A “chain of failures” in emergency response and process safety management led to the November 2014 deaths of four workers following a methyl mercaptan release at the DuPont Plant in La Porte, TX, according to the U.S. Chemical Safety and Hazard Investigation Board (CSB).

The root cause of the leak was a flawed engineering design and lack of safeguards, CSB said in its final report.

Factors contributing to the severity of the incident included numerous process safety management system deficiencies in auditing and corrective actions, formal process safety culture assessments, management of change, safe work practices, shift communications, and troubleshooting operations, as well as, problems with building ventilation design, toxic gas detection, and emergency response.

While DuPont had a corporate process safety management system, it was not properly implemented at the La Porte facility, CSB concluded.

November 2014 incident

Nearly 24,000 pounds of methyl mercaptan escaped through two valves in a poorly ventilated manufacturing building at DuPont’s La Porte facility on November 15, 2014. Operations personnel attempted for several days to clear blocked piping outside of the manufacturing building.

Believing there was a routine pressure problem, DuPont sent two workers into the manufacturing building to drain liquid from piping inside. Unfortunately, the pressure problem was actually related to the staff’s clearing activities.

Liquid methyl mercaptan drained from the piping, filling the building with toxic vapor. One of the workers was able to make a distress call before the two succumbed to the vapor. Both died, unable to escape from the building.

Four more operators entered the building in response to the distress call. Two of the workers succumbed to the toxic vapor and also died, two others survived.

The incident led OSHA to cite DuPont for three willful, one repeat and four serious violations and expand a National Emphasis Program for chemical facilities. The company also agreed to pay a $3.1 million civil penalty for violations of the Environmental Protection Agency’s Risk Management Program regulations.

Facility closed, lessons learned

The La Porte facility has since closed. Several lessons can be learned from the November 2014 incident about emergency planning and response, process safety management systems, and process safety culture, CSB said.

In addition to failing to effectively implement the corporate process safety management system at the La Porte facility, other problems included:

• Disorganized emergency response efforts that placed operators, emergency responders, and potentially the public at risk—chemical plants need a robust emergency response program to mitigate emergencies and protect workers’, emergency responders’, and the public’s health;
• DuPont did not formally evaluate the process safety culture at the La Porte before the November 2014 incident;
• La Porte’s personnel did not identify, prevent, or mitigate significant process safety deficiencies at the facility that contributed to the incident—a company must effectively implement a process safety management system and its corresponding programs to reap the accompanying process safety benefits; and
• The bonus structure of the employee incentive program at the La Porte facility discouraged workers from reporting injuries, incidents, and “near misses” to company management—employees must be able report injuries or incidents in accordance with regulations, without fear of discrimination, retaliation, or other adverse consequence.

Recommendations for DuPont

CSB recommended that DuPont personnel work with the other companies on the emergency response team at the La Porte Facility and the International Chemical Workers Union Council of the United Food and Commercial Workers (ICWUC/UFCW) Local 900C, as well as, national ICWUC/UFCW staff, if requested by the union local, to update the DuPont La Porte emergency response plan.

CSB said the group should:

• Assign knowledgeable personnel the responsibility for assessing process safety hazards;
• Identify technical personnel to act as unit experts, as well as, backup personnel when unit experts are not available;
• Evaluate high-hazard areas to determine whether chemical release detectors and alarms are needed;
• Detail emergency response procedures and notification protocols;
• Develop and implement written procedures for updating the emergency response plan when new hazards are identified;
• Develop maintenance schedules for maintaining emergency response vehicles;
• Ensure emergency response team members have reliable means to identify hazardous atmospheres; and
• Ensure the emergency response plan accounts for possible difficulties in carrying out emergency response efforts.