annual presentation to board of oil, gas & mining
TRANSCRIPT
© Rio Tinto 2018
Utah Board of Oil, Gas & MiningBingham Canyon Mine Reclamation
Rio Tinto Kennecott
April 25, 2018
© Rio Tinto 2018
Pioneering human progress for 115 years
© Rio Tinto 2018
Legacy Waste Rock
• Highly visible from throughout the SLC metro area.
• Huge material movement requirements to reclaim them in a conventional fashion by dozer push or by use of loaders made rehab impracticable.
• Not required to be reclaimed in the 1976 Mining and Reclamation Plan.
© Rio Tinto 2018
Legacy Waste Rock Technical Challenges
• Tall angle of repose pile slopes created in the 1970s and 1980s before Rio Tinto acquired Kennecott.
• Continuous slope up to 1200 feet high
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Legacy Waste Rock Technical Challenges
• Acidic waste rock,
• Unable to support vegetation,
• Prone to severe erosion events
• Promote oxygen ingress and ARD generation from the dumps behind
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The Solution
• RTKC began looking for a solution to this intractable challenge roughly ten years ago
• Developed an innovative solution
• Harness future waste rock production from the open pit
• Build a stair-stepped reclaimable landform in front of the tall slopes
• From the bottom up instead of the top down
© Rio Tinto 2018
Reclamation Overview – First StepsPreparation for final
land form
• SWPPP BMPs
• Salvage growth
media and
stockpile
• Replace WRCW
collection
infrastructure
• Install surface
water
infrastructure
• Place waste rock
© Rio Tinto 2018
Implementation• Implementation began
in earnest - 2006
• Bingham Canyon, East and South Waste Rock
• Over $100 million spent to date on construction
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Growth Media Salvage
• Before waste rock placement begins strip native soils to bedrock
• 12 million cubic yards of topsoil and subsoil stripped from the footprint
• Carefully stockpile and vegetate for future use
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Waste Rock Contact Water Capture
• Install toe drain and cut-off walls
• Secondary containment
• Segregate surface water from contact water
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Surface Water Capture
• Design to manage 100yr-24hr rain events
• Redundant and maintainable structures
• Minimize risk of release
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Overburden Placement
• 27 million tons of waste rock placed to date in a reclaimable landform
• Concurrent reclamation placed in 200’ lifts
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Regrade Overburden • Initial lifts have been re-contoured to a 2.5:1 slope
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Place Growth Media Cover• Cover placement averages 1 meter in thickness
• Cover blended with native soils and mine-salvaged materials
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Growth Media Cover with Vegetation
• DOGM approved seed mix of native grasses, forbes and shrubs
• Furrows capture water and promote vegetation establishment
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Research & Development
• Drill through hundreds of feet of waste rock to measure geochemical performance
• Sensors installed to measure oxygen, temperature and water content
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Research & Development• Store and release cover trials
• Testing different blends of cover
• Cover mixing optimization
• Geochemistry and gradation
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Industry Expertise in Mine Reclamation
Working with industry leaders to research, design and implement best reclamation practices.
Research and Design: Implementation:
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Progress Made in Overall Construction
• Total acreage reclaimed since 2006: 550 acres
• Total storm water capacity: Approximately 110 acre feet
• Total soil/growth media salvaged: 13 million cubic yards
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Upon Completion
• It will create hundreds of acres of new wildlife habitat
• is predicted to cut oxygen increase and future ARD generation in the dumps by more than half
• This will improve long term post closure water quality in waste rock dump seepage.
© Rio Tinto 2018
Conclusion
RTKC is proud of identifying, designing and implementing a world class, innovative solution to a unique and difficult challenge.
© Rio Tinto 2018
Thank you Board of Oil, Gas and Mining for the opportunity to present our reclamation work.