Feb. 29—Los Alamos National Laboratory's waste-cleanup contractor has taken about a dozen corrective actions in the past two years to keep storm runoff from carrying toxins from the lab's contaminated sites down the hillsides and canyons.

About a dozen more actions are planned in the coming year, Grayson Vogel said Wednesday during an online public hearing on the cleanup's progress. Vogel is water program engineering manager for Newport News Nuclear BWST, or N3B for short. N3B has overseen the lab's legacy waste cleanup since 2018.

Corrective actions include building earthen berms, fiber-log barriers and rock dams to suppress runoff, as well as lining a swale with rip-rap.

Stormwater flowing down Pajarito Plateau tainted by contaminants in the canyons and from streets, buildings and other hard surfaces, has been a problem for decades.

Around 2008, a water advocacy coalition sued the lab and the U.S. Department of Energy, arguing the lab's contaminated sites posed a serious threat to the environment and public health.

In 2011, the federal government settled the lawsuit, resulting in the EPA issuing an industrial stormwater permit requiring the lab to address the polluted discharges, said Rachel Conn, deputy director of Taos-based Amigos Bravos, one of the groups in the coalition.

"It's been plugging along," Conn said. "This has been ongoing for years."

State and federal regulators have said runoff from the plateau contains mercury, copper, nickel, cyanide, radiation and polychlorinated biphenyls, cancer-causing chemicals known as PCBs. These toxins can be carried into the Rio Grande, which is used for drinking water and irrigation.

Several years ago, the state Environment Department pegged PCBs at 14,000 times the level deemed safe for human health in Sandia Canyon and 11,000 times the limit in Los Alamos Canyon.

Contaminated runoff is enough of a concern that the Buckman Direct Diversion, which draws water from the Rio Grande, has monitoring devices near the Otowi Bridge in the San Ildefonso Pueblo area, where stormwater from Los Alamos Canyon flows into the river. A significant storm leads to the system shutting down for 10 hours in this area and triggers a device that collects water for analysis.

During a slide presentation, an N3B manager noted PCBs and other toxins were detected at high levels at legacy sites, such as defunct firing and explosive ranges, and areas where polluted discharges were released.

Two of the more contaminated sites — where polluted water was discharged — had PCBs measured at 160 times the accepted levels. They will be capped by concrete.

One water advocate questioned how well the contractor's methods are working.

Joni Arends, executive director of Concerned Citizens for Nuclear Safety, asked whether N3B could produce a summary report on the progress made since the cleanup began 13 years ago.

Karly Rodgriguez, an N3B surface water program manager, said it's too soon for such a report.

"We have more to do," Rodriguez said.

After the meeting, Arends said building barriers seems a half-measure that slows the water flow but doesn't filter out the contaminated sediment, allowing the toxins to leach back into the ground.

"When the permit comes up for renewal, we're going to have to ask for some kind of analysis about the effectiveness of these methods," Arends said. "LANL is resistant to dig up these dumps in terms of doing real remediation."

Conn said N3B provides data every year on the contaminant levels. But she agreed there should be a periodic overview of the cleanup, so the public can see how well it's progressed over the years.

"I think it's very reasonable to ask for a summary report ... an overall update of what has happened since they started this back in 2011," she said.