TREND: Valle de México's surge in drainage works

The last six months have seen a flurry of drainage infrastructure tenders in Valle de México, near Mexico City. Flooding during the June to October rainy season has always been a problem in the region, and while the previous government launched construction of the Emisor Oriente stormwater drainage tunnel, billed as the world's largest drainage tunnel, Enrique Peña Nieto's administration has significantly stepped up efforts to improve drainage.

The largest project awarded so far - to a consortium consisting of Proacon México, Construcciones Aldesem and Regiomontana de Construcción y Servicios - is the US$138mn construction of the Emisor Poniente II storm water drainage tunnel. With capacity to handle 202m3/s, the 5.5km tunnel will run parallel to the existing drainage tunnel in the west of Valle de México, helping to reduce the risk of flooding in Atizapán de Zaragoza, Tlalnepantla and Naucalpan.

The year also kicked off with ICA's US$85.8mn winning bid for construction of the Canal General drainage tunnel. Construction of the 8km tunnel across the Chalco valley is expected to wrap up in March 2017.

A series of smaller tenders have also been published over the past few months, including dredging of the Churubusco water regulating reservoir and construction of flood protection infrastructure in the Nabor Carillo lake.

Most recently, the national water commission Conagua tendered construction of the 40m3/s Churubusco-Xochiaca drainage tunnel, with bids due on July 21.

So why the sudden uptick in drainage works?

Many of the projects are designed to improve drainage around the site of the proposed expansion of the Mexico City international airport, AICM.

The transport and communications ministry, SCT, announced plans in December to expand the existing airport on federal land adjacent to AICM.

Former Conagua director José Luis Luege has argued that construction on the site is prohibited by law and puts the city at risk of flooding.

Many of the capital's rivers and drainage tunnels converge on the area, and during the June-October rainy season, the land acts as a "buffer zone" during storms, as excess rainwater can be diverted to the land to ease the capital's drainage capacity.

However, Conagua director David Korenfeld has rejected any concerns about building in the area. "Engineering can solve everything, we see no problem with constructing an airport there," said Korenfeld.

The recent tenders are precisely designed to increase the drainage infrastructure in the area so that flooding of the land will not be required, according to the director.