Teck's tailings facilities are operated and maintained to meet global best practices for safety. We continually review our facilities and procedures and are committed to maintaining the highest standard of safety at our operations.
Tailings are a common by-product of the mining process. They are typically created as mined ore is crushed, ground and processed to separate the valuable minerals and create a saleable concentrate product. The waste from this process is called tailings. Due to the nature of the ore separation processes, tailings are commonly in the form of a slurry of fine mineral particles and water. Management of tailings involves storage in a specially-designed impoundment called a tailings facility.
Tailings facilities are historically well-managed with very few incidents; however, there have been incidents and from these we know that a tailings incident has the potential to have a significant impact on communities, local economies and the surrounding environment. As such, we take extensive measures during planning, design, construction, operation and decommissioning of our tailings facilities to confirm that:
Tailings facilities can follow a number of designs, based on factors including the composition of the tailings being stored, geotechnical considerations, precipitation, seismic activity, community preference, and environmental protection. Across Teck’s operations are examples of numerous types of tailings facilities, including facilities for storing dewatered “dry stack” tailings at our steelmaking coal operations and in-pit storage utilizing existing mined-out pits. The most common form of tailings impoundment at Teck and across the mining industry is created by constructing a dam (or dams) in conjunction with natural topography to create a tailings storage facility.
There are several primary methods of constructing tailings dams. The specific construction method, or combination of methods, for each of our tailings facility is chosen based on the factors above, with the first priority being the safety and security of communities, employees and the environment. Within these methods are three basic geometries defined by how the crest of the dam moves relative to the original “starter dam” at the outset of the tailings facility’s development.
Uptream construction begins with a starter dam constructed at the toe of the facility. The tailings are then discharged into the facility where they form a tailings beach. This tailings beach, which can be compacted/controlled, is then used to form the foundation for subsequent levels of the wall as the dam is raised. As such, the crest of the dam moves upstream with each raise.
In Centreline construction, the dam is raised vertically from the starter dam. The dam crest therefore remains fixed relative to upstream and downstream directions as the dam is sequentially raised. Unlike the upstream geometry, the dam wall does not used beached tailings for foundation support.
Downstream designs start with a starter dam similar to the other two construction methods. Tailings are then discharged into the dam and as the embankment is raised, each new wall is constructed and supported on top of the downstream slope of the previous section, so the dam crest moves downstream with each raise. Like the Centerline construction, the dam wall does not rely upon beached tailings for wall support.
A single stage dam is built to full height in one stage with no further raises. This design is most commonly used for smaller tailings facilities.
Teck actively manages 55 tailings facilities across our active and legacy mine sites. Of these Teck managed facilities, 16 are active and 39 are closed and no longer receiving material. We have one active upstream tailings facility and eight closed upstream facilities. 16 are unsaturated/dry stack facilities at our steelmaking coal operations, and 20 are closed facilities at legacy mine sites in various stages of reclamation.
We also have non-operated joint venture interests with tailings dams at Antamina in Peru and Fort Hills in Alberta.
Many sites include multiple tailings facilities, which are often a mix of active and inactive facilities.
Teck operates and maintains our tailings facilities to meet global best practices for safety including industry leading protocols established by the Mining Association of Canada and best practice technical guidance from the Canadian Dam Association and the International Commission on Large Dams.
1. Surveillance Technology: Sites employ surveillance systems such as GPS hubs, piezometers, inclinometers, pressure gauges, remote sensing and other technologies to monitor tailings dams, abutments, natural slopes and water levels.
2. Staff Inspections: Tailings dams are inspected by trained operators and expert technical staff as frequently as several times daily, with formal staff inspections at our operations at least once per month.
3. Annual Dam Safety Inspections: Formal dam safety inspections are conducted annually by an external Engineer of Record. Recent annual Dam Safety Inspections for our facilities are publicly available.
4. Detailed Third-Party Reviews: Comprehensive third-party dam safety reviews are conducted by a qualified independent tailings reviewer as frequently as every three years, based upon the consequence classification for each facility.
5. Internal Governance Reviews: Teck’s Tailings Working Group conducts internal management reviews of our tailings facilities as well as our major tailings projects on a regular basis.
6. Independent Tailings Review Boards: Our operations, higher consequence legacy facilities and major development projects have Tailings Review Boards made up of independent experts who meet regularly, at least annually, to conduct a third-party review of design, operation, surveillance and maintenance.
All Teck facilities have a detailed Operations, Maintenance and Surveillance manual and Emergency Preparedness and Response Plan, which are both regularly reviewed and updated. We also review Emergency Response plans with our local communities and stakeholders and undertake community meetings and emergency drills to work through these plans and discuss our approach to tailings management.
For all high-consequence facilities, a formal inundation study is conducted to identify any potentially impacted communities and waterbodies in the extremely unlikely event of a tailings incident, in order to evaluate design/mitigation strategies and to assist with emergency planning and response.
Teck follows the Canadian Dam Association Consequence Classification system that assigns a consequence ranking from Low to Extreme based upon the potential environmental, safety and economic effects of a failure. This ranking does not reflect likelihood of failure, but rather provides a tool to assist with facility design and emergency planning.
Teck is committed to being open and transparent with communities and other stakeholders regarding the construction and management of our tailings facilities. One of the most important pieces of information for each tailings facility is the annual Dam Safety Inspection (DSI). A DSI is conducted annually for each tailings facility by the third-party Engineer of Record. The DSI is a detailed examination of the facility and related infrastructure with the purpose of identifying any conditions or changes that might impact the safety and reliability of the structure and to make recommendations where any issues warranting attention are noted. Teck tracks the recommendations and works with the Engineer of Record to address each item in a timely manner.
In most jurisdictions, DSIs are provided to the government on an annual basis but have not often been made publicly available. Following the Mount Polley tailings dam failure in 2014, the Government of British Columbia, Canada, made DSIs for mines in B.C. publicly available. We support this transparency and have built on this disclosure by making the DSIs for our tailings facilities in all jurisdictions publicly available.
While we are confident in the safety and security of our tailings facilities, we are committed to continually reviewing our facilities and procedures to maintain the highest standard of safety at our operations. As such, following the tailings failure at Vale’s Feijão Mine in Brazil, we initiated a special review of our tailings facilities and procedures. This review will include external experts who will be independent to any aspect of the design or operation of any of our facilities.
We also work in partnership with numerous local, national and international organizations to support improvements in tailings and mine waste management across our industry, including:
Download this table for additional detail on each tailings facility with dam(s) managed by Teck at both our active operations and legacy sites.
Dam Safety Inspections (DSIs) are one of the measures in place for the safe management of our tailings facilities. DSIs are conducted annually by a third-party Engineer of Record for mine tailings facilities in order to to review the safe operation, maintenance and surveillance of the facility and to identify and make any recommendations.
Follow link for DSIs for Teck’s tailings facilities by operation.