Almost 31 years ago, an earthen tailings dam near the United Nuclear Corp. Church Rock Uranium mine collapsed, spilling ninety million gallons of liquid radioactive waste and eleven hundred tons of solid mill wastes into the Rio Puerco. The spill contaminated water, land and air at least 50 miles downstream on Navajo Nation land in New Mexico and Arizona. More radiation was released in the spill than in the Three Mile Island nuclear accident in Pennsylvania, making the Church Rock spill the largest release of radioactive waste ever in the U.S. — and second only to the Chernobyl meltdown globally. The privately-owned site of the Church Rock spill is a Superfund site — and it is still leaking radioactive waste throughout Indian lands to this day.
Yet few people today have ever heard of it.
The Northeast Church Rock Mine (NECR) is a former uranium mine that was operated by United Nuclear Corporation (UNC) from 1967 to 1982. Most of the 125-acre mine permit area is held in trust for the Navajo Nation by the United States Government and is immediately adjacent to the Navajo Reservation. Approximately 40 acres are patented mining claim land owned by UNC. There is a small community of residents that live immediately next to the mine site on the reservation, downstream and down-wind of the waste piles. The residents graze sheep, cattle and horses, and collect herbs around the area.
The mining activities have resulted in a legacy of waste piles, sediment settling ponds abandoned building pads and mine equipment debris. When the mine was closed, several basic activities took place to protect future land users and neighbors. The majority of the buildings and equipment were cleared from the area. Some of the mine waste piles were returned to the shafts. Remaining waste piles were contoured to reduce movement of the material. The ponds were drained and a fence was installed around the mine site and associated areas.
At present, there is an elevated health risk for people who frequent the site from inhaling radium contaminated dust particles, associated radon gas or utilizing contaminated rainwater and runoff that has pooled in the ponds. There is an elevated risk associated with livestock that may graze and water on the site. Elevated concentrations (activity) of Radium-226 have been detected throughout the 125-acre mine permit boundary and contiguous surface areas. Different radionuclides emit gamma rays of varying strength, but gamma rays can travel long distances and penetrate entirely through the body. Exposure to high levels of Radium-226 over a long period of time may result in harmful effects including anemia, cataracts, fractured teeth, cancer (especially bone cancer), and death. Exposure to high levels of uranium can cause kidney disease. It is not known to cause cancer, but can decay into other radioactive materials that may.
The sources of risk to people’s health comes from two aspects of this mine: dewatering the mine shafts while it was in operation and the mine waste piles that were created while removing the radioactive ore.
The miners would tunnel 1600-1800 ft below the surface to extract the uranium ore that was processed at the nearby UNC uranium mill, now a Superfund cleanup site managed by the U.S. EPA Region 6 (Dallas) and the NRC. The uranium ore was situated in the ground immediately adjacent to an underground aquifer (groundwater). This resulted in groundwater seeping into the mine shafts. That water was pumped from the mine shafts to the surface and had the potential to carry uncontrolled radioactive sediments held in suspension to the surface. UNC was required to treat this water before it was released into a wash called simply the unnamed arroyo.
Water pumped out of the mines was treated via a system of sequential treatment ponds where the suspended sediments would drop to the sides and bottom of the pond as the water flowed through and out of the third pond into the unnamed arroyo. The ponds have been drained for the most part, however they can fill up with seasonal precipitation. EPA has found that some of the sediments that dropped out of suspension were not completely removed from the ponds during active mining and NRC’s license closeout activities and lead to unhealthy surface water within the ponds. The water that flowed out of the final treatment pond carried contaminated sediments into the unnamed arroyo that flows between some of the residences.
Additionally, the State and NRC approved disposal of uranium mill tailings, concentrated with radium at the Site. Mill tailings were hauled to the Site, stockpiled in several areas known as Sandfills and were then slurried into the mine workings and stopes to prevent collapse. The sandfill areas and ponds present the most elevated radioactivity.
Mine Waste Piles
The waste piles are a result of removing dirt, rock, and rubble (overburden) from the mine shafts surrounding the valuable uranium ore bodies. Within these waste piles exists low-grade uranium, associated radioactive minerals, such as radium, and other heavy metals that were not separated from the overburden. This has resulted in large wastepiles of contaminated soil on the surface of the site, where plants have begun to grow and people may come into contact if walking on the site. Additionally, the contaminated overburden is carried off the Site by wind and water erosion.