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DEQ Home > Kennecott > Cornerstone Project

Kennecott Utah Copper LLC Projects

Kennecott's Expansion Project (Cornerstone)


In 2011 Kennecott Utah Copper LLC announced a proposal to expand the life of its Bingham Canyon Mine located in the southwest Salt Lake County. The expansion project, called "Cornerstone," included widening the Bingham Canyon pit to accommodate operations focused on the mining and processing of ore located on the southeast margin of the pit. The expansion project will require Kennecott to coordinate the modification of existing State of Utah protection permits that are currently associated with their mining operations.

In 2011 Kennecott began coordinating with the Utah Department of Environmental Quality (UDEQ) to begin the process of modifying and/or acquiring new permits under the Air Quality and Water Quality programs for various facilities associated with their expansion project. Collectively the divisions of UDEQ began to coordinate on the permit reviews.

These pages provide information on the permit modifications requests and UDEQ's oversight activities associated with Kennecott's expansion project. Principally Kennecott will be coordinating with the Divisions of Air Quality and Water Quality, but some of the other divisions of UDEQ will from time to time be involved with Kennecott's expansion plans.

Current Activities and Recent Decisions

Tailings Impoundment Expansion

Kennecott Utah Copper (KUC) has requested approval from the Division of Air Quality (DAQ) to expand its existing tailings site.

KUC submitted a Notice of Intent (NOI) for the Tailings Expansion Project on December 19, 2011. The NOI proposed a redesign of the Tailings Impoundment Facility to allow it to handle a total of 2.2 billion tons of tailings storage.  On March 22, 2014, DAQ issued a draft Approval Order (AO) or Intent to Approve (ITA) on the proposed tailings expansion.

DAQ will hold a 30-day public comment period on the ITA beginning March 22, 2014 and ending on April 21. 2014. The public will have the opportunity to review and comment on the proposal and the agency’s evaluation of the project’s impact on air quality. If a party requests a public hearing within 15 days of publication of this ITA, the hearing will be held as close as practicable to the location of the project. DAQ will evaluate any comments received during the public comment period and the hearing. The proposed conditions of the AO may be changed as a result of the comments received.

Email comments on the draft AO can be sent to Written comments can be sent to the Division of Air Quality, 195 North 1950 West, Salt Lake City, Utah, 84116. The project proposal, estimate of the effect on local air quality, and draft AO are available for public comment and inspection at the Division at the same address.

Public comment is a prerequisite to challenging permitting decisions. Under Section 19-1-301.5, effective May 8, 2012, a person who wishes to challenge a Permit Order may only raise an issue or argument during an adjudicatory proceeding that was raised during the public comment period and was supported with sufficient information or documentation to enable the director to fully consider the substance and significance of the issue.

Project Proposal

To provide additional tailings storage, KUC has proposed modifications to the existing operation along with an increase in the overall footprint for the tailings site. The proposed expansion project will require infrastructure modifications and relocation of equipment.

The first phase of construction will involve an expansion to the northeast of the existing tailings site. The total footprint for this first phase will be approximately 4,490 acres after the Northeast Impoundment is combined with the existing North Impoundment. The final phase of construction will raise the North Impoundment and combine it with a portion of the South Impoundment. This will result in a total foot print area of approximately 10,190 acres.

The ITA contains permit requirements for fugitive dust control. Fugitive emission increases associated with the tailings site expansion in tons per year (tpy) are estimated as follows: PM10 = 46.79, PM2.5 = 7.10. The Potential to Emit (PTE) for all sources associated with the tailings site will be as follows: PM10 (including PM2.5) = 83.05, PM2.5 = 12.58, NOx = 0.28, CO = 1.12, VOC = 0.04, and CO2e = 20.04.
The increase in PM10 emissions of 46.79 TPY from the tailings expansion, combined with the increase from the Bonneville Borrow Plant (BBP), will be over 50 tpy.  KUC will offset these increases at a ratio of 1.2:1. Offsets held in the Emission Credit Registry by KUC will be relinquished prior to the issuance of the AO.

Fugitive Emissions Increases Associated with the Tailings Expansion
(tons per year)

Particulate matter PM10 +46.79
Particulate matter PM2.5 +7.10


Potential to Emit (PTE) for All Sources Associated
with the Tailings Site
(tons per year)

Particulate matter  PM10 (including PM2.5)


Particulate matter  PM2.5


Nitrogen oxides (NOX)


Carbon monoxide (CO)


Volatile organic compounds (VOCs)


Carbon dioxide equivalent (CO2e)


Public Notice for Modification for Ground Water Discharge Permit

DEQ is soliciting comments on the request to renew a ground water discharge permit (Number UGW350011) under authority of the Utah Water Quality Act, Section 19-5-108(2) Utah Code Ann. 1953, as amended and Utah Administrative Code R317-6. Under Section 19-1-301.5, effective May 8, 2012, a person who wishes to challenge a Permit Order may only raise an issue or argument during an adjudicatory proceeding that was raised during the public comment period and was supported with sufficient information or documentation to enable the Director to fully consider the substance and significance of the issue.

Bonneville Borrow Plant (BBP)

On September 26, 2011, Kennecott Utah Copper LLC (KUC) submitted a Notice of Intent (NOI) requesting an Approval Order (AO) for the Bonneville Borrow Plant (BBP). The BBP will be a new crushed stone processing plant, specifically a crushing and screening plant. KUC will use the product from the BBP to supply building materials related to the construction of the expansion of the Tailings Impoundment.

This is a support facility for the Tailings Impoundment (TI) expansion and operation. The operation of the TI includes construction of the dikes. The BBP will provide material for the construction of the dikes for the TI expansion and future operations. KUC will use more than 50% of the material from the operation of the BBP for the dikes on the proposed TI expansion and future operations when the dikes are constructed and when KUC combines the existing TI (South TI), the current TI expansion (North TI) and the future TI expansion into one TI. This future expansion is part of the continuous operation of the TI site.

The Utah Division of Air Quality (UDAQ) reviewed and analyzed the NOI and prepared a draft AO or "Intent to Approve" (ITA) for the modification request. DAQ held a public comment period on the ITA from January 10, 2012 to February 10, 2012. The Division received comments that resulted in new conditions and additional requirements to the proposed BBP AO. DAQ held a second comment period to give the public the opportunity to review the new ITA. The second public comment period ran from March 16, 2013 to April 15, 2013.

Eastside Collection System (ECS) Modification

In September 2012 the Division of Water Quality received a modification application for Kennecott's Groundwater Discharge Permit #UGW350010. The permit modification entails the relocation of certain cut-off walls and toe drains of the ECS to facilitate the placement of overburden from the Bingham Canyon pit project in front of the existing Eastside waste rock dumps.

Modification of Molybdenum Autoclave Process (MAP) Plant

The MAP facility is currently under construction, and commissioning is expected to start in 2013. Public comment is being sought through March 11, 2013 on Kennecott's request to modify the design of the MAP plant.

Tailings Impoundment

On December 20, 2011, KUC submitted an NOI to expand the tailings impoundment to handle an additional 1.2 billion tons of tailings storage. The NOI contains a process description, emissions information, regulatory review, and control technology analysis.

Kennecott Power Plant

The request for approval of installation and operation of a new combined-cycle, natural gas-fired combustion turbine, that will replace three existing coal-fired boilers was approved on December 1, 2011.

Copperton Concentrator Plant Approval Order Modification Granted

On September 8, 2011, the Division of Air Quality approved Kennecott's request to modify its Approval Order, outlined in a Notice of Intent (NOI).


Bingham Canyon Mine Expansion Approval Order Modification Granted

On June 27, 2011, the Division of Air Quality approved Kennecott's request to modify its Approval Order, outlined in a Notice of Intent (NOI).

SIP Amendment

By a vote of 5-4, the Air Quality Board approved the Amendment to the Utah State Implementation Plan on May 4, 2011.


Public Participation

The UDEQ has an open and transparent public participation process that is implemented by the divisions during their review and decisions on permit modification applications and new permit applications. As applications are received and considered, quick links on the divisional activities can be found above under the section Current Activities and Recent Decisions.

Visit the DEQ Public Participation page for information about public meetings, how to participate and make public comments, and for GRAMA requests.

The public can also contact the Office of Policy and Public Affairs:

As noted previously, the Divisions of Air Quality and Water Quality are principally responsible for coordinating reviews of permit modifications and new permit applications submitted by Kennecott. However, other Divisions may become involved as the need arises. For Division specific information about the oversight activities associated with the expansion project, see the Contacts page.