United Nuclear Corporation

Site Summary

Site Identification

Type of Site: Uranium Recovery Facility
Location: Gallup, NM
License No.: SUA-1475
Docket No.: 40-8907
License Status: Possession Only License
Safety Review Contact: James Smith
Environmental Review Contact: Ashley Waldron

Site Status Summary

The UNC Mill Site is a non-operating uranium mill and tailings disposal site located approximately 17 miles northeast of Gallup in McKinley County, New Mexico. The Mill Site included an ore processing mill and a tailings disposal area (TDA) that covers approximately 10 and 40 hectares (25 and 100 acres), respectively. The previous reclamation plan for the TDA was reviewed and approved by NRC on March 1, 1991.

UNC operated the site as a uranium mill facility from 1977 to 1982. The mill, designed to process 4,000 tons of ore per day, extracted uranium using conventional crushing, grinding, and acid-leach solvent extraction methods. Uranium ore processed at the site came from the Northeast Church Rock and the Old Church Rock mines. The average ore grade processed was approximately 0.12 percent uranium oxide. The milling of uranium ore produced an acidic slurry of ground waste rock and fluid (tailings) that was pumped to the tailings disposal area. Uranium milling and tailings disposal were conducted and an estimated 3.5 million tons of tailings were disposed in the tailings impoundments. The tailings disposal area is subdivided by dikes into three cells identified as the South Cell, Central Cell, and North Cell. Surface reclamation is complete, except for the area of the south tailings cell covered by two evaporation ponds, which are part of the ground water corrective action plan. The current effort is a ground water corrective action plan which is also under oversight of the U.S. EPA through Superfund. A MOU was executed between NRC and EPA for this site in August 1988.

On September 24, 2018, General Electric (ADAMS Accession Numbers ML18360A424 and ML18267A235) requested an amendment to their reclamation plan approved as described in License Condition 34 as well as the reclamation timelines defined in License Condition 35. This amendment, if granted, would allow activities at the site include construction of a Repository for mine-impacted soil and debris on the licensed mill tailings disposal area.  Mine waste will be removed from the Northeast Church Rock Mine Site transported to and placed in the Repository, located on the existing TDA.  This LAR describes the nearby population, local climate, site geology, geomorphology, and seismicity. The LAR includes a review of the site surface water hydrology, groundwater hydrology and current environmental monitoring for the site.

On December 21, 2018, the NRC staff contacted GE-UNC, to advise them that the application had been deemed acceptable for review and the formal review process would begin. On March 7, 2019, the NRC staff sent a formal acceptance letter, (ADAMS Accession Number ML19044A592) which contained an initial schedule for the review. A revised schedule letter was issued July 29, 2020. The revised schedule for the NRC staff review is as follows:

NRC Milestones Projected Completion date
Safety review RAIs – Group 1 May 2019
Safety review RAIs – Group 2 July 2019
Environmental review RAIs August 2019
Safety Evaluation Report September 2020
Draft Environmental Impact Statement October 2020
Final Environmental Impact Statement August 2021
Complete Concurrence Process with appropriate Federal and State entities. December 2021
Issue Amendment Decision January 2022

Additionally, the NRC staff published a Federal Register Notice, Federal Register Volume 84, Issue 49 (March 13, 2019), regarding the License amendment application; the opportunity to request a hearing and to petition for leave to intervene.

The NRC began its environmental review after acceptance of the license application for detailed review. The NRC's environmental review process started with the publication in the Federal Register of the Notice of Intent to prepare the EIS (84 FR 2935 for this project). On March 19 and 21, 2019, the NRC staff conducted a set of public scoping meetings in Gallup, New Mexico to develop the scope of the EIS. In November 2020, the NRC published the Draft EIS for public review and comment (see link in table above). The Federal Register Notice of Availability for the Draft EIS (85 FR 72706) was published on November 13, 2020. The comment period will close on February 26, 2021.

Major Technical or Regulatory Issues

Ground water corrective action at the UNC Church Rock site includes three saturated units: the Southwest Alluvium, Zone 1 and Zone 3. For the Southwest Alluvium, the corrective action system was shut down. For Zone 1, the corrective action system, which was initiated in 1984, was decommissioned in July 1999 with the approval of the NRC, US EPA, and New Mexico Environmental Department. A monitored natural attenuation approach has been proposed for Southwest Alluvium. Currently, a small scale pump and treat system is operating in Zone 3. In addition, monitoring of the natural system's ability to stabilize seepage impacts into Zone 3 is continuing. Semi-annual ground water quality monitoring is ongoing at the UNC Church Rock site. Historically, UNC conducted an extended pilot investigation to evaluate the suitability of hydrofracturing to enhance the remedy for cutoff and containment of the migrating seepage-impacted Zone 3 water. Additionally, US EPA approved a supplemental pilot study for testing in-situ alkalinity stabilization to stop further migration of the seepage-impacted Zone 3 water. In December 2010, US EPA approved the application of alkalinity stabilization on Zone 3, which was discontinued in less than 2 years. UNC began developing a SWSFS as directed by EPA on June 24, 2005. Part 1 of the SWSFS was submitted in February 2007. Part 2 of the SWSFS was submitted in July 2009 and the NRC commented on this technical document. In September 2010, the EPA issued interagency comments to UNC on the SWSFS. Given stakeholder interest in the Church Rock site, significant coordination with various interest groups will be necessary. The Navajo Nation has had a major interest in the site which has resulted in several NRC presentations in an effort to increase public confidence. The Navajo Reservation is located less than a mile north of the Site. Sedimentation issues in the diversion channel have been communicated to the licensee as they relate to license termination.

Estimated Date For Closure


For additional detail, see the following related pages:

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Page Last Reviewed/Updated Thursday, December 10, 2020