Fast work on diversion channel for Otteri Nullah made possible with precast slabs

This year, residents of Anna Nagar are likely to be spared their usual annual problem — flooding of their locality during the monsoons.

With work on a long-pending project — the construction of a diversion channel to carry excess water from the Otteri Nullah to the Cooum river set to be completed soon — the area will remain high and dry come the rainy season, Water Resources Department (WRD) officials said.

The channel will carry 400 cubic feet per second of excess floodwater, all of which inundated areas in the locality until recently.

Work on the channel is proceeding at a rapid pace, thanks to the completion of work on precast concrete structures, WRD official said. These structures, which are being built at a site alongside Ambattur lake, will be used to create the concrete diversion channel.

Building them at a site away from the project allows work to proceed faster, and also does away with problems of traffic diversions near the project site, added the official. This way, as soon as the structures are ready, they are transported to the Nullah and placed there, he said.

Rows of concrete, box-like structures and large equipment dot the site near Ambattur lake, where apart from structures for the Otteri Nullah, structures for channels in two other locations — Velachery and Virugambakkam — are also being built.

Officials said that on an average, 10 concrete structures, each of which is 4 metres long and 1.3 metres wide, are constructed at the site for the projects, all of which come under the Jawaharlal Nehru National Urban Renewal Mission.

Operations at the site, which belongs to the WRD, began about four months ago.

WRD officials said the site had helped them speed up several projects to construct diversion channels on busy roads.

“Initially, the projects to construct channels in Anna Nagar and Velachery were delayed as we did not get permission from several government agencies, as they were to be built on busy roads. Now that we have these prefabricated structures, we can finish work on them soon,” an official said. The project to improve Otteri Nullah, which has been much-awaited by residents in the area, is set to be completed by June, well before the monsoons.

Nearly 1,160 concrete boxes are now ready. Of the channel’s total length of 1,450 metres, around 120 metres has already been built on Third Avenue, Anna Nagar.

“With the precast structures ready, we now expect to build around 20 metres daily. We have to proceed carefully as there are several utility lines running beneath the road. Thanks to the prefabricated structures, we have not had to obtain any permission for traffic diversions on the road,” the official said.

Residents of Anna Nagar Third Avenue however, said they wanted the work to be completed even sooner, as they were forced to negotiate an additional one-way, in an area that already had several due to Metro Rail construction work.

The diversion channel for the Otteri Nullah, is part of a larger project to improve the 11.68-km Nullah itself. About 70 per cent of this work, which includes deepening, desilting and building of a flood protection wall, has been completed so far. The waterway is being widened up to 40 metres wherever possible.

Nearly 520 encroached structures in areas including Kannigapuram and Otteri have been identified. These encroachments will be removed once alternative housing in Perumbakkam is provided, officials said.

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