Environmental Monitoring and Research

Walk the Line: The Delicate Balance of Setting Closure Criteria and the Relationship with Closure/Post-closure Monitoring

Thursday, November 21, 2019 - 8:20am to 8:40am Theatre Two


D.J. Pahl (Presenting)
Golder Associates Ltd.
B. Weeks
Golder Associates Ltd.
H. Machtans
Golder Associates Ltd.

In many jurisdictions, the development of a closure plan includes the development of closure goals, objectives and criteria. These are used to guide the transition of the site to the desired end land use, and demonstrate success. In some instances, particularly with sites that have a long mine life, these goals, objectives and criteria may need to evolve, to better reflect an achievable end land use, as well as criteria that are achievable and demonstrable. In other instances, sites must develop closure goals, objectives and criteria long after the start of operations. This means that the initial design of the operation may not be aligned with closure needs, and may not facilitate the transition to the desired end land use. At newer operations there are more opportunities to align design choices with closure goals and objectives, in a way that can benefit the transition to closure, end land use and eventual relinquishment of the site.

Both regulators and mine operators need achievable closure criteria, and the achievement of the criteria to be demonstrated in a realistic time frame. The setting of unrealistic or unachievable criteria may lock operators into years or decades of costly monitoring programs and impede relinquishment of the site. In an extreme case, unrealistic closure criteria may serve to discourage operators from completing reclamation, as the bar is seen to have been set too high. Hence, there is a difficult line to walk, requiring cooperation between regulators and operators to achieve desired outcomes.

In selecting appropriate goals, objectives and criteria, it is critical to be able to have achievable criteria that match the achievement of the desired end land use.

Closure criteria must be:

  • measurable or an easily discernable qualitative indicator
  • relevant to impacts from mining
  • indicative of a component of the targeted end land use
  • able to demonstrate that the final closure configuration endures over many years or decades.

Including the perspectives of Indigenous communities can help in determining the closure priorities for the site and hence selecting appropriate closure criteria. In isolated settings the land is often returned to traditional Indigenous use post-closure, where the fundamental rights to hunt and fish are often of primary concern and necessitate adequate ecological functioning of the post-closure landscape. In this manner, local stakeholders can be a valuable resource when setting closure objectives and criteria and should be included in the development process.

This presentation provide a retrospective analysis of closure criteria for common mine environment components such as tailings, water quality, and vegetation, and a discussion of whether or not this balance is achieved.