Webuild and Fisia Italimpianti complete Lot 2 of Riachuelo System, delivering Latin America’s largest wastewater treatment plant

Webuild and Fisia Italimpianti complete Lot 2 of Riachuelo System, delivering Latin America’s largest wastewater treatment plant

(IN BRIEF) Webuild Group subsidiary Fisia Italimpianti and its partners have delivered Lot 2 of the Riachuelo System to AySA in Buenos Aires, completing the most advanced wastewater treatment plant in Latin America. Supported by the World Bank, the project improves sanitation for over four million people, expands sewage services to 1.5 million more, and treats 2.3 million cubic metres of wastewater daily. Lot 2 includes high-capacity pumping and pretreatment facilities, forming the core of a system that culminates in a 12-kilometre subfluvial tunnel dispersing water into the Río de la Plata. The project, recognised with the 2021 ITA International Tunneling Award, marks a major step forward in urban health and environmental protection.

(PRESS RELEASE) MILAN, 21-Aug-2025 — /EuropaWire/ — Webuild Group and its subsidiary Fisia Italimpianti, together with consortium partners, have officially delivered Lot 2 of the Riachuelo System to client Agua y Saneamientos Argentinos S.A. (AySA) in Buenos Aires, Argentina, completing what is now the largest and most advanced wastewater treatment plant in Latin America.

The achievement marks a significant milestone in a transformative infrastructure initiative aimed at cleaning up the basin of the Río de la Plata, a project supported by the World Bank to improve health and sanitation for more than four million people living in Argentina’s capital region. The system, which serves 14 municipalities, has the capacity to treat up to 2.3 million cubic metres of wastewater daily while extending sewage services to an additional 1.5 million residents.

The Riachuelo System is divided into three interconnected lots: Lot 1 collects wastewater; Lot 2, now delivered, performs pretreatment; and Lot 3, also completed by Webuild, discharges the treated water through a 12-kilometre subfluvial tunnel located 40 metres beneath the riverbed. This tunnel is fitted with an innovative diffuser system of 34 vertical steel risers, ensuring safe and uniform dispersion into the river. The tunnel’s engineering excellence earned the project the International Tunneling Award (ITA) in 2021.

At the heart of Lot 2 are highly complex facilities, including an inlet pumping station with a capacity of 36 cubic metres per second, a pretreatment facility for 27 cubic metres per second, and an outlet pumping station. Together, these components form the core of the entire system, enabling efficient wastewater processing on a scale never before seen in the region.

The completion of Lot 2 further demonstrates Webuild’s capacity to deliver large-scale, strategic projects with far-reaching social and environmental impact. By addressing critical infrastructure needs, the Riachuelo System provides long-term health, environmental, and quality-of-life improvements for millions of people in Buenos Aires.

Webuild is a global leader in the construction of large, complex infrastructure projects, with a focus on sustainable mobility, hydropower, water treatment, and green buildings. A recognized leader in the water sector and active in about 50 countries, the Group employs approximately 95,000 people of over 125 nationalities. It boasts nearly 120 years of experience with over 3,700 completed projects. Its track record includes 13,648 kilometres of railways, 891 kilometres of metro lines, 82,577 kilometres of roads and highways, 1,022 kilometres of bridges and viaducts, 3,462 kilometres of tunnels, and 318 dams and hydropower plants. Among its most iconic projects are the expansion of the Panama Canal, the Long Beach International Gateway bridge in California (USA), the Second Bosphorus Bridge (Turkey), the Sydney Metro Northwest skytrain viaduct and bridge (Australia), the Kingdom Centre skyscraper in Riyadh (Saudi Arabia), and metro lines in cities such as Copenhagen, Paris, Rome, Milan, Naples, Doha, Thessaloniki, and Riyadh.

Ongoing projects include the New Genoa Breakwater, the Brenner Base Tunnel, the Pedemontana Lombarda Highway, Metro di Roma’s Line C, the Genoa-Milan and Naples-Bari high-speed/high-capacity railways, the Palermo-Catania-Messina high-capacity railway, the the Snowy 2.0 hydropower scheme in Australian and the the Trojena dams in Saudi Arabia. As of December 31, 2024, the Group registered total revenues for €12 billion. As of June 30, 2025, its total order backlog stands at approximately €59 billion, with over 90% of its construction backlog related to projects linked to the United Nations Sustainable Development Goals (SDGs). Listed on the Borsa Italiana stock exchange in Milan (WBD; WBD.MI; WBD:IM), it is member of the MIB ESG index of Italian companies with best ESG practices. Headquartered in Italy, it is subject to the management and coordination of Salini Costruttori S.p.A.

More information at www.webuildgroup.com

Media Contacts:

Francesca Romana Chiarano
Senior Manager – Media Relations
Tel. +39 338 247 4827
email: f.chiarano@webuildgroup.com

Micaela Montecucco
Communication Manager at Fisia Italimpianti
Tel. +39 331 6833169
email: micaela_montecucco@fisiait.com

SOURCE: Webuild