CHENNAI: A portion of the busy Sivasamy Salai in Mylapore caved in on Tuesday morning, the fourth such incident in the past three years.
Corporation officials who visited the spot initially thought the cave-in happened because of a Metrowater pipeline burst, but an inspection revealed that it was an old British era brick and mortar ‘arch sewer’ that gave away.
“During the British time, several such arch sewers were constructed. They are 7 feet wide and have a special water collection point," said an official. The name comes because it has an arch-like structure and it is that huge that even a car can pass through it.
Corporation officials said they do not have any data on British-era arch sewers in the city. “We know that in core city areas such as Royapettah, Mint Street and NSC Bose Road, many such drains are there. We discover them only when a road collapse is reported or when the Metrowater takes up work. Nobody has studied the existing network which is still functional carrying millions of litres of water during every monsoon," said one official.
In 2015, an arch sewer had collapsed near Mylapore tank, apart from another similar structure near Whites Road in Royapettah in the same year. One such drain is also present in Kaliamman Salai in Vadapalani.
An engineer, who was at the spot, said the road will be repaired soon. “Since it happened near the pavement, there is no hindrance to traffic movement on the road,” said the engineer. The debris will have to be cleared and since there is little flow of water, the corporation will place a top slab and repair it.
