The intervention concerns the safety upgrading of the Rossella Dam and the integrated Scanzano–Rossella system, a strategic infrastructure for the drinking water supply of the Palermo metropolitan area. The project is aimed at safely increasing the reservoir level up to 525.00 m a.s.l. and at the seismic upgrading of the existing structures, in compliance with current regulations.

With reference to the dam, the global and local slope stability analyses identified critical conditions associated with slow deformation phenomena and lithostratigraphic variability, making it necessary to implement an integrated system for slope stabilization and pore water pressure control.

The project also involves the Ancillary Structures, which form the reservoir management system. In particular:

Morning glory spillway: reinforced-concrete structure with a crest diameter of 20.00 m, connected to a discharge tunnel approximately 160 m long, subject to hydraulic and structural assessments to ensure the safe discharge of flood flows and compliance with seismic actions;

Intake tower: cylindrical reinforced-concrete structure with an internal diameter of 6.10 m and a vertical height of approximately 60 m, equipped with intake openings at different elevations to regulate the quality and quantity of the water withdrawn;

Access footbridge: prestressed reinforced-concrete structure consisting of two simply supported spans of 52.35 m each, with a 3.50 m wide deck, assessed and upgraded from both seismic and functional standpoints;

Ancillary buildings (guard house and generator building): masonry and reinforced-concrete structures dating back to the 1960s, subject to seismic vulnerability assessment and structural improvement works.

The design activities included advanced numerical modelling, including seismic analyses and geotechnical and structural assessments, geometric surveys and investigative studies, as well as the reconstruction of the overall knowledge framework through previous studies, bathymetric surveys and geotechnical investigation campaigns.

Overall, the intervention integrates geotechnical stabilization works, seismic upgrading and functional rehabilitation, with the aim of increasing dam safety, improving hydraulic regulation capacity, and ensuring the continuity and reliability of the water supply service within a complex territorial context.