Dizzy Helper and a Gasoline Pump in a Basement Sump Pit
A four-person crew is converting a basement pump room in an occupied six-storey office into a sump pit. The pit is 1.2 m deep and 0.8 m wide, left open overnight with about 150 mm of stagnant water at the bottom. A gasoline-powered transfer pump runs beside the pit; its exhaust discharges inside the room. The only outside opening is a stair door roughly 8 m away. A temporary 230 V extension cord crosses the wet floor to a clip-on light, and the cord's outer insulation is nicked about 300 mm from the plug. At 10:15 a.m. a helper reports headache and dizziness. The leadman wants the crew to finish pouring the 100 mm pit base before lunch. There is no gas monitor on site, and the permit-to-work book is in the site office. The basement has no mechanical ventilation, and other trades are working 15 m away.
1. List the immediate actions you would take in the first 10 minutes, in priority order, and explain the reasoning behind the order.
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Priority is life safety, then ignition and exposure control, then property and schedule.
- Stop all work and tell everyone to leave the basement by the nearest exit. Do not send anyone back for tools.
- Move the affected helper to fresh air, keep him seated, and call emergency services; do not let him drive. Note the time and symptoms.
- From outside the space, shut off the gasoline pump if it can be done without entering; do not operate electrical switches or the extension cord in the basement.
- Barricade the stair door and post a standby person. No re-entry until the air is tested and the source is controlled.
- Notify the site safety officer and building manager; isolate the temporary power at the panel.
Reasoning: carbon monoxide from the pump is the likely cause of the headache and dizziness, and the damaged cord adds shock and ignition risk. Rescue must not create a second casualty. The schedule is irrelevant until the atmosphere is proven safe.
2. Identify four hazards in the setup and match each with a control, stating where the control sits in the hierarchy of controls.
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Four hazards and controls, in hierarchy order:
- Carbon monoxide from the gasoline pump (eliminate/substitute): remove the pump from the room and use an electric transfer pump supplied from a GFCI-protected circuit, or pipe the exhaust outdoors. This eliminates the source rather than masking it.
- Damaged extension cord on wet floor (eliminate/engineering): remove the cord from service, inspect and tag it, use a GFCI and cable ramps, and keep connections out of water. Replacing the cord is an engineering control; wearing rubber gloves alone is not enough.
- Open pit (engineering): fit rigid guardrails and toe boards or a load-rated cover, and mark the opening. A barricade is not a substitute for a cover when materials are being moved.
- Stagnant water and biological growth (administrative/PPE): pump out, clean and disinfect, provide wash facilities, and issue gloves and boots. PPE is last because it does not remove the exposure.
Housekeeping and a pre-task briefing support all four, but they do not replace the higher-order controls.
3. What must be verified before work resumes, and what records would you require?
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Before resumption I would require: a gas test for carbon monoxide, oxygen and flammable gas at the bottom and at breathing height, recorded by a competent person; mechanical ventilation running long enough to clear the space; the gasoline pump removed and the temporary power inspected; guardrails or a cover on the pit; a permit-to-work signed by the site safety officer; a rescue plan and a standby person; and a toolbox talk covering the incident. The helper should not return until medically cleared.
Records: incident report, gas test log, electrical inspection tag, permit, corrected housekeeping checklist, and the names of the persons who authorized re-entry. If the atmosphere cannot be maintained, the work should be re-planned, not rushed.