By Martin Forstenzer
New York Times
Saturday, April 8, 2000
When the federal government conducted 828 underground nuclear tests at the Nevada Test Site from 1956 to 1992, its scientists knew that groundwater beneath the site would become contaminated. They believed that the underground water barely moved, and that radioactive particles would be sealed into cavities by the blasts or else absorbed by underground rock.
But studies in recent years have found that radioactive particles -- such as long-lived plutonium 239 -- can travel with water, and that water is flowing more rapidly beneath the site than was once believed. Scientists now agree that contaminated groundwater has the potential to flow out of the 1,573 square-mile test site in south-central Nevada toward populated areas.
The trouble is that no one knows how big the plumes of underground water are, where they have already traveled or what exactly they contain. Scientists from the United States Geological Survey and the University of Nevada say that a nuclear witch's brew could take as little as a decade to reach well water in Beatty, a town of 1,500 people in the Oasis Valley about 25 miles from the heavily contaminated northwest corner of the test site.
"Could it show up there in the next 10 years?" Randell Laczniak, a Geological Survey hydrologist and a co-author of a 1996 report on groundwater at the test site, said in an interview. "There's that possibility. Will it show up at a dangerous level? I don't know."
Bob Bangerter, manager of the Energy Department's program handling the groundwater issue, said that because some underground tests occurred near the test site's western boundary and the water was moving toward the southwest, "there is a high potential that it will move off of the test site toward the Oasis Valley." But he wouldn't estimate when this might happen.
Another Energy Department official in Nevada, Carl Gertz, assistant manager for environmental management, said there was no evidence that contamination had yet left the site and that it wouldn't be likely to reach a populated area even 100 years from now.
The Energy Department has already drilled dozens of monitoring wells both on and outside the test site and is installing eight wells northeast of Beatty. But agency critics say they are of limited value because they aren't designed to find and define the contaminant plumes.
"They should design monitoring systems to intercept the contaminants from some of the critical larger detonations so that they learn more about the plumes, where they are going and how fast they are going," said Dr. Dennis Weber, a physicist and groundwater researcher at the University of Nevada at Las Vegas.
Gertz of the Energy Department, though, said new wells weren't necessarily cost effective.
"Do you put a well every five miles?" Gertz asked. "Every six miles?" We have a site bigger than the state of Rhode Island. To go down to 6,000 feet, where we think you have to go in the northern part of our site, they're about $2 million a well. What is the appropriate cost to taxpayers?"
Some scientists emphasize that even if groundwater were to travel off the site, it doesn't mean that the radioactive contaminants would necessarily travel with it. It was once believed that plutonium 239 couldn't travel in groundwater, but in 1997, scientists from the Los Alamos National Laboratory concluded that plutonium 239 had traveled nearly a mile from the location of an underground blast by attaching itself to other particles suspended in water.
It is still not known whether the element, which has a half-life of 24,100 years, can move in groundwater over several miles in concentrations that would be harmful.
The one radioactive substance at the site that is known to travel freely with water is tritium, a hydrogen isotope that becomes part of water molecules. Tritium can remain dangerous to humans for hundreds of years when found in the kinds of large concentrations that the test site holds, Weber said.
Because Death Valley National Park is the end point of groundwater flow for the region, scientists said that water from the test site would probably reach there eventually and could threaten the park, although most believe that it would take longer than a hundred years.
For residents near the test site, the contaminated groundwater debate has compounded fears about the Yucca Mountain nuclear waste repository, which the federal government plans to build along the western border of the Nevada Test Site not far from Beatty and other populated areas. The site is to hold tons of high-level radioactive waste from around the country.
There is no feasible way to clean the groundwater of contaminants or divert it from flowing toward a particular place. But to prepare for the possibility that contaminants might someday reach a populated area, the Energy Department has studied a variety of costly, experimental plans, including trying to mine out contaminants at the test site, which would cost trillions of dollars and present serious health risks to workers, diverting the groundwater back onto the test site, and piping or trucking water to affected communities.
In Beatty, the issue has been a leading topic of discussion. "I'm concerned for a lot of reasons," said LaRene Younghans, who owns a ranch just north of Beatty. "We wanted to stay here until we died, and we'll probably have to move."