Lundin Mining employs a comprehensive and integrated approach to tailings management. This provides us with confidence that potential environmental and social impacts can be reliably identified and minimized. Efficient mining and mineral processing, along with disposal underground where practicable, allow our operations to minimize the quantities of tailings stored on surface. Our operations aim to minimize associated risk with a clear understanding of the tailings characteristics, the facility construction materials, and the final settings in which they are placed.
A full list of tailings facilities that Lundin Mining manages, including information on tailings management, construction method, maximum dam height and volume, can be found in our Tailings Management Information Sheet.
Lundin Mining operates five mines with five active tailings facilities and uses two widely accepted methods of tailings disposal:
underground disposal involves mixing tailings with products, such as sand or cement, followed by disposal as a paste backfill or hydraulic backfill in previously mined areas of underground mines; and
surface disposal involves placement in engineered surface impoundments or, in the case of Eagle, in a previously mined open pit.
Of the five Lundin Mining operations, Eagle Mine is the only operation that does not have a constructed tailings impoundment with dams. The five active tailings facilities use various construction techniques for the main and secondary or perimeter dams, but none use upstream construction. Lundin Mining also maintains and monitors six inactive/closed tailings facilities, one of which is a rockfill combination centreline and downstream design followed by rockfill upstream raises and buttresses at Zinkgruvan.
All tailings facilities are operated or closed as per the currently approved design. Full and complete engineering records including design, construction, operation, maintenance and/or closure exist for all tailings facilities except for the inactive Enemossen facility at Zinkgruvan, and closed San Esteban and Ojos del Salado facilities at Candelaria. San Esteban has an updated detailed design closure plan and the three Ojos del Salado tailings facilities are legacy sites that ceased operations in the 1960s. The Ojos del Salado tailings facilities were fully closed in 2012 as per an approved engineered closure plan.
A full list of tailings facilities that Lundin Mining manages, including information on construction method, maximum dam height and volume, can be found in the Tailings Management Information Sheet.
Surface tailings impoundments can represent one of the more significant environmental risks for the mining industry. Lundin Mining takes considerable care to ensure our tailings facilities are well-designed, built in accordance with leading industry practices and standards, well-maintained, inspected, independently reviewed, and carefully monitored.
Policies and Standards
Lundin Mining’s Responsible Mining Policy includes a specific Tailings Management Technical Standard. All Lundin Mining’s operations manage their tailings in accordance with this technical standard, developed in 2015, and currently under update. This technical standard requires that all tailings facilities, including major water retention dams, are planned, designed, constructed, operated, and, in the case of inactive or closed facilities, decommissioned and closed in such a manner that:
All structures are stable; and
All aspects comply with regulatory requirements, accepted international practice and any commitments to local stakeholders.
Monitoring and Surveillance
A requirement of the Tailings Management Technical Standard is for all sites to conduct regular geotechnical, hydrogeological and environmental monitoring to meet regulatory requirements and prevent the uncontrolled release of tailings and/or water to the environment.
All sites employ monitoring and surveillance systems which may include surface prisms, piezometers, inclinometers, remote sensing and other technologies to monitor tailings dams and water levels. Trigger action response plans (TARPs) provide clear guidance on how to respond to pre-determined trigger levels for surveillance activities.
All active tailings facilities have a closure plan which includes long-term monitoring requirements. The monitoring plan for the closed Ojos del Salado tailings facilities is under development and will be evaluated further in 2021.
Sites are required to identify a Responsible Person (RP) to ensure ownership and proper management of the tailings facility. The RP guarantees procedures for each facility, including an Operating, Maintenance, and Surveillance (OMS) Manual and Emergency Preparedness and Response Plan, are regularly documented and made available to site personnel.
The RP is an appropriately qualified, experienced and site-dedicated individual employed directly by the site. This person typically has an environmental or engineering background.
Tailings dams are regularly inspected by trained operators and technical staff, sometimes as frequently as several times daily, with formal documented staff inspections at least quarterly.
Engineer of Record
Each active and inactive tailings facility has an appropriately qualified, licensed and experienced third-party geotechnical engineer to act as an external Engineer of Record or Design Engineer in the relative jurisdiction.
Dam Safety Inspections
Formal dam safety inspections are conducted at least annually by the external Engineer of Record, and reports are issued to the Responsible Person for action on recommendations.
Tailings and water dam safety focused risk assessments are reviewed and updated at least annually and include input from site and corporate staff, the Engineer of Record and independent reviewers.
A component of the Tailings Management Technical Standard is the requirement for regular independent third-party tailings reviews, which are recognized as a leading practice for effective tailings and water dam stewardship. The reviews are focused on impoundment stability and integrity.
Annual site visits this year for the independent reviewers are all scheduled in the fourth quarter 2021. In addition, online progress meetings with the independent reviewers and Engineer of Record (EOR) are scheduled throughout the year to closely track progress made on outstanding recommendations.
Results from the independent reviews are carefully tracked, and progress updates are sent to the Board-appointed HSEC Committee each quarter.
Global Industry Standard on Tailings Management
Lundin Mining is committed to the implementation of the Global Industry Standard on Tailings Management (GISTM), which is the first global standard on tailings management.
Briefing workshops and information sessions started in early 2021 and are ongoing. The existing Lundin Mining tailings governance framework and relevant company policies and standards are being updated to align with the GISTM requirements. Formal gap analyses are being coordinated and site-level implementation action plans will be developed in 2021.
Lundin Mining plans for tailings facilities that are classified as having ‘Extreme’ or ‘Very high’ potential consequences of failure, as defined by the Standard, to be in conformance with the GISTM within three years of August 5, 2020, and all other facilities within five years.
Enhanced Tailings Governance, Monitoring, and Reporting Initiative
Lundin Mining is evaluating viable enterprise-wide business intelligence solutions for tailings governance, real-time monitoring and data management, and critical controls reporting in 2021.