CHENNAI: As they get ready to tackle the monsoon, a season during which the authorities find themselves at the receiving end of public criticism over inundation and stagnation, the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) officials are confronted with a familiar challenge: removing blockages caused by clothes, diapers, sanitary napkins, and other waste that the residents dump into the system.
The board, popularly called Metro Water, has begun precautionary work ahead of the monsoon, and has desilted roughly 6,000 km of active sewer lines twice already. Speaking to DT Next, a senior official said the workers have completed desilting sewer lines, covering about 1,70,000 manholes. Now the third phase of work is under way and will continue through the monsoon.
Of the pumping stations in the city, 423 are IoT-based and automated, which will switch on when the water reaches a set level, even without workers present, and switch off once levels fall.
The real challenge, however, lies elsewhere. According to the official, though the slum dwellers in the city are often blamed for misusing sewers resulting in blockages, the issue is not limited only to those areas alone. Clothes, napkins and diapers are dumped even from high-rise apartments and housing board flats, leading to blockages and resulting in sewer overflow, the official said.
To prevent waterborne diseases, the board will double sample testing to 1,800 during rains and to 600 during normal days. More samples will be collected from Tamil Nadu Urban Habitat Development Board complexes, said officials.
Officials said the city's infrastructure managed by GCC can handle up to 20 cm of rainfall a day. However, the actual intensity of the monsoon is unpredictable as witnessed during the 2021 and 2023 floods. Learning from that experience, the board has raised the height of 20 pumping stations in low-lying areas and placed generators there.
On the equipment front, generators are on standby, diesel for one to two months has been procured, and sandbags have been kept ready. A total of 740 machines, including high-speed sewage suction vehicles, are ready. Metro Water owns 600 of them, while 173 will be outsourced under the Annal Ambedkar Business Champion Scheme. Around 130 suction lorries will be brought from other districts and shared with the Greater Chennai Corporation (GCC).
The rainwater harvesting structures at about 10 lakh of the city's 12 lakh buildings are in working condition, while the remaining 2 lakh need maintenance. Among the buildings, around 90 per cent of structures in large houses, high-rises, hospitals and IT companies are functional, but small houses leave much to be desired, added the official.