Excavation progressing on Buenos Aires water supply tunnel

Hailed as the largest water infrastructure project to be undertaken in Argentina for the past 40 years, the 13.5km-long tunnel will convey drinking water from the General Belgrano Water treatment plant in Bernal to the city of Lomas de Zamora. Italy-based CMC di Ravenna is building the tunnel which, as the principal component of the Agua Sur system, aims to bring fresh water to 2.5 million inhabitants living in the southern metropolitan area of Buenos Aires.

The tunnel will be mined at an average depth of 25m, using precast segments of 4.4m outer diameter and 3.9m inner diameter. The essentially straight alignment has a maximum slope of 0.25%. Expected to encounter a varied geology, the TBM’s high-torque, soft-ground cutterheads feature a spoke-style design with a 49% opening ratio, and cutting tools comprising fixed and backloading knife bits designed to ensure rapid advancement and minimal interventions. The cutterhead has eight hydraulic motors with a total power of 792kW. Two boring machines are required for the project, launched and received from shafts. The first launch shaft comprises four interconnected circular sections forming a pit that is around 45m long, 12m wide and 25m deep.

As a major framework element, the entire Agua Sur project is expected to take around 10 years to complete.