The discharge channels of the steel plant of ArcelorMittal in Taranto function as a sedimentation basin where the suspended solids are removed from the water (= process + cooling + rainwater) coming from the steel plant before it flows back into the Ionian Sea. The channels need to be dredged periodically (every 5 to 6 years) in order to comply with Italian environmental discharge legislation. They were last dredged in 2005 so were fully loaded with sediments, which needed to be removed in the most environmentally friendly way.
DEME proposed a hydraulic dredging technique in a direct combination with a soil wash, dewatering installation to remove the sediments. We dredged the sediments hydraulically by a dredge pump with a cutter or auger head mounted on an excavator standing on a pontoon in Channel 1. A smaller dredge unit was deployed in Channel 2. We treated the sludge coming from the dredge unit directly in a soil wash plant where the sediments are separated from the water. The water was pumped back into the channel after we had treated it by using a water treatment plant. The project ran smoothly and we achieved high production rates of 500-600 m³ a day. The sediments that were separated in two fraction fines and sand were disposed of in an approved landfill.
In total around 60,000 m³ of in situ silt had to be dredged from the three channels.