The Serrù dam is a concrete gravity dam 41,5 m high on the Orco river, in the north western Piedmont, close to the Gran Paradiso natural park.
The dam was built in the ‘40s and completed in 1951. The reservoir is about 15 Mm3 and the normal elevation of the reservoir is 2,275.5 m a.s.l.
The owner was, at the time of performing the services described here, AEM (Azienda Energetica Metropolitana) Torino S.P.A. (currently it is consolidated in IREN with other energy companies), providing electricity from hydroelectric and thermal plants and other municipal services to Turin and neighboring areas in Piedmont.
The reservoir of Serrù receives the flow of the Agnel reservoir, located in the vicinities, and heads the hydroelectric system of the Orco Valley, including several dams and plants.
Along the main course of the Orco the Serrù dam provides a head of 700 m. The power station (Villa) is equipped with 40 MW machinery. Downstream, the Ceresole dam stores 34 Mm3 at 1,575 m a.s.l. producing a head of 813 m up to the Rosone power station (100 MW). Finally the Bardonetto – Pont run of river plant has 15 MW installed on a head of 111 m.
On the tributaries to the Orco several plants are built, as Valsoera Telessio, with Valsoera dam at 2,412 m a.s.l. and 7.7 Mm3 of reservoir (collecting water from the Piantonetto, Valsoera and Balma rivers) with a head of 555 m.
The power station of Telessio is reversible and the installed power is 38 MW.
The system Telessio – Eugio includes two dams, Piantelessio and Eugio, on the Piantonetto and Eugio rivers, having elevations of 1,917 and 1,900 m a.s.l. respectively and producing a head of 1,217 m. The machinery is installed in the Rosone power house (82 MW).
Finally, the run of river power house of S. Lorenzo, on the lower Piantonetto, produces a head of 254 m and allows a power of 4.3 MW.
The Serrù dam required several intervention of revamping: the upstream protection in “bolognini”, square cut stones, was unstable because of the erosion of the mortar due to the aggressive water, very pure and desalted, coming from the glacier melting. The inspection tunnels and the downstream facing were marked with heavy carbonate deposits. The drains of the dam body were obstructed in several points, and lost efficiency because of the carbonate deposits along the drain surface. The grouting screen was interested by water losses, and the instrumentation for displacement measurements needed to be integrated and in any case restored.
All the available data were gathered and analyzed to verify any trend in the dam displacements (temperatures, rotations, stresses, water losses). A tomography was performed to verify the change in density of the dam body.
According to the study several intervention of rehabilitation were designed and executed in the years 1999 – 2000
Waterways performed the survey, the feasibility of the work, the design and the supervision of the execution, with the contribution of Eng. Dolcetta Capuzzo, former Director of construction Division of ENEL. The supervision was executed in team with the technical staff of AEM Turin.
Employer: AEM Turin
Client: AEM Turin
Amount: 1.000.000 €