The U.S. Chemical Safety and Hazard Investigation Board (CSB; www.csb.gov) today released its second update on the agency’s ongoing investigation into the September 29, 2024, chemical fire at the Bio-Lab, Inc. facility in Conyers, Georgia.
The incident occurred when reactive materials stored in a warehouse came into contact with water. A chemical reaction occurred that generated intense heat, triggered the decomposition of materials, and ignited multiple fires. These events led to the release of toxic vapors and a massive plume of potentially toxic smoke, resulting in widespread public safety actions, including road closures, the evacuation of approximately 17,000 residents of the surrounding community, and, according to media reports, shelter-in-place orders affecting approximately 90,000 people across the Atlanta metropolitan area. Shelter-in-place alerts for a 2-mile radius around the facility continued nightly for nearly three weeks. The warehouse was ultimately destroyed, though no injuries were reported.
“The more we learn about this unacceptable incident, the more disturbing it is,” said CSB Chairperson Steve Owens. “This is a stark reminder of the very serious dangers that can occur when enormous amounts of reactive and corrosive chemicals are stored without proper safeguards in place.”
The CSB is still investigating the source of the water release that triggered the incident. However, information obtained by the CSB shows that there was recurrent corrosion in the facility’s fire protection system. Corrosion was noted shortly after the storage of corrosive chemicals including trichloroisocyanuric acid (TCCA) began in 2019, and repeated failures in the sprinkler system were documented in subsequent inspection reports.
Documents obtained by the CSB show that in 2019 Bio-Lab had anticipated that the warehouse would store an “average” inventory of approximately 6.2 million pounds of “trichlor,” TCCA, sodium dichloroisocyanurate (DCCA), DCCA dihydrate, and bromine or bromochloro-5,5-dimethylimidazolidine-2,4-dione (BCDMH). By September 2024, however, the warehouse’s inventory had grown to approximately 13.9 million pounds of various formulations of TCCA, DCCA, and BCDMH combined, over twice the amount initially indicated by Bio-Lab. Moreover, these oxidizers were packaged in very large bulk bags (called “super sacks”) holding approximately 2,750 pounds of material each. These super sacks were stored in multiple piles, within large racks alongside other dry chemicals, and were not segregated from the other chemicals.
On the morning of September 29, 2024, at approximately 5:00 a.m., a Bio-Lab employee heard a loud “popping” noise and detected heat and smoke near the warehouse floor—an indication that water may have interacted with reactive chemicals such as TCCA and DCCA. The employee subsequently alerted other Bio-Lab personnel and called 9-1-1. After emergency responders arrived and entered the warehouse, they observed significant volumes of water already flowing from the building even before they applied any water, suggesting that the facility’s sprinkler system had activated at some point.
By 6:00 a.m., local officials began issuing shelter-in-place orders, and evacuations followed shortly thereafter. Flames were first observed around 6:30 a.m. on the roof and inside the building. The roof fire was quickly suppressed using minimal water to avoid worsening the chemical reaction. A second, larger fire erupted around noon, producing thick, multicolored smoke and small explosions as unstable chemicals reacted violently. Emergency responders and Bio-Lab staff were able to safely remove only a relatively small amount of oxidizer material from the warehouse before conditions became too dangerous.
Structural collapse of the warehouse began around 12:40 p.m. By 8:00 p.m., most of the warehouse’s roof and walls had fallen. Firefighting operations continued into the night to control remaining hotspots and limit the release of toxic fumes from decomposing materials trapped beneath the rubble.
The CSB is an independent federal agency responsible for investigating industrial chemical incidents that result—or could result—in catastrophic releases of hazardous substances. The Board conducts thorough investigations, issues safety recommendations, and advocates for preventive measures to protect workers, communities, and the environment.
Board members are appointed by the President and confirmed by the Senate. The CSB does not issue fines or citations but makes non-binding safety recommendations to companies, labor organizations, regulatory bodies, and industry stakeholders.