EPA Finalizes Cleanup Plan for Iron King Mine-Humboldt Smelter Superfund Site
PHOENIX – The U.S. Environmental Protection Agency (EPA) has announced the signing of a plan for an $85 million Superfund cleanup of the former Iron King Mine and Humboldt Smelter site in Dewey-Humboldt in Yavapai County, Arizona. This landmark decision – known as a Record of Decision -- provides a comprehensive solution building on years of prior work by the agency and the State of Arizona to address arsenic, lead, and other heavy metals in soil at and near the site. The site was initially listed on the Superfund National Priorities List in 2008.
“This cleanup plan is a significant milestone that paves the way toward a final remedy at the Iron King and Humboldt Smelter Superfund site that will benefit local communities for years to come,” said EPA Pacific Southwest Region Superfund and Emergency Management Division Director Mike Montgomery. “This plan represents years of work by EPA, our state and local partners, and communities to meet strict standards for cleaning up legacy contamination that dates back over a century.”
“Reaching this final cleanup plan for the Iron King Mine/Humboldt Smelter was a collaboration among EPA, the community, and ADEQ and is a significant milestone toward protecting the health and well-being of both the Dewey-Humboldt community and our environment,” said Arizona Department of Environmental Quality Cabinet Executive Officer Karen Peters. “ADEQ looks forward to continuing to support EPA in implementing the final cleanup actions and seeing this through to completion for the people whose lives and land have been affected.”
The Record of Decision documents the cleanup option EPA chose after considering and responding to public comments. Next, the EPA will comprehensively design the cleanup action and implement it.
The Iron King Mine site contains about 4 million cubic yards of mine tailings with high levels of arsenic and lead. The Humboldt Smelter is contaminated with mine tailings and other smelter wastes. Wastes have also washed into drainages that lead toward the Agua Fria River. Over many years, lead emissions from the smelter stack, dust from the mine and the smelter, spills from rail loading areas, and commercial processing of mine tailings all contributed to lead and arsenic contamination in the soil of some residential yards in Dewey-Humboldt.
EPA is addressing residential contamination by cleaning up contaminated soil from homes where levels of lead or arsenic are above dangerous levels, and exposure for long periods could threaten human health.
The non-residential cleanup portion will consolidate mine and smelter wastes into two repositories. A waste repository is a large, stable, permanently covered holding cell that encapsulates wastes, keeps water out, and prevents wastes from moving further into drainages or the river. Mine wastes and contaminated soils from the former mine and surrounding areas west of Highway 69 will be moved into a repository on the existing mine tailings pile. Complementing ADEQ’s removal of the abandoned smelter and stack in 2021, wastes under the former smelter and in the Chaparral Gulch east of Highway 69 will be moved into a second waste repository, most likely in a natural depression on the former smelter property. Both repositories will be inspected periodically and maintained to remain intact and effective.
For more information on the Record of Decision, a summary of comments received, visit EPA’s IRON KING MINE - HUMBOLDT SMELTER DEWEY-HUMBOLDT, AZ webpage.
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