Environmental assessment of an offshore infrastructure using a beltline of concrete caissons and impact of logistical decisions

Abstract

: Mainly due to the attraction of the coastal areas, projects encroaching on the sea are growing in France and worldwide. Besides risk management (storms and flooding), coastal erosion and biodiversity loss, the issue of matter and energy consumption appears of importance for such infrastructures, inducing environmental impacts at a global scale. This study aims at quantifying these environmental impacts, using Life Cycle Assessment (LCA), applied to an offshore infrastructure using a beltline of concrete caissons. This technology has been used in Monaco, for the Anse du Portier’s extension, because it ensured a good wave resistance, a cost reduction (works in open sea being limited) and a soil level being in accordance with architectural landscape constraints and sea view. A realistic case study has been used to scale the assessment, suggesting optimal solutions based on the current knowledge. The main construction steps inducing environmental impacts as well as the opportunities of technical improvements allowing their reduction have been identified and characterized. Furthermore, effects of logistical decisions (for transportation distances and sourcing) on the global performances have been quantified. Results highlight the importance of supply chain choices on global performances. Territorial constraints can reduce logistical options, due to local deposit size and availability, time constraints for the construction, storage and loading capabilities on site.