HFS351 – Safety Management and Audit ECA – July Semester 2025, Singapore

Case Study: Environmental Health and Safety (EHS) Management in Wastewater Treatment Plant Operations

(Full marks: 100)

You are the newly hired Safety Manager at ABC Water Services Pte Ltd, a company specializing in wastewater treatment, recycling, and sludge management. Your responsibilities include managing the Safety Management System (SMS) and ensuring compliance with all Environmental, Health, and Safety (EHS) requirements throughout plant operations.

ABC Water Services Pte Ltd is certified to Singapore Standard, ISO 45001:2018, and is due for re-certification in December 2025. The general steps involved in wastewater treatment operations include preliminary screening, primary sedimentation, biological treatment, disinfection, sludge dewatering, and treated effluent discharge.

The company is licensed to store and use regulated chemicals, overseen by the Singapore Civil Defence Force (SCDF) and the National Environment Agency (NEA). Hazardous substances such as chlorine gas, sodium hypochlorite, polymers, and acids are stored in designated areas with secondary containment to prevent leaks and spills.

During a scheduled safety audit, you reviewed incident reports and noted several cases where plant operators entered restricted zones, demarcated by temporary barriers, where chemical dosing systems were being calibrated or tested. The incident reports stated that workers were unaware that such high-risk maintenance activities were in progress.

When you asked the Head of Operations how workers are informed of occupational health and safety (OH&S) risks, he stated that all safety concerns are addressed in weekly toolbox talks held every Monday morning, which all staff must attend. Upon reviewing the agenda, you found that key safety topics, including chemical dosing and confined space entry, were included.

However, when inquiring about attendance tracking, you were informed that records are not maintained, as it is common practice for all staff to attend. When asked how absent workers — due to operational shifts, illness, or leave — are briefed, the response was that area supervisors are expected to update them, though no formal process exists.

Additionally, during multiple walk-down safety inspections, the following observations were made:

1. Several electrical panels, mixers, and pumps lacked inspection tags or stickers from a Licensed Electrical Worker (LEW). One incident involved an operator receiving a mild electrical shock while working on a sludge dewatering unit.
2. Hazardous chemicals, including coagulants and acids, were found unlabelled or transferred to unmarked plastic containers in violation of the Global Harmonized System (GHS) requirements.
3. A strong odour of chlorine was detected in the chemical storage area, as reported by an operator during an interview, indicating a potential leak or poor ventilation.
4. An operator conducting maintenance at height on an aeration tank claimed that he was trained and certified. However, he was observed standing on the erected scaffold without a harness or fall arrest system, posing a significant fall risk. Further reviews revealed that the erected scaffold was last inspected 4 weeks ago.
5. Personal Protective Equipment (PPE), such as Self-Contained Breathing Apparatus (SCBA) and chemical-resistant suits for the Emergency Response Team (ERT), were found to be damaged or expired.
6. During routine operations in the sludge handling area, multiple safety hazards were identified, including:
   • Exposure to harmful gases, such as hydrogen sulfide, risking respiratory issues and unconsciousness.
   • Contact with corrosive chemicals, posing risks of chemical burns.
   • Inhalation of bioaerosols and particulates during high-pressure hosing or maintenance.
   • Noise hazards from machinery such as pumps, centrifuges, and blowers, which can lead to hearing damage.
   • Confined space entry hazards in tanks and manholes without proper permits or gas testing.
   • Electrical hazards from pump stations and control panels not adequately maintained.
   • Slips, trips, and falls hazards from wet surfaces, hoses, and tools left unattended in walkways.

Several lagging indicators were identified as contributing to unsafe conditions and behaviours in the wastewater treatment facility, such as:

• Lack of control over the storage and handling of hazardous chemicals.
• Human factors, including insufficient supervisory oversight, unsafe operator behaviour, and lack of contractor monitoring.
• Inadequate training on chemical handling, confined space entry, and the use of PPE.
• Insufficient preventive maintenance and inspection of critical safety systems, including gas detectors, eye wash stations, and emergency kits.
• Lack of formalized procedures to manage risks associated with hazardous energy (LOTO), confined spaces, and chemical dosing systems.

Question 1

An external audit by the certification body is due to commence in three months. In view of the preparation for the ISO 45001:2018 audit, the ABC Water Services Pte Ltd management team had tasked you to lead a team of internal auditors to perform management system audit on the plant.

Prepare your plan in a table addressing the following components:

• (a) Discuss the specific internal audit requirements, including the scope of coverage, evaluation criteria, and performance benchmarks necessary for compliance with ISO 45001:2018. (4 marks)
• (b) Examine the rationale behind the selection of individuals chosen to be part of the internal audit team. (4 marks)
• (c) Describe the training or qualifications that the selected audit team members must have. (4 marks)
• (d) Describe the key responsibilities and duties assigned to the trained internal auditors once they are appointed. (4 marks)
• (e) List the knowledge, experience and skills that the audit team members must have prior to conducting the internal audit. (4 marks)

Question 2

You are to lead the internal audit team to conduct a one-day sample audit. Apply your knowledge on ISO 45001:2018 Occupational Health and Safety (OH&S) Management System to develop a detailed internal audit schedule and present it in a table. Your response should include the audit schedule, clearly indicating the timeframe, organisational unit, processes or activities to be audited, audit team members involved, and the relevant ISO 45001:2018 clauses being assessed. (16 marks)

Question 3

A requirement of ISO 45001:2018 Clause 5.1 Leadership and Commitment is that top management shall demonstrate leadership and commitment with respect to the OH&S management system. Present the following in a table:

• (a) List each Clause 5.1(a) to (m) of ISO 45001:2018. (8 marks)
• (b) For each item, illustrate with at least TWO (2) action(s) that the top management can take to demonstrate leadership and commitment. (26 marks)

Question 4

The internal auditor team had completed the 1-day audit. You are to appraise the management. Present the following findings in a table:

• (a) Description of FIVE (5) non-conformities (5 marks)
• (b) Evidence associated with these identified non-conformities (5 marks)
• (c) ISO 45001 clause and requirement (10 marks)
• (d) Propose at least TWO (2) corrective actions to address each identified non-conformity. (10 marks)

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