LOS ALAMOS, N.M. – The EM Los Alamos Field Office (EM-LA) and its cleanup contractor have collected more than 3,100 soil samples and excavated more than 1,000 cubic yards of contaminated soil as they remediate land at the southernmost boundary of Los Alamos National Laboratory impacted by historical weapons research and development.

The cleanup at LANL’s southernmost boundary, which is shared by Bandelier National Monument and a portion of Los Alamos County, is intended to prevent contamination from migrating into watersheds that reach the Rio Grande.

The work by EM-LA and Newport News Nuclear BWXT Los Alamos (N3B) is part of a broader cleanup at the Lower Water, Indio, Chaquehui, Potrillo, Fence, North Ancho, and South Ancho canyons. Crews have excavated old incinerators, septic systems, and associated leach fields, as well as contaminated soil near underground firing chambers where high explosives and radioactive testing occurred in support of Cold War efforts.

“In addition to prioritizing human and ecological health at the specific sites N3B is remediating, we also consider the watersheds in each canyon,” said Nathan Canaris, a field execution technical lead in N3B’s Resource Conservation and Recovery Act Program. “We want to prevent any potential contamination from being washed into a watershed that leads to the Rio Grande — and we work to prevent contamination from making its way into groundwater. Protecting those resources is paramount.”

Cleanup at sites is considered complete once crews ensure, through extensive sampling and at times, excavation, that soil meets state environmental standards based on future land use scenarios. Depending on the site’s history, soil is sampled for a variety of contaminants, including metals, radionuclides, high explosives, and human-made chemicals known as volatile organic compounds, which are typically used in industrial solvents.

“Sampling in these canyons has been one of the most challenging aspects of the campaign due to the rugged terrain,” Canaris said. “At a lot of sites, we hike in with hand augers for the shallow digging necessary to collect soil samples because it’s too remote to bring in mechanized equipment.”

N3B has met nine Consent Order milestones associated with the Southern External Boundary Campaign, including three last month. The Consent Order is an enforceable agreement between DOE and the New Mexico Environment Department that guides EM-LA’s legacy environmental cleanup at LANL, and establishes an effective structure for accomplishing the cleanup on a priority basis.

More than half of the 2,100-plus potentially contaminated sites at LANL associated with historical operations and originally identified for investigation have been remediated. Areas range from small spill sites with a few cubic feet of contaminated soil to large landfills encompassing several acres.