Construction of the basin.
Circular basin 50 metres in diameter and 20 metres high. It is designed to store the sanitation system water (combined system). It is entirely underground and a public park will be created on the covering slab.
The circular peripheral walls are made from diaphragm walls (SOLETANCHE BACHY designs). The interior civil engineering is a slabs + pillars + walls + beams structure.
The foundations consist of isolated footings and a carried floor with a minimum ventilation space of 0.30 m in height due to potentially swelling marls.