Choked drains caused massive flooding in Orchard

Singapore's national water agency, PUB, has said the flood in parts of Orchard Road on Wednesday was caused by choked drains underneath roads in the area.

With no typhoon hovering over the island city state, suspected that the rains were brought by the southwest monsoon. The two-hour downpour registered 100 mm of rain & the amount of rainfall is higher than the average and incidents like this happen rarely.

At a news conference on Thursday, PUB explained that thorough investigations done by its officers found that debris was found trapped inside the culvert of Stamford Canal. It said the heavy downpour caused debris to build up and get trapped in a drain near Delfi Orchard. The culvert of Stamford Canal diverts water from Nassim and Cuscaden Road into two sections of Stamford Canal, which runs along Orchard Road.

The heavy build-up of debris partially trapped in the culvert caused the rainwater to be diverted to only one of two canals running beneath Orchard Road. And this caused water in the canal to overflow into Orchard Road.

PUB said the drain's capacity is adequate as it has handled previous rains of similar intensity. It will be stepping up the frequency of maintenance inspections of critical closed drains. It will also increase its maintenance inspections to monthly checks. Currently, it inspects drains every three to six months.

PUB will also install more litter traps along Stamford Canal to prevent the build-up of debris, and more water-level sensors along Stamford Canal to enable closer monitoring of unusual peaks and dips in water levels.