The explosion occurred Jan. 11, 2006, at the Bethune Point Wastewater Treatment Plant, owned and operated by the city of Daytona Beach. Two municipal workers were fatally burned and a third suffered grave injuries.
According to CSB, the explosion occurred inside a methanol tank when the lead mechanic and another worker were cutting the metal roof directly above the tank vent. Sparks showered down from the cutting torch and ignited methanol vapors coming from the vent, creating a fireball on top of the tank.
The CSB report states that the city of Daytona Beach has no program at city facilities to control hot work such as the use of cutting torches.
“This accident emphasizes the need for effective hot work programs, hazard communication and careful engineering of flammable liquid systems,” CSB member William Wright said. “If these measures had been in place this accident likely could have been prevented.”
CSB: Safety Policies Should Be as Tough as OSHA Standards
CSB is recommending that the Florida governor and legislature enact legislation to implement policies, practices and procedures covering workplace health and safety for Florida public employees. Such policies and procedures, CSB says, should be at least as effective as those established by OSHA. Florida is one of 26 states that do not require public employees to follow OSHA standards.
CSB also recommends that, until appropriate state laws are in place, the city of Daytona Beach adopt city ordinances to require departments to implement policies, practices and procedures for city employees to be at least as effective as relevant OSHA standards. According to CSB, these should include emphasis on compliance with industrial chemical safety standards such as hot work procedures.
“It is important for the state of Florida and the city of Daytona Beach to protect its employees from tragic accidents like this by promptly enacting new safety rules,” said Robert Hall, PE, CSB's lead investigator for the incident.
An additional recommendation was directed to the plant's methanol piping system designer, Camp, Dresser & McKee Inc., to ensure that wastewater treatment plant designers are aware of the importance of selecting the proper materials for flammable liquid piping.
CSB also made a recommendation to OSHA and to the National Fire Protection Association to revise their standards and codes to further restrict the use of plastic piping for flammable liquid service.
Safety Device Had Not Been Inspected or Cleaned
According to CSB, the agency's investigation found that the explosion inside the methanol tank caused multiple failures of polyvinyl chloride (PVC) piping located on the outside of the tank. Methanol then discharged from the failed pipes, ignited and burned – spreading the fire.
The burning chemical sprayed onto the cab of a crane near the tank, CSB says. The worker inside the crane was one of the two workers who were killed. The other worker who was killed was working over the methanol tank. A third employee also working over the tank was severely injured but survived.
According to CSB, the tank's aluminum flame arrester – a safety device designed to prevent flames from entering the methanol tank while allowing gases and vapors to flow – had not been inspected or cleaned since its installation in 1993. Any blockage in the flame arrester or corrosion of the device can render it ineffective.
CSB concluded that the flame arrester was severely corroded and did not prevent the fire and sparks outside of the tank from igniting the methanol inside the tank. According to the agency, the flame arrester had not been inspected in 13 years prior to the accident; investigators concluded that inspection could have revealed the corrosion before the tragic accident occurred.
In addition, CSB says that it found no evidence that the workers at the plant received any methanol hazard training in the last decade.
Free Video Available
CSB released released the report March 13 at a news conference in Tallahassee.
CSB also released an 8-minute safety video on the accident and its causes. The video is posted in the Video Room of the agency's Web site. Free DVD copies of the video are available by filling out the request form on the CSB Web site.