Humboldt Superfund site history
Dewey-Humboldt's Superfund site encompasses areas of contamination from two facilities: the Iron King Mine property and the Humboldt Smelter property.
The Iron King Mine was an active mine from 1904 until 1969. Tailings and waste rock piles cover the majority of this area.
The Humboldt Smelter is situated less than one mile east of the Iron King Mine property. The smelter operated from the late 1800s until the early 1960s. This area is covered in yellow-orange tailings, grey smelter ash, and slag.
Mining and processing have contaminated soil, sediments, surface water and groundwater with arsenic, lead, and other metals.
A significant residential area of the Dewey-Humboldt site sits between the mine and the smelter. Scientists have detected high levels of arsenic and lead in soil at the site.
The Arizona Department of Environmental Quality supports the Superfund listing, along with the D-H mayor and town council, who voted in support of listing.
In order to identify and address site conditions as soon as possible, EPA initiated a remedial investigation and feasibility study (RI/FS) in August 2008. The primary objectives of the RI/FS are to determine the nature and extent of contamination and to gather sufficient information so that EPA can select a remedy that eliminates, reduces, or controls risks to human health and the environment.
With Wednesday's decision, there are now nine Superfund sites in Arizona. Nationwide, the EPA has 1,587 sites listed on the NPL for cleanup.