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

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Achievable?

• Technically practical

• Pre-existing conditions

• Implementation time frame

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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

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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