National water agency PUB will be taking action against Straits Construction Singapore (SCS) for lapses in drainage maintenance, which resulted in flash floods in Geylang earlier this month.

Parts of Lorong 23 Geylang and the Kallang-Paya Lebar Expressway (KPE) slip road to the Pan-Island Expressway (PIE) were hit by flash floods following heavy rainfall on Nov 11.

In a statement yesterday, PUB said the construction contractor had failed to take proper measures to maintain the flow capacity of a pipe drain linking Lorong 23 Geylang to the Pelton Canal.

PUB's investigations found that the 1.2m-wide pipe drain passing through an international school construction site, which is operated by SCS, was choked.

Storm water was not able to flow into the Pelton Canal, resulting in flooding at the KPE slip road and Lorong 23 Geylang.

PUB said the storm water collected in the roadside drain in Lorong 23 Geylang is first discharged into a downstream drain at the KPE slip road, before it empties into the Pelton Canal.

This drain runs along Lorong 23 Geylang, Sims Place and Sims Drive before joining up to a culvert that crosses below PIE (including the KPE slip road to PIE towards Changi).

The culvert then joins the pipe drain that runs through the international school construction site.

PUB said it will be taking enforcement action against SCS for the lack of proper maintenance of the drainage system within its site.

"Storm water flows into roadside drains, canals/tributaries and rivers and eventually out to sea or into reservoirs. It is thus important to keep our drains free-flowing," the statement said.

The agency also reminded worksite developers and contractors to take active measures to ensure that drains within their development sites are free of silt, debris, litter and leaves.

"PUB will not hesitate to take action against those who fail to comply," the statement said.