Forty-one local citizens from Eureka, Beowawe, Crescent Valley, Diamond Valley, Pine Valley, and Carlin plus thirty White Pine County residents toured Yucca Mountain March 29 and got a firsthand look at the proposed nuclear waste repository site.

A wildlife biologist and a geologist from the Department of Energy's (DOE) Yucca Mountain Project Office staff, and two contractors to the State Nuclear Waste Office joined the tour buses for the trip to the site.

On the way to the Field Operations Center (FOC), the scientists discussed ongoing environmental studies. Air quality, meteorological, and radiological monitoring, a cultural resources program, and studies of ecosystems, water resources, and reclamation are in progress. Many small wildlife habitat study areas and meteorological testing stations can be seen along the road to the Yucca Mountain Crest.

At the crest, short presentations were made about the geology, biology, and background of the project. Russ Dyer, head scientist at the FOC, said that the repository would be required to safely isolate 77,000 metric tons of high-level radioactive waste for 10,000 years. After that time the hazard to health would remain about equal to that of a naturally occurring ore, such as is found at a mined uranium deposit.

He discussed volcanism and earthquake studies that are part of the project. The volcanoes are 20,000-50,000 years old and are not expected to be active any time in the next 10,000 years. Seismicity studies at Yucca Mountain are planned to determine whether fault movement or earthquakes could affect the suitability of the site. Scientists want to study the fault zones that crisscross the area to determine how much movement occurs during earthquakes and aftershocks. DOE scientists didn't know the Skull Mountain fault existed until two Southern California earthquakes triggered a 5.6 earthquake along the fault last June.

Trenches and test holes in Midway Valley near the proposed repository site have confirmed seismic activity within the past 100,000 years, but none in at least 12,000 years. State scientists, however, say the fault are active and could renew activity at any time. In addition, they point to documented evidence showing that minor volcanic activity occurred just south of Yucca Mountain within the past 5,000-7,000 years.

The tour continued to Midway Valley, where initial work has begun on an Exploratory Studies Facility (ESF). Earth-moving equipment was scraping out the side of a hill and scientists expect to begin tunneling into the mountain soon to evaluate whether the area's geologic barriers can sufficiently isolate the deadly waste.

State project office members say the DOE has greatly expanded plans for the ESF to get a head start on the actual repository, rather than developing another testing area as part of the agreed-to site characterization plan. They point to designs for underground tunnels that have grown from two miles to thirteen miles and two planned small diameter shafts that have been replaced by two twenty-six foot or larger diameter ramps, sized for later repository use. DOE scientists say the design changes were necessary to enhance studies of faulting in the area.

According to Dyer, one good aspect of Yucca Mountain as a repository is that the area is remote and dry. Drawbacks include the fact that the area is subject to faulting from earthquakes and that it has been difficult to characterize due to mixed geological strata.

After lunch at the FOC, the tour group visited the geology and hydrology labs. At the hydrology lab a scientist discussed studies of the movement of water through rock. Yucca Mountain is made up of layered volcanic ash, known as tuff, in various geologic states. The zone where the repository would be located is about 1200 feet below the crest, 800 feet above the current water table. A geological map on the lab's wall showed a number of faults zigzagging through and around the repository site.

In the Sample Management Facility, a clearinghouse for geologic materials, visitors saw rock saws and examples of various rock types in the area. A video on a specialized drilling rig called LM-300 was also shown.

Eureka County residents who participated in the tour included Norma Jean Allison, Carolyn Bailey, James and Vera Baumann, Carol and Frank Bluess, Beth and Lonny Brown, Barbara and Kenneth Dugan, George and June Espen, Stephen Farnum, Luther Fiorenzi, Charlie Harper, Bertrand and James Ithurralde, Floyd, Judith, and Kolbe Klindt, Henry Johnson, Sarah Layer, John Malloy, Cindy and Shiloah Manuel, Lloyd Martin, Tom Meal, Mary and Robert Michna, Evelyn Naillon, Jason Neugebauer, Eric Pastorino, Mary Pearson, Barbara Perez, Dick and Sedalia Rasplicka, Deborah and John Schweble, Laura Scott, Robert Smith, and Joy Snowden.