On the heels of a highly critical evaluation of DuPont’s safety practices by the US Occupational Safety and Health Agency (OSHA), the US Chemical Safety Board (CSB) in a preliminary disclosure of the results of its investigation into the leak of 24,000 lbs. of methyl mercaptan at its La Porte, Texas, plant in November 2015, has delivered an equally scathing appraisal.

The LaPorte incident resulted in the deaths of four workers, two of which were opening a drain on a vent line at the time. The two other employees killed were coming to their aid.

CSB said the US chemical giant did not have adequate safety measures in place at the facility employing 300 people.  It noted that the deaths occurred inside an enclosed and unventilated building, whereby part of the production process is enclosed in a building that “appears to serve no essential manufacturing purpose.”

Housing the process equipment inside the enclosed manufacturing building introduces highly toxic chemical exposure and asphyxiation hazards to personnel that DuPont has not effectively identified or controlled, CSB added.

The investigators noted also that the ventilation system of the building, which additionally discharges toxic chemicals to the outdoors, was critical to worker safety, but was not in operation at the time of incident. Even if in use, CSB said, preliminary calculations indicate that it would not have been sufficient to avoid a lethal atmosphere.

Moreover the board said, the design of the methyl mercaptan detection system does not effectively warn workers or protect the public from toxic gas release. On the evening of the accident, the detectors picked up releases, but these were not reported, it added.

As another hazard, CSB said the liquid methyl mercaptan feed line in three locations was connected by valves to a waste gas vent heater. Finally, pressure relief systems in the insecticide manufacturing process were improperly designed so that critical chemicals are discharged to safe locations as required by industry codes and standards.

In response to the CSB report, the agency said DuPont had “verbally committed” to address its recommendations by the end of July and also to suspend the restart of the facility that had been planned for August.

According to press reports, the deaths at La Porte brought to eight the total number of fatalities at DuPont sites in the last seven years.  Four of the company's sulfuric acid plants in four states remain under a federal court order.

Meanwhile, DuPont has announced a change in safety management. Marc Doyle has been appointed senior vice president for the Safety & Protection businesses, reporting to CEO Ellen Kullman. Matthew L. Trerotola, who had been executive vice president with responsibility for Safety & Protection and Electronics & Communications businesses, as well as the company's Asia Pacific region, has resigned.