The Fatal Mistakes of a Cable Laying Job: Lessons Learned from a Tragic Incident

Overview

In April 2000, a seemingly routine cable-laying task turned tragic when three workers lost their lives while working on a project involving multiple manholes. This incident serves as a stark reminder of the importance of adhering to safety protocols, especially in confined spaces like manholes. Let's delve into what went wrong and the key safety lessons that emerged from this tragedy.

The Incident Unfolds

A team consisting of a supervisor and four workers arrived at a worksite to lay cables involving four manholes. After pumping water out of Manhole A, two workers proceeded to open Manhole B, located 20 meters away. As the day progressed, the team opened additional manholes, and by evening, a fatal series of events began to unfold.

The Tragic Outcome

As the work continued into the evening, three workers and the supervisor were found motionless inside Manhole A by another team member. The cause of death was later identified as asphyxiation due to the accumulation of toxic gases, specifically hydrogen sulfide, which had been released during the work in the manholes.

What Went Wrong?

• Lack of Ventilation: No mechanical ventilation was used to supply fresh air into the manholes, allowing toxic gases to accumulate.

• Accumulation of Toxic Gases: The agitation of water containing sludge released hydrogen sulfide gas, which was allowed to accumulate due to the absence of ventilation.

• No Permit for Entry: The team had not applied for a confined space entry permit, and gas checks to determine the levels of oxygen and toxic gases were not conducted prior to entering the manholes.

• Lack of Emergency Response Procedures: The workers were not equipped with necessary safety gear such as a full body harness and a lifeline, and there was no confined space attendant assigned to keep watch.

Lessons Learned

• Risk Assessment: Conducting risk assessments before starting work in confined spaces is crucial to identify and mitigate potential dangers.

• Mechanical Ventilation: Adequate purging of the space to remove hazardous contaminants is essential, followed by continuous ventilation.

• Gas Testing and Monitoring: The atmosphere inside the manhole must be tested and certified safe for entry. Workers should also carry personal gas detectors to continuously monitor the air quality.

• Confined Space Entry Permit System: Ensuring that an entry permit is valid and endorsed, and that all necessary gas checks have been conducted, is vital for safe entry.

• Emergency Response Plan: Having a well-defined emergency response plan and not rushing into a rescue without proper preparation can prevent multiple fatalities.

The tragic outcome of this cable-laying job underscores the need for strict adherence to safety protocols when working in confined spaces. By learning from such incidents, we can work towards preventing future tragedies and safeguarding the lives of workers.

For more information on the importance of confined space safety, please visit OSHA's guidelines.

Watch the original video detailing this incident.