The US Chemical Safety Board (CSB) has released its final investigation report into a fatal chemical leak which killed four workers in November 2014 at the DuPont Plant in La Porte, Texas. The report, released on June 25, revealed that a number of safety deficiencies led to the release of methyl mercaptan and the subsequent death of four workers.
The CSB’s report highlights a chain of failures that cumulatively led to the incident as well as key lessons relating to emergency planning and response, process safety management systems, and process safety culture.
Lead CSB Investigator Tamara Qureshi said, “The CSB’s investigation determined that the cause of the toxic chemical release was a flawed engineering design and the lack of adequate safeguards. Contributing to the severity of the incident were numerous safety management shortcomings including deficiencies in formal process safety culture assessments, auditing and corrective actions, and troubleshooting operations.”
A key lesson from the 2014 incident, according to the report, was the disorganised emergency response to the chemical release which placed workers, operators, responders and potentially the public at risk.
Furthermore, despite DuPont having its own corporate process safety management system, the La Porte facility failed to effectively implement it, nor did it formally evaluate its process safety culture prior to the incident. Furthermore, the process safety management system did not identify, prevent, or mitigate significant process safety deficiencies at the plant which contributed to the leak of methyl mercaptan.
The DuPont La Porte bonus structure may have also disincentivised workers from reporting injuries, incidents, and “near misses.” The CSB says that ensuring employees can report injuries or incidents in accordance with regulations, without fear of discrimination, retaliation, or other adverse consequence is central to protecting worker safety and health, and aiding accident prevention.
Four workers died in the incident after almost 24,000 pounds of methyl mercaptan escaped through two valves in a poorly ventilated manufacturing building. For several days leading up to the leak, operations personnel attempted to clear blocked piping outside of the manufacturing building. In response to what personnel believed was a routine, unrelated pressure problem, two workers went to drain liquid from piping inside the manufacturing building. Unfortunately, the pressure problem was actually related to the clearing activities. Liquid methyl mercaptan drained from the piping, filling the manufacturing building with toxic vapour. Although one of the workers made a distress call, both died, along with two additional workers who were responding to the call.
The CSB’s Interim Executive Dr. Kristen Kulinowski said, “Process safety management is a critical tool for safe and efficient operations at any facility. This is a textbook example of the catastrophic consequences when process safety management is inadequately implemented and monitored.”