Stormwater drains in Chennai made headlines during the December 2023 floods. Many residents in areas that were waterlogged complained about their ineffectiveness. Since then, the Greater Chennai Corporation (GCC) officials have maintained that they have identified inundated areas and constructed stormwater drains in those specific locations under various schemes. While most of the construction work is ongoing in North and South Chennai, GCC officials claim that the Integrated Stormwater Drain (ISWD) project is almost at a completion stage in North Chennai.
Six months after the floods, we did a status check in parts of North Chennai and found that a lot of older issues remain unaddressed in the locality. For the second part of this series, we reached out to GCC officials to know what measures they have been taking to address these issues. Here is a low down on the problems with stormwater drains in the city and what the GCC is doing about it—
Addressing the older issues with stormwater drains
What is the problem: Broken manual doors and other pending repairs
What GCC says: Though desilting stormwater drains has been given priority, manual doors are being replaced wherever they were found to be broken. After the floods, the GCC conducted a survey to understand and address such minor issues and an estimate was made for this in particular. We have been carrying out those works in addition to desilting. Funding for this comes from the GCC budget.
The Corporation has initiated installation of shutters in many areas to prevent reverse flow. Unlike the previous years, we have started clearing the silt catch pits and desilting work much ahead. Earlier, Chennai did not get much rain during the southwest monsoon. Since Chennai has been seeing more rainfall now even in southwest monsoon, GCC has started these works well ahead of time. We will do the same again for the northeast monsoon.
What is the problem: Unscientific gradient of stormwater drains
What the GCC says: To address this issue, we have rerouted the stormwater drains. While reconstruction was required for this in a few areas, the GCC has arranged for pumping out the water in a some other areas. When there is a blockage in the SWD due to garbage dumping, the water will flow in the reverse direction leading to stagnation. There will not be any issues because of the gradient, unless there is a blockage this time.
Sewage polluting drains and waterbodies
What is the problem: Sewage being let out into the stormwater drains
What the GCC says: We have had a system in place to address this issue for more than seven years now. We have been identifying the violators and levying fines for illegal connections of sewerage lines that drain into the waterbodies/stormwater drains.
Accordingly, GCC levies the fine as follows
- Ordinary building (Residential) – Rs 5,000
- Ordinary building (Commercial) – Rs 10,000
- Special building (Residential) – Rs 25,000
- Special building (Commercial) – Rs 50,000
- Multistory building (Residential) – Rs 1 lakh
- Multistory building (Commercial) – Rs 2 lakh.
Inundation is not caused by sewage mixing. However, in construction zones, we have observed debris being dumped into stormwater drains, resulting in blockages. Also, blockages have been identified due to Chennai Metro Rail construction, and we have taken measures to address these issues.
What is the problem: Missing links between stormwater drains and canals; canals are not desilted
What GCC says: We have identified the missing links and have been carrying out work to plug these gaps. Canal cleaning works are also underway now. Stormwater drains are connected to the micro/macro canals from where it goes to the river and sea. We are using machinery to desilt these canals and monitoring the works through our JEs.”
Read more: GCC Budget 2024-25: Focus on education, health and SWD infrastructure of Chennai
On conserving rainwater
The idea of stormwater drains is to drain the water into the sea. On the other hand, of the 51 revenue blocks in Chennai where groundwater is extracted, 46 are over-exploited, according to a report from the Water Resource Department. To address this issue, the GCC has installed silt catch pits in the stormwater drain structure that will filter the silt first. For every 30m, GCC has also installed rainwater harvesting (RWH) structures which help in recharging the groundwater. “Our officials also conduct inspections to ensure the RWH structures are functional. This apart, we have also been rejuvenating the ponds, and lakes and creating sponge parks,” they add.
When asked how they monitor if these RWH structures have indeed helped in recharging the groundwater, they say, the Chennai Metropolitan Water Supply and Sewerage Board monitors this and updates the report on their website. “From their report, we have observed that the groundwater levels have increased since the installation of these structures,” notes the official.
Read more: Looking beyond stormwater drains to realise the dream of a flood-free Chennai
Involving citizens in flood mitigation
During rains, the public can contact the GCC’s helpline number 1913 or reach out to the zonal officers to address their grievances, say GCC officials.
Coordinating with the citizens is a crucial part of the flood mitigation plan. For this, GCC is conducting training programmes for the volunteers on rescue and disaster management. The public could get further details from the respective zonal offices. The zonal offices also conduct regular meetings with RWAs to create awareness among the public on other flood mitigation Initiatives.
[These inputs were shared with Citizen Matters by a GCC official in-charge of the stormwater drain work in Chennai on the direction of City Engineer S Rajendiren.]