EPA Proposes Cleanup Plan for the Iron King Mine-Humboldt Smelter Superfund Site

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EPA Proposes Cleanup Plan for the Iron King Mine-Humboldt Smelter Superfund Site

PHOENIX – The U.S. Environmental Protection Agency (EPA) has released its cleanup plan for addressing the Iron King Mine-Humboldt Superfund site in Dewey-Humboldt, Arizona. EPA invites the public to review and comment on the proposed plan until May 13, 2023. The efforts envisioned in the plan will clean up millions of tons of mine and smelter waste, as well as contaminated soils.

“This proposed plan is an important next step in our ongoing work to protect people and wildlife from contacting toxic mine materials,” said EPA Pacific Southwest Regional Administrator Martha Guzman. “EPA is committed to partnering with the Dewey-Humboldt community to clean up the site. We look forward to hearing the community’s feedback on our plan.”

The public comment period has been extended to ensure community members and stakeholders have enough time to review the plan and give feedback. EPA will hold a public meeting on the plan on March 29, 2023, at the Humboldt Elementary School gymnasium. The community may give comments orally at the meeting or send written or emailed comments to EPA.

The proposed plan includes:

  1. Digging up and consolidating mine waste and contaminated soils from different parts of the site.
  2. Preventing people and wildlife from contacting contamination and waste materials by putting a permanent engineered cap over them.
  3. Preventing waste materials and contamination from moving.
  4. Stopping mine waste from polluting the Agua Fria River.

The public can submit comments to EPA on the proposed plan until May 13, 2023, by:

  1. Mailing comments (postmarked by May 13th) to:

Jeff Dhont (Phone: 415-972-3020) 

Remedial Project Manager
EPA Region 9
Mail Code SFD-8-1
75 Hawthorne Street
San Francisco, CA 94105
  1. Emailing comments to Thompson.Georgia@epa.gov and Dhont.Jeff@epa.gov.
  2. Leaving oral comments on EPA’s voicemail box at: (800) 231-3075.

EPA will respond to all public comments in a document called a “Responsiveness Summary.” After considering all comments, EPA will issue a final plan to address the site in a document called the “Record of Decision.” EPA aims to issue the Record of Decision within a year after the comment period closes.

Decades ago, the former Iron King Mine and Humboldt Smelter left behind eight million tons of mining waste, including mine tailings, smelter waste, and contaminated soils. Waste washed into water drainages leading to the Agua Fria River. As a result, soil and surface water were contaminated. The mine waste, which contains arsenic and lead, can pose a health threat to people and wildlife that contact it. Since the site was added to the Superfund cleanup program in 2008, EPA has completed five early cleanups to protect human health and the environment, including three that involved residential soil cleanup. This plan is a long-term solution to address site contamination.

Learn more about this cleanup on EPA’s Iron King Mine – Humboldt Smelter Dewey-Humboldt webpage.

Learn more about EPA’s Pacific Southwest Region. Connect with us on Facebook and on Twitter.

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