By Kyle Greene
Florida hazmat team takes a patient, careful approach to a boiling, burning drum of chemicals
It was a typical Florida summer afternoon last month — 90 degree heat with 90% humidity — when the Tampa Fire Rescue Hazardous Materials Team was called for assistance from a neighboring county. A 55-gallon, double-walled drum was reported to be burning between two small industrial warehouses with no known cause.
The warehouse owner was on scene and stated that the drum contained sodium hydrosulfite powder, which they use in very small quantities for “cleaning purposes.”
First-arriving Pasco County Fire Rescue units isolated the drum, evacuated the warehouse and immediate area. They also set up an unmanned master stream just in case. Tampa units arrived on scene and met with PCFR command.
Drone video surveillance found that the drum was still smoking and had an internal temperature of 280 degrees F; the radiant heat to the building’s exterior walls was at 150 degrees F. Using the drone’s thermal camera, we could see the powder boiling and burning inside the drum.
Wiser app’s marplot was used to determine wind direction and the distance this specific vapor would travel if there was a release. We used that information to evacuate an adjacent neighborhood that would be within the toxic cloud if there was an explosion.
The concern for emergency crews was twofold. First, the chemical reaction was generating pressure, which could cause a pressure explosion and create a large chemical fire. The warehouse that the drum was up against had small quantities of hydrogen, acetylene and propane cylinders inside, all of which would react poorly with a chemical fire. Second, if the drum did explode, the resulting gas cloud would be a lethal mix of sulfur dioxide and hydrogen sulfide.
The risk of sending in an entry team to perform recon or attempt a mitigation was high. We saw no evidence that the drum could vent itself; the increasing pressure from the chemical reaction had nowhere to go. This meant that at any point, we could have a pressure explosion.
Mitigation options were limited. We considered applying a large quantity of sand or soda ash inside the drum to smother and disrupt the chemical reaction. Another option was to use a massive quantity of dry ice to attempt to cool the drum’s exterior. These were deemed too dangerous to the entry teams.
After investigation, we concluded that what most likely happened was that the 55-gallon drum was underneath a tarp, which accumulated moisture due to rainfall and humidity. When the lid was opened, an unknown amount of water entered the drum. That started an exothermic chemical reaction resulting in the powder boiling and burning inside the drum. The heat generated ignited the tarp, which then melted onto the drum.
The powder continued to boil and burn for 5 more hours.
After the sun went down, we saw a slow decrease in overall temperature and boiling activity of the powder. We believe this decrease was due to the chemical reaction using up all the water molecules inside the drum, thereby making the chemical reaction unsustainable. Once the internal temp was 212 degrees F and the thermal imager showed very little movement (boiling) inside the drum, a hazmat removal company was contacted to remove and dispose of the drum.
Here are three lessons we learned.
A competent and skilled drone pilot with an attached thermal camera was invaluable to this operation. He got up-close video and photos along with temperature readings without crews making entry.
Wind direction updates are key. This location was near the bay, so wind direction changes did occur. The command post had to be moved at one point because the wind changed, and all our units became downwind.
The research team and interviewing owners go hand in hand. The research group should be heavily involved in conducting interviews with owners and witnesses. These team members can ask the right questions for that specific chemical. That information assists the research team in determining the best course of action to present to hazmat ops.
About the Author
Kyle Greene works for the Tampa Fire and Rescue Department, where he is a hazardous materials technician, driver/engineer, paramedic, firefighter and fire instructor. He is also a registered nurse.
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