Confined Space Entry With Expired Permit and Missing Attendant
You are the safety inspector on a night shift at a wastewater treatment plant. Two workers are inside a 3.5 m deep wet well to remove debris. The entry permit expired 20 minutes ago. The gas monitor clipped to the attendant's belt was last calibrated 45 days ago; the manufacturer's interval is 30 days. The monitor displays O2 19.5%, LEL 8%, H2S 15 ppm. The attendant leaves the top of the well to get a radio from the truck, leaving the workers inside with no hole watch. The standby rescue tripod is set up, but the rescue line is not attached to either worker's harness. The crew leader says they are 'almost done' and asks you to wait five minutes before stopping the job. The space has a known history of hydrogen sulfide ingress.
1. What immediate actions must you take, and which conditions make this a permit-required confined space emergency?
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Order immediate evacuation of the wet well. The expired permit, unattended entry, uncalibrated monitor, and O2 at 19.5% (at the lower acceptable limit and potentially below the employer's entry threshold) make the entry non-compliant. H2S at 15 ppm exceeds the typical 10 ppm action level and is a serious exposure; LEL at 8% is below 10% but not reliable on an out-of-calibration monitor. The missing hole watch and unattached rescue line remove the emergency response capability. Under OSHA 1910.146, this is a permit-required confined space; entry must stop until the permit is reissued, the monitor is calibrated, the attendant is present, and rescue arrangements are verified.
2. What should happen before re-entry is authorized?
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Before re-entry: evacuate and account for both workers; calibrate or replace the gas monitor; purge and ventilate the space; re-test oxygen, LEL, H2S, and other credible contaminants from outside; issue a new permit with a defined entry supervisor, attendant, and rescue plan; attach the rescue line and confirm the tripod and retrieval system work; brief the crew. The permit must state the actual conditions and the monitor calibration date. If H2S cannot be controlled below the entry limit, use supplied-air respirators or do not enter.
3. The crew leader asks you to delay stopping the job for five minutes. How do you handle that, and what do you document?
Read the worked answer
Refuse the delay. Five minutes is not a safe interval when the hole watch is absent and the monitor is out of calibration; the risk is uncontrolled, not scheduled. I would stop work immediately, clear the space, and notify the entry supervisor and plant safety manager. I would document the time, the observed conditions (permit expiry, monitor calibration date, readings, attendant absence, rescue line status), the names of the workers, and the stop-work instruction. The record should be factual and objective, not a negotiation. Delaying a stop-work order to avoid inconvenience would be a professional conduct failure.