Traces of two highly flammable solvents were found in soil samples where an 8-foot-tall fire flared from a hole in the ground at Midway on Sept. 17 and then burned for about 40 minutes.
"It's not a mystery anymore," said Jim Sierzchula, the Baxter County emergency management director. "It was a prank."
The mysterious flaming hole of Midway drew national media attention. Initial suspects included a meteorite, methane and the devil.
Now, at least officials know it wasn't a serious public threat like a leaking natural gas line. Or the flames of Hell.
"The best explanation is it was a giant Sterno-can prank," Sierzchula said, referring to a brand of fuel that is made to be burned in its can.
Three soil samples were analyzed by the 61st Civil Support Team of the Arkansas National Guard at Camp Robinson in North Little Rock. In all three samples, they found traces of the solvents Toluene and Xylene as well as sulfur dioxide and ethylene oxide, according to an email Sierzchula forwarded to Mickey Pendergrass, the county judge in Baxter County.
Sulfur dioxide is a combustion product, said professor Wesley Stites, chairman of the department of chemistry and biochemistry at the University of Arkansas, Fayetteville.
"Finding sulfur dioxide in a place where there was a fire is completely non-surprising," he said. "Most of the smell of a burned match is sulfur dioxide. That's what brimstone is -- sulfur."
Stites said Toluene and Xylene are common solvents used in paint thinners. They can be purchased at Walmart, he said.
"That seems like the most plausible thing to me, that somebody dumped a quart of paint thinner down there and caught it on fire," Stites said.
He was somewhat concerned about ethylene oxide showing up in the soil sample results, but the amount of the chemical wasn't specified in the email Sierzchula sent to Pendergrass.
Stites said ethylene oxide is unstable and toxic.
"Unless you're in an oil refinery or chemical company you're just not going to find it," he said. "I'd be shocked if that were in there."
Ethylene oxide is a flammable, colorless gas at temperatures above 51.3 degrees Fahrenheit, according to the Occupational Safety and Health Administration. It is found in the production of solvents, antifreeze, textiles, detergents, adhesives, polyurethane foam and pharmaceuticals.
"Smaller amounts are present in fumigants, sterilants for spices and cosmetics, as well as during hospital sterilization of surgical equipment," according to OSHA.
Stites said ethylene oxide is a component of fire fuel-air explosive or thermobaric bombs dropped from the sky to clear jungles during the Vietnam War.
"The best argument that ethylene oxide was not the main fuel for the fire is that if it were there in large amounts, I would bet on an explosion or at least an extremely rapid flash-fire, not something that burned long enough for the fire department to respond," Stites said.
Sierzchula said there were no injuries or property damage from the fire. He said the sheriff's office isn't investigating it as a crime. Sierzchula said that except for a distant convenience store surveillance camera, nobody got photos or video images of the fire, and no human could be seen on the video in the proximity of the hole before or immediately after the fire started.
"I know it was man-made and put there, and in my opinion it was a prank," Sierzchula said. "I think it was to draw law enforcement to the area. It's all speculation."
Sierzchula said he's done with the flaming hole of Midway.
"I've had people call me at 2 or 3 in the morning telling me what it was," he said. "I don't need to play with it anymore."
The person who set the fire knew there was an animal hole on the property, said Pendergrass. The hole, which led to a nearby creek embankment, provided oxygen to the fire.
Pendergrass said county workers drove by Tuesday and saw a groundhog sticking his head up out of the hole.
Metro on 12/02/2018