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Environmental Protection Agency assesses permanent mine waste repository

Mayflower Tailings Impoundment offers large capacity for sludge created by water treatment
Machinery moves solids to dry them out in 2020 at the Gold King water treatment plant. (Jerry McBride/Durango Herald file)

Members of the Environmental Protection Agency Region 8 visited the Bonita Peak Mining District last week to evaluate remediation work and discuss future projects including a permanent waste repository for the mining district.

The original purpose of the visit was to show new EPA Region 8 Administrator KC Becker the Superfund sites in the mining district, however, she became sick before the trip and was unable to make the visit.

EPA Region 8 Superfund Project Manager Christina Progess said the goals for the Bonita Peak Mining Project are to improve water quality, minimize unplanned releases and stabilize source areas.

“By stabilizing source areas, we mean stabilizing them from erosion or mine waste,” she said.

Sunnyside Gold Corp.’s four massive tailings piles along the Upper Animas River are about a mile northeast of Silverton and south of the old Mayflower Mill. The sources of metal loading in the Upper Animas remains a mystery for researchers, yet these piles of mine waste have long been held under suspicion. (Jerry McBride/Durango Herald file)

Progess discussed the current state of the Gold King Mine, which infamously spilled toxic waste water into the Animas River watershed in 2015. She said since 2015, the EPA has been operating the Gladstone Water Inner Water Treatment Plant which has been treating the Gold King discharge.

The treatment plant removes metals in the mine that may impact the water. However, the treatment plant creates sludge and the plant is running out of space to manage it. Progess is evaluating the design of a long-term mine waste repository located at the Mayflower Mill tailings impoundment.

She said the community wanted the EPA to locate the waste repository in an area that has preexisting mine waste.

“The intent of the mine waste repository is a final resting place for any mine waste – both the sludge from the Gladstone Water Treatment Plant and any other mine waste through our other remediation efforts,” Progess said.

Progess said the EPA hopes the repository will have enough capacity to last 100 years. Construction of the mine waste repository will start next summer.

In addition to remediation work, the EPA has been involved with ongoing litigation as a result of the Gold King Mine release. Recently, the EPA settled with Sunnyside Gold Corp. for $90 million. The compensatory damages were divided among the EPA, U.S. Forest Service, Bureau of Land Management and the state of Colorado.

The EPA gained about $35 million from the settlement and will use the funds for additional remediation work at Bonita Peak sites.

“This will allow us to fund the project for many years to come,” Progess said.

The EPA also settled with the state of New Mexico and the Navajo Nation for around $30 million each. Both had sued the EPA as a result of the Gold King Mine spill.

Progess said the EPA will also be conducting investigations of contamination in the Bonita Peak Mining District.

A bladder holds solids in 2020 at the Gold King water-treatment plant that have been collected from the water flowing out of the Gold King Mine. (Jerry McBride/Durango Herald file)

Next year, the EPA will investigate the Sunnyside Mine workings. The Sunnyside mine was a conglomerate of several mines that are a source of contamination in Cement Creek.

“We’re going to be drilling several wells to try and understand how water flows within those mine workings,” Progess said. “That will help us understand if we were to employ certain remedies like bulk heading, how that water would be held back or where the water might go.”


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