After 17 days of meticulous tunnelling — passing just 66 cm beneath two major wastewater pipes — a 1,730 mm (external) / 1,400 mm (internal) diameter microtunnel in Port-Jérôme-sur-Seine (near Le Havre) is now complete. The 159‑metre-long microtunnel will double capacity in the area and significantly enhance the efficiency of Caux Seine Agglomération’s existing industrial water network.
OPTIMUM worked alongside SADE, who used an AVN 1200 equipped with an extension kit to drive the tunnel’s downward trajectory from an 11‑metre‑deep entry shaft through compact and weathered chalk.
Before construction works began, OPTIMUM engineers fine-tuned the microtunnel design and dimensions to align perfectly with SADEs equipment. A dedicated trenchless engineer then monitored the tunnelling parameters, geological conditions, and fluid management onsite — critical elements in achieving the accurate steering the project demanded.
Three weeks of tunnelling, zero downtime. Congratulations to everyone involved in delivering this precisely engineered and executed project.
