At approximately 8:45 am Thursday Watertown Fire Rescue was called to the Watertown Regional Airport for a called in explosion. The call came in via 911 from an airport employee who was on scene. While enroute to the scene, fire crews were notified by dispatch there was no active fire, but a fuel tank had been damaged from an apparent explosion while it was being filled by a fuel delivery truck. Upon arrival, crews found a 10,000 gallon fuel tank located at the fuel farm inside the airport with considerable damage.
Witnesses stated during the filling process of the tank that there was a small explosion followed by a plume of smoke coming from the top of the tank, near the tank vent. The fuel truck operator immediately stopped the fueling process, turned off the semi truck, and another airport staff member disconnected the power going to the fuel farm. Based on the location of the fuel tanks, the buildings located on the airport field did not require evacuation.
Fire crews proceeded to make entry in to the site with appropriate monitoring equipment and PPE gear. After confirming there were no unwarranted fuel vapors in the area and no physical leaks coming from the tank, the entry team was able to disconnect the fill hoses and equipment connected to the fuel trailer. In total there was less than 1 gallon of fuel lost during the entire process. After securing the site and equipment, fire staff moved the semi away from the fuel site and out of harms way.
The product being loaded in to the fuel storage tank was 100 octane low lead fuel, which is the most common type of avgas used in general aviation. Approximately 500 gallons of fuel was loaded in to the tank prior to the incident.
The cause of the incident is still under investigation. There were no injuries reported. Fire crews were on scene for approximately 2 hours. Watertown Fire Rescue would like to thank the Watertown Municipal Airport staff, along with ATY Aviation staff, Codington County Emergency Management, the Watertown Police Department, and LATC Aviation for their assistance during the incident.