On the morning of June 14, 2006, an operator was mixing and heating a flammable mixture of heptane and mineral spirits in a 2,200-gallon open top tank equipped with steam coils. The finished product, ‘Super Clean and Tilt’ is a proprietary mixture, which is applied to cured concrete surfaces to prevent bonding with wet concrete.

As the operator was adding an ingredient to the batch, he observed a ‘dense fog’ accumulating on the floor below the tank. He immediately notified a senior operator who helped him shut down the operation. They both exited the building and advised workers in adjoining areas to leave.

As the vapor cloud spread throughout the mixing area and surrounding workspaces, other employees exited the building.

Within about 10 minutes after the operator first observed the vapor cloud, most employees who were working in the area had evacuated. A contracted delivery driver passed some of these employees as he walked into the building and into the spreading vapor cloud. The cloud ignited within seconds of him entering. The driver died several days later from the burns he received.

The pressure created by the ignition blew the doors open to an adjacent area, injuring a temporary employee. This employee suffered second-degree burns and was hospitalized for three days. .

KEY ISSUES:
• FLAMMABLE LIQUID PROCESS DESIGN
• ENGINEERING CONTROLS
• PLAN REVIEW & CODE ENFORCEMENT
• EMERGENCY PREPAREDNESS

ROOT CAUSES:
1. The process was not designed and constructed in accordance with fire safety codes and OSHA regulations.
2. The Fire Department did not require UFC to comply with critical safety requirements (local exhaust and floor level ventilation)
3. The facility was unprepared for an emergency release of this magnitude.

Image credit: CSB