Launch of geotechnical and hydrogeological surveys on the route

As part of the resumption of studies on the project to extend Metro Line 1 to Val de Fontenay, RATP will launch several diagnoses on the nature of the soil and groundwater along the route from the end of August 2025.

These field surveys aim to complete the reconnaissance already carried out in previous studies, taking into account the lessons learned from the previous public inquiry and to better characterise the soils and groundwater. They will ultimately make it possible to:

• Refine the technical choices and the method of carrying out the work in complete safety;
• Refine the choices of location of each structure;
• Complete the environmental assessment of the project.

The results will be presented in the public inquiry file.

Surveys that are mainly carried out in public spaces may sometimes require access to private land. Each survey can last between 2 weeks and 1 month.

Different types of reconnaissance are planned:

• Hydrogeological to determine the presence and flow of aquifers over an annual cycle and to assess soil permeability;
• Geotechnics to qualify the composition and quality of the soil and determine the bearing capacity of the soil;
• Soil analysis to qualify the existing pollution of the land.