Management of maintenance dredging in the port of Piraeus
Topic of the practice
Dredging and dredging disposal activities could have various and serious negative effects in marine and land environment, so their proper management should follow all available good techniques and practices worldwide. The potential environmental effects of maintenance dredging are generally two-fold, firstly as a result of the dredging process itself and secondly as a result of the disposal of the dredged material.
Good Practice Information
An amount of 220,000 m3 of seabed material had to be dredged in the port of Piraeus, in order for the depths of the passenger and cruise ports to be increased.
The port carried out a thorough environmental impact study, assessing all possible environmental effects and technical solutions. According to the relevant environmental permits issued by the competent Hellenic Ministry, the dredging and the disposal activities should ensure no release of pollutants in the marine or land environment and promote the beneficial use of the dredged material.
The dredging was carried out by a mechanical dredger using in parallel an environmental friendly grabber and silt curtains devices to minimise resuspension of sediments.
The dredged material was encased in caissons used for the extension of the Pier No1 of the container terminal of the port, maximising the beneficial use.
The dredging activities were carried out considering timing to avoid the thermocline, the sensitive periods for the benthic communities and the tidal cycle in the area.
No need were for drainage of the dredged material, as the whole amount was enclosed in the caissons.
The whole work was financed by port's own funds.
As main evaluation criteria for the success of the methodolody applied, were a) the analysis of the polluting load of the dredged material and b) the application of a water quality monitoring system.
The methodology followed by the Piraeus Port Authority S.A. can be used by other ports as very good practice on the beneficial use of dredged material.
Evidence of success
The practice promoted the succesful beneficial use of the total amount of the material dredged, minimising in parallel the release of pollutants (e.g. heavy metals) in the marine environment.
The special designed environmental friendly grab and the use of silt curtains minimised the turbidity and release of pollutants during the dredging activity.
The solution applied has not taken longer to plan, obtain permits, realise the project, than excavation, processing and disposal.
The measurements taken on the water quality parameters (especially on heavy metals) at the work site have showed no difference with the rest marine area (no increase in concentrations before and after the work).
Contact details to obtain further information on the practice
Aristotle University of Thessaloniki
Annex completed on: 12-13-2011