Robbins TBMs Headed to Mexico City
Project Officials Celebrate Commissioning of First of Three EPB TBMs for Landmark Project

Mexico City’s Emisor Oriente pipeline will be the largest recent infrastructure project in Mexico, and will use three 8.93 m (29.3 ft) Robbins EPBs

Officials involved in the landmark Emisor Oriente drainage tunnel project in Mexico City traveled to Corpus Christi, Texas, Feb. 2-3 to celebrate the commissioning of the first of three Robbins EPB TBMs.
The TBM “Hidalgo” was fabricated at a Kiewit Offshore Services facility and is to be shipped to Veracruz and then trucked to Mexico City.

Two other TBMs are currently being assembled at the facility. All three machines are expected to be operating this summer.
The 29-ft diameter machines will be part of a $1 billion program that involves the construction of nearly 40 miles of tunnels under Mexico City. The project is designed to reduce the risk of potentially catastrophic flooding the in the Mexican capital.

“These machines are specially designed for the unique geology of Mexico. They have been engineered to handle a face of mostly clay with some basalt rock. Their flexible design is a great advantage to the project,” said José Luís Luege Tamargo, director of the National Water Commission (CONAGUA), the project owner.

Located in the Valley of Mexico City, the geology of the capital consists of a drained lake bed with clays, interspersed with volcanic rock and boulders from long dormant, buried volcanoes in the area. The TBMs will utilize clay spades and drag bits that can be changed out for 17-in. disc cutters depending on the geology. Two-stage screw conveyors will help to regulate high water pressures of up to 10 bar — some of the highest pressures EPBs have ever operated under. An initial 900 mm (35 in.) diameter ribbon-type screw conveyor will accommodate expected boulders up to 600 mm (24 in.) in diameter. Contractor CARSO Infraestructura y Construcción, S.A. de C.V. will utilize the TBMs on lots 3, 4 and 5, each between 9.5 and 9.7 km (5.9 to 6.0 miles) in length.

Lok Home, president of The Robbins Company, and dignitaries representing the Emisor Oriente tunnel project celebrated the commissioning of the first of three EPB TBMs Feb. 2 in Corpus Christi, Texas.

The Emisor Oriente line will utilize a total of six TBMs, and will add capacity of about 150 cubic meters of water per second (5,300 cubic ft/sec) once complete. The project will operate in parallel with the city’s aging main wastewater line, Emisor Central. Since the central line was built in 1964, Mexico has sunk at the rate of 4 inches per year, causing the drainage system pipe to lose its slope.

In addition, the Emisor Central’s concrete and rebar walls have been severely degraded by corrosive gases, leaving areas of the city at risk for flooding. “This project is very important for Mexico City,” said Jesús Medecigo Castañeda, superintendent of planning and control for CONAGUA. “We will avoid flooding in the downtown area, increase capacity, and all the water once untreated will now be treated at a nearby plant and reused for irrigation.”

Because of the reduced slope and capacity strained by a growing population – the city has grown from 10 million inhabitants in 1975 to about 20 million today and is one of the most populous cities in the world – the potential effects of flooding have been magnified, making the Emisor Oriente tunnel a government priority. The project is on a compressed 40-month schedule set for completion by September 2012.