Frequently Asked Questions

Acronyms and Mining Terms


CEQ - Council on Environmental Quality
CFR - Code of Federal Regulations
EA - Environmental Assessment
EIS – Environmental Impact Statement
EMS - Environmental Management System
EPA - Environmental Protection Agency
FONSI - Finding of No Significant Impact
GPO – General Plan of Operations
MARRCO - Magma Arizona Railroad Company
NEPA – National Environmental Policy Act
NDAA – National Defense Authorization Act
NOI - Notice of Intent
RCM – Resolution Copper Mining
ROD - Record of Decision
TNF – Tonto National Forest

Mining Terms

Acid-Forming Materials - Earth materials that contain sulfide minerals or other materials that, if exposed to air, water, or weathering processes, form acids that may create acid drainage (as in potentially-acid-generating or reactive rock).

CAP Water - Fresh make-up water that is drawn either directly from the Central Arizona Project (CAP) canal or through pumping of groundwater available through banking of CAP credits.

Crushers - Machines that reduce large rocks into smaller rocks.

East Plant Site - Current exploratory shaft sinking site; historic Magma Mine site.

Flotation - Process of separating small particles of various materials by treatment with chemicals in water in order to make some particles adhere to air bubbles and rise to the surface for removal while others remain in the water.

Loadout Facility – A proposed facility where copper concentrate would be filtered to remove water and then sent to off-site smelters via rail cars or trucks.

MARRCO Corridor - Magma Arizona Railroad Company railroad corridor that begins at the Union Pacific Line at Magma Junction and continues to the town of Superior. The corridor would be used for water pipelines, concentrate pipelines, power and pump stations.

Panel Caving – An underground mining technique in which a series of horizontal tunnels are constructed below the ore body. The process begins with an initial round of explosives at the bottom of the ore body to break up the rock. Then rock is funneled downward and removed. The void created in the removal process allows gravity to continue forcing the ore body downward.

Slurry – Mixture of a fine-grained solid material – such as copper ore concentrate or tailings - and water.

Smelter - An installation or factory for smelting a metal from its ore.

Subsidence – The gradual caving in or sinking of an area of land. In the context of underground mining, subsidence is the lowering of the Earth's surface due to collapse of bedrock and unconsolidated materials (sand, gravel, silt, and clay) into underground mined areas.

Tailings – Finely ground rock fragments that remain after minerals (such as copper) have been removed from the rock by the flotation process.

Tailings Corridor – A proposed corridor that begins at the West Plant Site, ends at the Tailings Storage Facility, which would be used for water and tailings pipelines and access.

Tailings Storage Facility - The final storage area for unrecoverable and uneconomic metals, minerals, chemicals, organics and process water.

Waste Rock – Valueless rock that must be fractured and removed from a mine to keep the mining scheme practical and gain access to ore.

West Plant Site - Current site of water treatment plant, historic Magma Mine Concentrator and Smelter, legacy tailings/waste rock.


What is NEPA?

The National Environmental Policy Act (NEPA) was signed into law on January 1, 1970. NEPA requires federal agencies to assess the environmental effects of their proposed actions prior to making decisions. The range of actions covered by NEPA is broad and includes making decisions on permit applications, adopting federal land management actions, and constructing publicly-owned facilities or infrastructure. Using the NEPA process, agencies evaluate the environmental and related social and economic effects of their proposed actions. Agencies also provide opportunities for public review and comment on those evaluations.

Has NEPA been initiated on this project? Will NEPA be required?

The NEPA process for the proposed GPO and the Land Exchange was initiated when the Notice of Intent to Prepare an Environmental Impact Statement (EIS) was published in the Federal Register.

What is an EIS?

"EIS" is the abbreviation for environmental impact statement, a document prepared to describe the effects of proposed activities on the environment. "Environment," in this case, is defined as the natural and physical environment and the relationship of people with that environment. This means that the "environment" considered in an EIS includes land; water; air; structures; living organisms; environmental values at the site; and social, cultural, and economic factors. An "impact" is a change or consequence that results from an activity. Impacts can be positive or negative, or both. An EIS describes impacts, as well as ways to "mitigate" impacts. To "mitigate" means to lessen or remove negative impacts. Therefore, an EIS is a document that describes the impacts on the environment as a result of a proposed action. It also describes impacts of alternatives, as well as plans to mitigate the impacts.

What is the “Proposed Action” to be analyzed in the EIS?

The proposed action is to approve the proposed plan of operations as submitted by Resolution Copper Mining LLC (Resolution Copper) and to complete the land exchange as directed by Congress under Section 3003 of the National Defense Authorization Act. The EIS will analyze three components. 1) The EIS will analyze the effects of approval of the proposed plan of operations. The Forest Service is required by federal regulation to respond to the proposed plan of operations. 2) The EIS will analyze the effect of the exchange of lands between the federal government and Resolution Copper. 3) The EIS will analyze whether to amend the Tonto National Forest Land and Resource Management Plan to facilitate the proposed mining operations and the land exchange.

Photo of USFS Deputy Forest Supervisor Tom Torres leading a public meeting
Photo: Public Scoping Meeting, Gilbert, April 6, 2016

What is “Scoping”?

The first step in the NEPA process is called “scoping”. Scoping is a process of seeking input from within the agency, from the public, and from other government agencies in order to define the scope of issues to be addressed in depth in the EIS. The scoping process will typically identify people or organizations who are interested in the proposed action, identify the significant issues to be analyzed in the EIS, identify and eliminate from detailed review those issues that will not be significant or those that have been adequately covered in prior environmental review, determine the roles and responsibilities of lead and cooperating agencies, identify gaps in available data, and identify other environmental review or permits and consultation requirements that will be integrated with the EIS.

Will there be public meetings where people can have their questions about the project answered and submit comments? If so, where will these meetings be held?

Public meetings are often part of the scoping process. At least four open-house public meetings will be held during the scoping period for the Resolution Copper Project and Land Exchange EIS. These will be:

  • March 31 – Queen Valley Recreation Hall, 1478 East Queen Valley Drive, Queen Valley, AZ
  • April 4 – Superior High School, 100 Mary Drive, Superior, AZ
  • April 5 – Elks Lodge 1775 East Maple Street, Globe, AZ
  • April 6 – Southwest Regional Library, 775 North Greenfield Road, Gilbert, AZ

If I can’t attend any of the meetings, how can I submit comments about the project? Aside from the public meetings, comments can be submitted in a variety of ways:

Land Exchange

What led to the initiation of this land exchange?

In December, Congress passed the Carl Levin and Howard P. ‘Buck’ McKeon National Defense Authorization Act for Fiscal Year 2015 (NDAA). Section 3003 of this law authorizes and directs the Secretary of Agriculture to administer a land exchange between Resolution Copper and the United States Forest Service, which will convey 2,422 acres of Forest Service land in the area of the proposed mine to Resolution Copper.

Photo of stream flowing through green riparian area
Photo: East Clear Creek Land Exchange Parcel

Where is the land being proposed for exchange?

The land being transferred to Resolution Copper is located east of the Town of Superior in the area of the Oak Flat Campground. The private lands that would become federal lands are located in various areas of Arizona including high-priority conservation lands that would become part of the San Pedro Riparian and Las Cienegas national conservation areas.

What would the federal government (taxpayers) get in return?

In exchange for transferring the Oak Flat parcel out of federal ownership, Resolution Copper will convey private land parcels to the Federal Government consisting of 5,344 acres of private land on 8 parcels located elsewhere in Arizona.

Why aren’t environmental studies being done before the land exchange?

This particular land exchange occurred as an Act of Congress, which does not always require environmental studies before land exchanges are completed. Because this project will have impact on federal land, NEPA will require that a thorough environmental analysis be done on the entire project, including public lands and the exchanged land.

Once the EIS is complete and the land has been transferred into private ownership, how will mitigation measures apply?

The EIS can identify issues and recommend mitigation measures for lands that will be transferred into private ownership. Although the Forest Service will no longer have regulatory jurisdiction for those lands, Resolution Copper will still be required to comply with numerous federal and state environmental laws, which address air quality, hazardous waste management, mine safety, mine reclamation, and other aspects of the proposed mine. The Forest would retain jurisdiction for the tailings storage facility and other mine infrastructure that would be located on approximately 4,500 acres of national forest lands not subject to the land exchange.

Where is the land being offered in trade located?

There are multiple parcels of land within the state of Arizona that are listed in the legislation as part of the land exchange. Lands exchanged would undergo an appraisal process to determine fair market value of the properties. See maps.

What will happen to Oak Flat Campground and Apache Leap?

The Oak Flat Campground will be conveyed to Resolution Copper during the land exchange. As a condition of conveyance of the Federal land, Resolution Copper must agree to provide access to the surface of Oak Flat Campground to members of the public, until such a time that operations of the mine preclude that access due to safety concerns. Apache Leap is not part of the area to be conveyed to Resolution Copper; rather, some private lands currently owned by Resolution Copper near Apache Leap would be conveyed to the Forest Service during the exchange. Apache Leap will be designated a Special Management Area, and will be managed to protect the cultural, archaeological, and historical resources found there.

Representatives from several Apache Organizations oppose this legislation and are occupying Oak Flat Campground. What is the Forest Service doing about it?

Allowing tribal members to occupy Oak Flat is part of our continued engagement to address tribal concerns. The Forest Service is working with tribal members to permit this activity.

General Plan of Operation

Photo of mining buildings at East Plant site
Photo: Resolution Copper East Plant Site

Where will the mine be located?

The mine would be located near the Town of Superior, approximately 65 miles east of Phoenix, Arizona, in the area of the former Magma Copper Mine. The deposit to be mined occurs nearly 7,000 feet beneath the earth’s surface.

What is panel caving?

With this technique, a series of horizontal tunnels would be constructed below the ore body. The process begins with an initial round of explosives at the bottom of the ore body to break up the rock. Then rock is funneled downward and removed. The void created in the removal process allows gravity to continue forcing the ore body downward. Automated loaders transfer the ore onto trains, where it is transported, crushed, and then conveyed to the surface for additional processing.

What is subsidence?

Subsidence is the gradual caving in or sinking of an area of land. In the context of underground mining, subsidence is the lowering of the Earth's surface due to collapse of bedrock and unconsolidated materials (sand, gravel, silt, and clay) into underground mined areas.

How much land subsidence is expected from this underground mine?

RCM predicts that land subsidence is expected to occur directly above the underground mine, and is expected to begin occurring after approximately two years of operation. After 40 years of panel cave mining, the subsidence is estimated to be, on average, about 500ft deep and reach a depth of 1,000ft at its deepest point. The magnitude of subsidence and associated effects to the environment will be analyzed in the EIS.

Where will the tailings be placed?

RCM has proposed construction of a 4,400 acre tailings storage facility on national forest lands in an area located northwest of the town of Superior and east of the town of Queen Valley. The proposed tailings storage facility location will be evaluated in the EIS, and alternatives will be developed and assessed.

How big will the tailings deposit be?

The quantity of tailings is estimated at 1.5 billion tons of rock crushed to a fine sand by the end of the life of the mine. The proposed tailings storage facility will ultimately require 4,400 acres (6.8 sq. miles) and will range in height between 300 and 500 feet. The design, configuration, affected area, and location of the proposed tailings storage facility may be modified based on the results of the EIS.

Why can’t the mine tailings replace the ore when it is removed?

This is a question that will be analyzed in the EIS process.

Why can’t the mine tailings be placed where the land subsides from the mining operation?

This is a question that will be analyzed in the EIS process.

Photo of railway with above ground water pipeline
Photo: MARRCO corridor railroad tracks

How will the copper be transported to market?

After crushing underground, the crushed ore would be transported to processing facilities located in Superior. The processing facilities would produce both copper and molybdenum concentrate. The molybdenum concentrate would be trucked directly to market from the processing facilities. The copper concentrate would be pumped as a slurry approximately 22 miles southwest to a loadout/filter facility. Once filtered, the concentrate would be sent to market via truck or rail.

Who is Resolution Copper and how did they acquire this land in the first place?

The General Plan of Operations was submitted to the Forest Service by Resolution Copper Mining, LLC. The discovery of the deposit was made by Magma Copper Company during exploratory drilling. In 1996, the company, along with the ‘Resolution deposit’, was acquired by BHP Copper Inc. However, shortly after, BHP ceased mining operations of the old Magma Mine and did not pursue further exploration. In April 2001, Kennecott Exploration signed an earn-in agreement with BHP Copper Inc. and initiated a five-year drilling program to further identify the size, grade and boundaries of the porphyry deposit while also initiating baseline environmental studies. During this time, Kennecott Exploration transferred all its assets and interests in the project to Resolution Copper Company, a wholly-owned Rio Tinto subsidiary.

By May 2004, Resolution Copper Company had met all the terms established in the earn-in agreement and became the managing member of the Resolution Copper Project.