MOSS POINT, MS (WLOX) - Investigators with U.S. Chemical Safety Board (CSB) discovered the fatal explosion that killed a contract worker and severely injured another at Omega Protein in Moss Point happened during "hot work" on or near a tank, according to a statement released Tuesday by CSB.
CSB investigators and OSHA inspectors working alongside one another found that the incident happened during hot work on or near a tank containing eight inches of a slurry of water and fish matter known as "stickwater," according to the statement.
The statement went on to say, lab tests of stickwater found signs of microbial activity in the samples, such as the presence of volatile fatty acids in the liquid samples and offgassing of flammable methane and hydrogen sulfide.
Though no combustible gas testing was performed on the contents of the tank before hot work started, the CSB says the stickwater inside the tank was thought to be nonhazardous.
Officials with CSB says the incident at Omega Protein highlights the importance of careful hot work planning, hazard evaluation and procedures for all storage tanks, whether or not flammable material is expected to be there.
Since 2008, the CSB has examined three hot work incidents involving fatalities on tanks of biological or organic matter.
The CSB is tasked with providing root cause analysis of the accident and issue safety recommendations to try and prevent future similar accidents. OSHA would be responsible for fines and citations.
CSB statement offers these recommendations:
"Mixtures of water with fish, potatoes, or cardboard waste could understandably be assumed to be benign and pose little safety risk to workers. It is vital that companies, contract firms, and maintenance personnel recognize that in the confines of a storage tank, seemingly non-hazardous organic substances can release flammable gases at levels that cause the vapor space to exceed the lower flammability limit. Under those conditions, a simple spark or even conducted heat from hot work can prove disastrous.
I urge all companies to follow the positive example set by the DuPont Corporation, after a fatal hot work tragedy occurred at a DuPont chemical site near Buffalo, New York. Following CSB recommendations from 2012, DuPont instituted a series of reforms to hot work safety practices on a global basis, including requirements for combustible gas monitoring when planning for welding or other hot work on or near storage tanks or adjacent spaces.
Combustible gas testing is simple, safe, and affordable. It is a recommended practice of the National Fire Protection Association, The American Petroleum Institute, FM Global, and other safety organizations that produce hot work guidance. Combustible gas testing is important on tanks that hold or have held flammables, but it is equally important—if not more so—for tanks where flammables are not understood to be present. It will save lives."