Underground space, whether a byproduct of mining or the result of dedicated excavation, serves many functions. A partial list of uses includes mining museums, archives, geothermal energy sources, truck terminals and warehouses, mushroom and poultry farms, bomb shelters, and waste repositories.

Permanent waste isolation underground continues to gain acceptance. It started with deep geologic disposal of chemically toxic waste in Germany three decades ago and reached a peak -for the time being- with the first four years of shipping low-activity radioactive and mixed waste to the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico. Deep geologic isolation of high-activity, heat-generating radioactive waste should be next, first probably in Finland, and second possibly in the United States (Yucca Mountain).

Prudent underground mine planning takes into account the opportunity for putting the resulting void space to secondary use. That evaluation is consistent with the wise and multiple use of public and private property. Geologic considerations are fundamental to that process.