Italian tunnel Contractor, CMC di Ravenna recently marked the commencement of the 13.5km long Río Subterráneo a Lomas tunnel, in Argentina, with a TBM cutterhead lowering ceremony that was attended by the country’s President Alberto Fernández. The event marked the assembly of the first of two 4.66m diameter Terratec EPBMs that will be used to excavate the tunnel in Buenos Aires.
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. The new system is the country’s largest water infrastructure project in 40 years and will provide access to fresh water for 2.5 million inhabitants in the southern metropolitan area of Buenos Aires.
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Along with its sister machine, the 4.66m diameter Terratec EPBM named ‘Eva’ will be deployed by CMC di Ravenna on the tunnel, which will eventually 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 EPBMs have 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 TBMs’ high-torque soft ground cutterheads feature with a spoke style design with a 49% opening ratio and cutting tools consisting of fixed and back-loading knife bits that will 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 machines progress, they will install a precast concrete lining ring consisting of six segments (four parallelograms and two keys) 250mm thick, 1400mm wide, segments.
The new Agua Sur System comprises a series of major infrastructure works that include a raw water intake, theexpansion of the General Belgrano Water Treatment Plant – which will increase its water production capacity from a current maximum of 1,950,000m3 per day to 2,950,000m3 per day – 23km of water conveyance tunnel (built-in two stages), two pump stations and 46km of pipe connections. The overall project is expected to take approximately 10 years to complete.