Section D

Factors and Processes that Affect Waste Disposal and Subsurface Transport of Contaminants in Arid Environments

In 1976, the U.S. Geological Survey (USGS) began studies of unsaturated-zone hydrology in the Amargosa Desert, near Beatty, Nevada. At that time, the research was conducted under the auspices of the USGS Low-Level Radioactive Waste Program. In 1983, agreements with the Bureau of Land Management and the State of Nevada established two field study areas for sustained study of arid-site processes: a 16-hectare (ha) area adjacent to a waste-burial facility and a 0.1-ha area about 3 kilometers farther south. The study areas are collectively known as the Amargosa Desert Research Site (ADRS). Investigations at the ADRS have produced long-term benchmark data on hydraulic characteristics and soil-water movement for undisturbed conditions and for simulated waste-disposal conditions in arid environments. In 1995, after the unexpected discovery of high concentrations of tritium and carbon-14 in the unsaturated zone beneath the ADRS, the scope of research was broadened to include the study of processes affecting radionuclide transport. The ADRS was incorporated into the USGS Toxic Substances Hydrology Program in 1997.

The goal of present research at the ADRS is improved understanding of processes controlling the migration and fate of contaminants in arid environments. Research at the site is a multidisciplinary collaboration among scientists from universities, research institutes, national laboratories, and the USGS. The papers that follow illustrate the main avenues of active research. They explore the application of new and emerging methods for characterizing hydrogeologic frameworks in desert alluvial basins; quantifying the exchanges of materials and energy across the land surface; and understanding the distribution, movement, and fate of radionuclides in deep unsaturated zones.

Information on ongoing research activities at the Amargosa Desert Research Site is available on the World Wide Web at: http://nevada.usgs.gov/adrs/.

For additional information contact:

Brian J. Andraski,
USGS, Carson City, Nevada
(email: ), or

David A. Stonestrom,
USGS, Menlo Park, California
(email: )