How Advanced Reverse Osmosis is Solving Northern Mining’s Biggest Closure Liability

The successful remediation of legacy mine sites hinges on one core challenge: water. Beyond the immediate risks of dam failure, the long-term liability associated with contaminated water – often laden with heavy metals and dissolved solids – can threaten ecosystems and downstream communities for decades. For the Canadian mining sector, particularly in remote northern territories, addressing this issue requires a commitment to perpetual water management and cutting-edge technology.

This is the challenge currently being tackled at the Wolverine Mine in southeast Yukon, located on the Traditional Territory of the Kaska Dena Council.

The Wolverine imperative

Following the cessation of operations in 2015, the mine’s tailings storage facility (TSF) began to accumulate significant volumes of contaminated process water. The escalating risk of an eventual overflow – releasing harmful contaminants into nearby rivers and wetlands – demanded immediate and innovative intervention.

Recognizing the severity of the closure liability, the Yukon Government engaged Milestone Environmental Contracting to design and execute a two-year remediation and stabilization project.

“Our immediate goal is to safely draw down the water levels for discharge. Crucially, we are also leveraging this project for research and development to establish a robust, long-term closure solution,” explains Elden MacIver, Director of Water Management at Milestone Environmental.

Going beyond conventional treatment

Mine site water remediation typically involves standard physical and chemical treatment, sufficient for most operational discharges. However, the complexity of the accumulated water at Wolverine required a solution capable of the highest level of contaminant removal.

Milestone opted for a multi-stage process featuring a high-polish, two-pass Reverse Osmosis (RO) system. This comprehensive train is engineered to handle the site’s complex water chemistry:

1. Pre-treatment: Initial removal of suspended solids via ultra- and micro-filtration.
2. Primary polish: Two-pass RO to strip out a vast majority of the dissolved contaminants, including difficult-to-treat metals and total dissolved solids (TDS).
3. Final quality control: Post-RO polishing, including pH adjustment, ion exchange, and absorption, ensures the treated water meets the rigorous discharge standards set for the local creek environment.

As MacIver notes, “We are running the water through RO twice. That level of complexity demands a truly polished output to guarantee safety for fish, wildlife, and surrounding Indigenous communities.”

Compliance is non-negotiable, confirmed through a rigorous regime of field analysis, online monitoring, and independent third-party lab verification, including toxicity testing.

Lessons from the frontier: Logistics and safety

Remediation in Canada’s remote regions introduces a layer of logistical complexity that often dictates project success. Operating the Wolverine treatment facility requires planning that goes far beyond standard industrial procedures.

• Mobilization and access: The site is remote – an eight-hour drive from the nearest major airport. The specialized RO equipment and treatment systems required meticulous, long-distance mobilization from outside the territory.
• The climate clock: The operating window is tightly constrained. The team had only a month for mobilization, leaving a short summer period for the primary treatment phase. Operations must also be prepared for early-onset winter temperatures, with protocols in place for running systems at -20 Celsius. 
• Safety and wildlife: Beyond standard chemical-handling training for operators, the team must implement enhanced safety measures for wildlife, including bear awareness and stringent lone-worker protocols for night shifts.

Setting a new standard for closure

The Wolverine project is more than an isolated cleanup; it serves as a powerful illustration of the need for integrated environmental solutions across the industry. It demonstrates that the closure phase of a mine does not signify the end of responsibility, but rather the beginning of a long-term commitment to water stewardship.

By integrating advanced technology like two-pass RO with comprehensive logistics and safety planning, projects like this establish a new model for responsibly managing Canada’s mining legacy. Water stewardship is no longer just about meeting compliance; it’s about investing in the future of our northern ecosystems and communities.