Written Reply to Parliamentary Questions on Choa Chu Kang Waterworks Incident

Written Reply to Parliamentary Questions on Choa Chu Kang Waterworks Incident by Ms Grace Fu, Minister for Sustainability and the Environment

Ms Poh Li San: To ask the Minister for Sustainability and the Environment (a) what are the initial findings from investigations into the incident resulting in the death of a worker and injuries sustained by two others during routine tank cleaning at PUB's Choa Chu Kang Waterworks; (b) what is the cause of the hydrogen sulphide gas leak; (c) whether an update can be provided on the condition of the two workers under intensive care; and (d) what are the lessons learnt to ensure such mishaps do not repeat.

Mr Melvin Yong Yik Chye: To ask the Minister for Sustainability and the Environment with regard to the incident at PUB's Choa Chu Kang Waterworks where two workers inhaled toxic gas when carrying out tank cleaning works, what safety measures are in place at all PUB's waterworks to ensure the safety of workers against the risk of exposure to toxic gases and chemicals.

Answer:

1 First, I would like to express my deepest condolences to the families and loved ones of Mr Srinivasan Sivamaran and Mr Izzat Naqiuddin Bin Dawood, who lost their lives due to the incident at PUB's Choa Chu Kang Waterworks on 23 May 2024. The third worker, Mr Erifin Anak Awan, was discharged from hospital on 22 June 2024. I wish him a swift and full recovery.

2 I seek Members' understanding that I can only provide basic information due to the ongoing investigation by the Ministry of Manpower (MOM).

3 On 23 May 2024, during routine cleaning of a water treatment process tank at Choa Chu Kang Waterworks, three contractor workers were found to have collapsed. Initial investigations indicated that they had inhaled hydrogen sulphide. Hydrogen sulphide is a gas that is typically emitted when sludge is being drained from the tank. At the time and location of the incident, hydrogen sulphide levels were higher than normal based on the hydrogen sulphide sensors installed.

4 As a precaution immediately after the incident, PUB issued a Board-wide safety time-out. During the time-out, PUB carried out comprehensive checks on its processes and safety procedures, both at Choa Chu Kang Waterworks and across PUB. Checks were specifically made in the management of work in confined spaces and locations where there was risk of exposure to toxic gases and chemicals. Work resumed across PUB after ensuring that safety procedures were adequate and in place, with the exception of Choa Chu Kang Waterworks where MOM's Stop Work Order is still in force.

5 Hydrogen sulphide emitted during tank cleaning works will be dispersed by wind, with no adverse impact on the environment, flora and fauna in the area.

6 To prepare for the upgrading of Choa Chu Kang Waterworks which is expected to commence later this year, PUB completed an Environmental Impact Assessment (EIA) in end-2021, which was released for public consultation in mid-2022. Measures recommended by the EIA as well as key feedback and suggestions made during public consultation will be adopted once construction works start, to mitigate the project's impact on the environment.

7 PUB takes workplace safety and health seriously. Once the construction works commence, PUB will work with the contractors to ensure that measures relating to workplace safety and health requirements are adhered to and in place for all working on-site, including the management of work in confined spaces and the risk of exposure to toxic gases and chemicals.

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