What Happened

The plant was producing a specialized explosive for the mining industry. Operators were experiencing persistent problems with the mixing process for the new explosive compound. The mixture was unusually sensitive and difficult to control. Despite these ongoing issues, production continued. On the day of the incident, a small spark or friction event during mixing triggered a detonation that leveled the building.

Root Causes

The CSB investigation identified two major failures:

• Lack of Sensitivity to Operations: Operators and supervisors repeatedly observed extended operating problems (unstable mixture, difficulty controlling the process) but treated them as normal variations rather than serious warning signs. No one systematically investigated why the process was behaving differently.
• Poor Management of Change: The plant had recently switched to a new, more sensitive explosive formulation. This significant process change was not properly evaluated through a formal Management of Change (MOC) process. Hazards associated with the new chemistry were not fully identified or mitigated.

The Sherlock Holmes Lens

A Sherlock Holmes approach would have treated the repeated operating difficulties as important clues, not routine annoyances. Instead of accepting the unstable mixture as “just how it is,” investigators would have asked:

• Why is the new formulation behaving differently?
• What has changed, and what are the new hazards?
• What data should we collect to understand this anomaly?

By failing to investigate these subtle signals, the organization missed multiple opportunities to prevent the explosion.

Key Lessons Learned

• Sensitivity to Operations requires actively noticing and investigating anything unusual — even small, recurring problems.
• Management of Change must be applied rigorously to any modification in chemistry, process, or materials.
• Repeated operating difficulties are often early warnings of a larger problem.
• Changes that affect process safety must be evaluated under all expected conditions, including abnormal operation.

Practical Recommendations

• Treat recurring operational problems as leading indicators and investigate them thoroughly.
• Apply formal MOC to any change in raw materials, formulation, or process conditions.
• Encourage a culture where operators feel safe raising concerns about unusual behavior.
• Use the “Sherlock Holmes” mindset: ask “What exactly changed?” and “Why is this happening?”

Call to Action

Review your own operations through the Sherlock Holmes lens. Are you truly paying attention to small anomalies and changes? Are all process changes — even seemingly minor ones — rigorously evaluated? What is one practical step your team could take this quarter to improve sensitivity to operations and management of change?

References

U.S. Chemical Safety Board (CSB) Investigation Report: Sierra Chemical Company Explosion Klein, J.A., “The ChE as Sherlock Holmes: Investigating Process Incidents,” Chemical Engineering Progress, October 2016