LAS VEGAS – EM recently achieved a groundwater characterization milestone at the Nevada National Security Site (NNSS) when the State of Nevada Division of Environmental Protection approved transitioning a groundwater investigation area to long-term monitoring.

That’s the end goal of a strategy outlined in the Federal Facility Agreement and Consent Order for five groundwater investigation areas at NNSS. Frenchman Flat, the site of 10 underground nuclear tests between 1965 and 1971, is the first to enter this important final stage.

   The Frenchman Flat success follows over 20 years of hard work and continuous study by multiple organizations, including two external peer reviews. In that time, multiple groundwater characterization wells were drilled, three-dimensional computer models were developed and refined and boundaries for restricted access were established.

   “The NNSS is one of the most studied locations in the world, and this achievement is a testament to the teamwork between all organizations involved,” said Bill Wilborn, manager of NNSS groundwater characterization for EM.

   The underground nuclear tests at Frenchman Flat provided valuable data in a few spectacular seconds. In the decades to follow, NNSS scientists worked to understand the effects of those tests on the site’s groundwater. Their studies confirmed that the contamination from nuclear testing in groundwater at Frenchman Flat poses no risk to the public.

   While entering long-term monitoring signifies a thorough understanding of the groundwater flow system, routine monitoring at Frenchman Flat will continue, and results will continue to be reported annually in a publicly-released report. 

   Scientists prepared a report detailing the Frenchman Flat studies. Their findings include that contaminated groundwater is not expected to leave the Frenchman Flat basin, and that radionuclides in the groundwater will travel less than a mile in 1,000 years.

   “The groundwater flow system and potential for contaminant movement is well understood, to the point that protection of the public is ensured,” said Wilborn. 

   Transitioning Frenchman Flat to long-term monitoring provided NNSS scientists and staff with an invaluable experience for understanding the necessary balance of modeling, monitoring and restricted access protective of the public and the environment. It also sets the stage for other NNSS groundwater investigation areas.

   “Although the regulatory strategy is the same, each will have unique challenges due to the varying subsurface environments,” said Wilborn.

   NNSS groundwater studies will continue with the goal of transitioning all areas of the NNSS to long-term monitoring. 

   Click here to learn more about groundwater characterization at the NNSS.