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Acceptable, Achievable, Sustainable? Assessing Closure
Goals at Legacy Mine SitesWalter Weinig
February 16, 2015SME Annual Conference
Begin with the End in Mind—Stephen Covey
The End is Nigh…
Legacy Mine Sites
Active, older properties
Inactive
Abandoned
Modern vs. Legacy
Modern LegacyPlan for Closure Yes NoClosure Period Defined UnclearRegulations Usually UnclearFinancial Assurance Yes MaybeResponsible Party Company Varies
Evaluating Goals
Acceptable?
Achievable?
Sustainable?
Acceptable?
Multiple Stakeholders, Multiple Views
• Regulators
• Local community
• NGOs
• Corporate standards
6
Achievable?
• Technically practical
• Pre-existing conditions
• Implementation time frame
7
Sustainable?
• Financing, responsible party
• Community capacity
• Bias toward passive, natural systems
• “In perpetuity”
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Case Studies
Wellington-Oro
Wellington Oro circa 2002, from U.S. EPA
Wellington Mine, 1909From USGS archives
Wellington Oro
• Point of compliance in receiving stream to protect aquatic life, fishery
• Active treatment in relatively developed area by mining standards
• Treatment plant operated by town
11
Tiger & Jessie
Denver Public Library archive
Tiger & Jessie Mine, Mill• Natural wetlands attenuate metal concentrations
before outflows reach stream
• Remove mill tailings from stream banks for source control
• Stabilize historic mill, administrative controls
• Attraction along hiking trail in county open space
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Somewhere in the West…
100+ years of mining
Identified groundwater impacts
Mix of operating, inactive, and abandoned mines
Somewhere in the West…
• Standards complicated by overlapping regulatory programs
• Source control: grading, hydraulic barriers
• Active groundwater pump & treat
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Somewhere Else…
Historic mining district
Possibly re-opening existing mine
Legacy facilities vs. new requirements
Somewhere Else…
• Define existing impacts as basis for standards related to new development
• Proposed new construction on top of historic facilities
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Legacy Pit Lakes
Photos courtesy of Dr. Glenn Miller, University of Nevada
Legacy Pit Lakes• Neutral vs. acidic conditions
• Appropriate standards – aquatic life, terrestrial wildlife, human contact
• Access for treatment can be difficult
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Legacy Mine Closure Goals Summary
• Acceptable? Stakeholder opinions may vary
• Achievable? Different constraints, existing conditions
• Sustainable? Financing, operational responsibility, time frames
• Each site is unique, but solutions can be found