Three construction workers died when they entered a manhole Monday without taking any of the precautions needed to safely enter a confined space. The hazards of the space were readily predictable and preventable. Many workers have died in manhole entries. Any one of several key confined space safe entry procedures likely would have prevented this tragedy.
The incident occurred when a private contractor who was fixing a roadway in Key Largo climbed into a 15 foot deep hole to investigate complaints of sewage backups in the neighborhood. Reportedly the first man went in and lost contact with his coworkers above. The second worker climbed down in search of the first coworker and also lost consciousness. A third man then went down in a desperate search to find his two coworkers. A volunteer Key Largo firefighter attempted to rescue the downed workers and entered the space without an SCBA since the space was so narrow. He became incapacitated within seconds of entering. The space was later tested and found to contain elevated levels of methane and hydrogen sulfide as well as decreased oxygen levels. Atmospheric hazards in confined spaces are typically the result of material previously stored in the space, or in this case likely were the result of decaying organic material and rust.
While many news reports point to the lack of “air packs” being used as the problem, respiratory protection, such as self-contained breathing apparatus are the last line of defense to be used only after all other control measures are applied. They can rarely be used in spaces such as manholes due to the small configuration of the space.
The real reason for this incident involved the lack of confined space entry procedures that would include;
- Recognition that this was a confined space and evaluation of the atmosphere using a calibrated gas monitor
- Identification of all hazards in the space and control of the atmospheric hazards using ventilation
- Issuance of a permit by the on-site entry supervisor that included rescue procedures
If the workers had recognized that the space was a confined space and used a properly selected and calibrated gas monitor, they would have known the space was unsafe to enter. If the workers had identified the atmospheric hazard and used ventilation to remove the hazardous atmosphere, they would not have entered until the atmosphere was verified as safe to enter. Finally, if confined space entry procedures were followed, an entry supervisor would have issued a permit that would describe the hazards and control measures for the entry and would have established a non-entry rescue procedure. A non-entry rescue procedure would require the first worker to enter the space with a harness attached to rescue equipment such as a tripod/winch system so that the attendant could remain outside the space and winch the first worker to safety should the worker become incapacitated or the atmosphere become unsafe. If the confined space procedures had been established, there would be no need for the second or third worker or the firefighter to enter for rescue. These basic requirements have been present in OSHA’s confined space regulation 1910.146 for over 20 years.
In an effort to further improve confined space safety, and recognizing that confined space incidents continue to occur, the recommendations in NFPA 350 Practices for Safe Confined Space Entry and Work were established to provide more detailed information on “how to” implement the requirements in the OSHA standard. NFPA 350 explains how to select, calibrate and use the atmospheric monitoring equipment and how to ventilate a space depending on the hazard. Competencies are included for those performing various aspects of the confined space entry and a rescue procedures with pre-plans are established.
For more information you may view NFPA 350 free of charge at www.nfpa.org/350. You will also find a free 5 minute video on confined space identification as well as information about on-line and instructor lead confined space training.