Ensuring safety in and around manholes involves understanding confined space entry procedures, using proper personal protective equipment (PPE), and following safety protocols.
Before the manhole cover is removed and work begins, first determine if the manhole is a permit-required confined space.
A permit-required confined space (PRCS) is a confined space with one or more of the following characteristics: 1) contains or has a potential to contain a hazardous atmosphere, 2) contains a material with the potential for engulfment, 3) has an internal layout that could trap or asphyxiate someone inside, and/or contains any other serious physical or health hazard.
There are many things that can go wrong when working in a manhole. Most incidents will be caused by these dangerous scenarios:
- Workers are not trained to recognize confined space hazards and to take protective measures.
- The atmosphere in a manhole is not assessed to see if conditions are safe before or during entry.
- Proper ventilation is not used to control atmospheric hazards in a manhole.
- Protective and emergency equipment is not provided at the worksite.
- An attendant is not stationed outside a manhole to monitor and call for emergency services.
Personal protective equipment (PPE) is essential when working in manholes. Required PPE may include:
- Hard hats to protect from falling objects
- Safety goggles or face shields to prevent eye injuries
- Gloves to protect hands from sharp objects and contaminants
- Protective clothing to prevent exposure to hazardous substances
- Steel-toed boots for foot protection
- Respirators if harmful gases or insufficient oxygen is detected
Before entering a manhole ensure all safety equipment is inspected and in good working condition. Eliminate any conditions (example: high pressure) that could make it unsafe to remove the cover. If needed, ventilate the space using fans or blowers to ensure a safe atmosphere.
OSHA Standards 1910.146(d)(9) and 1926.1204(i) Develop and implement procedures for summoning rescue and emergency services, for rescuing entrants from permit spaces, for providing necessary emergency services to rescued employees, and for preventing unauthorized personnel from attempting a rescue.
Always have a rescue plan in place with a designated attendant outside the manhole to monitor the situation and respond to emergencies.
Confined spaces like manholes can have limited entry and exit points, poor ventilation, and potential for hazardous atmospheres. Perform pre-entry testing for oxygen content, flammable gases and vapors, and potential toxic air contaminants.
OSHA Standard 1910.146(d)(5)(iii) and 1926.1204(e)(3) When testing for atmospheric hazards, test first for oxygen, then for combustible gases and vapors, and then for toxic gases and vapors.
In a confined space, like a manhole, changes in atmospheric conditions over time might be due to organic matter like dead plants, animals, or animal waste products that decay in the soil using up oxygen and producing hazardous gases like carbon dioxide and hydrogen sulfide.
Although conditions within these spaces could seem acceptable during initial entry, atmospheric changes could occur over time and result in fatalities. Eliminate or control atmospheric hazards by ventilating, purging, inerting, or flushing the manhole as necessary.
After entering a manhole that is classified as a permit-required confined space workers inside must maintain constant communication with the attendant. If needed, use radios or other communication devices to stay in contact.
OSHA Standard 1910.146(d)(6) and 1926.1204(f) Provide at least one attendant outside the permit space into which entry is authorized for the duration of entry operation.
Ensure there is proper lighting provided inside the confined space to avoid tripping and falling hazards. Be aware of the surroundings and any potential for flooding or engulfment.
Use appropriate tools and equipment designed for confined spaces. This includes non-sparking tools to avoid igniting flammable gases and insulated tools to prevent electric shocks. Follow lockout/tagout procedures to ensure that no machinery can start while workers are in the manhole.
Continuously monitor the atmospheric conditions to ensure safety throughout the duration of the work. Stay alert and aware of any changes in conditions while working in the manhole. Report any unsafe conditions or incidents immediately.
Manholes are often located in high-traffic areas, posing additional risks to workers due to the proximity of moving vehicles and pedestrians. Wear high-visibility clothing to be easily seen by drivers and other workers.
Be mindful of the risks associated with working in or near traffic. Use barriers, warning signs, and cones to divert vehicular and pedestrian traffic away from the work area.
OSHA Standard 1910.146(c)(5)(ii)(B) and 1926.1203(e)(2)(ii) When entrance covers are removed, the opening must be immediately guarded by a railing, temporary cover, or other temporary barrier that will prevent an accidental fall through the opening and that will protect each employee working in the space from foreign objects entering the space.
When manhole work is required, maintain a safe job site both for those inside the confined space and for those working or passing by the area. Ensure the work area is clearly marked and secure. Workers inside the manhole must be protected from external hazards and falling objects.
To protect pedestrians from the hazard created by an open manhole, erect a sturdy barrier or guardrail around the opening to prevent accidental falls.
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