Flash flood at Upp Serangoon Rd due to choke in illegal drainage

Sharon See Channel NewsAsia 22 Oct 11;

SINGAPORE: The national water agency PUB said Friday's flash flood along Upper Serangoon Road was due to a choke in a temporary drainage which was constructed without PUB's approval.

PUB said the choke occurred in a temporary diversion drainage located next to the slip road leading from Upper Serangoon Road to MacPherson Road.

It added the temporary drainage was constructed by a contractor carrying out road works for the Land Transport Authority (LTA) at the Woodsville flyover.

The contractor had demolished an existing 5 metre-stretch of box drain and diverted the flow to two pipes.

PUB said these pipes were under-sized and not properly connected.

Its officers also found debris and obstruction in the drain, severely restricting the flow of rainwater, which then caused the flood.

The problem has since been rectified under PUB's instructions and supervision.

The contractor will be prosecuted for obstructing and altering the drainage system without approval.

- CNA /ls

Contractor's actions led to flash floods: PUB
Straits Times 24 Oct 11;

FLASH floods last Friday in Upper Serangoon Road were caused by a choke arising from unauthorised changes to a drainage system, said national water agency PUB.

A temporary drainage was built by a contractor undertaking a Land Transport Authority roadwork project at the Woodsville flyover, said a PUB spokesman.

The contractor had demolished an existing 5m stretch of box drain and diverted the flow to two pipes measuring 30cm in diameter, she added, noting that they were undersized and not properly connected.

Investigators found debris and obstruction in the drain that severely restricted the flow of rainwater and caused the flash flood.

Floodwaters subsided only after an hour and 15 minutes.

The spokesman said the contractor has since made rectifications under PUB's instructions and supervision. The work was completed at 4am last Saturday.

'PUB takes a serious view of the contractor's actions and will prosecute the contractor for obstructions in the drain and altering the drainage system without approval,' she said.

Other areas hit by floods during the two-hour heavy rain included a section along Ang Mo Kio Avenue 5, the junction of Jalan Pemimpin and Bishan Street 21, and the slip road from Kranji Expressway to Woodlands Road. In Little India, areas affected included Norris Road, Owen Road and Roberts Lane.

The National Environment Agency website said showers with thunder in the afternoon are expected today and over the next two days.