The propane gas cloud preceding a fire two weeks ago was so large that investigators can’t determine what exactly ignited it.
Jackson Hole Fire/EMS released its investigation report of the blaze Tuesday, stating that while investigators could determine the source of the leak, they could not determine the cause of the explosion.
“The propane cloud from the leak spread out over such a wide area that there are literally hundreds, maybe thousands of possible ignition sources,” Fire Marshal Kathy Clay said. “The right conditions existed in so many places, it’s not really possible to determine which one started the fire.”
The fire ignited at around 12:45 p.m. Nov. 20 at the AmeriGas facility on Gregory Lane and quickly spread to businesses and storage units in the area. A rough estimate puts damage from the blaze at $3 million, Clay wrote in her report.
The report confirms early eyewitness accounts that the fire started when a truck arrived to fill underground tanks at the facility, and ruled the cause “accidental.”
The truck’s driver, Mario Carillo, of Roy, Utah, reported hearing a “popping sound” after he started the filling process and then propane filled the air “in seconds,” according to his written statement included in the investigation report.
Clay, with the help of a third-party propane expert, concluded that the leak came from either the hose leading to the underground tank or the equipment that helps to power it.
The cloud spread quickly, witnesses to the early moments of the blast reported the day of the fire, going from something that resembled an exhaust problem with a car parked in the area to something that resembled fog off Flat Creek.
The cloud of propane then found the unknown source of ignition and the flames spread “everywhere” in moments.
Several people claimed to have witnessed the moment of ignition, but none of those accounts was clear enough to make an official conclusion, Clay said. No statements from those people are included in the investigation report.
Security video from Smith’s Food and Drug, which is between the AmeriGas facility and U.S. Highway 89, shows the flames start relatively small, but spread to a major fire rapidly, even burning along Flat Creek itself, where Clay said gas found the lowest point in the area.
Nearby storage units were “destroyed” and Bell Fitness took substantial damage to the parts of the building closest to the fire.
Though reports from the scene mentioned several smaller explosions, Clay said only one five-gallon propane tank actually exploded.
Most of the flames were the result of tanks venting due to increased interior pressure and the vented gas catching fire. More explosions that made some of the noises audible from surrounding blocks were exploding tires on nearby vehicles as they caught fire.
At least a dozen vehicles parked at AmeriGas, Bell and the adjacent storage units were destroyed in the fire.
The wide reach and sudden spread of the blaze likely was due to the size of the propane cloud that preceded the fire, Clay said. By the time the flames started, gas had leached into buildings and vehicles throughout the area.
At its peak the fire produced flames 75 feet high and a column of black smoke that was visible as far away as the Jackson Hole Airport in Grand Teton National Park. Photos taken from a helicopter show the smoke stretching into the sky well above surrounding buttes.
Carillo and AmeriGas office manager Jessica Davis of Jackson got out of the area uninjured and no one else was seriously hurt in the incident.
Some of the patrons of Bell Fitness received minor cuts and scrapes after escaping out of a broken picture window in the gym’s day care area. Personal trainer Scott Edwards broke the window and helped customers to safety after the flames engulfed the gym’s front door.
“This went about as smoothly as something like this can,” Clay said. “We all feel it’s a reflection of the training we do as an organization and of the way everyone responding knew their job.”