Diavik Diamond Mine Closure Overview

Introduction

• Location: Lac de Gras, Canada's Northwest Territories
• Part of Rio Tinto's operations
• Closure planned for 2026
• Operations since 2003
• Workforce: Over 1,300 people
• Diamonds recovered: Over 145 million carats
• Spending: $10.5 billion (over $7.5 billion with northern businesses)

Closure Plans

• Planned from the beginning of operations
• Closure and remediation until 2029
• Environmental monitoring for several years post-closure
• Aim: Leader in responsible mine closure

Site Decommissioning

• Removal of all buildings and infrastructure
• Revegetation of certain areas
• Exploration of repurposing existing infrastructure

Water Management

• Water treatment facility in place
• Cleans water before release into Lac de Gras
• Engineered closure controls to ensure safe water without active treatment

North Inlet

• Part of operational water treatment
• Water reused or treated and released
• Sediment bioremediation process

Processed Kimberlite Containment Facility (PKCF)

• Lined rock-filled dam for processed kimberlite storage
• Construction of solid rock cover (66% complete)
• Continuous ground stability monitoring

Reclamation Work

• Waste rock reclamation with thick cover
• North Country Rock Pile (96% complete)
• Indigenous Traditional Knowledge Panel involvement
• Wildlife already accessing reclaimed areas

Rock and Waste Management

• South Country Rock Pile for clean rock storage
• Landfill for non-hazardous waste
• Hazardous waste removal via winter road

Mining Details

• 4 mined pipes (3 active underground)
• Refilling A418 with processed kimberlite

Operational Challenges

• Managing large groundwater volumes (40 million litres per day)
• Plan to flood operations with clean lake water post-closure

Renewable Energy Efforts

• Wind turbines reducing diesel usage (48 million litres)
• Largest off-grid solar panel plant
• 32% of electricity from renewables during closure

Post-Closure Plans

• Collaboration with Northwest Territories government
• Benefits from solar infrastructure for the region
• Commitment to safe and stable site for all stakeholders

Community and Government Engagement

• Collaboration with community partners, government, and regulators

Conclusion

• Commitment to safe and responsible mine closure
• Ensuring safety and stability for people, wildlife, and aquatic life
• Contact for further inquiries: Diavik representative