Chennai’s stormwater drains: a subterranean magic bullet? 

While the Greater Chennai Corporation has embarked on an ambitious project of constructing new stormwater drains across the city in a seemingly impossible timeline for flood mitigation, residents express hope that the inconvenience caused at the execution stage will be worth the outcome

August 28, 2022 12:47 am | Updated 01:01 pm IST

The Greater Chennai Corporation has planned to complete the construction of the stormwater drains in the Cooum and Adyar basins, covering the central and south Chennai, by this September.

The Greater Chennai Corporation has planned to complete the construction of the stormwater drains in the Cooum and Adyar basins, covering the central and south Chennai, by this September. | Photo Credit: K.V. Srinivasan

Last Tuesday, when residents of Fourth Main Road of Kasturba Nagar at Adyar in Chennai rushed out of their home, startled by a loud noise, their frustration with the condition of the road they were putting up with for nearly a month worsened.

The noise was the result of earthmoving equipment disturbing the underground electric cable. With the entire stretch of road dug on one side, the carriageway has been reduced by half. Many apartments have been unable to take out their vehicles, even in a medical emergency.

The stormwater drains project, which is being executed at a breathless pace at multiple locations, has caused a lot of inconvenience to the residents. 

The stormwater drains project, which is being executed at a breathless pace at multiple locations, has caused a lot of inconvenience to the residents.  | Photo Credit: K.V. Srinivasan

The residents of this road are, however, not alone in facing this predicament as hundreds of city streets and roads are in a similar condition. It has become impossible to commute a few kilometres in Chennai without being forced to take diversions because of work along the roads. 

The unprecedented rain and flooding witnessed by the city last year prompted the Tamil Nadu government to take up the construction of stormwater drains as a top priority following the recommendations submitted by retired IAS officer V. Thirupugazh. 

The construction by the Greater Chennai Corporation is in full swing. The projects in the Kosasthalaiyar Basin (covering areas such as Tiruvottiyur, Manali, Madhavaram and parts of Madhavaram) and the Kovalam Basin (covering Chennai’s southernmost areas) are expected to get over only by 2024. 

Stormwater drain work under progress on Dr. Besant Road, Ice House, Triplicane on August 26, 2022.

Stormwater drain work under progress on Dr. Besant Road, Ice House, Triplicane on August 26, 2022. | Photo Credit: K.V. Srinivasan

However, the GCC has embarked on an ambitious plan to complete the work in the Cooum and Adyar basins, covering the central and south Chennai, by this September before the start of the northeast monsoon. Officials acknowledge that the work, which should have taken at least 12 months to complete, is being targeted for completion in four to five months. 

Inconvenience

The project, which is being executed at a breathless pace at multiple locations, has invariably resulted in a lot of inconvenience to the residents. Business enterprises at some locations have complained about reduced access to their shops or having to shut them down owing to the digging of roads right in front. 

One of the common problems being faced in the construction is the accidental disturbance of sewer lines, drinking water lines and electric cables. Recently, residents of many pockets in Velachery and Adyar complained about the stagnation of sewage in the trenches dug for stormwater drains for many days. 

Sewer lines were also punctured at places such as Vembuliamman Koil Street at K.K. Nagar and Arunachalam Street at Saligramam. A portion of Anna Main Road at K.K. Nagar which is already prone to frequent cave-ins for various reasons, including old sewer lines, also has water lines running closer to the stormwater drain under construction.

At some places, officials of Chennai Metropolitan Water Supply and Sewerage Board said that rerouting of the stormwater drain alignment was sought as it fell along the drinking water pipelines in narrow streets. A minimum of 20 locations have faced the issues of either damage to utility lines or rerouting of the alignment, they said.

Traffic snarls have become common on many roads. For instance, E. Ravi, a resident of MGR Nagar, said roads such as Rajamannar Salai, Ponnambalam Salai and R.K. Shanmugam Salai at K.K.Nagar witness traffic snarls in the evening hours. So do Dr. Ranga Road, TTK Road and C.P. Ramaswamy Road in the Teynampet zone. 

Pointing out that the city roads had already been used to their maximum capacity, a traffic police officer said any further reduction in the carriageway would certainly affect traffic movement. “Congestion in one spot will have a domino effect, leading to congestion in nearby junctions and often resulting in a gridlock,” the officer said. 

Residents have raised concerns about the slow pace of the work. For instance, work is going on near Seethammal Colony at Teynampet, one of the worst-affected areas during last year’s rain.  

N. Sivakumar, a resident of Vijaya Nagar North Extension at Velachery, said the trenches dug up in the area were left open for several days without any work happening. Similar concerns have also been raised by residents of Kasturba Nagar at Adyar. 

While members of the public are ready to bear with the inconvenience in the short run, considering the importance of the flood mitigation work, there have been concerns about whether the project will deliver the results. 

Will it work?

For instance, since the beginning of the project, residents of Besant Nagar voiced concerns over the need for stormwater drains made of concrete as the locality has sandy soil in which the water can percolate faster. Following their concerns, the GCC has stopped the work in the locality and has decided to create percolation pits at regular intervals. The residents along East Coast Road have raised similar objections.  

Meera Ravikumar, a resident of Gandhi Nagar at Adyar, questioned whether the civic body exercised due diligence in each street, including her locality that had never suffered major flooding in the past. She also expressed concern over the lack of adequate consultations with residents.

When the project was started, residents of Tiruvalluvarpet near Mandaveli were concerned that the alignment of the drain went against the natural gradient of the locality. Similar concerns have been raised by residents of a few other localities. 

Another key concern raised by residents of some localities has been the level of the stormwater drains being higher than the level of the road, which makes one wonder how the run-off water from the road will enter the drain. 

Kalpana Jayakumar, of K.K. Nagar, said the alignment in her locality appeared to be at a higher level. “We are worried whether water from our apartment complex will be able to drain,” she said. S. Nachiappan, secretary, Abhiramipuram Residents’ Welfare Association, said the stormwater drain being built in the locality was not uniform.

N. Venkatramani, an elderly person from Aziz Nagar at Kodambakkam who worked as a civil engineer for 38 years, said the drains, however large, might not work unless the gradient, gravity, contours and mean sea level were taken into account. Though the design may have been reviewed properly and may sound good on paper, he expressed concerns about the execution of the work by lower-level workers day and night without inadequate supervision.

“The Chief Minister has sanctioned crores of rupees, all of which will literally go down the drain if the project is not implemented properly,” said Mr. Venkatramani, who has been visiting government officials to make them understand his concerns.

People are worried by the felling of trees at many localities. While the civic body has exercised caution and avoided felling trees at many localities by changing the alignment of the drain, digging up closer to trees has left many of them in a precarious state. At least two such trees fell recently at Adyar. A tree closer to the site of the work at K.K. Nagar fell in June, resulting in the death of a bank employee. The GCC, however, denied that the fall of the tree was due to the work. 

Ms. Ravikumar said many trees had been felled at K.K. Nagar, which is known for its tree-filled avenues. “No consultations were done with the residents. Most of these trees are very old. We are losing precious green cover,” she said. 

Allaying concerns

GCC Commissioner Gagandeep Singh Bedi’s table at his office is filled with documents, maps and review reports on flood mitigation projects, indicating the attention being paid to them. In a candid conversation with  The Hindu, he  acknowledged that the project had caused inconvenience to people. But the discomfort in the short run, he said, was needed to develop a long-term solution to the flooding, with extreme rainfall events becoming more frequent. 

Allaying concerns over the design and implementation of the project, he said the design had been vetted at different levels. While the designs for the drain on the smaller roads and lanes were handled by GCC engineers, the designs for key roads, especially the ones that suffered excessive flooding, had been tested through computer simulation and reviewed by IIT Madras. 

On the disruption of sewer and electric lines at a few places, he said he had issued detailed circulars instructing officials at the zonal level to regularly coordinate with their counterparts from line departments to ensure synergy and prevent recurrence of such issues. However, on a few occasions, the officials and even private internet providers who have optical fibre underground were unclear about the exact alignment until a disruption happened. Such issues are immediately addressed in coordination with the respective departments. He added that detailed instructions had also been given for ensuring safety on the margins by placing barricades.

Pointing to the colour-coded maps indicating the stages of execution of the project, he said both the pace and the quality of the work were being regularly monitored. Highlighting that he was reviewing the progress twice a week, he said the progress was also regularly reviewed by Secretary of Municipal Administration and Water Supply Department Shiv Das Meena, Minister for Municipal Administration and Water Supply K.N. Nehru, Chief Secretary V. Irai Anbu and Chief Minister M.K. Stalin himself. 

As for the felling of trees, he said he was particular that not a single tree was felled unless it was necessary. Highlighting that the civic body was focusing on tree plantation and did not want to lose the green cover, he said he had asked officials to approach the Green Committee to get approval if trees were to be cut. “Even if the project is getting delayed, we want to follow due process,” he said. In spots where the ground near trees had been dug, the officials had been asked to prune the branches to minimise the risk of their falling. 

Apart from the construction of drains, the GCC is carrying out the desilting of the existing drains at a cost of around ₹70 crore. He said the work had been started five months in advance and was on track to get over well before the monsoon. He said the desilting of the Mambalam canal, which is crucial to avoiding flooding in the T. Nagar area, had also been completed. 

While the Kosasthalaiyar and Kovalam Basin stormwater drain projects are to be completed over the next two to three years, Mr. Bedi expressed confidence that around 80% of the work in the remaining areas would be completed by September. 

He said the work in the key flood-prone areas like Seethammal Colony and some areas at Pulianthope and Kolathur would be completed by September. The work in smaller roads and lanes that might be pending would be completed soon after. 

No doubt, the inconvenience now being caused to the residents would all seem worth it, maybe it will even be forgotten if, and only if, this northeast monsoon does not drown the city again.

( With inputs from K. Lakshmi, Aloysius Xavier Lopez, and R. Sivaraman)

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