Contractor, manager charged over fatal 2024 Choa Chu Kang Waterworks toxic gas incident

A contractor and its manager face charges after two workers died from toxic gas exposure during tank cleaning operations at Singapore's Choa Chu Kang Waterworks in May 2024. The incident highlights critical failures in workplace safety protocols.

Stargroup, the contractor engaged by the national water agency PUB, was carrying out routine tank cleaning when the tragedy occurred. On May 23, 2024, four workers entered an enclosed passage beneath a water treatment tank. They collapsed after being exposed to hydrogen sulphide gas, a toxic substance emitted when sludge is drained. Despite alarms triggered by sensors detecting levels exceeding safe thresholds, three workers were affected. Two were pronounced dead on May 24 and May 28, while a third worker recovered after medical treatment.

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At the time of the incident, sensors installed at the location recorded hydrogen sulphide levels that exceeded safe thresholds, and the alarm had been triggered.

The Ministry of Manpower (MOM) stated that its investigations revealed the workers were exposed to hydrogen sulphide, a colorless gas lethal even at low concentrations. Stargroup has been charged with failing to implement reasonably practicable measures to minimize workplace risks. Additionally, Lim Beng Hock, the authorized manager for confined space entry permits at Stargroup, faces charges for failing to exercise due diligence in issuing these permits.

The MOM also issued a stern warning to a PUB officer for not cooperating with his employer to ensure compliance with the Workplace Safety and Health Act. PUB itself was fined for allowing employees to enter confined spaces without adequate ventilation on previous occasions. The ministry reiterated the legal requirements for employers working in confined spaces, emphasizing the need for pre-work risk assessments, atmospheric testing, provision of respiratory equipment, and constant monitoring by a trained standby person. Workers also bear responsibility for adhering to safety procedures and using required protective gear.

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Employers carrying out work in confined spaces are reminded that they are legally required to conduct a risk assessment before works commence, test the atmosphere within the confined space, provide workers with appropriate respiratory protective equipment, and ensure that a trained standby person is stationed outside the confined space at all times.