INELFE — Biscay Gulf — Electrical Interconnection FR-SP — Onshore Geotechnical and Geophysical Site Investigations at ‘Les Casernes’ Landfall

Description

Onshore geotechnical and geophysical campains in the area of ‘Les Casernes’ (Biscay Gulf — France (40). Lot 1: The services consist of onshore surveys: Geophysical and Geotechnical to be performed at the locations of ‘Les Casernes’ on Seignosse municipality in France (40). The purposes of the geophysical and geotechnical investigations are the determination of the detailed ground conditions and stratigraphy with detailed characterization of the materials in the surface and sub-surface soil layers in which the landfall of submarine cable will be executed. The geophysical investigation shall include both surface and sub-surface survey (Electrical Resistivity Tomography or similar) The required penetration depth is 50 meters below ground. The Contractor must elaborate drawings merging their information with the topography available from a previous work performed. The geotechnical investigation shall consist in deep sampling boreholes onshore from 35 m depth to 50 m depth to characterize the materials with SPTs, pressure meter boreholes from 30 m to 50 m, CPTs, and similar. It is to be noted that some operations have to be performed from the beach. It includes the collections of quality samples of soil and rock and their testing in laboratory for the determination of physical and mechanical properties, to support the interpretation of the geophysical data. Thermal resistivity tests to be performed in-situ and on laboratory. The results will then be used in order to determine the most appropriate trenchless technique to be used (Horizontal Directional Drilling, Direct Pipe, Micro-Tunneling, etc.) for cable installation works. In addition to the geophysical and geotechnical data report, the Integration of geophysical and geotechnical data shall be developed in a dedicated report.