According to CSB, the June 14, 2006, explosion occurred when hazardous vapors – generated by overheating a flammable liquid in an open-top tank – ignited.

CSB said that the Universal Form Clamp plant process was not designed and constructed in accordance with fire safety codes and OSHA standards, which required – among other things – that the plant have a ventilation system to control flammable vapors. Investigators also determined that UFC was unprepared for an accidental chemical release of this magnitude, did not have an emergency action plan and had not conducted an evacuation drill.

“This accident could have been avoided had the company complied with OSHA and NFPA fire safety standards, which require engineered safety controls such as local exhaust and floor-level ventilation systems,” CSB lead investigator Randy McClure said. “In addition, there likely would have been no fatality or injuries had the company installed an employee alarm system, put adequate emergency action plans in place and conducted regular emergency drills so that employees knew what to do in an emergency.”

UFC manufactures hundreds of products for the concrete industry, according to CSB, and added the chemical mixing area to produce two specialty products in 2002 and 2003.

No Alarm System to Warn Employees

According to CSB, the mixture likely overheated because a mixing tank temperature controller was not installed or maintained in accordance with the manufacturer's specifications, causing it to malfunction.

As the temperature of the flammable mixture increased to its boiling point, vapors overflowed the open-top tank and spread along the floor throughout the mixing area and surrounding workplaces.

According to CSB, a worker notified a senior operator of the vapor cloud, and the operation was shut down. Both men exited the building and advised workers in the adjoining areas to leave. Other workers left because they saw or smelled the vapor cloud.

According to the agency, there was no alarm system to warn employees to evacuate.

Driver Died From Burns

A delivery driver, unaware of the hazard, walked into the building past employees who had left the building. According to CSB, witnesses said they attempted to alert him to the presence of the vapor cloud but said he was talking on a cell phone and may not have heard them.

Shortly after the driver walked into the area, the vapor cloud ignited – creating a large fireball. The driver died several days later from burns.

A temporary employee in an adjacent area – unaware of the hazard – suffered second-degree burns and was hospitalized. A third employee suffered a minor injury to his arm.

CSB determined that mechanical design plans that should have illustrated ventilation and other safety systems were not reviewed by a registered design professional before being submitted to the village of Bellwood. In addition, Bellwood, during its 2002 review of the project, did not ensure compliance with required codes and standards, CSB said.

“The CSB case study cites several lessons learned that we believe could help prevent accidents at similar facilities if studied and applied,” CSB member Gary Visscher said. “These include the importance of having qualified professionals manage the design and construction of facilities using flammable liquids, the need for comprehensive building permit code reviews and the need for emergency action plans.”

A UFC spokeswoman told OccupationalHazards.com that the company has no comment on the CSB report at this time.

Recommendations Made to OSHA

CSB made two recommendations to OSHA regarding its emergency action plan requirements. The first recommends that OSHA amend its Flammable and Combustible Liquids standard to require facilities that handle these liquids to implement the requirements of its Emergency Action Plans standard. As it is currently written, the Flammable and Combustible Liquids standard covers technical issues pertaining to facility design but does not contain a requirement for companies to have Emergency Action Plans.

Additionally, CSB recommended that OSHA amend the Emergency Action Plans standard to require employers to conduct practice evacuation drills at least annually, but more frequently if necessary to ensure employees are prepared for emergencies. Currently this standard does not specifically require such drills or rehearsals.