Coastal Protection Measures Phase II, Cotonou

Inros Lackner, has been commissioned by the Department of Quality of Life and Sustainable Development to evaluate coastal protection measures on a coastal stretch of approximately 10 km east of the port of Cotonou. During the first phase Inros Lackner verified the existing design and studies which were realised. Once the existing studies were verified and improved, they were executed and applied during the construction phase of works. 

In respect to the project budget following concepts & design had been applied:

• Construction of four groins, length between 170 m and 270 m, that have been installed between existing groin structures in particularly in endangered areas, 
• Revetment and toe protection measures on the groins,
• Hydraulic dredging works of approximately 900,000 m³ of sand between the groins were performed,  
• Armour stones which weight up to 10 tons have been extracted from stone quarries located around 130km away from the construction site and were then transported overland to the installation site. 
• The construction works of the groins have been performed by long-boom hydraulic dredgers on a 24/7 basis as construction had to be accomplished within a delay of 20 months.

The following supporting measures had been performed by Inros Lackner: 

• Bathymetric and topographic surveys of maritime zones and terrestrial zones, 
• Numerical simulations of different coastal protection measures for the assessment of long-term coastline evolution, 
• Hydraulic model tests for the determination of the stability of the selected stone dimensions, 
• Environmental and Social Impact Assessment and Supervision
• Project Management 
• Construction and Site supervision