United Nuclear Corporation

1.0 Site Identification

2.0 Site Status Summary

The facility is a conventional uranium mill site under reclamation. The site includes a former ore processing mill and tailings disposal area, which cover about 25 and 100 acres, respectively.

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 EPA through Superfund. A MOU was executed between NRC and EPA for this site in August 1988. The cost for decommissioning is estimated to be approximately $3.7 million; however, this estimate may be changed based on the results of the SWSFS.

3.0 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 NMED. A monitored natural attenuation approach has been proposed for Zone 1. 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 a small scale pilot study to evaluate the effectiveness of a hydraulic barrier on Zone 3. UNC began developing a Site-Wide Supplemental Feasibility Study (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 US EPA issued interagency comments to UNC on the SWSFS. Completion of the SWSFS (Parts 1 thru 3) is expected to occur in late-summer 2011. 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.

4.0 Estimated Date For Closure

12/31/2015