The lack of a robust overfill prevention system with an independent or redundant level alarm can lead to catastrophic results as demonstrated by both the Buncefield fire and the 2009 Caribbean Petroleum overfill incident in Bayamón, Puerto Rico. Preventing such catastrophes requires the tank terminal industry go above the current regulatory requirements and industry and consensus standards to implement a reliable safety management system that incorporates an automatic overfill prevention system.
The U.S. Chemical Safety Board is finalizing its report on the Oct. 23, 2009 overfill incident at the Caribbean Petroleum refinery in Bayamón where a 5 million gallon capacity aboveground storage tank overfilled while fuel was being transferred from a barge. During the overfill, gasoline spray from the tank vents aerosolized forming a vapor cloud and pooled in the secondary containment where it leaked through an open dike valve to the wastewater treatment area, where it ignited. The vapor cloud explosion led to multiple tank fires that burned for two days. Local community members, lacking adequate emergency preparedness, were forced to evacuate in the middle of the night. The explosion and fires compromised 17 of 48 tanks at the facility, caused three off-site injuries and damaged or destroyed approximately 300 homes in the nearby communities. The magnitude of the incident caused President Barack Obama to declare a state of emergency.
Employing an overfill prevention system that includes automated and independent level alarms within a robust safety management system offers multiple layers of protection that can prevent a catastrophic incident like Caribbean Petroleum or Buncefield. A strong safety management system encompasses formal overfill procedures that incorporate the best available practices and ongoing operator training in addition to regular testing of the overfill prevention system. The success of the overfill prevention system rests on conducting a comprehensive risk assessment to determine the level of risk posed at the facility. The risk assessment should consider the hazards posed by site operations including the type of flammable liquid stored, the reliability of the tank gauging system, the adequacy of operator monitoring of tank liquid levels and the tank farm’s proximity to local communities.
Current EPA and OSHA regulations do not require an automatic overfill prevention system with an independent level alarm. Similarly, even the best available practices under the National Fire Protection Association, the International Code Council’s International Fire Code or the ANSI/API 2350 standard on “Overfill Protection for Storage Tanks in Petroleum Facilities” do not recommend an overfill prevention system with automated independent level alarms for tank terminals storing petroleum or other similar flammable liquids that are not remotely operated. Unfortunately, even if the industry and consensus standards were adequate, tank terminals are not required to follow them because they are not subject to the EPA Risk Management Program or OSHA’s Process Safety Management program that requires covered facilities use recognized and generally accepted good engineering practices.
Until there is a change in regulatory requirements or guidance from industry and consensus standard making groups, the onus is on the aboveground tank industry to take the initiative to prevent another catastrophic overfill incident such as Buncefield or Caribbean Petroleum from occurring.
For more information, contact Parasram at vidisha.parasram@csb.gov or (202) 261-7652.