Test Site wells planned to gather information on groundwater

By Mary Manning

Tuesday, June 2, 2009 | 12:19 p.m.

The Energy Department is digging deeper wells at the Nevada Test Site to gather additional information on how groundwater moves near underground nuclear weapons experiments.

Researchers will begin digging the first of nine new groundwater monitoring wells on and near Pahute Mesa in the northwestern corner of the Nevada Test Site in early June.

At a cost of $5 million to $7 million for each well, the Energy Department's National Nuclear Security Administration plans to use some funding from the American Recovery and Reinvestment Act, allowing all nine wells to be completed within three years.

Digging the new wells is the latest in a long-term effort to better define the location and extent of groundwater contaminated from underground nuclear tests at the Test Site. The Test Site, larger than the state of Rhode Island, hosted a total of 928 above- and below-ground nuclear weapons experiments from 1951 until 1992.

Early sampling efforts already have identified contamination near nuclear tests within the boundaries of the Test Site, located 65 miles northwest of Las Vegas.

"The expectation predicted by the (computer) model is the first well drilled, which is on the NTS, will show detectable levels of tritium, and the appropriate safeguards are planned," said Bill Wilborn, the Nevada site office sub-project director responsible for drilling the wells and monitoring the groundwater.

Tritium is a radioactive isotope used to fuel nuclear weapons' explosions and is carried in water.

The Energy Department produced a report in October 1997 predicting contaminants will migrate from the Test Site from the Western Pahute Mesa region within 50 years of the first nuclear detonation there in 1966. A February 2009 report, based on computer modeling, further supported the predicted movement of contaminated groundwater beyond the Test Site's boundaries.

Each well will be drilled from 2,500 feet to 3,700 feet deep to reach the water table in the complex rock and soils at the Test Site, Wilborn said. The depth and complex geology contribute to the costs of the project.

The new wells will provide information critical for long-term monitoring of the groundwater to protect public health. Residents in communities around the Test Site, northwest of Las Vegas, are involved in monitoring efforts that sample their water supplies annually to test for man-made radioactivity. The first new well at Pahute Mesa was selected as a result of public information through the Community Advisory Board for Nevada Test Site programs.