Tyrrhenian Link – Selargius HVDC Converter Station

In 2022, Terna Rete Italia launched the Tyrrhenian Link tender for the construction of an electrical interconnection between Sicily, Sardinia and the Italian peninsula through a submarine cable and converter and switching stations.

The project includes a western branch between Termini Imerese, in Sicily, and Selargius, in Sardinia, and an eastern branch between Termini Imerese and Eboli, in Campania.

Impresa Manca was invited to join a temporary joint venture with Siemens Energy, FATA of the Danieli Group and Impresa Pizzulo for the construction of the four converter stations included in the Terna Rete Italia Tyrrhenian Link project. In 2023, the joint venture was awarded the entire project under an EPC contract, and the internal allocation of activities assigned the construction of the Selargius station to Impresa Manca.

Construction of the Selargius station, which will be built opposite the existing Terna electrical substation along the Selargius–Ussana municipal road, on a site covering more than 7 hectares, began in January 2025.

The characteristics of the site required the excavation of more than 200,000 m³ of soil, with the excavated material transported to destination sites identified by Impresa Manca. The station will be developed on two terraced levels, respectively at elevations of 54.00 and 57.00 metres above sea level.

Impresa Manca’s scope of work can be summarised as follows:

– Construction-site facilities

Construction and maintenance of the site facilities until commissioning of the station, including 150 m² of fully furnished and air-conditioned offices for the client, complete with a meeting room; 360 m² of fully furnished and air-conditioned offices for the joint-venture companies, also including a meeting room; a 50 m² room for personnel training before access to the construction site; changing rooms, sanitary facilities with showers and a personnel canteen.

The works also include a 70 kW electrical supply line connected to the nearest Enel pole-mounted substation, located approximately 900 metres away, water-storage tanks for the site water supply, a water-treatment system and a sewage-disposal system.

– Construction-site protection

The site is protected by a security service operating 24 hours a day, 7 days a week, and by a perimeter fence consisting of 100 cm-high New Jersey barriers topped by 110 cm-high corrugated metal sheeting.

– Civil works for the station

reinforced-concrete retaining walls up to 10 metres high, serving both retaining and perimeter-enclosure functions;
concrete piles with a diameter of 600 and variable lengths, and 300 mm micropiles with a 193.6 core and thicknesses of 12.5 and 8 mm, subject to testing in accordance with Terna standards;
reinforced-concrete works for the transformers and associated firewalls;
reinforced-concrete works for circuit breakers, disconnectors, current transformers, voltage transformers, shelters, surge arresters, busbar gantries, lighting towers and kiosks;
electrically operated access gates;
stormwater drainage and disposal systems;
wastewater and oily-water collection and treatment systems, including the related oil-separation systems;
oil-collection tank;
firefighting water tank;
supply and installation of the primary and secondary earthing grids;
reinforced-concrete foundations for the prefabricated buildings supplied by another joint-venture partner: Pole 1 and Pole 2 Converter Towers, Pole 1 and Pole 2 Valve Buildings, Pole 1 and Pole 2 Direct Current Buildings and the warehouse;
cable trenches and cable routes;
roads and operational yards.