N3B Los Alamos Releases LANL Interim Facility-Wide Groundwater Monitoring Plan

Los Alamos Daily Post

Los Alamos National Laboratory Environmental Management contractor N3B has released the Interim Facility-Wide Groundwater Monitoring Plan for the 2019 monitoring year which runs from October to September 2019.

N3B environmental remediation manager Joe Legare told the Los Alamos Daily Post at the Northern New Mexico Citizen’s Advisory Board meeting Wednesday at Santa Fe Community College that he was pleased to announce that the report, a milestone for the new LANL Environmental Management contractor, has been issued.

Groundwater monitoring has been conducted at LANL 60 years beginning in 1945 with water supply studies by the U.S. Geological Survey and continuing with Lab groundwater quality monitoring in 1949.

While the first groundwater monitoring network consisted of water-supply wells, several observation wells and springs, the network evolved through the years and additional wells have been installed primarily in the shallow alluvia systems as potential monitoring points where samples are collected and analyzed for specific constituents.

The plan states that it monitors four occurrences of water: 

  • Base flow—persistent surface water that is maintained by precipitation, snowmelt, effluent, and other sources;
  • Alluvial groundwater—water within the alluvium in the bottom of the canyons;
  • Perched-intermediate groundwater—localized saturated zones within the unsaturated zone; and
  • Regional groundwater—deep, laterally continuous groundwater beneath the Pajarito Plateau.

Storm runoff and snowmelt monitoring are addressed under a different reporting requirement. Base flow and in some cases persistent flow derived from snowmelt are monitored under the plan.

Seven major watershed groupings are monitored: Los Alamos/Pueblo Canyons, Sandia Canyon, Mortandad Canyon, Pajarito Canyon, Water Canyon/Cañon de Valle, the combined watersheds of Ancho/Chaquehui/ Frijoles Canyons, and White Rock Canyon. Monitoring outside the Laboratory boundary is conducted to collect baseline data in areas that have been affected by past Laboratory operations, such as Guaje and Rendija Canyons, or that have not been affected by Laboratory operations.

The plan also includes monitoring in off-site areas that could potentially be impacted by the Laboratory such as the Rio Grande and springs in White Rock Canyon. Some off-site monitoring is also performed under cooperative agreements with Los Alamos County, which owns and operates water-supply wells within and near the Laboratory.


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