The Wellington Oro Mine was the largest mine in Summit County, with active underground mining from the late 1880s until its closure in 1972. The mine produced silver, gold, lead and zinc from an extensive network of tunnels and adits. When the Wellington Oro Mine ceased operation, it left an unintended environmental legacy – water draining from the mine site is contaminated with dissolved metals including cadmium and zinc. Known as acid rock drainage (ARD), the contaminated water can be harmful to river ecosystems.
In 1989, the mine site was identified for potential Superfund listing by the US Environmental Protection Agency (US EPA). A team was formed to address the area’s water quality issues while protecting alpine habitat and open space. The goal of the mine cleanup was to lower the concentration of dissolved metals in French Creek and the Blue River to meet Colorado Water Quality Standards and protect the brown trout fishery. In 2005, the Town of Breckenridge and Summit County purchased the site as part of an 1,800 acre open space plan, and an international call for proposals was issued to find a water treatment solution for the metal contaminated water.
BioteQ’s ChemSulphide® process was selected instead of lime treatment for application at the Wellington Oro site because it meets strict water quality targets and does not generate a waste sludge that would otherwise require disposal and ongoing monitoring. An equivalent capacity lime plant would have produced an estimated 390,000 US gallons of metal-laden sludge annually, leaving an environmental liability and adding to long-term operating costs. Instead, the sulphide precipitation plant produces a saleable zinc-cadmium sulphide product, which can be sold to off-set treatment costs, and recycled into useful products.
In addition to delivering operating cost savings, the capital cost of the sulphide precipitation plant for this site was estimated to be approximately 33% less than a lime plant with equivalent capacity, delivering lower life cycle costs.
BioteQ provided process design and engineering, procurement support, plant commissioning, and operator training. The plant was commissioned in 2008, and is operated by the Town of Breckenridge Water Division.