Safe Practices for Working in Confined Spaces
Occasionally, you may be required to do your work in a manhole or vault. If this is the case, there are some special safety considerations that you need to be aware of.
A confined space includes (but is not limited to) any of the following: manhole, boiler tank, trench (four feet or deeper), tunnel, hopper, bin, sewer, vat, pipeline, vault, pit, air duct, or vessel. A confined space is identified as follows:
• It has limited entry and exit.
• It is not intended for continued human occupancy.
• It has poor ventilation.
• It has the potential for entrapment / engulfment.
• It has the potential for accumulating a dangerous atmosphere.
Confined Space Hazard Review
Before determining the proper procedure for confined space entry, a hazard review shall be performed.
The hazard review shall include, but not be limited to the following conditions:
• The past and current uses of the confined space
• The physical characteristic of the space including size, shape, air circulation, etc.
• Proximity of the space to other hazards
• Existing or potential hazards in the confined space, such as atmospheric conditions (oxygen levels, flammable / explosive levels, and/ or toxic levels)
• Presence / potential for liquids
• Presence / potential for particulates
• Potential for mechanical / electrical hazards in the confined space ( including work to be done)
Once the hazard review is completed, the supervisor, in consultation with the project managers and / or safety manager, shall classify the confined space as one of the following:
• A nonpermit confined space
• A permit-required confined space controlled by ventilation.
• A permit-required confined space
Once the confined space has been properly classified, the appropriate entry and work procedures must be followed.
Tunnels, shafts, chambers, and passages located underground have their own special safety requirements. Because underground workspaces are completely enclosed except for access and equipment tunnels, the results of an accidental release of gas, fire, and other hazards are magnified:
Click on each button to know more:
Before going underground …
… ensure that the proper safety precautions are in place both above-ground and in the workspace.
When underground …
… familiarize yourself with the location of safety equipment, potential hazards, and escape routes. Be prepared, so that in an emergency you can take the correct action immediately to protect yourself and your co-workers from injury and death.
Employers are responsible for ensuring that their employees who work underground receive proper training on underground hazards and safety.
This training includes the following elements when appropriate: access, air monitoring, ventilation, illumination, communication, PPE, explosives, fire prevention and protection, emergency procedures
The next slide gives a brief introduction of these elements.
Click on each essential requirement for underground safety to know more:
There should be access shafts for personnel and equipment. Hoisting mechanisms are used in shafts to provide access to workers. These hoists must be able to operate safely and effectively in an emergency. They must be able to operate even if the power fails in the rest of the underground workplace.
Independent power sources for personnel hoists should meet all safety requirements for the underground workspace.
Air Monitoring and Ventilation
Fresh air must be supplied to underground work areas in sufficient quantities to prevent the build-up of harmful dust, fumes, mist, vapors, or gases.
Use only approved lighting requirements when working underground.
All employees working underground should have a portable lamp for emergency use.
Use radios, walkie-talkies, or other approved communications equipment when voice communications are not effective within the workspace or between the workspace and other surface.
Ensure that powered communications systems are able to operate even if one of the units breaks down. Test radios and other communications equipment before going into the underground workplace.
Personal Protective Equipment
All plumbers should wear proper PPE. Ensure that all respirators and other safety equipment are properly maintained according to the manufacturer’s specifications.
Explosion and Fire Hazards
Open flames and fires are not permitted underground. Smoking is also prohibited, and all ignition sources, such as matches and lighters, must be collected before workers are allowed to descend underground.
Ensure that appropriate warning signs are posted where fire and explosion hazards are present.
Employers must ensure that rescue teams are on site or are available to respond to an emergency within 30 minutes.