The research project entitled ‘LIFE MARINAPLAN PLUS: Reliable and innovative technology for the realisation of a sustainable marine and coastal seabed management plan’, began in October 2016 and was completed in December 2020. Funded by the European Commission within the framework of the LIFE programme and co-funded by the Executive Agency for Small and Medium-sized Enterprises (EASME), the project was coordinated by the Italian company Trevi. A world leader in subsoil engineering, Trevi coordinated the research team that included the participation of three partners: the Municipality of Cervia (Italy), that played the role of technology end-user; the University of Bologna, responsible for the impact monitoring of the installation; and the International Council of Marine Industry Associations (ICOMIA) that acted as main dissemination and communication contributor.
The project team received EUR 1.45 million to design, realise, operate and monitor the firstof- a-kind demonstration plant installation (from here on referred to as ‘the ejectors plant’) at industrial scale of an innovative solution for the sustainable management of sediment in marine infrastructures. The ejectors plant operated from June 2019 to September 2020 and was able to guarantee navigability of Marina di Cervia’s harbour entrance for the whole period. This article presents the preliminary assessment of the ejectors plant results after 15 months of continuous operation and monitoring.
The need to remove deposited material from water basins is a common feature shared by many ports, harbours and waterways, and has been since the earliest settlements along coasts and rivers. Normally, the most widely used solution to remove sediment deposits is dredging. Dredging is a well-known, reliable and diffused technology. Nevertheless, in specific conditions (i.e. smaller marinas and channels), dredging in shallow water requires scaled technologies that are less productive and more expensive than standard configuration.
While dredging is able to restore the desired water depth, it is not without impact on sedimentation causes and therefore cannot guarantee avoiding sedimentation over time. Furthermore, dredging operations can often interfere with navigation and other nautical activities, and imply potential environmental impacts for the marine ecosystem: modifying marine habitat related organisms and disturbing contaminants already present in the seabed. Therefore, maintenance dredging operations often become too expensive and/ or are not allowed by normative framework due to the related environmental impact.
Description of the ejectors plant
Cervia is a municipality of ~30,000 inhabitants, located along the Adriatic Sea in the Emilia-Romagna region. Marina di Cervia is located on the north-east side of the old harbour (Figure 1B), reserved for recreational craft, consisting of a dock with eight piers. The marina has a capacity of 300 boats with a maximum length of 22 m. The harbour is affected by a cyclic problem of inlet sedimentation. The technological solutions adopted until now, including seasonal dredging and/or sand underwater resuspension by boat propellers, as well as docks lengthening (completed in 2009), have not solved the sedimentation problem. In fact, from 2009–2015 ~EUR 1.3 million was spent on dredging and sediment handling with propellers (i.e. a mean yearly cost of EUR 185,000 (Pellegrini et at., 2020).