Mexico City is prepared to build the largest wastewater system worldwide

The "East Tunnel" wastewater duct in Mexico City is the largest inner urban wastewater system being built in the world, with an investment volume of more than 650 million Euro. With this project, the Mexican government plans to solve the massive wastewater problems being faced by the Mexico City conurbation with its more than 20 million inhabitants.

Herrenknecht AG is providing three tunnel boring machines (Earth Pressure Balance Shields) for this project with diameters of 8.70m and 8.89m. They will be used in the construction of the new Eastern Wastewater Tunnel in Mexico City with a total length of more than 60 kilometers and a depth of up to 200 meters. The first tunnel boring machine, the Herrenknecht EPB Shield S-497 (Ø 8.70 m), has just been accepted by ICA Ingenieros Civiles Asociados at the Schwanau plant.

On the occasion of his visit to the Herrenknecht plant in Schwanau, the CEO of the Mexican water authority CONAGUA, Mr José Luis Luege Tamargo, witnessed the completion of the first tunnel boring machine. "The Eastern Wastewater Tunnel is one of the most important water projects in the world, if we consider the investment volume, the length of the tunnel and the technology used", said José Luis Luege Tamargo. "The project will significantly reduce the risk of flooding in Mexico City and it will improve the safety and the well-being of the inhabitants and protect their properties."

The Chairman of Herrenknecht AG's Board of Management, Dr. Martin Herrenknecht, expressed his gratitude for the trust that has been placed in Herrenknecht and its tunnelling technology. "We are very proud that our tunnelling technology is part of this gigantic and internationally trail-blazing wastewater project. As part of this project, we can show how high-tech tunnelling technology made in Germany is making it possible to build very efficient inner city tunnel constructions safely and precisely and without major inconveniences for those living in the city."

Background: The "Emisor Oriente" project

Water problems in Mexico City
The drainage system of Mexico City and its conurbation is not sufficient for the more than 20 million people living there.

• Due to an excessive use of its groundwater reservoirs, Mexico City sees itself confronted with increasing problems in securing its water supply.
• As a consequence, the soil has subsided by about 10 meters. That means that today more and more pumps have to be used to drain the wastewater from the city.
• Between 1975 and 2008, the wastewater capacity of Mexico City’s drainage system has decreased by approx. 30 percent, from 280 cubic meters per second (m³/s) to 195 m³/s. At peak times, up to 315 m³/s actually have to be drained.
• The Valley of Mexico is been threatened by strong flooding because of deficient wastewater ducts, the lack of alternative ducts and very heavy rainfall.

Program for regenerating the water reservoirs in the basin of the Valley of Mexico
To solve the wastewater problems, the government of Felipe Calderón has launched a program which aims to regenerate the water reservoirs in the basin of the Valley of Mexico:

• Less excessive use of groundwater reserves
• Treatment of all wastewater
• Exploitation of new supply sources
• Construction of the Eastern Wastewater Tunnel to avoid flooding

Eastern Wastewater Tunnel

• The Eastern Wastewater Tunnel is to serve as an alternative drainage system in addition to the central tunnel.
• It has 24 inflow ducts at a depth of between 150m and 200m.
• The Eastern Wastewater Tunnel consists of 6 stretches with a total length of 63km and a planned inner diameter of 7m.
• The drainage capacity is 150 m³/s on average.
• The investment volume amounts to over 650 million Euro.
• Completion is planned for September 2012.

3 Herrenknecht EPB Shields fort he project Emisor Oriente, Mexico City
S-497 and S-498:

• Diameter: 8,700mm each
  
• Installed power: 1,600kW each
  
• Total thrust: 73,187kN each
  
• Cutterhead torque: 9,772kNm each
  
• Total weight: 905t each
  
• Total lenth: 97m each
  
• Tunnel length: 10,023m, 8,786m
  

S-519:

• Diameter: 8,890mm
• Installed power: 2,080kW
• Total thrust: 62,437kN
• Cutterhead torque: 14,043kNm
• Total weight: 867t
• Total length: 84m
• Tunnel length: 11,743m

Contact:
Herrenknecht AG
Schlehenweg 2
77963 Schwanau
PH.: +49 (0)7824 302-540
FAX: +49 (0)7824 302-473
E-Mail: pr@herrenknecht.com
Internet: www.herrenknecht.com