SUSTAINABILITY TSF life cycle
Tailings storage facilities (TSFs) must be, operated, closed, and rehabilitated to ensure negligible operator and public health and safety risks and acceptably low community and environmental impacts.
Leading principles in tailings management practice are underpinned by a risk-based approach to the planning, design, construction, operation, closure, and rehabilitation of TSFs. In this approach, plans need to be tailored to manage the TSF effectively over its entire life cycle, with sufficient detail to address the potential risks within acceptable limits. TSFs with a high consequence category require more rigour in the design phase, greater quality control during construction, and closer attention to risk management, emergency action planning systems, and documentation during the operational and closure phases.
The phases of a TSF life cycle comprise:
Project Conception and Planning: commences at the outset of planning a proposed TSF and is integrated with conception and planning for the overall site, including the mine plan and ore processing plans. This phase includes using rigorous decision-making tools to support the TSF site selection, the outcome of the multi-criteria alternatives analysis, and the technology to be used for tailings management.
Design: begins once the knowledge base is mature. The location of the TSF is supportive of long term mine planning. Detailed engineering designs are prepared for all aspects of the TSF and associated infrastructure.
Initial construction: involves constructing of features, structures, and infrastructure that must be in place before tailings deposition commences. For example, initial construction activities may include site clearance and construction of starter embankments and drainage systems, tailings delivery and distribution pipelines, access roads, and associated water management infrastructure.
Operations and Ongoing Construction: involves transporting and depositing of tailings to the TSF. The embankment may be raised in a series of lifts or wall raises using the downstream, centreline, or upstream methods, which are so-called because they involve the crest advancing downstream, vertically upwards, or upstream, respectively, requiring progressively less containment wall earthworks.
Standby Care and Maintenance: the mine has ceased commercial operations, and tailings placement into the facility is not occurring. The Owner expects to resume commercial operations at some point, so surveillance and monitoring of the tailings facility continue. The facility and its associated infrastructure are not decommissioned, and the closure plan is not implemented.
Closure: commences when the deposition of tailings into the TSF ceases permanently. The facility and associated infrastructure are decommissioned, and the closure plan is implemented, including:
Post-closure: begins when decommissioning work is complete, the closure plan has been implemented, and the TSF has transitioned to long-term maintenance and surveillance. During post-closure, responsibility for a TSF could transfer from the Owner to jurisdictional control.