Cell preparation

Four years are needed to prepare a cell: after the regulatory archeological excavations have been completed, the cell is dug down to the first layer of impermeable ground. A 2-meter layer of clay is spread over this, followed by a 4-meter layer of a bentonite-fine sand mixture.
To ensure the end result is absolutely watertight, a 2-millimeter-thick sheet of high density polyethylene is used to line the bottom of the cell. A network of drains is then installed, covered by 50 centimeters of draining materials in order to collect the leachate. The cell can then be operated.