top of page

Emergency WTP Response, Cost-Saving Sludge Management Approach, and WTP Operations at Remote Abandoned Site (Gold King)


Bonita Peak Superfund Site


Water Management, Site Operations

Key Words

Accidental, Release, Metals Treatment, Abandoned, Remote, Site, Sludge Management, Remote, Location, High, Altitude, Operations, WTP, Operation, Water


Silveton, CO

Project Summary

Rainy River Face of Lime WTP Looking East 2020.jpeg

Bonita Peaks, Lime Water Treatment Plant

In 2015, a contractor working for the United States Environmental Protection Agency (EPA) inadvertently damaged the portal plug, and approximately 3 million gallons of water/sludge was released from the mine into Cement Creek near Silverton Colorado, ultimately polluting the Animas River. An immediate solution was needed to mitigate ongoing discharges and prevent future natural resource damage. Ensero successfully designed, constructed, and commissioned an interim water treatment plant within 21 days of the contract award. Although initially intended to be an interim measure, we recently implemented design improvements intended to extend the plant life until 2027. The plant operates 24/7, year-round above 10,000 feet of elevation, operating through annual snow falls exceeding 13 feet, spring freshet events that cause flowrate, pH, and metal loading fluctuations of more than 200%.. Our innovative and cost-saving sludge management approach have saved the client over $800K/yr in operation costs. Ensero continues to operate the water treatment plant year-round, with an average reduction of metal loading by 93% prior to discharge.

Rainy River Rapid Mix Tank, Lime Silo 2020.jpeg

Winter at Bonita Peaks


Rainy River Aeration and Biomedia Close-up.jpeg
bottom of page