Milan, 20 March 2025 – Work on Lot 2 of the Riachuelo System, a major infrastructure project aimed at reducing pollution in the Matanza-Riachuelo River in Buenos Aires, Argentina, is nearing completion. Lot 2 includes the construction of a major wastewater treatment plant, led by Fisia Italimpianti, a Webuild Group subsidiary specializing in water treatment and desalination, on behalf of AySA (Agua y Saneamientos Argentinos). In recent weeks, technical testing has been completed, and with the project now 95% finished, full completion is expected by the end of May.

The Riachuelo System is the largest project of its kind in Latin America and has received support from the World Bank due to its significant social and environmental impact. This ambitious initiative will benefit 14 municipalities in Buenos Aires, improve sanitary conditions for over 4.3 million people, and eventually expand sewer access to an additional 1.5 million residents.

The Riachuelo System consists of a wastewater treatment plant and an extensive network of tunnels. These tunnels run approximately 27 meters below the Río de la Plata, the main waterway into which the Riachuelo River flows. 

The project is divided into three sections. Webuild has already completed Lot 3 and, together with Fisia Italimpianti, is now finalizing Lot 2. Fisia Italimpianti leads the consortium with Acciona, holding a 65% stake.

Lot 2 involves the construction of a wastewater treatment plant that, once completed, will be among the largest of its kind in the world. It will be capable of treating up to 2.3 million cubic meters of wastewater per day. The project includes an inlet pumping station with a capacity of 36 cubic meters per second, a pre-treatment facility designed for 27 cubic meters per second, and an outlet pumping station.

Lot 3, completed by a consortium led by Webuild, involved building 12 km of the main tunnel, which serves as the discharge conduit for the wastewater treatment plant. Excavated 40 meters beneath the riverbed, the tunnel has an internal diameter of 4.3 meters and is designed to channel treated water from the plant, dispersing it at a rate of 27 cubic meters per second. A key feature of this project is its advanced diffuser system, comprising 34 vertical steel pipes known as “risers.” Each riser, just under one meter in diameter, extends vertically to the riverbed, ensuring efficient dispersion of treated water. This complex engineering solution played a crucial role in the project's success and earned it the prestigious ITA International Tunneling Award in 2021.

For over a decade, Webuild has been a global leader in the water sector and continues to drive sustainable development through a series of major projects worldwide. In the U.S., the company is finalizing the Northeast Boundary Tunnel (NEBT) to strengthen Washington, D.C.’s sewer system against extreme weather events. It has also completed Lake Mead’s Hydraulic Tunnel No. 3, an advanced water intake and transport system designed to supply Las Vegas and surrounding areas. In Tajikistan, it is building the Rogun Dam, the tallest in the world, which will double the country’s energy production capacity. Similarly, in Ethiopia, Webuild is leading the construction of the Grand Ethiopian Renaissance Dam (GERD), the largest in Africa, to boost hydroelectric power generation and drive regional development. Meanwhile, in Australia, the company is working on Snowy 2.0, the country’s most ambitious hydroelectric project.