ABSTRACT
Among the various techniques of confinement, the 'capillary barrier' seems to meet the basic criterion of durability. This principle is based on the difference in grain size between two materials. In an unsaturated medium, the interface between a fine material and the coarser material functions as a 'capillary barrier' and water cannot pass from the fine medium to the underlying coarse medium due to the difference in capillarity, which is stronger than gravity. The shape decided on for the capillary barrier was the dome. It is essential that the flow rate allows water to drain laterally through the fine sand. This flow rate increases with the length of the system. At the bottom of the containers, the earth domes are covered by a watertight membrane upon which is spread a film of very soluble salts, simulating the waste to be protected beneath the barrier and acting as a tracer for any infiltrations.
