Confined Space Awareness

Although NIOSH published the Criteria for a Recommended Standard: Working in Confined Spaces in 1979 and OSHA’s Final Rule for Permit-Required Confined Spaces became effective in 1993, the annual U.S. rate of fatal injuries related to confined space entry has yet to substantially drop (according to Bureau of Labor statistics). Why?

Although there are several probable reasons for this lack of real progress in the last 34 years, one prominent reason is a tendency to simply fail to appreciate the degree of risk posed by entry into confined spaces.

The most common cause of occupational fatalities in confined spaces has been oxygen-deficient and/or toxic atmospheres. Yet, many underground vaults and tanks are not treated as posing an atmospheric hazard. Even underground facilities that have traditionally been recognized as presenting a risk from toxic atmospheres, such as those related to sanitary sewers, are still entered without recognition of the hazard, continuing to result in fatalities and OSHA violations and fines.

Other types of underground facilities, where the risk may be less obvious, may also have a hazardous atmosphere. For instance, an incident occurred in 1990, in which 3 volunteer firefighters died while attempting to assist a local resident to remove the remains of a dead animal from a well. A 9-horsepower gasoline-powered engine pump was taken mid-way down the 33-foot well, to pump water out of the bottom of the well. This resulted in a carbon monoxide level in the well that was later determined to have been approximately 13 times the IDLH (immediately hazardous to life and health) level. Startlingly, after the second of two firefighters collapsed in the well, a total of eight volunteer firefighters eventually entered over a period of 3 hours, in multiple rescue attempts. Even after it was clear that there was a severe atmospheric hazard in the well, and with SCBAs (self-contained breathing apparatus) available on the site, firefighters continued to enter the well without protection. Two of the eventual victims were rescuers.

Three years later, 2 men died in another well-cleaning operation. They failed to conduct any air testing and again used a gasoline-powered pump to remove water from the well. It was determined that they fell into the cold water and died from drowning, subsequent to carbon monoxide poisoning.

In these incidents, it may seem that the hazard was predictable, posed either by the type of space or the activities performed inside the space. However, any underground space may pose a risk from a hazardous atmosphere, especially if there are seams, cracks or an open bottom, that allow a path inward from the surrounding soil and/or groundwater. Underground conditions can be dynamic and may change without any obvious indication that changes have occurred.

In an example of this, a construction worker was overcome by carbon monoxide in a manhole that had been recently installed. Two other workers were also overcome while rescuing him and one of the rescuers died. The manhole was not, at the time, connected to any existing municipal storm sewer, sanitary sewer or water lines. Although it had been entered several times earlier that day (without air testing or incident), and did not present an obvious hazard, it was later determined that carbon monoxide had migrated through the soil from the site of an earlier underground detonation nearby. Even after the first man was down, the 2 rescuers entered without respiratory protection.

The following is another example where again there was not an obvious hazard, in which a water system operator was asphyxiated after entering an underground valve vault at a municipal water system plant. He had been assigned to turn on the water line valve and was discovered an hour later by a co-worker, who summoned help. Although municipal water works employees attested to over 200 entries into this vault without a problem, air testing subsequent to the accident showed the air in the vault to be severely oxygen-deficient.

Again, the victim had entered the vault without first ventilating or testing the air. Rescuers did use ventilation and entered with SCBAs. However, 3 hours later, a city detective and police officer attempted to enter the vault with assistance from a water system plant employee. They did not ventilate or test. After experiencing chest tightness and difficulty breathing, they came back out (having made, between them, 3 attempts at entry). Although a fatality had occurred in the space only 3 hours earlier, and there was no urgency at that point as there would be to rescue a person down, still they failed to recognize and address the potentially hazardous atmosphere in the space.

NIOSH investigators later determined that gases from a sewage dewatering pit had entered the vault when the water table rose to an elevation just beneath the concrete floor in the bottom of the vault, forcing gases normally trapped deeper within the surrounding soils toward the surface. These gases had filled the valve vault, displacing oxygen. Even after the space was ventilated during the rescue, the gases began again to infiltrate, resulting in the chest tightness experienced by the people who attempted to enter later in the day.

Prior to entry into a confined space, use OSHA’s two-stage definition to determine whether it is a permit-required confined space and the required steps to ensure safe entry. The first stage of the definition is to determine whether the space is a “confined space”, meaning that it is large enough to bodily enter, is not designed for continuous human entry, and has restricted means for entry or exit. The second stage is to determine whether there is a potential hazard, including toxic, flammable or oxygen-deficient atmospheres, mechanical hazards, engulfment hazards, tapered floor or inwardly converging walls, electrical hazards, and heat or steam hazards.

Train employees in the confined space hazards they may encounter. Where entry into underground spaces is necessary, don’t underestimate the dynamic and potentially changing nature of conditions underground.

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ABOUT THE AUTHOR: Michelle Copeland
Michelle Copeland is a Certified Industrial Hygienist in Seattle, WA who has worked in the field of occupational safety/health for 35 years and been a CIH since 1986.

In private industry, she did long-term strategic safety planning, program/training development and implementation, auditing, coaching/counseling, accident investigation, data analysis/presentation, and coordination with plant supervision, employees and contractors. Her work instituting a competency-based program resulted in significantly improved production, with reduced injury rates and employee turnover. As a consultant, she has worked in general industry, maritime, and mining, and on multi-employer construction sites. She has been self-employed since 1999.

She has also provided expert witness assistance on topics related to occupational safety and health, working for both defense and plaintiff’s attorneys, as well as for OSHA directly. She has provided testimony before a jury in both civil and criminal cases.

Copyright Michelle A. Copeland, CIH - Occupational Safety Resource Inc.

Disclaimer: While every effort has been made to ensure the accuracy of this publication, it is not intended to provide legal advice as individual situations will differ and should be discussed with an expert and/or lawyer.For specific technical or legal advice on the information provided and related topics, please contact the author.