The dredgings in harbour areas: case study of Naples (Italy)

The area object of the present work is positioned inside the Naples port, coastal city in the South of Italy. Three discharges of civil sewerage confer in the underlying zone of the quay. This situation involves an exaltation of the phenomenon of the solid deposition, with the consequent irregular outflow of the discharges of sewerage. The reliefs, effected during dredgings, show that the background native quota of the dock in absence of sediments was of over 10 meters. More recently a specific relief (mesh 10*10), performed by a hydrograph fathom and radio position system, has evidenced that the natural conditions is decidedly changed and that the course of the background quotas is notably varying. The removal of the sediments, considering the in relief quotas during the precedents dredgings, would need a big action. In 1998 the material accumulated in the Marinella dock was esteemed in around 300.000 m3. In base to the most diffused typologies of contaminated sediments treatment (devoted to the optimization of the processes of volume reduction), after an accurate characterization more representative typologies of samples, a plan of recovery of the sediments is effected for haranguing the dock of Vigliena. The choice of the treatments has kept in mind of the necessity of recovery and of the sandy fraction from re-use. In the proposed plan it has been considered all the aspects related to the operation in sea and to earth considering the peculiarities of the site and the technical limits to it connected.