ASARCO Hayden Plant

Superfund Alternative Site | ASARCO Hayden Plant

EPA Superfund Alternative Site Designation:

EPA #: AZD008397127
The site is currently administered through an Administrative Settlement Agreement and Administrative Order on Consent (AOC) between the Environmental Protection Agency (EPA), ASARCO and ADEQ. Site contamination is caused by historical mining operations including smelting and ongoing processing operations.

Site Location:

The ASARCO facility includes the smelter, concentrator, former Kennecott smelter and all associated tailings facilities. The facility is adjacent to the towns of Hayden and Winkelman, 100 miles southeast of Phoenix and about 50 miles northeast of Tucson. The project site is located in the area surrounding the confluence of the Gila and San Pedro Rivers.

Contaminants of Concern:

Almost 100 years of smelting activities at this site has deposited lead, arsenic and copper across residential and industrial areas with the highest concentrations located on the north edge of town, near the old Kennecott smelter and on the east side near the concentrator and the No. 9 conveyor.

The school complex on the north end of Winkelman indicate relatively low soil concentrations all below soil remediation levels.


The site is located within the Upper San Pedro groundwater basin. The major components of this system are the water-bearing sands and gravels of the Gila River and San Pedro River flood plains that are recharged from groundwater flows within smaller tributary stream alluvium. Ground water beneath the smelting and slag deposition areas of the site is impacted by selenium and molybdenum. Tailings impoundments along the Gila River have caused elevated levels of contaminants to be discharged into surface and groundwater.

Regional groundwater flow direction within Hayden and Winkelman is in a southerly direction towards the Gila River/San Pedro River confluence.

The groundwater flow direction between the two tailings impoundments is generally in a northwesterly direction, consistent with the surface water flow direction of the Gila River.

Action Taken: 

Between 2008 and 2009, the soil was excavated and replaced in about 250 residential properties in Hayden and Winkelman. The remainder of the homes did not require cleanup. In addition to residential yard cleanups, other areas such as vacant lots, commercial areas and alleys were sampled and the soil excavated and replaced if above residential soil remediation levels.

In 2018 ASARCO completed installation of new process equipment and pollution control technology at the operations plant (smelter). Also, in 2018 ADEQ issued ASARCO a renewal Title V Air Quality Permit.

ASARCO is currently in the Remedial Investigation (RI) phase and released in a draft Phase II RI report to EPA and ADEQ in December 2020 for review. Once the Phase II RI report is finalized, a Feasibility Study will be performed as the next milestone for the Alternative site. Learn more about this Superfund Alternative Site on the EPA website | View Site >