An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »


ASARCO LLC Settlement

(Washington, DC – November 3, 2015) Today, the U.S. Department of Justice and the U.S. Environmental Protection Agency announced a settlement with ASARCO requiring the company to spend $150 million to install new equipment and pollution control technology to reduce emissions of toxic heavy metals at a large smelter located in Hayden, Ariz. The company will also fund local environmental projects valued at $8 million, replace a diesel locomotive with a cleaner model for $1 million, and pay a $4.5 million civil penalty.

On this page:

Overview of Company

ASARCO is a fully integrated miner, smelter, and refiner of copper in the United States. ASARCO’s operations include three copper mines in Arizona that produce a combined 350 to 400 million pounds of copper per year, a primary copper smelter in Arizona, and a copper refinery in Texas, along with cathode copper production operations co-located with two of the Arizona mines. The primary copper smelter in Hayden, Arizona is the facility at issue in this settlement.

Operations at the Hayden smelter take shipments of ore, which is then processed through grinding and milling into a fine powder that is concentrated through a flotation process into a material called copper concentrate, which is about 28 percent copper. Copper concentrate is stored in outdoor piles and then combined with other materials in the bedding operations, which are basically long trenches of fine grained sand or powder-like material. The bedded material is then fed into a flash furnace, in which it ignites with oxygen to burn off large quantities of sulfur and other impurities. The copper-rich material exiting the flash furnace is called copper matte, and it is transferred by ladles to copper converter furnaces. The converter furnaces blow air, or oxygen-enriched air, through the material to burn away iron impurities and any remaining sulfur. The material exiting a converter furnace is transferred in batches to an anode furnace, which blows natural gas into the material to burn off oxygen. The final material is then cast into anodes and shipped offsite to a facility for further refining by passing an electric current through a liquid (electrolysis).

The facility produces approximately 300 million pounds of copper anodes per year. Each furnace has a ventilation hood to capture gases leaving the furnace, but some gas still escapes as fugitive emissions, and the control devices do not remove 100 percent of the hazardous air pollutants (HAPs) routed to them. This settlement will improve the capture and control of HAP emissions from the furnaces and reduce fugitive HAP emissions from dust sources at the facility, such as outdoor piles of copper concentrate.

Top of Page


The Clean Air Act requires the EPA to periodically publish a list of all categories and subcategories of major sources and area sources of air pollutants that have been listed as HAPs; the EPA is then required to establish emissions standards for each such category and subcategory. Primary copper smelters have been listed as a category of major sources of HAPs, and the emissions standards for such facilities are found at Part 63, Subpart QQQ. Section 112(a)(1) defines a “major source” as “any stationary source…that emits or has the potential to emit considering controls, in the aggregate, 10 tons per year or more of any hazardous air pollutant or 25 tons per year or more of any combination of hazardous air pollutants.”

An inspection conducted by the EPA’s National Enforcement Investigations Center concluded that the facility is a major source of HAPs because it has a potential to emit greater than 10 tons per year (tpy) of both arsenic and lead individually, and a potential to emit of greater than 25 tpy of total HAPs. However, ASARCO has claimed minor source status since Subpart QQQ was promulgated, and the facility has therefore failed to comply with Subpart QQQ since the rule’s effective date of June 13, 2005. This settlement will bring ASARCO into compliance with the requirements of Subpart QQQ and resolve alleged noncompliance with Subpart QQQ at the Hayden smelter, as well as provide a release for ASARCO’s failure to include those requirements in its air permit required under title V of the Clean Air Act.

Top of Page

Injunctive Relief

The settlement requires the following actions to resolve the Clean Air Act violations:

  • ASARCO will meet requirements for operation of gas capture systems at all process furnaces, including installation of upgraded primary and secondary hooding systems for control of emissions from the copper converter furnaces and installation of a tertiary hooding system. Further, ASARCO will replace the existing copper converter furnaces with furnaces sized to allow production at current capacity with only one converter furnace blowing at any given time such that all gas collected in the primary hooding system and all gas collected by the secondary hoods during blowing operations will be sent to the existing acid plant at the facility to improve control of both particulate matter (PM) and sulfur dioxide (SO2) emissions.
  • ASARCO will install long-path optical density/opacity monitors on the outside of the buildings housing the copper converter department, the building housing ore crushing operations, and the fine ore storage building to monitor for fugitive emissions that may be escaping openings on these structures and initiate investigation and corrective actions if emissions are detected.
  • ASARCO will meet PM emission limits set forth in Subpart QQQ for various process emissions, and will also install and operate PM continuous emissions monitoring systems on five gas streams. These systems will give a real-time indication of compliance with the PM emission limits, as opposed to annual snapshots through stack testing requirements. Additionally, ASARCO will comply with a total PM emission limit from the entire process from drying copper concentrate in dryers through the anode casting department, inclusive of those end point steps. This limit is a variation of the limit for new construction area source copper smelters that is set forth in Part 63, Subpart EEEEEE and reflects performance levels anticipated in that rulemaking to be reflective of a well-controlled, greenfield source. ASARCO will use the data from the PM monitoring systems to comply with this limit, along with estimates of fugitive emissions from various process steps as determined by two fugitive emissions studies to be conducted by third parties.
  • ASARCO will replace an existing R&R Cottrell electrostatic precipitator with a new baghouse designed to achieve improved PM control for the emissions routed to that control device.
  • ASARCO will operate baghouse leak detection systems and maintain a minimum inventory of replacement bags at all times to ensure timely response to alarms from those systems. Additionally, for venturi wet scrubbers used to control PM emissions at the facility, ASARCO will install continuous monitoring devices for gas pressure and liquid flow rate and transmit those values to an electronic data storage system that has an associated alarm system if those values fall outside of ranges established for those parameters during performance testing.
  • ASARCO will develop a fugitive dust plan that includes the following controls for fugitive emissions sources at the facility:  installation of wind fences, installation of concrete pads to help control loose materials, installation of a new enclosed system for drying of acid plant scrubber blowdown solids, paving of a main road with significant truck traffic, upgrades to water sprayer systems, relocation of revert crushing operations away from a proximate high school, and tarping of materials stored in trains and trucks. Further, ASARCO shall employ a third party to conduct an audit of fugitive dust controls at the facility to identify and recommend possible improvements.
  • ASARCO will maintain five ambient air monitors in proximity to the facility to continue current monitoring for PM10, PM2.5, lead, arsenic, and cadmium ambient concentration levels and undertake an investigation and corrective actions if trigger levels established in the consent decree are exceeded.
  • In addition to requirements targeted to reduce HAP and PM emissions, the settlement includes requirements relating to SO2 emissions controls because of the replacement of the existing copper converter furnaces with new copper converter furnaces. New Source Performance Standard (NSPS) Subpart P includes performance standards for SO2 emissions from new copper converters. The settlement includes the Subpart P compliance obligations. Further, the settlement secures additional SO2 emissions reductions by requiring use of high-surface-area hydrated lime injection to meet a fifty percent control efficiency for SO2 emissions routed to the secondary baghouse and the new R&R Cottrell electrostatic precipitator replacement baghouse. At a 50 percent control efficiency, lime injection is expected to result in an additional 1,200 tpy of SO2 emission reductions.

Top of Page

Mitigation Projects

ASARCO will spend no less than $8 million on the following projects: 1) lead-based paint abatement in the adjacent towns of Hayden and Winkelman; and 2) paving of unpaved county roads that generates fugitive dust emissions close to the towns. The lead-based paint abatement project will provide funds for lead-based paint testing and abatement for homes, schools, and other public buildings in Hayden and Winkelman, Arizona. Lead is one of the two primary HAPs emitted from the smelter, so reducing potential community exposure from lead paint will mitigate lead exposure from the smelter. The road paving project will allow for paving of unpaved roads that are closest to the communities of Hayden and Winkelman to reduce exposure to fugitive PM emissions in those communities. This will also include reductions in HAPs, like arsenic, that are contained in low levels in the local soil. 

Top of Page

Supplemental Environmental Project

ASARCO will replace one existing diesel switch locomotive operated at the facility with a diesel-electric switch locomotive controlled to Tier 3 or better emissions standards at a cost of approximately $1 million. This project will result in reduced emissions of nitrogen oxide (NOx) and, owing to the use of diesel-electric engines that will result in reduced fuel consumption, greenhouse gases. Further, because NOx is a precursor to PM2.5, this project will result in reduced PM2.5 in the vicinity.

Top of Page

Pollutant Impacts

The Hayden area of Gila and Pinal Counties is currently classified as nonattainment for the 2008 lead National Ambient Air Quality Standard (NAAQS) and the 1-hour primary SO2 NAAQS. Since the facility is the only source of lead and SO2 emissions in the Hayden nonattainment area, emission reductions must come from the smelter to allow for attainment of the NAAQS. While compliance with this settlement will result in SO2 emissions decreases from approximately 21,400 tpy to approximately 2,000 tpy, modeling performed by ASARCO’s consultants indicates that all but approximately 1,200 tpy of that reduction would be required to achieve compliance with the NAAQS. Emissions reductions from this settlement will help address both the Hayden-area’s lead and SO2 NAAQS nonattainment status, as well as reduce community exposure to arsenic and other HAPs, and PM, PM10, and PM2.5 generally.  The EPA estimates that the settlement will reduce emissions by no less than approximately 3,500 tons per year of PM and 8.5 tons per year of HAPs.

Top of Page

Health Effects and Environmental Benefits

HAPs, also known as toxic air pollutants, are those pollutants that are known or suspected to cause cancer or other serious health effects, such as reproductive effects or birth defects, or adverse environmental effects. This means that people exposed to toxic air pollutants at sufficient concentrations and durations may have an increased chance of getting cancer or experiencing other serious health effects, such as damage to the immune system or neurological, reproductive, developmental, or respiratory problems.

Long-term inhalation exposure to inorganic arsenic is associated with irritation of the skin and mucous membranes and effects in the brain and nervous system and has been strongly associated with lung cancer. Exposure to lead (inhalation or oral) can cause effects on the blood, as well as the nervous, immune, renal, and cardiovascular systems, and early childhood and prenatal exposures are associated with slowed cognitive development, learning deficits, and other effects. Particle pollution, especially inhalable coarse particles (PM10) and fine particles (PM2.5), can cause coughing or difficulty breathing, decreased lung function, aggravated asthma, and even premature death in people with heart or lung disease. SO2 has also been linked to a number of adverse effects on the respiratory system, and SO2 is also a precursor to the formation of PM2.5.

Fine particles are also the main cause of reduced visibility (haze) in parts of the United States, including national parks and wilderness areas. The PM2.5 and SO2 emission reductions achieved through compliance with this settlement will also serve to reduce visibility impairment owing to emissions from the facility.

Top of Page

Civil Penalty

ASARCO will pay a $4.5 million civil penalty

Top of Page

Comment Period

The proposed settlement, lodged in the U.S. District Court for the District of Arizona, a 30-day public comment period and final court approval.   Information on submitting comments is available at the Department of Justice website.

Top of Page


Virginia Sorrell
Air Enforcement Division
Office of Civil Enforcement
U.S. Environmental Protection Agency
Phone: 303-312-6669

Ivan Lieben
USEPA Region 9
75 Hawthorne Street
Mail Code: ORC-2-2
San Francisco, CA 94105
(415) 972-3914

Top of Page