Geohydrology of rocks penetrated by test well UE-25p No. 1, Yucca Mountain Area, Nye County, Nevada
Test well UE-25p No. 1 was drilled to a total depth of 1805 meters. To a depth of 1244 meters, the rocks are predominantly ash-flow tuffs of Tertiary age. From 1244 to 1805 meters, the rock is dolomite of Paleozoic age. The composite static water level was approximately 381 meters below land surface for the Tertiary section and 361 meters for the Paleozoic section. The hydraulic-head difference indicates a major hydrologic barrier to vertical movement of fluid. The likely confining layer is a conglomerate (unnamed) near the bottom of the Tertiary section in the depth interval from 1138 to 1172 meters. Any vertical fluid movement between the Tertiary and Paleozoic sections would be small and would be from the Paleozoic rocks into the Tertiary rocks. In the Tertiary section, an interval of less than 30 meters in the upper part of the Prow Pass Member of the Crater Flat Tuff has an apparent transmissivity of 14 meters squared per day. The saturated part of the tuffaceous beds of Calico Hills has an apparent transmissivity of about 0.5 meter squared per day. The Bullfrog Member of the Crater Flat Tuff has an apparent transmissivity of 1.5 meters squared per day. The lower part of the Prow Pass Member and the Tram Member of the Crater Flat Tuff, and most of the Lithic Ridge Tuff have no significant fracture permeability. The lower part of the Lithic Ridge Tuff, the underlying older tuffs, and the upper 97 meters of the Paleozoic section have an apparent transmissivity of about 10 meters squared per day. In the Paleozoic section below 1297 meters, an interval of less than 22 meters in the upper part of the Lone Mountain Dolomite has an apparent transmissivity of 69 meters squared per day. Below this permeable zone, the next 190 meters have an apparent transmissivity of 33 meters squared per day. Between 1550 and 1805 meters, the apparent transmissivity is 6 meters squared per day.
- Research Organization:
- Geological Survey, Denver, CO (United States)
- DOE Contract Number:
- AI08-78ET44802
- OSTI ID:
- 59686
- Report Number(s):
- USGS/WRI--84-4248; ON: DE85006360
- Country of Publication:
- United States
- Language:
- English
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