Not stormwater drains, UG sewer lines carried floodwater: Data

According to Metro Water data, the sewage pumping stations of the water manager pumped around 25 per cent more sewage in the last few days than the amount of sewage pumped on normal days. This suggests that the extra sewage pumped was sewage mixed floodwater.

On Saturday, the five sewage pumping stations pumped 911 million litres of sewage, as per data. On Friday and Thursday, as much as 916 million litres and 884 million litres were pumped. Interestingly, the Metro Water pumped only 690 million litres on November 6, a day before the incessant rains started.

When asked, a Metro Water engineer said the floodwater from low-lying areas was pumped out by the Metro Water tankers and in some areas rainwater from the streets was pumped into underground sewer lines. “Due to some reasons, water flow was affected in stormwater drains. Corporation workers pumped the rainwater into the sewer lines. This has overloaded the underground sewer network leading to issues at 15 sewer main pipes across the city. The issues have been attended to,” the engineer said.

The engineer opined that the Chennai Corporation should appoint contractors who could maintain the stormwater drains throughout the year by arresting illegal sewage inlets and desilting them periodically rather than carrying out desilting work before monsoon.

Meanwhile, Jayaram Venkatesan, convenor of Arappor Iyakkam, said the gradient of the stormwater drains is not properly designed, forcing the workers to let water into sewer lines.

“We have visited low-lying areas in Kolathur, Royapet, Royapuram, Pudupet and other areas. In all those areas, rainwater was seen let into the sewer lines. For example, Besant Road in Royapet has a stormwater drain, but workers were pumping the rainwater into a sewer line,” he added.

Siddharth, a resident of Devanathan Street in Mandaveli fumed that rainwater remained stagnant for three days in the area.

“Finally, Metro Water tanker lorry removed the water from lanes along the street. The lanes do not have stormwater drains and the level of the street is higher than the level lanes. This prevents water flow from lanes to the street, where stormwater drains are present,” he said.