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Humboldt Smelter Project




Contaminants of Concern (COCs): 

Concern for public safety is the reason for the work being conducted for this project. Please refer to the Iron King Mine-Humboldt Smelter Superfund Site webpage for information on contaminants of concern | Visit Page >


The Humboldt Smelter portion of the Superfund Site operated from the late 1800s until 1969. The structure most visible from a distance is a tall brick smokestack (circa 1917) remaining from past smelter operations. The smokestack consists of an attached rectilinear brick converter flue on elevated steel reinforced concrete piles. The converter flue measured approximately 140 feet long prior to its partial collapse in 2021. The large portion of the converter flue that collapsed caused destabilization of the structure and raised concern for public safety. According to a 2008 Cultural Resource and Historic Building Survey, the smokestack measures approximately 156 feet by 18 feet and is elevated 30 feet above ground level.

The surrounding area to the smokestack and flue is contaminated with chemical hazards from formerly mined metals contained with a dust-control cover called Posi-Shell® that was installed by Environmental Protection Agency (EPA) on the dross material nearby. The Humboldt Smelter area contains fencing and signage to warn trespassers not to enter the area. ADEQ and EPA continue to advise people to avoid the smelter stack area and follow the posted warning signs.

Project Activities:

The Humboldt Smelter Project will be led by ADEQ, in coordination with the EPA. This specific project will occur on the Humboldt Smelter portion of the Iron King Mine-Humboldt Smelter Superfund Site located in Dewey-Humboldt, Arizona.

In early 2022, ADEQ plans to disassemble both the Humboldt Smelter smokestack and the remaining attached brick converter flue in a controlled fashion. To ensure the safety of the community and the staff conducting the work, safety measures will be implemented during the project that include site security, dust control and air quality monitoring. All brick debris will be consolidated and will remain encapsulated in-place around the stack foundation utilizing sprayed concrete.

Additional fencing will be installed within the smelter plateau. In addition, if disturbed during project work, the dust-control cover (Posi-Shell®) previously installed by EPA will be repaired.


Mobilization for the project began on January 3, 2022. The project is expected to continue for approximately six weeks.  For more information, see the project documents listed on the sidebar under SEE MORE.