CSB Report Lists Multiple DuPont Failures Behind LaPorte Deaths

"Our investigation revealed a long chain of failures which resulted in this fatal event, including deferring much-needed process improvements, improvements that could have prevented the toxic release," said CSB Interim Executive Dr. Kristen Kulinowski.

The U.S. Chemical Safety Board on June 25 released its final investigation report into the Nov. 15, 2014, methyl mercaptan release at the DuPont plant in La Porte, Texas, that killed four workers. The report lists numerous weaknesses and failures by the company as contributing to the incident, in which nearly 24,000 pounds of highly toxic methyl mercaptan escaped through two valves in a poorly ventilated manufacturing building at the facility.

The investigation found that, for several days prior to the incident, operations personnel tried 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. But the pressure problem was actually related to the clearing activities. Liquid methyl mercaptan drained from the piping, filling the manufacturing building with toxic vapor. Although one of the workers made a distress call, both died. Four additional operators responded to the distress call and entered the manufacturing building. Two of them also died, while the other two survived.

According to the report's executive summary, the cause of the methyl mercaptan release was the flawed engineering design and the lack of adequate safeguards, and contributing to the severity of the incident were "numerous safety management system deficiencies, including deficiencies in formal process safety culture assessments, auditing and corrective actions, troubleshooting operations, management of change, safe work practices, shift communications, building ventilation design, toxic gas detection, and emergency response. Weaknesses in the DuPont La Porte safety management systems resulted from a culture at the facility that did not effectively support strong process safety performance."

The building's ineffective ventilation system was not addressed after DuPont auditors identified it as a safety concern about five years before the incident, according to the report, and at the time of the incident, neither of the manufacturing building's two rooftop ventilation fans was working, despite an "urgent" work order written nearly a month earlier. "Even had the fans worked, they probably would not have prevented a lethal atmosphere inside the building due to the large amount of toxic gas released," the report states.

"Our investigation revealed a long chain of failures which resulted in this fatal event, including deferring much-needed process improvements, improvements that could have prevented the toxic release," noted CSB Interim Executive Dr. Kristen Kulinowski.

The plant has since been closed, but the board noted that the incident offers important lessons for the chemical industry that relate to emergency response, DuPont's process safety management system, and DuPont La Porte's Employee Incentive Program. On page 119 of the report, the board describes that system as a variable compensation (bonus) system called the La Porte Local Performance Based Compensation program. It did not use process safety management performance metrics, instead using a safety modifier based solely on OSHA total recordable injuries, "and it was constructed in a way that could have potentially disincentivized reporting injuries," the report states.

"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," Kulinowski said.

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