Bulkheads caused the Gold King Mine spill. Could they also be part of the solution? Remediation tool can limit acidic drainage, but experts must also understand the complicated hydrology — The #Durango Herald

Click the link to read the article on The Durango Herald website (Aedan Hannon). Here’s an excerpt:

Bulkheads remain relatively obscure except to those involved in mine remediation, but their purpose is to plug mines and limit the release of mine waste while reversing the chemical processes that contribute to acid mine drainage. They can be simple fixes for extraordinarily complex mining systems and produce unintended consequences. But they are also a critical tool for the EPA and those working to improve water quality and reduce the lingering effects of more than a century of mining in the Bonita Peak Mining District…

The role of bulkheads in the Gold King Mine Spill

In its October 2015 technical assessment of the incident, the U.S. Bureau of Reclamation argued that bulkheads were at least partially responsible for the Gold King Mine spill. The Gold King Mine is a maze of tunnels, faults and fissures located at different elevations inside Bonita Peak and the surrounding mountains in Gladstone. The mine opening that drained when the EPA crews struck a plug holding back water was actually what’s known as the “Upper Gold King Mine,” or Gold King Mine Level 7. A short distance away lies the “Gold King Mine,” which refers to a mine adit called American Tunnel…

With oversight from the Colorado Division of Reclamation, Mining and Safety, Sunnyside Gold Corp. first installed a bulkhead in American Tunnel in 1995 to stop mine drainage from entering Cement Creek. The company closed the valve on the first bulkhead in October 1996 and would go on to install two other bulkheads in American Tunnel. With the installation of the bulkheads, the flow of toxic mine waste into Cement Creek decreased from 1,700 gallons per minute to about 100 gallons per minute. But as the impounded water rose behind the bulkheads, the water rose elsewhere, including in Gold King Mine Level 7, which sits about 750 feet above American Tunnel, according to the Bureau of Reclamation’s assessment…The EPA has yet to determine if it was faults and fractures in the rock or other internal mine workings that carried water from American Tunnel to Gold King Mine Level 7, but the EPA and the Bureau of Reclamation have both said the spill was in part the result of this buildup from the bulkheads in American Tunnel. Bulkheads have been used in mine remediation efforts in Colorado for more than three decades, and there are about 40 installed across the state, said Jeff Graves, director of Colorado Division of Reclamation, Mining and Safety’s Inactive Mine Reclamation Program…Bulkheads back up water and fill mine tunnels. When they do so, they limit the air rocks can come into contact with, preventing the chemical reaction that creates acid mine drainage…

Acid mine drainage can also still make its way into river systems. Water naturally moves through rock and can turn into acid mine drainage when exposed to oxygen, though in smaller volumes.