Italian contractor CMC di Ravenna has taken delivery of the first of two new Terratec TBMs that will excavate the Río Subterráneo a Lomas tunnel, in Buenos Aires, Argentina, following successful factory acceptance testing last week.
The 4.66m diameter Terratec EPBM will be deployed on a 13.5km-long tunnel that will carry drinking water from the newly expanded General Belgrano Water Treatment Plant, in the city of Bernal (Quilmes district), to the city of Lomas de Zamora.
The tunnel is a key component of the multi-billion-dollar Agua Sur system that is currently being built by Argentina’s national water and sanitation company AySA. Financed by the Government and the Development Bank of Latin America (CAF), it is the country’s largest water infrastructure project in 40 years and will provide access tofresh water for 4 million inhabitants in the southern metropolitan area of Buenos Aires.
The EPBM has been designed to tackle the variable soft ground geology along the project alignment, which ranges from silts to sandy silts with some cobbles expected. The TBM’s high-torque soft ground cutterhead features a spoke style design with a 49% opening ratio and cutting tools consisting of fixed and back-loading knife bits to ensure rapid advancement and minimum interventions.
The tunnel will be excavated at an average depth of 25m, beginning with an approximately 400m radius curve and continuing along an essentially straight alignment, reaching a maximum slope of +/- 2.0%. As the machine progresses, it will install a precast concrete segmental lining ring consisting of six (four parallelograms and two keys) 250mm thick, 1400mm wide, segments.
Last year, Terratec opened a new large-diameter TBM facility that has delivered more than 12 new machines in the second half of 2017 and beginning of 2018.