Chennai Corporation will start mechanised desilting of storm-water drains and old arch drains in the city in May to prepare for the northeast monsoon this year. 

A total of 3,040 km of storm-water drains, including 46 old arch drains constructed during the British rule, are likely to be cleared using machines.

Even though workers could walk inside the large arch drains, manual labourers have not been deployed for desilting many of the arch drains for several years. The use of machines, instead of manual labourers, is expected to improve monsoon preparedness this year. “We will start desilting early this year to prepare for the northeast monsoon. Starting from May 15, the machines will desilt the drains in three months,” said an official.

Over 15% drains have been clogged with silt in the city. Many drains have been polluted because of illegal sewage connections. The GCC will deploy high power suction-cum-jetting machines with CCTV system for desilting the drains. It is planning to explore the feasibility of restoring damaged arch drains to improve flood preparedness in the city. Many of the arch drains in stretches such as Flag Staff Road have disposal in the sea. Arch drains in Harrington Road have disposal points along the Cooum.

The old arch drain in Cemetery Road in Royapuram zone has been damaged inside the Railway compound, while the arch drain in Taylors Road has collapsed. Some arch drains are not draining water owing to Metrorail work in areas such as Millers Road. The old arch drain in Venkatnarayana Road in T.Nagar has also been damaged, affecting disposal in Mambalam Canal during the monsoon. Many old arch drains in stretches such as Sriman Srinivasan Road need minor repair. The old arch drains in stretches such as Avvai Shanmugham Salai, Dr.RK Salai and Luz Church Road are in good condition, officials said.