The geotechnical study of a project using trenchless method is essential for determining the choice of technology and project design. The success or failure of the project is intrinsically linked to the use of the appropriate technique for the site conditions. Geotechnical work validates the following elements:

• The nature of the existing soils and their compaction;
• The presence of debris, stones, or blocks in the soil, their proportions, frequencies, and dimensions;
• The consistency of soil characteristics along the insertion path;
• Laboratory and field tests to determine the geotechnical design parameters;
• The presence of groundwater in the soils.

The feasibility study and risk analysis indicated a favorability for insertion by guided horizontal drilling.

The design calculations were specifically executed for the guided horizontal drilling technique according to industry standards.

• Induced stresses on the steel pipe;
• Friction and necessary pushing forces;
• Thickness and strength of the pipe;
• Soil settlement;
• Stability at the face of the tunnel;
• Stability of the tunnel wall;
• Closure of the tunnel.