Barrier at Gold King Will Prevent Another Release, EPA Says

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By Tripp Baltz

Large, sudden wastewater spills at southwestern Colorado’s Gold King Mine—such as the 3-million-gallon leak in August 2015—will be prevented by a new barrier and valve the EPA is installing, federal officials told Bloomberg BNA.

Workers are installing a thick steel plate and a 12-inch valve designed to block spills and help regulate the flow of wastewater draining from the mine, Rebecca Thomas, Environmental Protection Agency project manager for the Bonita Peak Mining District Superfund site near Silverton, Colo., said Sept. 21.

Installation of the $300,000 plate and valve just inside the Gold King Level 7 adit— the horizontal passage leading into the mine—is scheduled to be completed by the end of October and cost $150,000, Thomas said.

Valve to Moderate Flow

The valve will moderate the flow of wastewater leaking from the mine so it will not overwhelm an EPA-operated wastewater treatment plant downstream, she said.

Wastewater from mining is leaking from Gold King all the time, Thomas said. But during the Aug. 5, 2015 incident, about 3 million gallons of waste and sediment were released all at once while EPA workers and contractors were clearing dirt and debris from the entrance of the mine.

The release of mining wastewater laced with heavy metals poured into the Upper Animas River in Colorado, which merges with the San Juan River in New Mexico.

Gold King is one of 37 leaking mines in the Bonita Peak district, and the district was placed on the National Priorities List after the 2015 spill, Thomas said. The district contains more than 300 inactive and abandoned hard rock mines, she said.

To contact the reporter on this story: Tripp Baltz in Denver at

To contact the editor responsible for this story: Rachael Daigle at

For More Information

The EPA's web site about its emergency response to the Gold King Mine spill is at

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