Tadoussac, Québec


As part of this project, BLM was responsible for the technical part of the mandate (carrying out the inspection work, producing the technical report and recommendations, etc.).




Prince Shoal Pillar – St. Lawrence River Estuary




PWGSC – Public Works and Government Services Canada


Nature of the mandate


The general inspection consisted of quantifying the evolution of the damage observed during previous inspections and making recommendations for maintenance and repair work. For purpose, residual thickness measurements were taken to compare the steel loss on the day of inspection with previous data. Next, the objective of the underwater inspection was to visually and tactically assess the submerged components. In addition, an inspection of the seabed around the periphery of the structure was to be carried out in order to detect signs that could suggest scouring problems.

Service rendered


  • Visual inspection of the structure with simultaneous video recording.
  • Comparative evaluation with previous reports of overall structural and component deficiencies.
  • Technical report including complete plans of the structures, underwater video and photos of each component and recommendations for repair and maintenance interventions.
  • Technical report and complete description of the observed structure

Challenges and solutions


One of the issues of this mandate is the management of the work according to highly variable weather
conditions and the presence of strong currents during tidal changes. The level of experience of the inspection team was crucial in carrying out the inspection work. The work had to be carried out efficiently and safely in order to optimize data collection during the available time windows. For this reason, SSBLM developed several work methods and access methods to optimize the inspection work.