History

The dam in the SAC area and Sinnai’s water supply

The system of dams overlooking the SAC area’s landscape is of particular historical, architectural and community importance.

Known as the first gush of water in a public fountain in Piazza Yenne, Cagliari, this also marked the inauguration of the first dam in Sardinia, which was one of the most advanced in Italy at that time. Built in 1867 in the surroundings of Sinnai, the dam known as Corongiu was constructed as a barrage on the river called Rio Corongiu.

Considering this remarkable achievement, and the need for water supply to Sinnai, in 1891 the town council entrusted the engineer Gustavo Ravot with the task of designing a new dam in the area known as Bruncu sa Cresia. The overall cost of the new aqueduct was estimated to be 155,000 Lire. To be able to fund this project, the municipality sold 2,532.83 acres (1,025 hectares) of a glandiferous estate in an area locally known as S’Ollioni di Mont’Arbu to the Genoese Bartolomeo Sanguinetti, earning 86,000 Lire. The Provincial Council ensured a grant of 38,750 Lire, whereas the remaining funds were obtained as a loan from the Cassa Depositi e Prestiti (a prominent Italian development bank), to be returned in 30 years.

Once secured the fundings, the construction works were executed by Carlo Barbera’s company and, on July 15, 1894, the dam was inaugurated, supplying Sinnai with water for decades and offering a stunning water gush in Piazza Municipio, known as Piazza di Chiesa. The dam that had just come into service was the third barrage on a waterway built in Sardinia up to that time.

The project included the damming of the river called Santu ‘Atzolu, the filter system and internal reservoir facility, the pipeline connection to Sinnai, and a water reservoir for storing and distributing water in the town. The latter was located in the area known as Cuccuru Arritzoni; partially in ruins in the late 1990s, it was buried under the current skating rink to preserve it and avoid demolition.

In the mid-20th century, the municipality of Sinnai decided to build a new reservoir upstream, entrusting the task to engineer Giorgio Marini. This project involved the construction of a dam located at a higher location than the previous one, in an area called Cuili Is Coccus. In the 1960s, the Rome-based company DIPENTA S.p.A. was appointed to carry out the construction works. The first task was to work on a fault in the underlying rocks detected during the excavations, so as to ensure the dam’s stability. Construction was completed on May 15, 1969, resulting in the creation of a catchment area of approximately 10 km, at 277 m above sea level and with a maximum flow rate of 300 m3/s.

After the demolition of the first dam in Corongiu and the abandonment of the dam called Bunnari Bassa in Sassari, the dam of Santu ‘Atzolu dam is today the oldest operating dam in Sardinia.

The dam system on the river is managed by the company A.c.q.u.a. V.i.t.a.n.a. S.p.A. and continues to supply Sinnai.

The dam’s filter room

A special note should be addressed to the dam’s filter room, which was built concurrently with the original dam in 1894 and now represents a civil engineering site of historical importance. The building has a rectangular layout featuring a stone-walled perimeter, a double-barrel vault ceiling in Sardinian bricks, as well as relieving arches reinforced with steel tie rods. On the inside, the walls are plastered with lime.

Upon entering, visitors reach the main corridor; on both sides, two rooms of approximately the same size are paved with flat bricks in a herringbone pattern. These spaces were once used by the caretaker: on the left side of the corridor was the bedroom, whereas on the right was the kitchen/living room, still presenting a corner fireplace.

Following a short hallway paved with straight and laid-flat bricks, is the filter room. The first element that can be seen is the division into three basins: the central and narrower one, facing the hallway; the two on the sides, equal in size and larger than the first.

From the central basin, the water passed into the lateral ones by overflow through two openings in the partition walls.