Subsidence and collapse at several salt domes in Texas have been investigate to determine the causes and potential impact such processes may have on the suitability of a dome for use as a site for toxic waste disposal. Boling salt dome, located in Wharton and Fort Bend Counties, was of particular interest during these investigations because of several factors: extensive recovery of multiple resources including sulfur, oil, gas, salt, and ground water, extensive areas of subsidence and collapse resulting from the removal of these resources, and its consideration as a candidate for a toxic waste disposal facility.

Boling Dome has undergone more subsidence and collapse than any other salt dome in Texas. The greatest vertical movement is 35 feet (based on the Boling 7.5-minute topographic map, last surveyed in 1953). Most of the subsidence (83%) can be attributed to sulfur production, and a minor amount (11-12%) can be attributed to oil and gas production. The remaining volume (5-12%) may be attributed to groundwater production, original porosity, subsidence yet to reach the surface, or error in measurement. Both reservoir compaction, resulting from hydrocarbon production, and trough subsidence, collapse, and piping resulting from sulfur production are present over the crest of Boling Dome. The structural and hydrologic stability of the surface and subsurface at Boling Dome is compromised by these active deformation processes. Research such as that conducted at Boling Dome emphasizes the importance of considering the potential for subsidence and collapse before selecting a site for toxic waste disposal. The potential for subsidence and collapse should be a primary consideration in the selection of sites for the disposal of toxic waste in solution-mined caverns in salt domes.

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