Drilling Latin America's largest sewer

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In this Aug. 19, 2014 photo, workers shovel ground rock, left by the giant boring machine, to a conveyer belt inside the Tunel Emisor Oriente in Zumpango, Mexico. Scheduled to be completed by 2018, a decade after it was begun, the 62 kilometer (38 mile) tunnel will be the largest sewer in Latin America. (AP Photo/Sean Havey)

ZUMPANGO, Mexico (AP) — Some 110 meters (120yards) beneath a Mexico City suburb, a boxcar-size machine digs Latin America's largest sewer.

The drill developed by U.S. based The Robbins Company uses pressure, water, chemicals and cutting bits to bore a hole the width of a three-lane highway through rock and other terrain. Behind it, the Eastern Discharge Tunnel seems to stretch into infinity.

The machine advances along a railroad track at a rate of 30 yards (meters) a day as workers inside reinforce the freshly made sewer with concrete supports.

The tunnel will stretch 38 miles (62 kilometers) when finished in 2018, a decade after it was begun, said Carla Toledo, a communication officer with the National Water Commission, which heads the project.

Mexico City was built on top of a drained lakebed and is constantly sinking, making the city prone to flooding and putting stress on successive drainage systems over the centuries. The new tunnel will carry wastewater from the Mexico City to a treatment facility in the neighboring state of Hidalgo.