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    Working Safely in Confined Spaces

    A couple weeks ago our Durham team completed an OSHA course entitled “Working Safely in Confined Spaces + Lockout/Tagout Procedures.” The course was held at one of the city of Durham’s municipal buildings, and other participants included folks from the construction and stormwater industry, equipment operators, and general contractors.

    A confined space is defined by three characteristics that all must be true for it to be considered “confined” by OSHA standards. The instructor explained it to us in the following way:

    • [The space] is large enough and so configured that an employee can bodily enter and perform assigned work; AND
    • Has limited or restricted means for entry and exit (for example, tanks, vessels, silos, pits, vaults, hoppers); AND
    • Is not designed for continuous employee occupancy.

    When the three conditions are met, and there is an actual or potential hazard that cannot be eliminated, the space is then deemed a “permit-required confined space.” Examples of actual or potential hazards could include atmospheric, contact with venomous animals, and the possibility of engulfment.

    When non-eliminable hazards are present, it is the responsibility of the employer to control, and, where appropriate, protect employees from permit space hazards and regulate employee entry into permit spaces. This means that documentation must be completed before the employee can “break the plane” of whatever space they will be entering. The employer must have a “permit system” in place, which is “a written procedure for preparing and issuing permits for entry and for returning the permit space to service following termination of entry.”

    For entry into a “permit-required confined space,” there are two procedures. If an atmospheric hazard is the only one present, and it is: checked first without entry and continuously monitored during entry (i.e. “sniffer”), and is controlled safe with continuous forced air (i.e. “blower”), it is called an “alternate procedure” and does not require a permit or attendant.

    A “full-permit entry” would be into a space that has the following characteristics:

    • Contains or has the potential to contain a hazardous atmosphere;
    • Contains a material with the potential to engulf someone who enters the space;
    • Has an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section; and/or
    • Contains any other recognized serious safety or health hazards.

    In this situation the employer must provide: a non-entry rescue team on-site and ready before entry; entry supervisor, authorized entrant, and attendant; additional special equipment and training is also required.

    The instructor stated that a space that is greater than or equal to 4 ft. in depth, and is 24 in. in diameter is considered a confined space. In a stormwater context, a manhole structure, underground vault, or riser structure would be examples of non-permit spaces (if conditions described above are met) that may require the potential for entrance in performing maintenance and inspection. It is often best management practice to implement a technique that achieves the same goal (maintenance, inspection) without entering into the confined space. Examples would include camera inspection, jet-vactor tools, etc. that would improve efficiency and enhance safety while performing the applicable service. For more information on Confined Space Entry, visit: