Orphan Mine CERCLA Site | Community Fact Sheet | April 2025 Update

 

Note: the information on this page was updated in April 2025 and March 2019.

Site Background

The Orphan Mine Site (Site) is located on and below the South Rim in Grand Canyon National Park. The Site is approximately two miles northwest of Grand Canyon Village, between Maricopa Point and the Powell Memorial along the Hermit Road. The South Rim Trail detours around the Site.

The approximately 20-acre Site, extending from approximately 500 feet south of the South Rim to approximately 1,100 feet below the South Rim, is the former location of a copper and uranium mine operated by a private mining company. The Site is contaminated with elevated radiation levels and other contamination associated with historic mining activities.

In 1951, geologists discovered high- grade uranium deposits on Site and by 1956 a private mining company had purchased the Orphan claim to develop a uranium mine. The company built many structures to support its mining activities, including an aerial tram system for hauling ore from the lower mine area to the upper mine area on the South Rim. To increase uranium production, in 1959 the tram was replaced by the construction of a vertical hoisting mineshaft. The hoist system, supported by a headframe, was used to haul ore, personnel, and materials between the lower mine workings and the upper mine area on the South Rim.

 

Site Legacy

The legacy of uranium mining at the Orphan Mine resulted in the presence of mine waste on the upper and lower mine areas and on the steep slope down the canyon. Access to the upper mine area (Operable Unit (OU) 1) is restricted by two protective fences and a locked gate to protect park visitors from any potential exposure to radiation and other mining-related contaminants. The chain-link fence was expanded in 2017 to enclose an additional approximately 1.25-acres of the Site. Soil stabilizer has been applied to the area within the chain link fence to reduce erosion and dust generation. Soil stabilizer, SoilSement®, was originally applied twice between 2012 and 2017. SoilTac®, a more effective and longer lasting stabilizer, was applied after SoilSement® use and was reapplied in October 2019, September 2022, and September 2025.

The lower and middle mine areas (OU2) are inaccessible to park visitors. The original “glory hole” in the lower mine area, though isolated, is clearly visible from Maricopa Point. The lower mine area will be addressed in the future.

 

Environmental Investigations

 

Park employee testing for elevated radiation levels.

NPS

In 1981, NPS began environmental investigations to evaluate potential threats posed to public health or welfare or the environment by contaminants at the Site and to evaluate potential responses to address identified threats. These investigations are being conducted pursuant to NPS cleanup authority under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also referred to as Superfund. NPS is the CERCLA “lead agency” at the Site, responsible for planning and directing the Site investigation and cleanup activities.

Preliminary environmental investigations of the upper mine area identified areas of elevated radiation levels and other contamination associated with historic mining activities at the Site. NPS determined that further evaluation of the Site pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) was needed.

 

NPS is proceeding with studies to determine whether a CERCLA cleanup action is required to reduce potential risks posed by hazardous substances present at the site through the development of an Engineering Evaluation/Cost Analysis (EE/CA) for the upper mine.

The development of the upper mine area EE/CA has three phases. Phase I was the Man-Made Features Removal project, completed in June 2009, that consisted of removing concrete, debris, and other mining-related equipment from the upper mine area so that field investigation activities such as soil sampling could be performed. In 2011. Phase II of the EE/CA process included a year-long radon monitoring effort and a soil investigation.

 

The Next Steps

 

Signs show that the Site is restricted.

NPS

Phase III of the EE/CA process is the development of the EE/CA Report. The EE/CA will analyze the nature and extent of contamination, determine the human and ecological risk from the contamination, and identify and evaluate cleanup alternatives for the area, if appropriate. This report will be made available for public review and comment.

With limited exceptions, monthly inspections of OU1 will continue during the months of March through October. The purpose of the inspections is to verify the ongoing effectiveness and reliability of the selected Site controls to protect human health and the environment. OU1 inspections evaluate the condition of security fences, gates, and locks, Site signage alerting Site users that the Site is restricted, and soil stabilizer has been applied to the ground surface for wind and water erosion control.

 

Community Involvement

Community involvement is an important part of the CERCLA process. In 2009, public meetings were held in the Park and in Flagstaff, AZ to give the public an opportunity to learn about the Man-Made Features Removal Project and the EE/CA process in general.

The public will have the opportunity to review and comment on the Orphan Mine Site EE/CA.

Report and proposed cleanup plans for the upper mine area (OU1) once the EE/CA Report has been completed. A public meeting will be held in connection with the public comment period. NPS has established a Site website at www.nps.gov/grca/learn/management/publications.htm on which it will post general Site information as well as key cleanup and community involvement documents.

NPS has established an information repository, which houses a copy of the Orphan Mine Administrative Record File.

CERCLA Administrative Record Files consist of those documents that form the basis for the selection of the response at the Site. The Orphan Mine Administrative Record File currently includes documents associated with environmental investigations, ecological and human health risk assessments, community relations materials, public comments, and responses to significant comments. The Orphan Mine Administrative Record File will be updated periodically as new information and reports are finalized. The public can view the Orphan Mine Administrative Record File and make copies of documents at the following information repository location:

Grand Canyon National Park
Museum Collection Office
2C Albright Ave.
Grand Canyon, Arizona 86023
Contact: Colleen Hyde
Phone: [phone]
Monday - Friday 8 am – 5 pm

 

For More Information

If you have questions concerning the information contained in this Community Update, please contact Mr. Eric Lam by email or mail at P.O. Box 25287, Denver, CO 80225. Additional information and project updates are available through the Grand Canyon National Park website: https://www.nps.gov/grca/.