scope:

Description of Driving Event:

A 55-gallon drum of paint wastes subsequently ruptured after being overpacked into an 85-gallon salvage drum due to leakage from the original drum. Pressure had built up inside the drums to the point where both the inside drum and recovery drum burst, propelling the drums 26 feet in the air, at which point it dented the roof and spilled hazardous waste into the containment area. The incident occurred late at night and no personnel were injured or exposed.

Primary Cause: The waste stream contains a mixture of solvent-base paints and cleanup solvents. None of the vapor pressures of the waste components were great enough to cause failure of the drum. The pressure build-up was likely due to a chemical reaction producing a gaseous product. Polyurethane paint components of the waste stream contain isocyanate compounds which react with water to produce carbon dioxide. Although there were no accounts of water-based paints being added to the drum, the generator also uses latex paints, and some may have been accidentally added to the drum. The drum was routinely opened and closed during waste accumulation allowing release of the pressure. It was only when the drum was sealed for storage that pressure increased to deform and eventually rupture the drum.

Contributing Factors: The bulging condition of the original 55-gallon drum was first noticed at a hazardous waste storage facility. The drum was overpacked into an 85-gallon recovery drum to correct the container condition deficiency, but the facility operator was unaware that the drum was continuing to build pressure. The 85-gallon salvage drum then obscured the condition to the hazardous waste shipper, transporter, and offsite receiving facility.

Root cause: 1) Commingling reactive paint chemicals in a sealed, nonpressure vessel container.

Contributing causes: 2) Lack of root cause analysis and corrective action implementation upon initial discovery of bulging 55-gallon drum. 3) Obscuration of problem progression due to overpacking of bulging container.