WASHINGTON D.C. – A U.S. Chemical Safety Board (CSB) case study released on the 2009 explosion and fire at the Veolia ES Technical Solutions L.L.C. facility in West Carrollton, OH, calls on the industry to improve safety standards covering hazardous waste processing, handling and storage facilities. The board also recommended that fire-protection codes be revised to require companies to determine safe distances between occupied buildings and potentially hazardous operating areas.
The accident occurred on May 4, 2009, when flammable vapor was released from a waste recycling process, ignited and violently exploded. The blast seriously injured two workers and damaged 20 nearby residences and five businesses. CSB investigators found that the north wall of the lab and operations building, where the victims were injured, was less than 30 feet from the waste recycling processing area where the flammable vapor was released.
CSB Chairman Rafael Moure-Eraso said, “This accident should not have happened. Our report notes that OSHA cited the company for inadequate attention to process safety management practices in the handling of flammable liquids. But in case of an accident, I believe it is absolutely critical that buildings at chemical facilities be sited safe distances from process equipment to maximize the safety of workers. We are making recommendations that would help ensure that operating areas with occupied buildings such as control rooms be sufficiently separated from process areas containing flammable liquids and gases that have the potential to explode.”
The Board issued a recommendation to the National Fire Protection Association (NFPA), which develops codes and standards for industry, urging NFPA to require companies to perform engineering analyses to determine safe separation distances between buildings occupied by administrative and other personnel not essential to process operations, and buildings housing the potentially hazardous process equipment.
The Board also revised a previous recommendation to the Environmental Technology Council, a hazardous waste industry trade group, to petition the NFPA to develop a standard specific to hazardous waste treatment, storage and disposal facilities. This would include guidance on reducing the likelihood of fires, explosions and releases of hazardous waste.
Moure-Eraso noted, “The Environmental Technology Council did not respond adequately to our 2007 recommendation, which we issued following an explosion and massive fire at the Environmental Quality hazardous waste facility in Apex, NC, to work for more stringent standards in the hazardous waste industry. I strongly urge the industry to act now. These facilities, by their nature, contain wide varieties of flammable and toxic materials that can cause significant injury to workers and threaten the wellbeing of nearby communities. Facility owners and operators need stricter technical requirements to improve the safety of life and property.”
The report notes that after a normal run of the tetrahydrafuran (THF) solvent recovery process at the Veolia facility, the unit operator began a routine shutdown. Completing the process required blowing nitrogen back through the circulation piping to clean it, prior to closing valves.
CSB lead investigator Johnnie Banks said, “At the time of the shutdown, witnesses reported hearing the sound of a sudden, loud vapor release and smelling a very strong odor of THF solvent, which knocked several employees to their knees. It was a matter of just a couple of minutes until the highly flammable vapor ignited.”
The vapor drifted to the laboratory and operations building and found an ignition source inside the building. A worker in the control room reported being enveloped in a fireball that went through the building. The first explosion knocked over a bank of lockers, severely injuring an employee and pinning him underneath.
Because of the extensive fire damage, the CSB was unable to conclusively determine the exact initiating event for the vapor release, concluding that one of two possible scenarios likely occurred. In the first scenario, air may have been drawn into a tank containing THF residue and peroxides, causing increased pressure in the tank and forcing flammable vapor from the tank to escape through a manway cover or a vacuum breaker.
In the second possible scenario, CSB investigators believe a line hose, intended to send pressurized nitrogen into a different tank, may have instead been connected to a tank containing unprocessed, flammable liquid. When the nitrogen was applied, it forced flammable vapor out through the tank vent. In either scenario, the vapor drifted to the operations building and ignited, causing the injuries.
In addition to issuing recommendations to NFPA and the hazardous waste industry, the board also issued recommendations to Veolia, which is rebuilding the plant. The CSB called on the company to restrict occupancy in buildings in close proximity to the operating plant to personnel trained in the safe operation and orderly shutdown of the plant. The board also called on the Center for Chemical Process Safety, a division of the American Institute of Chemical Engineers, to revise control-room siting guidelines to address the characteristics of all Class 1B flammable liquids.
CSB Issues Report on Explosion/Recommends New Safety Standards
August 1, 2010