Abstract: Hydrologic Stability of North Louisiana Salt Domes--Potential Sites for Radioactive Waste Disposal

C. G. Smith, J. D. Martinez, R. L. Thoms

Storage and/or disposal of radioactive wastes is a critical problem in the continuing development of nuclear energy. The long half-life of plutonium requires that some wastes be contained for 250,000 years or more. The development of storage cavities in salt domes offers a potential solution to the problem. Before a particular dome is selected for implementation of waste storage, however, a satisfactory degree of hydrologic stability must be demonstrated.

The relative hydrologic stability of 11 domes was determined on the basis of (1) the position of the Midway shale (a thick, regional aquiclude) relative to the salt dome and the surrounding freshwater aquifers and (2) the pattern of salinity distribution, as determined from electric logs, in adjacent Tertiary aquifers. Three examples typify the various degrees of hydrologic stability.

Rayburn's dome apparently is hydrologically stable. The Midway shale appears to encase the dome and prevent dissolution of the salt by shallow, fresh groundwater. Winnfield dome is hydrologically unstable. More than 500 ft (150 m) of Wilcox sand is in contact with the upper part of the dome. Ground-water salinities in these sands are highest at the dome and diminish with increasing distance from the dome. The relative hydrologic stability of Vacherie dome can not be determined from existing data. A limited body of highly saline ground water near the dome may result from (1) salt dome dissolution or (2) vertical discharge of brine from uplifted and faulted saline aquifers.

Preliminary estimates of rates of salt dissolution suggest that storage cavity sites which will remain hydrologically stable for more than 250,000 years can be selected.

AAPG Search and Discovery Article #90972©1976 AAPG-SEPM Annual Convention and Exhibition, New Orleans, LA