Construction firm, director and employees charged over Tanjong Katong sinkhole

SINGAPORE: Ohin Construction, its managing director and several employees were charged on Thursday (Jun 11) over alleged lapses linked to the sinkhole that appeared in Tanjong Katong in July 2025.

The company faces eight charges, mostly under the Building Control Act, Workplace Safety and Health Act and Workplace Safety and Health (General Provisions) regulations.

Its managing director, 64-year-old Ivan Ong Khiaw Yang, and six others were also charged in relation to the case.

A car had fallen into the sinkhole when it opened up along Tanjong Katong Road South on Jul 26, 2025, although the female driver was rescued by workers from a nearby construction site. 

The area was adjacent to a PUB worksite where a 16m-deep shaft was being built to connect existing sewer lines.

National water agency PUB and Surbana Jurong Consultants were separately given conditional warnings under the Building Control Act.

Ohin Construction was engaged as a licensed specialist builder for ground support and stabilisation works.

It is accused of carrying out unauthorised building works, road resurfacing and specialist building works, according to a joint statement by by the Building Construction Authority (BCA), the Ministry of Manpower (MOM) and the Land Transport Authority (LTA).

Ohin is also alleged to have failed to carry out mandatory tests and notify authorities of a road depression that occurred days before the sinkhole formed.

Authorities also alleged that there were false declarations over the appointment of a site supervisor.

According to the joint statement, the construction works involved soil strengthening works using jet grout piles and the casting of reinforced concrete caisson rings.

Jet grout piles are cylindrical columns of solidified soil and cement formed by injecting cement grout into the earth to strengthen the soil.

A caisson ring is a reinforced concrete structure that provides structural support for deep excavations. These rings are installed progressively as excavation deepens, to prevent soil collapse.

The company is accused of failing to ensure that the works were carried out according to approved structural plans.

It allegedly constructed jet grout piles with smaller diameters and failed to carry out the required jet grouting trial and other stipulated tests.

The firm also created additional openings in a caisson ring and horizontal grouting works at another ring that were not approved.

One of the caisson rings was allegedly cast in a non-circular shape instead of a uniformly circular one.

When the company became aware of a road depression along Tanjong Katong Road on Jul 15, 2025, it failed to immediately notify the Commissioner of Building Control, the charges stated.

The company is also accused of failing to take measures for the safety and health of its employees, including ensuring there was an adequate risk assessment and safe work procedure for horizontal grouting works.

Ohin Construction is also accused of failing to ensure that a video surveillance system was in good working order and operational at all times.

According to the joint statement, part of the shaft that was under construction allegedly failed at about 5.50pm on Jul 26, 2025, leading to soil going into the shaft.

At around the same time, the sinkhole formed at Tanjong Katong Road South.

Six others were charged in relation to this case: Ohin Construction's managing director, 64-year-old Ong Khiaw Yang Ivan; Yau Tze Yin, 49, the qualified person appointed to supervise the carrying out of structural works; Raajkumar Nadarajan, 58, the project director at the worksite adjacent to Tanjong Katong Road South; Kee Chen Siang, 39, the qualified person appointed to prepare the plans of the structural works and supervise their implementation; Sellappan Saravanakumar, 35, who was project manager at the worksite; and Senthilnathan Mathyalakan, a 56-year-old resident engineer.

Ong was handed six charges, the most among the accused persons.

A representative for Ohin Construction told the court that the company is under provisional liquidation.

The cases were adjourned to July.

CONDITIONAL WARNINGS

PUB, which received a conditional warning from BCA, said it takes the matter seriously.

Work on the project remains halted.

For works to resume, the new project parties to be appointed by PUB will have to submit new structural plans, which will be subjected to comprehensive safety assessments and approval, they added.

In response to CNA's query, Surbana Jurong said it took the conditional warning from BCA "seriously".

"We're continuously working to improve our procedures for identifying and escalating any irregularities on site," the company said. 

"Surbana Jurong continues to work closely with PUB to deliver the project safely and is committed to upholding the highest safety standards."

After the incident, the affected sections of Tanjong Katong Road South were closed for about a week to allow for government agencies to stabilise the ground by backfilling the sinkhole with liquefied stabilised soil.

The Ministry of Sustainability and the Environment (MSE) said last July it would convene an internal panel to investigate the cause of the sinkhole, with BCA also conducting an independent investigation into the incident.

BCA, MOM and LTA jointly said on Thursday they had completed their respective investigations into the sinkhole incident. 

"BCA, MOM, and LTA take a serious view of any safety or compliance breaches that place the public at risk. This incident demonstrates the critical importance of proper supervision and adherence to safety protocols. Enforcement action will be taken against public sector agencies, companies and individuals who fail to fulfil their statutory duties," they added.

PUB on Thursday said that it had terminated its contract with Ohin for the project. 

The national water agency also blacklisted Ohin for 18 months starting in August last year, and will not award the company any new projects during that period.

"The Ministry of Sustainability and the Environment had also earlier convened an internal investigation panel to examine the causes of the incident and make recommendations for PUB to help prevent similar incidents," said PUB.

"The panel has recommended that PUB strengthen its processes for identifying and responding to irregularities in projects carried out by contractors, including escalating the irregularities to the relevant authorities."

Beyond its statutory requirements, the panel also recommended that PUB reinforce the roles and responsibilities of parties involved in its construction projects, including through its regular industry engagements. 

The national water agency said that it has since implemented the recommendations.