The U.S. Chemical Safety and Hazard Investigation Board has released an update on its investigation into the September BioLab fire, which led to road closures, hospitalizations and evacuations of 17,000 people in the surrounding community due to the chemical plumes of smoke and toxic vapors.
According to the CSB, a BioLab employee who was assigned to watch at Plant 12 storage warehouse on the Conyers site reported hearing a ‘popping sound’ upon starting their 5 a.m. round on Sept. 29.
After noticing the “product was wet,” they notified the only other employee on-site and tried to isolate the reacting product but failed, according to the CSB. There were no flames, but they called 911 at 5:10 a.m. due to the “large toxic vapor plumes inside the building,” the report stated.
BioLab officials told the safety board that its facility had started a permanent fire watch up to three months earlier after finding strong order from oxidizers at two buildings, including Plant 12. They had hoped to stop any future product from decomposing and releasing toxic gas, according to the CSB.
The two BioLab employees were on fire watch at the time of the incident. Their responsibilities included finding and managing hazards, detecting fire hazards or early signs of product decomposition, telling site leadership of any leaks or other water intrusions, and contacting a third-party sprinkler company if a head was leaking, the report stated.
By 6:30 a.m., the fire was visible through the roof, located above where the employee first saw the chemical reaction, the CSB said. An hour later, the report stated a shelter in place order was issued, though it was unclear how expansive. Rockdale fire crews extinguished the fire by 8 a.m.
Credit: Ben Gray for the AJC
Credit: Ben Gray for the AJC
But a second fire erupted at about noon, producing the thick black and multicolored plumes of smoke that was ultimately seen for miles. The CSB stated a first responder described the scene as “major chemical reactions.”
Just before 12:30 p.m., first responders started to evacuate the area, and I-20 was shut down 30 minutes later. The building was ultimately destroyed in the fire, which crews extinguished at about 4 p.m. I-20 reopened at 7 a.m. the following day, the report stated, but nearby smaller roads remained closed for even longer.
The 275,125 square foot building has seven sprinkler systems, and its chemical storage area is separated from the main warehouse area by a firewall and sprinkler system. Its role is to distribute the materials to the other productions buildings, while raw and package materials were also stored its racks.
The report stated that the bulk chemicals at Plant 12 were 99% trichloroisocyanuric acid (TCCA) and 99% sodium dichloroisocyanurate (DCCA), solid oxidizers that were stored in super sacks before being taken to other parts of the complex.
According to the CSB, oxidizers “‘readily yield oxygen or other oxidizing gas or that readily react to promote or initiate combustion of combustible materials and that can, under some circumstances, undergo a vigorous self-sustained decomposition due to contamination or heat exposure.’”
Officials said those chemicals have a chlorine odor and can release “toxic and corrosive products” like chlorine gas and hydrogen chloride “upon decomposition.”
The building also stored super sacks of bromochloro-5,5-dimethylimidazolidine-2,4-dione (BCDMH), which can release chlorine gas and hydrogen chloride, along with bromine gas and hydrogen bromide when it breaks down, the report stated.
According to the CSB, gasses continued to be released after the fire was put out because residual TCCA product was still beneath the collapsed structure. Heavy equipment was required to access and remove the TCCA.
Credit: John Spink
Credit: John Spink
For several weeks, those within a two-mile radius were given nightly shelter-in-place warnings by the county emergency management agency. The last one expired Oct. 17, 2024. The smoke eventually drifted to metro Atlanta, whose residents reporting a chlorine smell and haze.
Near the site, chlorine and hydrogen chloride were detected above action levels from 5 p.m. to 5 a.m. between Sept. 30 and Oct. 2, according to the Environmental Protection Agency. The highest levels of chlorine, about 20 times the hourly action level, were recorded at a monitoring station located southeast and downwind of the site between midnight and 3 a.m. Oct. 1.
Thousands in metro Atlanta were told to shelter in place while the thick plume shifted west. Several lawsuits have been filed, including a federal one announced by Rockdale County in October. Officials still don’t know what the long-term environmental consequences from the blaze will be. The report stated the plumes of toxic smoke contained hazardous substances and caused “significant offsite impacts.”
Air monitoring was stopped by the EPA after concentrations were well below the average on Oct. 17. BioLab has issued statements promising to remediate the situation.
In October, the company opened a claims center in Conyers that was visited by hundreds of residents and business owners, the company said. But county commissioners have said the company has not communicated well with county officials.
BioLab also had a history of fires at its facilities in Georgia and elsewhere.
In 2004, a fire broke out at the Conyers facility, prompting thousands of residents to evacuate. In September 2020, a chlorine vapor cloud rose from the BioLab facility in Conyers due to a chemical reaction and shut down I-20 for six hours. Nearby businesses evacuated and residents were encouraged to shelter in place and the board deployed a team to investigate.
The CSB said it continues to investigate the cause of the material decomposition, off-gassing and the September fire. Officials are are also looking into the storage and handling of oxidizers, their compatibility and best practices for responding to emergencies involving such materials, along with regulatory and industry guidance on fire protection systems for bulk solid oxidizers.
“This incident and the substantial potential risk that it posed to the surrounding community was completely unacceptable,” CSB Chairperson Steve Owens said in a statement. “Reactive chemical incidents can have severe environmental and public safety impacts due to the combination of fire, toxic gas emissions, and hazardous materials involved, and Bio-Lab and any other facility that has reactive chemicals onsite must manage those materials safely.”
The CSB said its finding and recommendations, “if appropriate” will be detailed in its final investigation report.
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