The project for the Genoa junction road and highway, the so-called “Gronda”, involved the construction of a new highway interconnection between the A10 Genoa - Ventimiglia, the A26 Genoa - Gravellona Toce, the A7 Milan - Genoa and the A12 Genoa - Livorno . The road connection includes highway sections that are developed outdoors, on viaducts and in tunnels. Ingegneri Riuniti collaborated in the executive planning for the regulation of the waters during the construction and final settlement of the tunnel entrances. The entrances, which are all located in the Municipality of Genoa, include among others: East Amandola, West Amandola, Borgonuovo (Savona side), East Borgonuovo, Bric del Carmo, Bric du Vento – Baccan – Polcevera, Ciocia, Delle Grazie, Forte Diamante, West Granarola Genova, Montesperone, Morego, Moro, Torbella, East Voltri, West Voltri.
The hydrological-hydraulic study is aimed at dimensioning the elements for the interception, treatment and discharge of rainwater from run-off of the excavation areas during the gradual lowering of the soil level and the regulation of the slope water in respect of the hydraulic continuity. The hydraulic regime established in each watercourse interfering with the project works was simulated by implementing a hydraulic model created by using the HEC-RAS software, defining the detailed hydraulic conditions of the final arrangements and the provisional structure. As far as the dimensioning, different return periods were used depending on the element. Moreover, the drainage system allowed the water falling in the site areas to be conveyed into a storage tank, which can contain a certain amount of rain and then send it to the treatment plant. For each entrance, a specific drainage network has been defined for each construction phase of the project; each network can collect and convey the rainwater for treatment.