Standby Person at the Grease Interceptor
At 10:15, the standby person at a 2.4 m deep underground grease interceptor at a food factory in Yuen Long sees the entrant - who is wearing a full-body harness attached to a tripod and winch - slump against the wall about 1.8 m below the rim. The standby person has a radio, a first aid kit and a 4-gas detector. The entrant's personal monitor is not visible. The standby person shouts; there is no answer. His own detector, held at the rim, reads O2 18.9%. About 300 mm of liquid lies at the bottom of the chamber. The nearest ambulance is 12 minutes away. The standby person is 24, holds confined space certification, and has never performed a rescue. A second worker is 50 m away operating a jetting machine. The permit lists one standby person and no rescue team; the rescue plan reads simply "call 999".
1. What should the standby person do in the first 60 seconds, in order? Justify each action.
Read the worked answer
Sequence
- Shout for the second worker and raise the alarm. He cannot manage a casualty, a radio and an access point alone. The jetting operator is the only immediate assistance.
- Call 999 immediately - do not wait to see whether the entrant recovers. Give the address, the fact that it is a confined space with an unconscious casualty, the likely gas (H2S), the access size, and the 12-minute ETA. Then notify the site's emergency contact.
- Do not enter the chamber. His detector reads 18.9% oxygen at the rim, so the atmosphere at the casualty is worse; he has no breathing apparatus and no rescue training. Would-be rescuers are consistently a large share - commonly cited as the majority - of confined space fatalities.
- Attempt retrieval from outside using the tripod and winch, if the harness is properly attached and the line runs clear. This is the only safe rescue available to him. If the casualty is fouled on pipework, stop pulling, keep the line tensioned and supported so the head stays above the liquid if possible, and hold until the rescue team arrives.
- Keep ventilation running if it is already set up, and monitor at the rim, staying upwind at the access.
- Prepare the scene for the rescue team: clear the approach, control traffic, identify isolation points, brief the team on the layout and the last readings.
Reasoning: the standby's value is in early alarm, outside retrieval and accurate information - not in climbing down.
2. Was the pre-entry emergency arrangement adequate? State what should have been in place.
Read the worked answer
No - it was a statement of intent, not a rescue plan.
Deficiencies
- "Call 999" is not a plan. A plan identifies who rescues, with what equipment, from where, and how quickly. The Fire Services Department may take longer than the casualty's survival time; the plan must cover the gap.
- No rescue team and no BA at the access. A vertical entry of 2.4 m with a deteriorating atmosphere and liquid at the bottom requires trained rescuers with breathing apparatus available at the site, not 12 minutes away.
- No rehearsal or drill. The standby had never done a rescue; a plan nobody has practised is a document, not a capability.
- No oxygen resuscitation equipment at the access, and no second person to assist the standby.
- The entrant's monitor was not readable from outside, so the standby had no confirmation of what the casualty had been breathing.
What should have been in place
- A named rescue team with BA, harnesses and retrieval equipment, on site or on a guaranteed response.
- Tripod, winch and retrieval line rigged before entry, tested under load.
- Oxygen and resuscitation equipment, first aid trained personnel.
- Reliable communication, rehearsed drills, and a designated person to meet the emergency services.
- A rescue plan specific to this chamber - its depth, access size, pipework obstructions and liquid.
Judgement: the liquid adds a drowning hazard, so retrieval must start within seconds, and the plan must acknowledge that.
3. After the casualty is brought out, what first aid and follow-up actions matter most?
Read the worked answer
Immediate care
- Airway and breathing first. Check responsiveness, airway and breathing. If not breathing normally, start CPR and attach an AED; do not delay for suction or for removal of clothing unless it blocks the airway.
- Give high-flow oxygen (100% via a non-rebreather mask) to a breathing casualty with suspected H2S exposure; continue during transport. H2S can cause delayed pulmonary oedema, so a person who seems to recover still needs hospital assessment.
- Assume spinal and musculoskeletal injury from a fall or winch retrieval; keep the casualty still and support the head.
- Decontaminate: remove contaminated clothing, irrigate any skin or eye contact with clean water, keep the casualty warm.
- Hand over exposure information to the ambulance crew: the gas readings, the duration down, the liquid present, and the possibility of hydrogen sulphide.
Follow-up
- Preserve the scene, the gas detector data and the permit; do not reset or re-calibrate equipment before the investigation.
- Report the incident to the Labour Department and police as required, and conduct an investigation that tests the system - risk assessment, emergency plan, standby training - not just the individual's behaviour.
Reasoning point: an H2S casualty who walks away can still deteriorate; the exam answer that stops at "give oxygen" is incomplete without the referral and the reporting.