URANIUM MINE WASTE | WASTE MANAGEMENT V Different parts of the two sites to be addressed are


licensed by different agencies – the US Nuclear Regulatory Commission (USNRC) licenses the tailings impoundment at the UNC Mill Site, for example, but does not license other parts of the site. Interim EPA cleanup has seen over 200,000 tonnes of


contaminated material removed from residential areas to address immediate exposure concerns. In 2005, following a request by the Navajo Nation Environmental Protection Agency (NNEPA), the EPA agreed to assume jurisdiction for the mine cleanup and act as the lead regulatory agency for the NECR Mine Site. In the next step UNC wants to transfer around 765,000 m3


of waste from the NECR mine to be stored above the tailings impoundment at the UNC Mill Site. Principal threat waste (PTW) would not be moved. PTW is defined by EPA as source materials that are considered to be either highly toxic or highly mobile. EPA has defined PTW at the site as material that contains 7.40 Bq/g or more of Ra-226, and/or 500 (mg/kg) [500 ppm] or more of total uranium. That material cannot be sent to the disposal site above the UNC tailings impoundment. Instead UNC’s proposal is to transport the PTW to the White Mesa uranium mill in Blanding, Utah, but UNC is not expected to finalise arrangements for disposal until the current works is completed.


The proposal The UNC Tailings Impoundment is an engineered and covered impoundment located on the UNC Mill designed and constructed to address NRC criteria to isolate tailings from the environment, control radiological hazards, and limit radon releases for up to 1,000 years. Eventually, the NRC expects the tailings impoundment would be transferred to a government custodial agency for long-term surveillance. The mine waste has radiological characteristics


comparable to the tailings at the UNC Mill Site because both are derived from the same uranium ore material. NECR mine waste that exceeds a Ra-226 concentration of 200 pCi/g would not be sent to the UNC Mill Site because it is considered PTW. UNC proposes to transfer the NECR mine waste to the


proposed disposal site using articulated dump trucks on access and haul roads that connect the two sites. One alternative would use an elevated conveyor system to transfer most of the waste at an additional cost of $1 million. In this case about 5% of NECR mine waste would still have to be transferred by truck (which would have a slightly higher impact than in the main proposal because it could not use specially constructed haul and access roads). But most of the NECR mine waste would avoid crossing New Mexico Highway 566 at ground level, which would reduce the potential transportation-related impacts. UNC estimates that this alternative would disturb 0.8Ha less than the proposed haul and access roads although construction of the conveyor and a bridge over the highway would involve shipments and temporary lane closures and interruptions to transportation. Another alternate would source cover material from


other areas. This would reduce costs by $3 million, the assessment says. UNC proposes to install permanent stormwater controls for the proposed disposal site using existing swales and


www.neimagazine.com | February 2023 | 25


channels constructed on the tailings impoundment, with improvements and supplemental controls where necessary. The proposed project phases would last around four


years, to include construction and transfer of NECR mine waste, and closure of the constructed disposal site. Another 10 years may be needed for other activities, including the completion of UNC Mill Site reclamation, groundwater corrective action and NECR Mine Site The long-term (post-closure) timeframe includes long-


term isolation of tailings and wastes and the effects of land use restrictions and requires that a mill tailings disposal facility be designed to provide “reasonable assurance of control of radiological hazards to… be effective for 1,000 years, to the extent reasonably achievable, and, in any case, for at least 200 years”. In the EIA the NRC recognised that “the Navajo Nation


government and members of local Navajo communities oppose the proposed action – the transfer and disposal of mine waste onto the existing UNC Mill Site – and prefer that the waste be moved far away from the Navajo Nation”. It also recognised that “Navajo Nation communities are closer than any other community to the proposed project area and would be disproportionately affected by transportation- related impacts, impacts to air quality, increased noise levels, and visual disturbances”. Mitigation included EPA programmes to provide community members with voluntary alternative housing and mitigations proposed by UNC during the action. But, overall, the NRC concluded that the programme would be beneficial. Removal of mine wastes from the former NECR Mine Site and consolidation of the mine materials over existing mill tailings on private property would minimise the footprint of waste disposal facilities and allow beneficial reuse of the NECR Mine Site. ■


Below: Abandoned uranium ore mines are dotted across Navaho Nation lands


Left: The Church Rock site post clean-up


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53