Contaminated ground water is discovered near Test Site


The following article was published in the "Las Vegas Sun", March 23, 2000. It was sent to us by Connie.


The Department of Energy has discovered radiation in ground water about a mile outside the Nevada Test Site, officials said.

The type of radiation -- tritium, which could occur naturally -- is most commonly found in nuclear bombs and power plants. It is generally considered an early indicator of more serious radioactive contamination.

However, small amounts also are found in nature from cosmic rays reacting with nitrogen and oxygen in the earth.

The tritium was found in an exploratory well in July one mile from the Pahute Mesa in the northwest corner of the Test Site. The DOE kept the find quiet, because it believes it is from a natural source. The find became public last week when a member of the agency's citizen advisory board on the Test Site read a report that detailed the find.

Scientists found 126.8 picocuries of tritium per quart of water in the well, Bob Bangerter, director of DOE's ground water monitoring, said. A picocurie is a common measurement of radiation in the environment.

Although the Environmental Protection Agency considers any radiation in drinking water as being unsafe, there are currently no standards for tritium.

Levels of tritium have been discovered in the area before -- both on and off the Test Site -- but at levels usually in the single and double digits, they have been assumed to be from nature. The highest levels of 120 and 190 picocuries -- found in test wells in Pahrump and Rachel -- also have been presumed to be from nature.

The DOE believes the tritium near Pahute Mesa, found at a depth of 5,000 feet, came from natural sources, said Carl Gertz, the DOE's assistant manager for environmental management. The radiation also could have come from surface contamination injected into the well during drilling, he said.

The difference in the current find is that the well northwest of the Test Site is downstream from the testing, but not downwind. If the contamination is found to be from bombs, it would have traveled through the water. Rachel, which is downwind of the Test Site, received radiation during above-ground testing in the 1950s and '60s.

If further tests show the tritium came from nuclear weapons experiments, it would be the first time that contamination has been discovered outside the Test Site, 65 miles northwest of Las Vegas.

Radiation 25 times federal safe drinking water levels were found in a test well in Nye County last month, but both state and federal tests determined that the radiation came from natural sources, not the Test Site.

The well near the Pahute Mesa where the latest discovery was made is not used for drinking and the contamination does not pose a threat to human health and safety, DOE officials said Tuesday.

However, independent researchers worry that radiation is spreading in plumes of contaminated ground water from 260 nuclear bomb craters on the Test Site that could move across the boundary.

A scientist from UNLV on Tuesday called for further analysis of the Test Site's ground water to find out how much radiation is there and whether it is moving off site.

The contamination was found in one of seven new wells the DOE drilled last year about a mile away from Pahute Mesa, where some of the largest of the 828 nuclear weapons exploded below ground from 1956 until 1992, officials said.

The off-site wells were installed after the DOE unexpectedly discovered in 1997 that bomb-related plutonium had traveled almost a mile from a Test Site crater.

Lawrence Livermore National Laboratory in Northern California is trying to determine how old the tritium found in well water is, Bangerter said. Results are expected to take more than a month. If the element is less than 40 years old, it is more likely from bombs, he said.

Scientists have known that ground water beneath the Test Site would become contaminated, Bangerter said. The DOE believed for decades that the radiation would stay put for thousands of years, but the plutonium discovery changed that assumption. They now estimate that Test Site contamination will take at least 100 years to reach a populated area.

Pahute Mesa's water appears to flow 12 miles southwest toward the Oasis Valley. The nearest populated town is Beatty, 25 miles southwest of the Test Site.

"Even if the result is from testing, it is at very low levels so it is not moving off the site very fast," Bangerter said.

But hydrologist Earle Dixon, a technical coordinator for the DOE's Citizen Advisory Board, is not convinced that the DOE monitoring effort is adequate.

"What are the odds of the NTS monitoring system being capable of detecting the off-site migration of radioactive water from Pahute Mesa?" asked Dixon, who teaches in the UNLV Environmental Studies program. "There are tens of square miles without a monitoring well to provide an early warning detection of off-site migration. Even though the DOE has not detected any radioactivity off-site, it does not mean with absolute surety that the radioactivity is not there."

The appearance of tritium in the new exploratory well could indicate that surface water has reached 5,000 feet deep in the last 40 years, Dixon said. More resolution of this complicated flow system and the potential for contamination migrating off the site are needed, he said.

The Test Site's complex ground water flows also were noted last year by a team of scientists, who found the DOE's computer model prediction of contamination for Frenchman Flat unacceptable.

By Mary Manning
From "Las Vegas Sun", March 23, 2000


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