EM-LA’s top environmental remediation project is the hexavalent chromium plume in Mortandad and Sandia Canyons at Los Alamos National Laboratory (LANL). The primary source of the plume was a non-nuclear power plant at LANL that periodically flushed coolant water containing potassium dichromate from the plant’s cooling towers into Sandia Canyon from 1956-1972. Potassium dichromate (the primary contaminant of concern is hexavalent chromium) was a permitted effluent used as a descaling agent in power plants worldwide during this time. Up to 160,000 lbs. of hexavalent chromium was released from the cooling towers, a small portion of which migrated into the regional aquifer.
Current measurements indicate the plume is approximately one mile long by half a mile wide. The primary objective of Chromium Plume Control Interim Measures (IM) under the 2016 Compliance Order on Consent, as revised in 2024 (Consent Order) between the U.S. Department of Energy and the New Mexico Environment Department (NMED) is to prevent migration of the hexavalent chromium plume beyond the LANL boundary.
On March 30, 2023, EM-LA shut down operation of the IM as a result of complying with NMED’s direction to cease injection by April 1, 2023.
In August 2023, EM-LA and NMED received a recommendation from the Radioactive and Hazardous Materials Committee of the New Mexico Legislature to engage in a third-party review regarding the IM. In December 2023, EM-LA and NMED requested Dr. Ines Triay, Interim Dean, College of Engineering and Computing, and the Executive Director for the Applied Research Center, Florida International University, to organize and conduct an independent technical review of actions taken by EM-LA to characterize and model the hexavalent chromium plume at LANL, and the efficacy of Chromium Plume Control Interim Measures (IM) taken to prevent plume migration offsite.
In March 2024, EM-LA and NMED convened a team of experts from the Network of National Laboratories for Environmental Management and Stewardship, industry, academia, and EPA Region 6 to perform a technical review and help facilitate a technical discussion and resolution of EM-LA and NMED’s differing professional opinions.
Prior to finalization of the report, EM-LA worked together with NMED to resume partial operation of the Chromium IM on September 30, 2024. The IM is running 24/7 as expected with two extraction wells and three injection wells.
The Hexavalent Chromium Project Expert Technical Review Team has issued the Independent Review of the Chromium Interim Measures Remediation System in Mortandad Canyon Los Alamos, New Mexico, December 2024 report.