Residents of the extended areas of the Chennai Corporation have raised concerns over whether the extensive stormwater drain network under construction in these areas will serve the purpose of preventing flooding.
Residents of Kolathur, Nolambur, Red Hills, Madhavaram, Maduravoyal, Valasaravakkam, Porur, Alandur, Madipakkam, Pallikaranai, Sholinganallur, Velachery, and Thiruvanmiyur are among those who have expressed doubts, given the nature of the construction as also the lack of maintenance.
After the unprecedented rains of December 2015 which saw several thousand streets across the city inundated for more than a week, resulting in huge financial losses, the Chennai Corporation proposed to construct an Integrated Storm Water Drain (ISWD) network under the Development and Management of Disaster Resilient Infrastructure. As part of the ISWD network, work on stormwater drains was carried out in the extended areas of Virugambakkam, Red Hills, Nolambur, Villivakkam, Maduravoyal, Madhavaram, Porur, Alandur, Pallikarani, Velachery and Perungudi.
The Chennai Corporation segregated the areas based on basins of Kosasthalaiyar, Cooum and Adyar rivers, and identified 859 locations likely to face inundation, of which 306 were prone to chronic flooding. The civic body also identified places where despite the presence of stormwater drains, there are no links to evacuate the rainwater and prevent flooding.
As part of the ISWD project, the Corporation completed construction of drains in several places including Perambur, Jawahar Nagar, Periyar Nagar, Valasaravakkam, Nolambur, Mogappair, Virugambakkam, Ashok Nagar, Kodambakkam, Porur, Nanganallur, Adambakkam, Velachery and Taramani.
Sewage pips rainwater
However, residents of some areas find the drains more of a bane than a boon with complaints of shrinking road width, sewage water being let into them, and incomplete work.
Secretary of the Nolambur Residents’ Welfare Association M. Selvamani said sewage had started flowing into the stormwater drains long before any rainwater trickled in. Mr. Selvamani, a resident of Nolambur TNHB Phase 1, said sewage from nearby areas of Jaswant Nagar, IBA Nagar and Thiruverkadu, which do not have a sewage network, is being let into the stormwater network. He added that even lorries engaged to drain sewage from houses let out the wastewater into the stormwater drains, resulting in stagnation and posing a health hazard.
He said several complaints regarding stagnation of sewage water in the stormwater drains had been lodged with the Corporation but no steps have been taken to prevent the misuse of the stormwater network, despite senior officials having visited the spot.
M.P. Kumar, a resident of Golden George Nagar in Mogappair, raised concerns over the failure to maintain a uniform level between the stormwater drain and the roads. He also pointed out that the grates meant to allow rainwater to flow into the drains have not been properly installed and could pose a danger for motorists in the dark.
Mr. Kumar, a construction engineer, also faulted the failure of officials to conduct a flow test while constructing the drains. He said for any work related to water, a flow test is important to identify the speed of the water flow. “But in our locality where new stormwater drain has been constructed, no flow test seems to be have been conducted, going by the way water is stagnating in the network even when there is no rain,” he said.
Lack of maintenance and desilting of the stormwater drains and cleaning the grates by the civic body has also been a bone of contention for residents. With sewage being let into the newly-constructed macro canals, they have become a breeding ground for mosquitoes, they allege.
S. Venugopal, a resident of Balaji Nagar in Valasaravakkam, said the stormwater drain had helped in preventing stagnation of water in their locality. The lack of stormwater drains in Valasaravakkam had left the area badly in the 2015 flood. The newly-constructed network has helped in alleviating the problem, he said.
Kolathur ignored
On the other hand, A.H. Chandra Bose, social activist, said areas in Kolathur, including Mohammed Hussain Colony, Thirumalai Nagar, Srinivasa Nagar, Venus Nagar, and Krishna Nagar, that were badly affected by flooding, and have been requesting construction of stormwater drains, have been ignored by the civic body.
A senior official of the Chennai Corporation said more than 99% of the ISWD work has been completed on the Adyar and Cooum basins for a length of 405 km through funds from the World Bank, at a cost of ₹1,200 crore. Representatives of the World Bank also visited the sites of the ISWD work and have been positive about the progress and the quality of the work carried out, he said. The official said as part of flood alleviation work, new macro canals were constructed like the Padikuppam and Ambattur Sidco canals.
Under the Kovalam basin which is to benefit Perungudi and Sholinganallur, a feasibility study has been completed and work could start by September 2019. The work, to be carried out at a cost of a further ₹1,200 crore, would have ISWD for a length of 360 km with the German Development Bank funding the project. Similarly, a DPR for the Kosasthalaiyar basin covering Manali, Thiruvottiyur, Madhavaram and portions of Ambattur has been readied. The Kosasthalaiyar basin would have the largest ISWD network of 750 km and would cost ₹2,518 crore.
The ISWD work would prove its worth when the rains hit the city, he added.
