The U.S. Chemical Safety Board recommended March 13 that Camp Dresser & McKee Inc. ensure that designs for methanol systems in wastewater treatment plants specify appropriate materials and comply with applicable safety standards. The Cambridge, Mass.-based firm designed the methanol piping system at the Bethune Point plant in Daytona Beach, Fla., where a January 2006 explosion was tied to workers accidentally igniting vapors from a methanol storage tank vent.
The board found that methanol piping and valves were built of polyvinyl chloride rather than steel, citing it as a contributing cause of the explosion and fire, which killed two workers and severely burned a third. It also cited use of an aluminum flame arrester on the methanol tank vent. “Methanol corrodes aluminum,” the board says.
The probe found that the explosion inside the methanol tank caused multiple PVC pipe failures on the outside of the tank. Methanol released from the pipes ignited and spread the fire. Burning methanol sprayed onto the cab of a crane, killing the operator. An employee cutting the metal roof over the methanol tank also died. Another on the roof was injured. The methanol tank flame arrester had not been inspected or cleaned since 1993, according to the report.
The board also suggested CDM recommend to all customers that they replace plastic pipe with appropriate materials and perform periodic maintenance on flame arresters. CDM has notified its customers, says a company spokeswoman. The firm also hired a former NASA fire safety expert and will take other actions based on his recommendations, she says.
Lack of proper controls for hot work at the plant was the accident’s root cause, the board says. It cited the city for not implementing adequate safety programs and called on Florida to require public employee workplace safety rules. It is one of 26 states that do not require federal OSHA standards.
The Water Environment Federation, Alexandria, Va., and the Methanol Institute, Arlington, Va., are promoting an “aggressive” methanol safety campaign at wastewater treatment plants as the board recommended, says John Lynn, institute CEO.