Hazardous waste containment

ABSTRACT Containment systems that have been developed to isolate wastes from the soil and water that surround them in the ground include compacted clay barriers, slurry trench cutoff walls, geomembrane walls, concrete diaphragm walls, sheetpile walls, grout curtains, hydraulic barriers, compacted clay liners, and geomembrane liners. The choice in any case is dictated by whether waste from an existing facility or spill or from a new disposal site is to be contained and by the geological setting. Properly compacted clays have properties that are well-suited for waste containment, as do flexible membrane liners. Compatibility between these materials and the waste must be considered in any case. Evidence is accumulating that the hydraulic conductivity of properly compacted clay is not significantly affected by exposure to most organic solvents and inorganic chemical wastes in dilute solution. Double liner designs that incorporate both compacted clay and flexible membrane liners as well as leachate collection systems have been proposed to satisfy the requirements of recent legislation in the USA. The higher temperatures and long times associated with nuclear waste isolation by deep burial pose special problems of barrier stability. It appears that smectite clay has adequate stability to be used for repository buffer and seal material.