SINGAPORE: Floods at Tampines Avenue 12 last week were aggravated by runoff from a construction site after a ditch near the worksite was blocked by a temporary access road, national water agency PUB said at a media briefing on Wednesday (Jan 17).
A PUB spokesperson shared that stormwater runoff from a construction site and a field next to the flooded area would typically flow into an "earth drain", then discharge directly into Sungei Tampines.
However, PUB's investigations revealed that the contractors of the construction site built a temporary access road across the ditch, obstructing its flow completely.
The runoff flowed into the roadside drain on Tampines Avenue 12, which was already overwhelmed by the heavy rainfall on Jan 8.
PUB said the flash floods in the area subsided in 25 minutes.
The agency said it will work with the developer, understood to be the Housing and Development Board (HDB) to improve drainage at the access road, and a permanent drainage system will be built "in tandem" with the upcoming development project, PUB added.
PUB INVESTIGATING WHETHER ACTION SHOULD BE TAKEN AGAINST CONTRACTOR
PUB said the contractor, Huationg Contractor, should not have built the access road without first informing the agency, saying they "changed the entire landscape".
It said the key issue was the access road that ended up obstructing the flow of the stormwater runoff.
Any works that may impact the drainage system need to be run by PUB, but it said it did not receive such plans from the contractor.
These are some issues it needs to investigate before taking any prosecutorial action, PUB said. Meanwhile, its immediate focus is to improve drainage in the area.
PUB said it will also ensure that the contractor removes the section of the access road that resulted in the obstruction of the ditch, to restore the original flow.
This involves digging out a part of the road, which should be done by the end of the week.
It said it would also consider reaching out to other contractors to ensure they do not disrupt drainage systems without first consulting the agency.
CONTRACTOR THOUGHT EARTH DRAIN WAS ABANDONED: HDB
Responding to queries, HDB confirmed that Huationg did not seek PUB's approval to build the access road over the ditch. That was because it thought the ditch "appeared abandoned".
HDB was not aware that the contractor did not seek PUB's approval to build the access road.
It said its tender specifications require contractors to comply with PUB's code of practice on surface water drainage during works.
Additionally, worksites require contractors to engage a qualified erosion control professional to design the "earth control measures" and seek PUB’s approval before work starts.
Once approved, the professional has to ensure the contractor implements the measures. Such works are also to be supervised by qualified staff.
"HDB is conducting an investigation and will take action against the contractor accordingly," it said. It added that the contractor was carrying out ground preparation before construction for any development begins.
Tampines Avenue 12 was among nine locations in the eastern part of Singapore that experienced flash floods due to intense rainfall last week.
PUB shared that the other eight locations experienced flash floods due to their locations in low lying areas.