Could the tunnel impact the springs of the Parc de la Mairie?

Hydrogeological studies (i.e. groundwater in relation to soil types) were carried out in order to adapt the design and methodologies of the works to the characteristics of the soils, aquifers and springs.

The analysis of the water tables revealed that the tunnel will pass through an impermeable clay layer, located well below the level of the groundwater pockets, which will therefore be very little impacted by this underground structure.

It should be noted that once completed, the tunnel will be completely impermeable thanks to the concrete rings that compose it. There will therefore be no communication with the environment once the work is completed.

During the work, the park's water will be continuously monitored. Devices such as filter points, collection networks and piezometers will be installed to ensure hydraulic transparency and control of groundwater levels. The flow of the springs will also be continuously controlled.

All of these elements will be monitored and controlled by the Water Police.