Insoluble solid wastes can be buried at shallow depths in locations where they are safe from exhumation. If any parts are soluble, the solution must be managed as with any similar liquid waste. Programs for the management of waste liquids must be tailored to the chemical and physical characteristics of the liquids.
Geologic requisites for successful underground management of liquid wastes include: (1) porous and permeable reservoir rocks, in which the storage space may be caverns, intergranular pores, or fracture crevices; (2) impermeable seals to prevent escape of fluid wastes; (3) adequate understanding of hydrologie parameters and planning to prevent undesirable migration of fluids; (4) compatibility between waste materials and the reservoir rocks and their natural fluids.
Layered sedimentary rocks, rather than igneous or metamorphic rocks, provide the most suitable reservoir space, for both geologic and hydrologie reasons. If the wastes are hazardous to the biosphere, objective reservoir formations must be deep enough to provide permanent protection to groundwater aquifers.
The site must be reasonably stable seismically and not actively moving along, or broken by, faults.
Choice of a suitable underground disposal site can be made only after a thorough investigation of available subsurface data, supplemented by drilling and various other processes of subsurface exploration if sufficient data are not already available. Preliminary investigations and later subsurface operations will be expensive, but they cannot be avoided. Public insistence on an end to pollution must be accompanied by public understanding that a clean environment can be purchased only by higher taxes, if government managed, or by higher prices for consumer goods, if industry managed, plus individual awareness and practices.
As waste-management costs rise, it will become more economical to convert wastes into usable products, in effect eliminating, rather than managing, wastes.