(CHARLIE RIEDEL ~ Associated Press)
A series of 55-gallon drums ignited at the Chemcentral Corp. plant Wednesday, sending fireballs hundreds of feet in the air and causing an ominous plume of black smoke to drift over the downtown skyline. Nobody was killed in the blasts, but two workers at the plant suffered minor injuries.
The inferno had mellowed enough by late evening to allow firefighters to approach the site and apply flame-suppressing foam. The last of the hot spots were being doused Thursday morning when another explosion came from inside the facility, battalion chief Joe Vitale said.
People within a one-mile radius of the site have been evacuated and have not yet been allowed to return.
Vitale said the explosion did not come from one of the three 30,000-gallon rail tank cars that were parked nearby. Firefighters were concerned the tank cars, which held flammable materials, would ignite under the intense heat of the fire.
At one point Wednesday, witnesses said the cars appeared to glow red from the heat, but their pressure relief valves activated to let fumes escape before they cooled down.
Fire chief Richard Dyer said firefighters hope to have the fire extinguished sometime Thursday. "We hate to give a time frame because it seems like it always seems to take longer than we anticipate," he said.
Officials are still trying to determine the cause of the blast, Dyer said. Plant employees have already been interviewed, but the small pockets of fire and threats of additional explosions have kept investigators from examining the site.
Dyer said preliminary indications are that some chemical was released in the plant and ignited, setting off additional explosions.
"Right now we don't have any information to discredit my speculation," he said.
Once firefighters have given the area the all-clear, Dyer said the site will be turned over to the Missouri Department of Natural Resources and the Environmental Protection Agency to begin assessing the ecological impact of the explosion.
Despite the smoke plume's ominous appearance -- and its unsettling resemblance to a huge tornado -- officials reported late Wednesday that tests by the EPA found no threat to human health.
Still, residents were cautioned against touching any debris or what appeared to be a sticky substance deposited by the cloud as it streamed southwestward.
Dyer said the material was not highly toxic.
"None of these are what those of us in the field would call exotic chemicals. None of these have a high rating for toxicity," he said.
The roof of one home ignited from the radiant heat, but the flames were quickly doused and there were no other early reports of damaged buildings.
Ken Hannon, a spokesman for the Missouri Department of Natural Resources, said there was a 15-page list of chemicals at the property, including mineral spirits, turpentine and other solvents.
"I'm looking through the list. I'm not seeing anything that's jumping out at me" as particularly hazardous, he said. "Flammability seems to be the main concern right now for most of these chemicals."
Dan Brennan, an attorney for Bedford Park, Ill.-based Chemcentral, said the plant has 15 to 20 workers, nine of whom were in the building at the time.
Dyer said the Chemcentral facility did not have a history of problems, but it is a location that has always troubled the fire department because of its proximity to a casino and residential neighborhoods.
"It's a well-run facility with a pretty darn good safety record," he said. "When you ask if it's something that comes up as a problem facility -- absolutely not."
Plant superintendent Craig Nienhueser said workers heard a hissing noise inside the building. He went around to the back and noticed some flames, at which point the workers were evacuated.
"We are just thankful everybody is OK," Nienhueser said.