Tannery Workers Killed by Hydrogen Sulfide

Two workers died trying to fix a wastewater valve housed in a manhole. Tannery workers routinely entered the manhole to waist height to adjust the flow by turning a wheel, but the atmosphere below was deadly.

The victims were to fix a cracked pipe in the manhole. Investigators say the first victim descended into the confined space and collapsed almost immediately. The second worker entered in a rescue effort but was also overcome.

At lunchtime, the foreman saw the second worker in the manhole, but couldn’t see the first man, submerged in water at the bottom. The foreman climbed in, but grew dizzy and exited, calling for help. Five other workers, including a worker with breathing apparatus, also tried unsuccessfully to help. The victims were pronounced dead at the scene.

The foreman spent two days in hospital and the other four who attempted the rescue were released almost immediately. But all could have died in the same way the first two men did.

The employer had written rules for manhole entry, but they weren’t enforced. Make sure your safety policy isn’t just a piece of paper. And always test the air in a confined space. After the incident the company moved the valve control wheel above ground. If a process cannot be made safer, engineering out unnecessary hazardous exposures should always be the next choice. Could a dangerous process be made safer in your workplace?

Source: National Institute for Occupational Safety and Health, Fatality Assessment and Control Evaluation (FACE) Program, Case Report 8928