Buenos Aires takes a major step toward environmental sustainability with the launch of the Riachuelo System, the largest wastewater treatment project ever built in Latin America. Developed in three main lots, two of which were constructed by the Webuild Group, the system is now operational with the commissioning of Lot 2 by Webuild’s subsidiary, Fisia Italimpianti.

This milestone marks the completion of one of the world’s largest water pretreatment plants, representing a strategic infrastructure project co-financed by the World Bank. The Riachuelo System will enhance sanitation services for over 4.3 million people in the Buenos Aires metropolitan area and support the environmental recovery of the Río de la Plata. Once fully operational, it will treat up to 2.3 million cubic metres of wastewater per day and expand sewer access to 1.5 million additional residents across 14 municipalities.

Lot 2, scheduled for delivery to client AYSA by the end of July, comprises 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.

Lot 2 is central to the three-phase Riachuelo System: Lot 1 collects the wastewater; Lot 2 handles pretreatment; and Lot 3, also completed by Webuild, discharges treated water into the Río de la Plata via a 12-kilometre subfluvial tunnel, built 40 metres beneath the riverbed. With an internal diameter of 4.3 metres, this tunnel carries the water to an advanced diffuser system consisting of 34 vertical steel pipes (“risers”) that ensure uniform and safe dispersion of treated water along the river bottom. This highly complex engineering feat earned the project the prestigious ITA International Tunneling Award in 2021.

With the Riachuelo System, Webuild reaffirms its commitment to sustainable development and water resource protection, helping to improve quality of life for millions. A global leader in the water sector, as recognized for over a decade by the ENR rankings, Webuild is currently engaged in major infrastructure projects worldwide. These include the Northeast Boundary Tunnel in Washington, D.C.; the Rogun Dam in Tajikistan — the world’s tallest; the Grand Ethiopian Renaissance Dam — Africa’s largest; and Snowy 2.0 — Australia’s most ambitious hydroelectric project.