NRC grants review of Homestake Mining’s groundwater ACL application

The Nuclear Regulatory Commission has announced that it will begin review of Homestake Mining Company's application to pursue alternative concentration limits (ACLs) and revised treatment options of groundwater contaminants at its Grants Reclamation Project site near Milan, N.M.

In a letter dated September 24, the NRC declared that Homestake Mining's license amendment request (LAR), filed on June 30 of this year, presented sufficient information to allow a technical review of the request to proceed. This stands in contrast to the NRC's denial, citing a lack of information, of a similar application that Homestake Mining submitted in 2022, a decision that some local groups celebrated. It also follows the NRC's September 1 announcement of a proposed two-part rule to establish new groundwater safety standards and decommissioning timelines for uranium recovery sites.

The NRC's recent response to Homestake Mining noted that its decision "does not constitute a determination that the ACL LAR should be approved." The commission expects to complete its assessment and publish its findings by September 2027.

Long-running remediation work: Uranium milling began at what is now known as the Grants Reclamation Project site in 1958 and ended in 1990. Although facilities at the mill had been constructed according to industrial standards at the time, the mill's uranium tailings were discarded in two unlined impoundments, and hazardous metals and radionuclides seeped into the aquifers below the site as a result.

The NRC approved a groundwater corrective action program (GCAP) for the site in 1989. According to the plan, Homestake Mining would treat groundwater contamination at the site using an ongoing strategy that included "source control, groundwater plume control, evaporation, and water treatment."

Homestake Mining submitted requests to revise the GCAP in 2006, 2012, and 2019. The 2006 and 2012 requests were not approved; in 2020, it responded to a request for supplemental information from the NRC with an updated GCAP document, an updated environmental report, and a notice that the company intended to request ACLs that, if approved, would remove the need for the GCAP.

Homestake Mining filed its initial LAR on August 8, 2022, and in it stated that "further groundwater restoration, including to background or current license groundwater protection standards, is not technically feasible." The NRC formally denied the request on May 17, 2023, and listed three chief reasons for its decision:

No information regarding acquisition and ownership of properties adjacent to the site.

No response from Homestake Mining to comments that NRC staff made in a pre-submission audit of the request.

No explanation of contaminants continuing to be found and removed from groundwater despite the company's claim that further remediation was impossible.

Homestake Mining's recent, amended LAR from June 2026 addresses the property ownership concern by noting that the company now owns "approximately 86% of the surface estate and 77% of the subsurface estate within the proposed long-term control boundary" and is pursuing efforts to obtain the rest. Prior to filing the amended LAR, the company also asked the NRC for a series of audits on the site's groundwater model and a demonstration to show that decades of treatments have removed contaminants to the standard of as low as reasonably achievable (ALARA).

Local friction: Homestake Mining's 2026 request comes against the backdrop of a petition that the New Mexico Environment Department submitted to the NRC in October 2025. In that petition, NMED asked the NRC to bring groundwater protection standards at the Grants Reclamation Project site closer to the state's standards, which include a drinking water standard for uranium of 0.03 milligrams per liter. NMED said that "groundwater does not conform to regulatory boundaries delineated on maps" and noted that local organizations such as the Bluewater Valley Downstream Alliance and the Multicultural Alliance for a Safe Environment have for decades opposed the standards currently in place at the site.

In a public informational meeting held on September 9, Eric Burch, program manager for the Grants Reclamation Project, informed a resident that the proposed new ACL for uranium at the project site would be 50 milligrams per liter but also said that uranium concentrations in groundwater beyond the project boundary would be below 0.03 milligrams per liter. Homestake Mining's LAR also proposes higher limits for such contaminants as vanadium and thorium-230.

NMED's petition has been in abeyance pending the results of the current LAR review.

Friction around nuclear energy has appeared recently in New Mexico in other contexts. In letters to Secretary of Energy Christopher Wright and President Donald Trump dated September 16, the state legislature's Radioactive and Hazardous Materials Committee accused the Department of Energy of denying the Defense Nuclear Facilities Safety Board access to biweekly safety meetings as well as information needed to provide oversight of such facilities as Los Alamos National Laboratory. Separately, on September 4, New Mexico Land Commissioner Stephanie Garcia Richard announced an executive order prohibiting new uranium mining on state-owned lands, specifically citing the number of unremediated uranium sites in the state as a reason.