SPOTLIGHT: Mexico's super sewer

Once Mexico's Túnel Emisor Oriente is completed it will rank among the biggest wastewater pipelines in the world.

But the project is taking longer than originally forecast and the price tag has grown, according to information from Mexico's finance ministry.

Investment is due to end in 2018 which means it could be ready for commissioning around that time.

The project, known as Teo, a stormwater drainage and sewage tunnel that will serve Mexico valley, got underway with investment set at 9.6bn pesos (US$630mn).

But over the years the price tag has increased to 39.0bn pesos.

Of this amount, authorities are planning to invest about 4.5bn pesos this year, 3.9bn pesos next year, 4.2bn pesos in 2017 and the last 1.6bn pesos in 2018, the finance ministry said.

Construction got underway in August 2008, and the tunnel was scheduled for completion in 2012. But construction work was halted in 2010 because of flooding. At that time authorities said that Teo would be completed in 2014.

Teo is a 62km underground tunnel that will pass through three Mexican states.

Teo will comprise six sections but only the first section has been completed, according to information from water authority Conagua.

Contractors are carrying out civil works and preparing for the installation of the second and fifth sections, according to Conagua.

Luis Torregrosa of the Mexican college of civil engineers (Cicm) told BNamericas that the tunnel was vital to Mexico City.

"Without Teo we could face a catastrophic scenario during a big storm, because without it Zócalo, the heart of Mexico City, could be flooded with 2-3m of wastewater," he said.

He added that it will complement the existing Emisor central tunnel, currently the main drainage pipeline.

Water carried away by the tunnels will be treated at the Atotonilco wastewater treatment plant, which is expected to be commissioned in December.

Teo is being built by a consortium that includes construction companies Carso Infraestructura y Construcciones, ICA and its subsidiary Cotrisa, Constructora Estrella and Lombardo Construcciones.

The project also includes the purchase or lease of land for tunnel connection points as well as advisory services and technical consultation.

TECHNICAL DATA

The project is designed to channel raw sewage and wastewater away from Mexico valley.

It will have a drainage capacity of 150m3/s and will benefit some 20mn people.

It is expected to generate around 7,000 direct jobs and 5,000 indirect jobs and is part of the 2014-18 national infrastructure program of President Enrique Peña Nieto.