N3B: Los Alamos Interim Measure To Control Contaminant Plume Beneath LANL Reaches Full Operation - 9:38 am N3B’s Ryan McGuill assists in replacing an ion exchange unit in January 2020 where groundwater contaminated with hexavalent chromium is treated. Courtesy/N3B N3B News: This week’s EM Update newsletter from the Department of Energy’s Office of Environmental Management announced that an interim measure to control migration of a groundwater plume containing hexavalent chromium beneath Los Alamos National Laboratory (LANL) is now fully operational. The milestone marks a major achievement for Newport News Nuclear BWXT Los Alamos (N3B) in its efforts to shrink the plume and protect area water quality.