Magazine article Risk Management

Scratching the Surface: The Animas River Spill and the Real Risks of Abandoned Mines

Magazine article Risk Management

Scratching the Surface: The Animas River Spill and the Real Risks of Abandoned Mines

Article excerpt

THE ACIDIC, heavy metal-laden wastewater and sludge released from the Gold King Mine into the Animas River in southern Colorado is, in itself, a serious environmental event, but the incident has also revealed issues of greater concern in mining-impacted areas across the United States.

Mining has always been an environmentally intensive activity. Extracting ores from natural deposits requires the movement of massive quantities of materials through underground tunneling or surface excavation. Separation of metals from ore requires mechanical or chemical processes that generate mountains of waste rock and pools of contaminated wastewater. For low-grade ores, cyanide is typically used to extract the metals from rocks on leach pads that may be several acres in area with ore piled to heights of 60 feet or more.

Mining and mineral processing account for more than 44% of all toxic releases into the environment, making it one of the most polluting industrial activities in the country today. The volumes of contaminants, including heavy metals, cyanide, arsenic, radioactive wastes and solid particulate, likely exceed those of pollutants discharged by chemical plants, petroleum refineries, coal- and nuclear-powered electric generation facilities, steel and paper mills, cement plants, heavy and light manufacturing and agricultural operations.

While state laws require mine operators to post evidence of financial responsibility to demonstrate their ability to operate, close and clean up mine sites, the amounts of cash deposits, trust funds, bonds or parent company guarantees to pay have often been inadequate when crises actually occur, and operators have failed to honor their obligations. Bankruptcies are also common among mining companies, leaving state regulators with inadequate funding to safely close mines that continue to cause environmental damage. Ultimately, these costs are borne by taxpayers.

Worse than the pollution from current operations is the legacy of more than 125 years of mining operations that were completely unregulated. The resulting conditions have destroyed watersheds, polluted thousands of miles of rivers and left behind mines like the Gold King. The Environmental Protection Agency (EPA), the Department of Agriculture's Forest Service, the Department of the Interior's Bureau of Land Management and Office of Surface Mining Reclamation and Enforcement--all federal agencies that share responsibility for mine cleanups in the United States--do not know how many abandoned mines there are in this country. A 2014 Government Accountability Office study estimated there are more than 161,000 mines in 12 western states where hardrock mining of metal ores is prevalent. Of these, more than 33,000 are thought to have caused, or are still causing, environmental damage. The amounts of contaminants that are seeping into the nation's rivers every day from abandoned mines far exceed the quantity released from the Gold King Mine in the Animas River spill.

The primary cause of environmental damage from abandoned hardrock mine sites is acid mine drainage, which carries dissolved heavy metals and arsenic into surface water, soil and groundwater. Many mines also left behind tailing ponds with millions of gallons of contaminated wastewater, which can be released into streams and lakes if earthen dams fail or floods overflow impoundments. Mills and ore-processing facilities have added to widespread pollution in mining areas and continue to cause environmental damage today.


In 1977, mining activities became subject to environmental regulation. These regulations, however, have little impact on the problem of abandoned mines and insolvent or unknown past owners and operators. The Clean Water Act applies to discharges of contaminants that impact surface water and groundwater, including acid mine drainage from abandoned mines, but thousands of old mines continue to leak into streams, rivers and lakes unchecked. …

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