Chennai Corporation using 'sump and pump' method to prevent reverse flow of stormwater

CHENNAI: The Greater Chennai Corporation (GCC) is using a 'sump and pump' method in 48 flood-prone locations to prevent reverse flow of stormwater in drains and to pump out water from low-lying areas.

When it rains heavily, canals swell, leading to water entering drains and flooding residential areas. The GCC has constructed sumps just before the outfall points of drains. Shutters are used to close the drains. The shutters block water from the canal entering the drain. A 100 HP motor is used to remove water from the sump.

Officials said drain outfalls are usually five to six feet below the topmost part of a canal, and swelling canals can hold up water in drains. Such 'sump and pump' systems are installed along the Otteri Nullah in Pulianthope, North Avenue Canal in Korattur, four points of Buckingham Canal in North Chennai, Veerangal Odai and others.

Superintending engineer for mechanical department K Vijayakumar said the motors could pump out even bottles, solid waste and clothes. "These will be filtered in the sump before water is pumped into the canal," he said.

Nearly 114 hundred HP pumps are used for this initiative, which is a common in countries like the Netherlands, to drain water from low-lying areas.

Prabhakaran, an executive engineer in the mechanical department, said it is a cheap methodology. "Motor rent is Rs 3,000 per day, and diesel costs are other expenses as per running time," he said. Workers and staff, including civil engineers, are hired to monitor the system during the monsoon period.