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Los Alamos National Laboratory is beginning to repair a degraded channel in Pueblo Canyon on the northwest side of the White Rock interchange with NM 502. While the work will have some short term impacts, the laboratory expects the job of stabilizing the wetland in the area to have positive results for the long term.
The work is part of the comprehensive cleanup project at the laboratory, which is governed by the Consent Order with the New Mexico Environment Department.
“The complex topography that makes up Los Alamos is one that challenges our cleanup all the time,” said George Rael assistant manager of environmental operations at the Los Alamos Site Office. “Water goes down stream carrying contaminants, and the movement of sediments concern us. Wetlands help reduce the velocity of water that allows the sediments to be filtered out.”
The project aims to prevent the upstream gradient from continued erosion and a deepening drop-off and to restore a more gentle flow by installing $2 million-worth of grade control structures, made up of tightly packed rocks wrapped in wire mesh.
“In Pueblo Canyon, this is a really long wetland that starts a couple of kilometers up the canyon,” said Danny Katzman, who is in charge of the laboratory’s water stewardship project.
Upstream, the project has planted 10,000 willows, Katzman said. Cross-vane structures that slow the sediment transport and concrete-lined ditches, or flumes, will be built to help control the channel.
After the Cerro Grande Fire in May 2000, the main concerns were about mudslides on the barren hillsides well upstream that could dislodge tons of sediment down the canyons, including natural and made-made pollutants that were concentrated in ash that has made its way down the canyon in storm water and flooding events.
The main purpose of the Pueblo Canyon work is to reduce the risks that contaminated soil will migrate off-site from LANL, according to the officials. The laboratory has recorded sediment contamination transported downstream from historic operations going back more than 50 years.
In its most recent annual environmental surveillance report, the laboratory noted some of the environmental hazards associated with Pueblo Canyon, which include traces of radioactive materials, mainly plutonium and cesium.
One drinking water well has been shut down because of discharges of perchlorate, recorded at 16 percent of the Environmental Protection Agency’s interim health advisory level for perchlorate. Well 0-1 in Pueblo Canyon is the only production well in the county to be taken out of service.
The laboratory and the county are always careful to note that all the drinking water produced by the county meets federal and state standards.
Required to monitor potential offsite effects from its surface water emissions, the laboratory also points out that stream flows, particularly from Pueblo Canyon sometimes extend onto the neighboring Pueblo de San Ildefonso, where spring water is sometimes used by tribal members in traditional ceremonies.
An announcement by the laboratory also noted that the Pueblo Canyon work “was considered important to the Buckman Direct Diversion Project,” that will draw water from the Rio Grande down stream from the tributaries draining the Los Alamos canyons.
Among the many constituents to be monitored, the project will evaluate how effectively the actions reduce transport of PCB’s.