Metro Water uses new method to avoid digging roads in Chennai

Chennai Metro Water has adopted an innovative technique for laying underground sewage and water pipes that may make digging of roads a thing of the past. 

Published: 12th November 2018 01:37 AM  |   Last Updated: 18th November 2018 08:30 AM   |  A+A-

The site from where a 40-ft sewage pipe was laid under KK Salai in Sholinganallur without any digging activity. | (Debadatta Mallick | EPS)

Express News Service

CHENNAI: Chennai Metro Water has adopted an innovative technique for laying underground sewage and water pipes that may make digging of roads a thing of the past. 

The Horizontal Directional Drilling (HDD) technique has been used for the first time by Metro Water to lay sewage pipelines at Sholinganallur under the Buckingham Canal.

To transport sewage from a pumping station on ECR to another pumping station on OMR, a 180-metre long pipeline was placed under the canal using this method. Though this technique is costlier, citizens will not have to bear the brunt of commuting on damaged roads.

“As the normal procedure of open-cut excavation is not possible here, we made use of HDD technique to place the pipe four metres below the canal. This is a smaller version of how excavations for Metro Rail are done,” said a Metro Water official.

In this method, a drilling machine digs through the soil underground with varying diameters of five, 18 and 26 inches to gradually widen the hole to fit the pipe.

A survey of the location is done beforehand to identify the existing electricity cables and other pipes so as to not disturb their alignment.

“We have used a high-density polyethylene pipe due to its flexibility. The line has been laid and the pressure test is under progress. In a month’s time, the pipe will be fully functional after we check for leaks,” the official said.

Pipe laying work for this stretch, which commenced in August, is part of the Sholinganallur-Karapakkam underground sewerage project which is finally nearing completion after much delay. The project which was started in 2013 with a budget of Rs 110 crores is yet to be completed. But, officials said that by March 2019 all residential houses in these two areas will have sewage connections as proposed.

Similarly, another sewage pipeline part of the Sholinganallur- Karapakkam project was laid using the push through or trenchless system, a technique similar to HDD.

Without disturbing the outer surface of the road, a 40ft pipe was inserted underground on Kalaignar Karunanidhi Salai recently.

“Though we have used this method several times in the past, this is the first time that a long pipeline of 40ft is laid using this method,” said an official.

Trenchless system

Another method that has been used is the push through or trenchless system. Using this, a pipe was laid six metres under the Kalaignar Karunanidhi Salai. It will not disturb other cables as they are laid only two metres below the ground, said an official. “We do not have to get road-cut permission as well,” the official added

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