Progressive damage was observed at the head of the ‘Epi Arrêt de Sable’, the sand retaining groyne south of the Cotonou Port. Initially, the protective ACCROPODETMII concrete armour units at the head of the groynes were disappearing, later followed by the rock under-layers and the tip of the concrete causeway. CDR has provided recommendations on temporary repair works and ‘damage control’ and has performed an independent investigation on the cause(s) of this armour failure.
The analysis included interpretation and data-handling of regular drone inspections, including an assessment of the progressive damage before start of the repair works, extensive review of the design and construction documentation, wave analysis to assess i) the impact of the changed situation (bathymetry) and ii) to determine the conditions which have caused the damage and an assessment on the concrete material. Conclusions and recommendations were provided to the Client, based on which the next steps have been defined.

CDR has carried out the following assignments:

  • Undertook a site visit with droning and inspection of the Breakwater and Armour units;
  • Studied all available construction and maintenance & repair reports (2010 onwards);
  • Performed wave modelling assessments and analysis;
  • Analysed quality of construction material;
  • Submitted a comprehensive report including conclusions and recommendations;