Attendant Leaves Post During Entry
A single entrant is inside a 6 m deep vertical tank performing inspection. The attendant is stationed at the top manway with a radio and retrieval line. After 20 minutes, the attendant's radio battery dies. The attendant decides to walk to the site office, about 150 m away, to get a spare battery, leaving the manway unattended for an estimated 5-8 minutes. During that absence, the entrant reports feeling dizzy over the radio (which the entrant does not know is dead on the attendant's end) and sits down near the bottom. When the attendant returns, the entrant is not responding to voice. The entrant's personal monitor later shows oxygen at 16.5%.
1. Evaluate the attendant's decision and the entry program failures it reveals.
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The attendant must never leave the post while an entrant is inside. Leaving to fetch a battery violated the core attendant duty: continuous monitoring and communication. The program failed in several ways: no spare battery or backup communication at the post; no procedure for communication loss (which should trigger evacuation of the entrant); no second means of summoning help; and the entrant continued working without knowing communication was lost.
When communication was lost, the correct action was to order the entrant out using an alternative signal (e.g., retrieval line or voice) and to summon backup without abandoning the post. The oxygen drop to 16.5% also shows atmospheric conditions deteriorated, which continuous monitoring and communication would have caught earlier.
2. Describe the correct emergency response now that the entrant is unresponsive.
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The attendant should not enter. The attendant should raise the alarm, summon the rescue team and emergency services, and attempt non-entry retrieval using the retrieval line if the entrant is attached and it is safe to do so. The attendant should stay at the manway, keep communicating, and provide information (atmosphere, entrant condition, depth). Only trained rescuers with appropriate respiratory protection and equipment should enter. The 16.5% oxygen reading indicates the atmosphere is not safe for unprotected entry and may deteriorate further. After the incident, the program must be reviewed: backup power/communication, communication-loss procedure, rescue readiness, and attendant training.