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“Gronda” highway bypass
The construction of the "Gronda" highway bypass involves the planting of about 8.4 million cubic meters of spoils, of which about 5.2 potentially containing asbestos.
The area identified for the disposal of the material produced by the excavation of tunnels, is the port area overlooking the Genoa airport “Cristoforo Colombo”, and in particular the Stilling Channel that separates and protects the airport from breakwater overflowing.
Project: “Gronda” highway bypass – Marine deposit of the Genoa Airport
Location: Genoa, Italy
Client: Autostrade per l'Italia S.p.A. and Spea Ingegneria Europea S.p.A.
Cost of total Works: 218,000,000.00 €
Services: Environmental Impact Assessment and Preliminary Design
Period: 07/2010 – 04/2011
The deposit consists of a 180 m wide and about 3,600 m long strip, located in front of the airport, at depths ranging from -14.50 m asl and -10.00 m asl, obtaining a narrowing of the stilling channel from 240 m to 60 m.
The study of the effects induced by the implementation and the presence of the marine deposit requires the ability to represent the behavior of the aquatic system in which the deposit is located. The level of details shall be useful to identify the main changes due to the construction and presence of the work.
To achieve this purpose, an integrated system of mathematical models able to represent not only the area of the project but also a wider part of the coastal strip, which affects the local hydrodynamic and dispersive conditions, is applied.
The hydrodynamic model is the main model which is connected to the dispersive model, the model of sediment transport (which simulates the erosion / sedimentation in the short / medium term), the morphological model (simulating morphological evolution in the long period) and the quality model, with which it is possible to study both the processes related to the oxygen kinetics (primary production, debris cycle, etc.) and the variation of toxic substances, considering them conservative and also applying a degradation kinetics.
The main activities carried out were:
- Data collection for the definition of the base condition of the main environmental factors (water quality, air quality, noise condition, soil quality, etc.);
- The analysis of the interactions between environment and works.
The information was used to describe the current status of the environment and to calibrate the models.
The analysis of the interactions between environment and works were performed on the two main conditions that may generate effects on the environment: construction and operation phases.
In addition, micro-simulation of the behavior of the contaminants was carried out, and in particular:
- The contaminants flow through the deposit barrier
- The contaminants flow in sediments under the deposit
The results of the simulations were used to evaluate phenomena such as: the variation of the spare time and the generation of turbidity plumes.
The analysis of the compatibility of the use of the stilling channel for industrial purposes and for local transport was carried out.
Special attention has been paid to the impacts associated with the transfer of asbestos materials, considering the potential release of asbestos fibers into the atmosphere and marine waters during both construction and operation phases.