This report presents data collected to determine the hydraulic characteristics of rocks penetrated in test well UE-25b#l. This well is one of a series of test wells drilled in and near the southwestern part of the Nevada Test Site in a program conducted in cooperation with the U.S. Department of Energy. These investigations are part of the Nevada Nuclear Waste Storage Investigations to identify suitable sites for storage of high-level radioactive wastes. Data on drilling operations, lithology, core analyses, borehole geophysics, hydrologic monitoring, hydraulic testing, and groundwater chemistry for test well UE-25b#l are contained in this report.

Test well UE-25b#l, located on the east side of Yucca Mountain in the southwestern part of the Nevada Test Site, was drilled to a total of 1,220 meters and hydraulically tested as part of a program to evaluate the suitability of Yucca Mountain as a nuclear-waste repository. The well penetrated almost 46 meters of alluvium and 1,174 meters of Tertiary volcanic tuffs. The composite hydraulic head for aquifers penetrated by the well was 728.9 meters above sea level (471.4 meters below land surface), with a slight decrease in hydraulic head with depth.