monitoring where the industry has perhaps seen the greatest discrepancies in best practice; where thousands of lives could have been spared.

Until recently, many TSFs have been monitored with an array of instrumentation, largely based on time-consuming manual readings, with inevitable inconsistency and human error. Enter the 21st century and real-time performance monitoring: according to Michael; a good tailings management system is set up through customized data parameters; where users are alerted to issues as and when they arise- before it is too late. 

Swift Geospatials’ proactive satellite approach, methodology and live dashboard display

Sourced from our partner, Planet (who revolutionized the earth observation industry with the highest frequency satellite data commercially available); Swift Geospatial uses 3 metre resolution, multispectral-4 band satellite imagery, which is collected on a daily basis. 

Because Planet images the earth every single day; even the slightest change detection may therefore be monitored, and is actionable. Furthermore; access is granted to the latest and highest quality cloud free imagery for analysis- ideal for TSF sites that are typically hindered by cloud cover. What is more; our RADAR imagery is able to penetrate through clouds, smoke, fog and may even be collected at night.

Swift Geospatial uses high quality, 3 metre resolution, multispectral-4 band and cloud-free satellite imagery, which is collected on a daily basis from our partner platform, Planet.

The resultant output may be performed at a customized frequency, which is typically a weekly dashboard summarizing the required data for decision-support. 

Our resources (and partners):

  • Planet’s 3 metre resolution, satellite imagery which is updated daily
  • Maxar’s constellation of ultra-high resolution 30cm to 50cm satellite imagery
  • Capella Space’s set of Synthetic Aperture Radar (SAR) ranging from 50cm to 1.2m resolution satellite imagery. 
  • All of our imagery is compatible with ESRI software.

Methodology:

The below image summarizes the process that Swift Geospatial undertakes for TSF monitoring. We collect the satellite imagery, delineate the tailings dams per site and apply the surface water index analysis per TSF site. Automatically, the standing surface water is calculated on an ongoing basis at the desired frequency (usually weekly). 

Swift Geospatial’s Methodology for TSF monitoring

Output: the typical imagery feed includes (but is not limited to):

  1. A map displaying all imagery and analysis
  2. Site information and surface water percentage calculation per site (per latest image date)
  3. Active ongoing tracking week on week surface water accumulation per TSF site
  4. Different alert levels per risk
  5. Data may be presented and shared across a given network within mining management for immediate, pro-active response

Ease of use: SWIFTview

Douglas Bradley, co-director of Swift Geospatial enthuses that having access to these incredible sources of optical and SAR data is one thing, but transforming this data into actionable knowledge is the key deciding factor.

Working behind the curtain is one aspect of the larger solution; as Swift Geospatial weighs huge importance on the delivery mechanism with which to display the resultant data. Findings are thus displayed in an easily digestible manner that allows all personnel access to the information presented; which  is vital to the success of our monitoring solutions. 

At Swift Geospatial; we are cognisant of the fact that not all of our customers have a Geographic Information Systems (GIS) background;  therefore emphasis is placed into how we display the results in such a way that all could benefit from the analysis.

Moreover, it is important to be cognisant of the fact that more often than not, responsible persons are not always on site; therefore the method of remote sensing significantly reduces the need for direct interaction through time consuming and unnecessary site visits.

This approach saw the development of what is known as SWIFTview, a dynamic online web-application that offers the end-user an ongoing view of their mine with frequent updates and tracking features to provide a true monitoring experience. 

Displayed analytics through bar graphs, pie charts and visualization allows for a simple, yet effective, means of data display while still providing the GIS expected download capabilities and integration into third party mine software via our REST API service.

Swift View | GIS

A fully-automated, cloud-based solution:

Furthermore; as a company, Swift Geospatial decided early on to move our analytics and processes to Amazon Web Services (AWS) to provide our clients with 99.99% up-time with quicker processing and delivery times (read more about this here).

Additional services

Through the implementation of using multiple satellite imagery services, Swift Geospatial may provide the following additional services within the mining environment:

  • Tailing Dam Monitoring
  • Illegal Mining Monitoring
  • Rehabilitation Monitoring
  • Encroachment Monitoring

Conclusion: moving into the future by using smart technology

Using the sophisticated technology at hand, remote sensing is the most cost-effective, time-saving strategy for the monitoring of Tailings Dam Facilities. Swift Geospatial can confidently vouch for our refined approach to TSF management- empowering managers to detect with immediate effect if any risks or triggers are activated- as and when they happen.

Stay tuned for our next article- which delves into further depth with regards to our additional services for mining applications.

 

References:

Feb, 2019. Tailings Management: learnings and good practice. Responsible Mining Foundation. [Online] Available at <https://www.responsibleminingfoundation.org/research/tailing-management/> [Accessed 27 August, 2021].

13 Nov 2019. Meintjes, A.The evolution toward TSF performance monitoring. Mining Journal. [Online] Available at <https://www.mining-journal.com/partners/partner-content/1373003/the-evolution-toward-tsf-performance-monitoring> [Accessed 27 August, 2021].

August, 2021. A.Global Industry Standard on Tailings Management. International Council on Mining & Metals (ICMM). [Online] Available at <https://www.icmm.com/en-gb/guidance/environmental-stewardship/global-industry-standard-on-tailings-management> [Accessed 27 August, 2021].

Date & author unknown. Tailings. Earthworks. [Online] Available at <https://www.earthworks.org/issues/tailings/> [Accessed 27 August, 2021].