The new procurement code regulations for dredging require the use of environmentally friendly equipment for the extraction of aggregates from ports, whether polluted or not.
Low-impact dredging procedures are based on selectivity requirements, precision in positioning and cutting, minimization of turbidity and material loss, optimization of dredged material concentration, and worker safety. Selectivity and precision are fundamental economic principles: it is crucial to be able to excavate different types of materials with varying degrees of pollution and contaminants separately. Limiting and controlling turbidity generally require modifications to the dredging head or suction pump to ensure all cut or suctioned material is removed.
Since a fraction of the material on the bottom tends to adhere to the removal mechanism and is released during handling, additional mitigation measures such as floating barriers or fixed barriers are employed. Additionally, it is necessary to minimize the dredged volume by limiting the amount of water contained in the dredged sludge, as this water often lacks the characteristics to be directly reintroduced into the environment and must be treated, resulting in higher costs.
When designing a new dredging system to meet these new conditions, we have extended the concept of ENVIRONMENTAL DREDGING. The dredging operation does not end with the extraction of the material but also includes transporting it to its final disposal. Therefore, not only must dispersion be prevented during the SEDIMENT EXTRACTION, but also throughout all stages of TRANSPORTATION until DISPOSAL.
Based on this “expanded” definition of ENVIRONMENTAL DREDGING, we have developed an ECOLOGICAL DREDGING SYSTEM as an alternative to traditional ecological buckets, which are less productive and more expensive: a completely closed system that eliminates material dispersion risks. With a three-way valve system with remotely controlled guillotines, the operator can discharge non-contaminated material at various distances as required by the dredging plan without ever coming into contact with contaminated material, which will be treated by the shore-based facility.
The pump dredger is superior to the bucket dredger for the following reasons:
– Ability to extract sediments exactly according to the dredging plan, thanks to the machine’s agility and the versatility of the disaggregator, which can dredge while advancing and moving laterally, and especially allows for centimeter-precise selective extraction;
– Selective and ecological extraction thanks to the bucket disaggregator system;
– Direct transport in a closed circuit to the Soil Washing plant, which decontaminates and removes pollutants from the selected material, concentrating them in the fine fraction and dehydrating it, returning water with parameters suitable for discharge into the sea, thus eliminating any risk to the surrounding environment and operators;
– Ability to perform ecological dredging for all sediments, including non-polluted ones, but especially for “potentially polluted” sediments, to prevent the dispersion of hydrocarbons that, due to their low concentration, were not included in the waste to be disposed of but still contribute to the dredging problem of any port;
– Absence of suspended material at every stage of dredging;
– High productivity of the dredger;
– Safety of personnel and environmental protection;
– Extraction speed.
The bucket disaggregator is an innovative disaggregating system equipped with hollow buckets that work vertically, allowing the dredger to operate even during linear advancement. This, along with the precision of the cut due to the disaggregator’s power and the bucket design, almost completely eliminates water turbidity during work phases. All suspended material is immediately captured by the depression created by the pump and, thanks to a special blade, is directed straight into the suction mouth.
To optimize the potential of the bucket disaggregator and perform the work with surgical precision, the ID 200 DDOT ECO is equipped with a front pull winch. The combined effect of these two elements allows for strip-by-strip subdivision of any area. The dredger can operate on parallel strips, advancing thanks to the front pull winch. At the end of the planned strip, the installed excavation control system, after automatically adjusting the excavation depth according to the dredging plan, will stop operations with centimeter precision. The dredger can then, thanks to the lateral pull, move perpendicularly to the dredging line to start removing a new strip of sediment parallel to the previous one. The precision of excavation achievable with these technologies is unmatched by any alternative method available on the market today.
Furthermore, the disaggregator will be equipped with a special cover designed to rotate in unison with the disaggregator wheel, adapting to the type of seabed and preventing the dispersion of any material that might be outside the buckets.
In the context of dredging and port seabed remediation works, the design of the Soil Washing system and its complementary plants is part of the broader concept of “environmental extraction,” which underpins the design of all elements of the entire processing process, from dredging to the final reuse of recovered materials. The design philosophy views environmental extraction as the sum of all operations necessary to achieve the project’s overall goals while respecting specific design criteria. The Soil Washing plant is a fundamental element of the environmental extraction process and is implemented as a process closely interconnected with all others.