Establishing root cause after an incident involving hazardous chemicals

May 8, 2019 Posted by Walter Ingles

A worker slips and grabs the side of a chemical tank to catch his fall, he loses his balance and his hand is immersed in acid. Maybe he was running because they were behind production schedule that day. Or maybe he was walking but didn’t see the ‘wet floor’ warning signs due to poor lighting. Maybe it was both. Dangerous incidents involving hazardous chemicals in the workplace rarely have a single isolated cause, and to uncover all the contributing factors you need a systemised process.

This blog follows on from our post How to compile an ‘Incident Sequence’ in a HAZCHEM incident investigation and provides a simple methodology for establishing the root causes of Dangerous workplace incidents (especially if hazardous chemicals were involved).

Identifying system failures

If you have been conducting a thorough HAZCHEM incident investigation you will have already gathered and collated a range of physical evidence, witness testimony, and supporting documentation. You should have also compiled an ‘Incident Sequence’ which lists in order, every event which contributed to the incident. Here’s a quick example:

  1. WORKER A is asked to check the main light switch in the chemical store.
  2. WORKER A walks into the chemical store and heads to the gas bottle cage.
  3. WORKER B calls out to WORKER A.
  4. WORKER A turns around to answer but keeps walking.
  5. A gas bottle trolley containing a cylinder of acetylene is sitting in front of the gas bottle cage. It is not visible because of the lighting failure.
  6. With his head turned back to WORKER B, WORKER A collides with the gas bottle trolley.
  7. The cylinder of acetylene has not been strapped in properly and falls off. It explodes.
  8. WORKER A is seriously injured in the explosion.

To get to the root causes of this incident you’ll now be looking through the incident sequence and identifying everywhere a system failure occurred. Sometimes this exercise highlights gaps in your understanding and requires you to review your evidence or re-interview witnesses.

Let’s say in this example you identify 3 x system failures. First, the fact that the main light is out and there appears to be no backup lighting. Second, the gas bottle trolley left in a walkway is now a tripping hazard. Third, the acetylene cylinder not strapped in correctly.

NOTE: There are probably other system failures but this is merely an example to demonstrate a process.

Applying a causation model

We now recommend applying a causation model to each of the system failures. Even a simple causation model (like the one we illustrate below) opens up the way you think about an incident and helps you identify contributing factors from all facets of the business. Our causation model opens up a line of questioning in five different areas.

Simple causation model

1.

TASK

Considers the actual task and work procedures being carried out when the incident occurred.

   

Was a safe work procedure being followed correctly? Was it appropriate to the task? Were there any changes to the way the task was being carried out? Was all the equipment necessary to perform the task available?

2.

MATERIAL

Focuses on the machinery, tools, PPE, chemicals, and substances being used during the incident.

   

What machinery was being operated at the time? Did any equipment fail? Had maintenance been carried out? What chemicals were involved? Where were the Safety Data Sheets (SDS)? Were all labels and placards in place? Were workers using any makeshift tools?

3.

ENVIRONMENT

Looks at the weather, time of day, housekeeping and other environmental factors.

   

How was the weather at the time of incident — rain/heat/snow/wind? Was there enough lighting? Could the worker have been impacted by hazardous dust, vapours, or fumes?

4.

PERSONNEL

Identifies individual people involved and looks at things like their training, experience, fitness, and state of mind.

   

Were the workers involved tired, stressed, or under pressure to meet a deadline? Had workers been trained? Was there any history of poor performance? Were they physically capable of doing the work?

5.

MANAGEMENT

Examines the impact of management and their overall approach to chemical safety, supervision, and compliance.

   

Was there enough supervision? Had workers received proper safety inductions and follow up training? Were written procedures in place and understood by workers? Had risk assessments been carried out? Were there any issues of non-compliance at the scene of the incident?

Establishing root causes

To demonstrate how the causation model could work during your own HAZCHEM incident investigation, let’s apply it to one of the system failures we identified in our earlier example.

Acetylene cylinder not properly strapped to the gas bottle trolley.

1.

TASK

There was a broad work policy requiring cylinders to be secured using the straps on the gas bottle trolley. The procedure was not specific and did not include any post-operation checks to ensure cylinders were actually secure.

2.

MATERIAL

The safety straps on the gas bottle trolleys were faulty and did not adequately secure the cylinder. The trolley had never been inspected for integrity/maintenance since it was purchased 2 years earlier.

3.

ENVIRONMENT

The lighting had failed in the chemical stores and the trolley had been put away in the dark. The worker assumed the cylinder was secure.

4.

PERSONNEL

The worker claims to have strapped in the cylinder. The worker had been using the same trolley for 2 years and assumed it was safe. On the day of the incident they were behind in their work schedule and in a hurry to get back to the production floor.

5.

MANAGEMENT

There were no procedures in place for workplace audits, inspections, and integrity testing of equipment.  Supervisors had never checked to see if workers were actually following procedures when placing gas cylinders on trolleys.

Even though our example is fictional, it still gives you the idea that a system failure often has a range of contributing factors. And from different areas of the business. In a real incident investigation you would apply the causation model to each system failure then list each causal factor for discussion by the investigation team. The team would begin to look at corrective actions.

 

Any questions, comments or queries? Feel free to contact one of our friendly team here.  Alternatively, you can call us on our support line: 1300 134 223

Walter Ingles

Walter Ingles Compliance Specialist

Walter is STOREMASTA’s Dangerous Goods Adviser. He loves helping businesses reduce the risk that Dangerous Goods pose upon their employees, property and the environment through safe and compliant dangerous goods storage solutions.

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