GROUND WATER IN THE OAK SPRING FORMATION AND HYDROLOGIC EFFECTS OF UNDERGROUND NUCLEAR EXPLOSIONS AT THE NEVADA TEST SITE
Tuff, welded tuff, and tuffaceous sandstone of the Oak Spring formation of Tertiary age overlie unconformably diverse types of Paleozoic rocks. Beneath the major basins of the Test Site the main zone of saturation is in alluvial fill or the Oak Spring, which is an aquifer of moderate to low permeability. Hydraulic gradients are low. Several zones of perched ground water were defined in tuff of the Oak Spring formation near the explosion sites. The Rainier test took place in a unit stratigraphically above a thin, probably discontinuous zone of perched water. The tunnel system for the Logan and Blanca experiments encountered ground water and acted as a drain until the Logan explosion, when flow ceased. Approximately 30 acre-ft of water drained from this tunnel system in about 7 weeks. The Logan site was at or near a perched or semiperched water table; the Blanca site was above the same water table. Water from the Oak Spring formation has a relatively high concentration of silica but otherwise is low in dissolved solids, and the level of radicactivity is low. Hydrologic ef fects of the explosions involve changes in rock characteristics that directly or indirectly control (1) volume of water in storage, (2) rate and direction of ground-water movement, and (3) chemical and radiochemical equilibrium between the rock and its contained water. The radius of effect is small compared to the probable areal extent of the perched water zone. Analyses of water samples from the zone affected by the Logan explosion and leaching experiments on other radioactive rock indicate that some fission products are taken into solution by percolating ground water. A probably slow rate of ground-water movement, low solubility of the explosion-produced glass, and lag effects due to ion adsorption tend to retard movement of contaminants from the sites. The remoteness of the area further reduces the risk of off-site contamination. (auth)
- Research Organization:
- Geological Survey, Washington, D.C.
- NSA Number:
- NSA-15-000384
- OSTI ID:
- 4128958
- Report Number(s):
- TEI-759
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ADSORPTION
CONFIGURATION
CONTAMINATION
DENSITY
DEPOSITS
DISTRIBUTION
ELECTRIC CONDUCTIVITY
ELECTRONS
FISSION PRODUCTS
GEOLOGY
GEOLOGY, MINERALOGY, AND METEOROLOGY
GLASS
GROUND WATER
HYDROLOGY
IONS
LIQUID FLOW
MEASURED VALUES
NEVADA TEST SITE
NUCLEAR EXPLOSIONS
POLARIZATION
POROSITY
PROJECT BLANCA
PROJECT LOGAN
QUANTITY RATIO
RADIOACTIVITY
ROCKS
SILICON OXIDES
SOLIDS
SOLUBILITY
SOLUTIONS
SPECTRA
STABILITY
THORIUM OXIDES
TRAINING
TRANSPORT
UNDERGROUND EXPLOSIONS