MARENGO, Iowa — More than a dozen people were injured after an explosion at an alternative fuel production plant in eastern Iowa on Thursday caused a fire, prompting the city to urge residents to evacuate.
Black smoke billowed for miles as the fire burned overnight. Crews put out the blaze around 4:30 a.m. Friday after it started around 11 a.m. the day before, Marengo Police Chief Ben Gray said.
At least one person was in serious condition at the University of Iowa Hospital's burn unit, Gray said.
The cause of the explosion is under investigation, but Gray said it appeared employees were doing maintenance on a piece of equipment when the building exploded.
In October, a fire also broke out at the facility while workers were doing maintenance when a tank caught fire while being welded, Gray said, injuring one person and causing smoke and fire damage to the building.
Here's what we know.
How many people were injured?
There were 30 people were inside the C6-Zero fuel production plant when it exploded and caught fire Thursday morning, Iowa State Patrol Senior Trooper Bob Conrad said.
All 30 people have been accounted for.
The University of Iowa Hospitals & Clinics treated 10 to 15 patients, most of whom suffered mild to moderate injuries ranging from cuts and scrapes to burns and trauma, said Dr. Theresa Brennan, chief medical officer, on Thursday afternoon.
Brennan said during severe emergencies, the hospital classifies patients as being in green, yellow or red categories, ranging from least to most severe. Only one patient being treated by the hospital was in the red category, she said.
What was being produced at the former Heartland Crush plant?
The plant has changed hands several times in the last few years, causing confusion Thursday over what was actually produced at the plant.
Heartland Crush LLC, a soybean processing plant, opened in 2017 in the building, which was previously a printing and graphic facility, according to a 2017 article.
In 2018, a district court appointed the Iowa Department of Agriculture as receiver of Heartland Crush after the agency received a complaint indicating the company did not have a grain license. Two years ago, Grinnell State Bank sought to foreclose on Heartland Crush, saying the business had defaulted on a 2017 loan and owed the lender about $430,000.
Eventually, the building became the site of C6-Zero, an alternative fuel plant. A video on the C6-Zero website, describes its work as turning asphalt shingles into its component parts — oil, sand and fiberglass.
The Iowa Department of Natural Resources said Thursday it has been in discussions with C6-Zero officials about the permit the company needs to operate in Iowa. The agency hadn't determined which environmental regulations may apply to the business, based on what it knew about the manufacturing process.
On Friday, the agency said it had received no complaints about the facility.
What caused the Marengo explosion? Expert says dust could be source in manufacturing facilities.
Officials haven't said what may have caused the explosion at the plant, but high concentrations of dust can be a source of fires in grain handling and manufacturing facilities, said T. Renée Anthony, director of the Great Plains Center of Agricultural Health at the University of Iowa.
When large sources of settled dust become airborne and there's a spark — anything from an overheated bearing to an electrostatic shock — can cause a fire, Anthony said.
Inside an enclosed space, an expanding fire creates pressure that can lead to an explosion, she said.
“A lot of agricultural products do have combustible dust of concern,” said Anthony, who pointed to dust that caused an explosion at a sugar plant in Georgia in 2008 that killed 14 people.
Another source of fires and explosions is flammable gas inside an operation, she said.
Drone footage shows the fire
Below, see drone footage of the fire from We Are Iowa Local 5 News.
Where is Marengo?
Marengo is located in eastern Iowa, about 80 miles east of Des Moines and about 30 miles from Cedar Rapids and Iowa City. It has a population of around 2,400, according to the most recent census data.
Francesca Block is a breaking news reporter at the Des Moines Register. Reach her at FBlock@registermedia.com or on Twitter at @francescablock3.
This article originally appeared on Des Moines Register: Marengo explosion in Iowa injures several; fire burns at plant