A new main sewer was to be constructed for the eastern outer districts of Mexico City. The background to the project is an incident some years ago, when the Rio de la Compañia canal broke its banks, deluging the surrounding area to a depth of several meters with an obnoxious mixture of rainwater and raw sewage. To prevent more incidents like this occurring, the Mexican National Water Commission reached the decision to build a six-kilometer-long tunnel for the drains in the eastern suburbs.
In March 2007, the Herrenknecht EPB Shield S-364 started tunnelling in the muddy clays in this area. The route is around 27 meters under the surface, and is therefore well above the groundwater conduit, that supplies drinking water to a large proportion of the 22 million population of Mexico City. Breakthrough was achieved on July 16, 2009. After completion, the tunnel serves as the main sewer for around five million people in the suburbs.