There are Urgent Projects…and Then There’s Emisor Oriente
After visiting Mexico City’s Emisor Oriente Wastewater Tunnel, I realized something: there are urgent projects, and then there are URGENT PROJECTS. Túnel Emisor Oriente, often abbreviated to TEO by those involved, is the latter. We visited the site in 2011 to see the assembly of an EPB and learn about why the project is so important.
On a good day with light traffic, the jobsite is about an hour’s drive away from the Distrito Federal, the downtown zone of Mexico’s capital city. Our first day, I noticed how the high rise buildings and restaurants slowly dissolved into ramshackle huts as we drove further from the city to an area known as Ecatepec. Approaching the site, we crossed a bridge in our SUV that spanned an extremely slow moving grayish brown river (more about this soon).
It was a warm day in June, Mexico’s rainy season, which is quite different from the rain in my home town of Seattle in the U.S. Each day during the rainy season, the morning dawns sunny and warm–but by 4:00 in the afternoon a torrential downpour begins. The water floods city streets throughout Mexico City, whose storm drains can’t handle the sudden inundation. Sometimes the rain only lasts a few minutes, and sometimes it goes for longer. The water eventually runs into rivers like the one we crossed by the jobsite, creating flooding risks.
We exited our SUV at the Lot 1 shaft and were greeted by several Robbins Field Service guys, including our Field Service Manager for the Americas, Jeremy Pinkham. I was excited to learn more about the TEO project, where we have three EPB machines among six TBMs that are excavating an epic 62 km (39 mi) long wastewater tunnel. The tunnel will feed into the country’s largest water treatment plant, which is currently being built.
As Jeremy and the group walked towards the shaft to be lowered down the elevator, I was struck by a smell—something akin to a vast field of poorly maintained port-a-potties. I asked Jeremy about the Robbins machine, which was originally intended for Lot 5 but had been fast tracked to bore part of the tunnel section at Lot 1. I was wondering why this particular section had been deemed top priority. “Did you see that river just a few meters away from our jobsite?” he asked. “Most rivers, when you throw a stone in, it splashes or skips and then sinks. This one, you throw a stone in and it just goes ‘plop’, then sits there.” It was only then that I realized that this “river” was El Gran Canal, Mexico City’s infamous open sewer originally commissioned in 1910 by President Porfirio Díaz.
The Robbins guys as well as engineers from the Lot 1 contractor Ingenieros Civiles Asociados (ICA) then explained to me that the canal in this section, lined with shacks, was prone to flooding during each rainy season due to a loss of its slope. The effects on the people and infrastructure were severe, so the National Water Commission (CONAGUA) had fast-tracked Lot 1. A pumping station would be put in and the first section of tunnel sealed off so that wastewater from this area could be pumped into a section of the canal downstream that still maintained its negative slope. I was beginning to realize the importance and urgency of this project!
The guys gave us a tour of the TBM being assembled at the bottom of the shaft, which was specially designed for high pressure conditions under the water table.
On the ride home that day we were hit by a particularly nasty rainstorm that went on for several hours. I learned via the local news later on that the very roads we had driven on to get to the jobsite were now flooded with wastewater and impassable—apparently a regular yet extremely concerning event.
The next day we went to CONAGUA’s offices to speak with José Miguel Guevara, General Supply Coordinator for Potable Water and Sanitation. He spoke with us about the massive scope of Emisor Oriente—a project that could improve the lives of over 20 million people in the area by increasing wastewater capacity by 20% during each rainy season. The new pipeline will bolster current wastewater lines (both El Gran Canal and Emisor Central—a pipeline built in 1964) that have lost their slope due to Mexico City’s sinking lake clays.
While Guevara was optimistic, he admitted that health problems caused by El Gran Canal were numerous for the people living on its banks. When asked about future plans, he expressed grave concern that funds were not currently sufficient for a covered option to the open waterway. “At this moment,” said Guevara, “The Valley of Mexico is vulnerable. Our new treatment plant will treat 60% of the area’s water, but we need more alternatives as well. We are working on pieces to the problem, but the problem is not solved yet.”
With Emisor Oriente scheduled to be complete in 2014, I am hopeful that at least some of those problems will be alleviated. This is a great example of the magnitude that civil engineering works have on societies. I for one am proud that Robbins has a part in this monumental solution to an age old problem.