Tanjong Katong sinkhole: BCA to conduct independent probe, act against any non-compliance
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- BCA investigates the Tanjong Katong Road South sinkhole to identify causes and any Building Control Act non-compliance; probe may take months.
- PUB will conduct tests before repaving the road, ensuring safety.
- A concrete shaft structure failed on July 26, around the time the sinkhole formed; the cause of the "caisson ring" failure is unclear.
AI generated
SINGAPORE – The Building and Construction Authority (BCA) will carry out an independent investigation into the sinkhole that formed in Tanjong Katong Road South, said National Development Minister Chee Hong Tat.
In a video statement on July 28, Mr Chee said BCA engineers have been on-site, working with national water agency PUB and the Land Transport Authority (LTA) to ensure the surrounding buildings, roads and infrastructure remain structurally safe.
“Now that the ground situation at the incident site has been stabilised, BCA is conducting an independent investigation into the incident,” he said.
BCA said the probe will examine the circumstances leading to the sinkhole’s formation, identify the causes, and act against any non-compliance under the Building Control Act and Regulations.
“Given the complexity of the incident, the investigations could take several months to complete,” the authority added in a statement.
The probe will include a detailed geotechnical analysis, which evaluates a site’s soil and geological conditions to determine the safety of structures, and other validation tests by BCA and its appointed consultants.
BCA said the backfilling of the sinkhole and an adjacent shaft, which was completed early on July 28, stabilised the site, and the adjacent buildings remain safe.
Earlier on July 28, Mr Goh Pei Ming, an MP for Marine Parade-Braddell Heights GRC, said PUB will conduct tests before the caved-in road is repaved.
The sinkhole was located near a PUB construction site with sewer laying works.
PUB’s tests will include drilling probes, which are up to 20m deep, to check that there are no air pockets in the soil, Mr Goh said on Facebook.
These come on top of radar scans to assess ground conditions.
A section of Tanjong Katong Road South collapsed
The road has since been closed, with traffic and bus services diverted.
The tests and analysis will take some time, said Mr Goh, who is also Minister of State for Home Affairs as well as for Social and Family Development.
“I understand residents are keen to know when the road can be reopened. I think it is best we give the agencies the time to be doubly sure the road is safe before we reopen,” he added.
Mr Goh said traffic was smooth when he visited the site on the morning of July 28, noting that LTA had put out messages to motorists, as well as worked with the Ministry of Education to notify parents about road diversions.
Tanjong Katong Road South is on the boundary of Mountbatten SMC and Marine Parade-Braddell Heights GRC.
PUB said on July 27 that the works at the site next to the sinkhole involved the construction of a 16m-deep shaft to connect three existing sewer lines, and a structure in the shaft had failed at about 5.50pm on July 26 – around the same time the sinkhole formed.
It is still unclear what contributed to the failure of the caisson ring, a concrete structure in the shaft.
A caisson ring is a watertight concrete cylinder that is sunk underground to form a stable foundation for other structures.
PUB did not address questions from The Straits Times about the nature of the failure, the ground monitoring regime in place before the incident, as well as whether a reported burst water pipe nearby on July 25 was linked to the sinkhole occurring the following evening.
Editor’s note: An earlier version of this report quoted MP Goh Pei Ming saying that LTA will conduct tests before the road is repaved. Mr Goh has since updated his Facebook post to say PUB is carrying out the tests.
