On the morning of September 29, 2024, Bio-Lab, a subsidiary of KIK Custom Products, Inc., experienced the chemical reaction involving hazardous chemicals inside a warehouse at its Conyers facility.
The reaction caused extensive off-gassing, excessive heat generation, multiple fires, and a massive plume of toxic smoke containing chlorine, hydrogen chloride, and bromine along with other substances. These conditions prompted shelter-in-place orders, evacuations, and road closures by local authorities. Roughly 17,000 people in the surrounding community evacuated, and 90,000 people in the Atlanta metropolitan area had to shelter in place due to toxic smoke from the fires, according to the final report from the Chemical Safety and Hazard Investigation Board (CSB).
The corrosion resulted from the corrosive environment created by stored chlorine-based chemicals in the building, an issue that was not proactively addressed, according to the CSB.
Causes
The discrepancy between the design of the warehouse and the hazardous categories and large volumes of the materials stored inside, the lack of corporate implementation of risk mitigation strategies across all facilities, including the Conyers site, and gaps in NFPA guidance regarding the storage and handling of pool-treatment chemicals with multiple hazardous characteristics all contributed to this incident, the report found. Also contributing to the incident was the insufficient regulatory coverage of reactive hazards.
On the morning of September 29, a decomposition reaction started in Bio-Lab’s Plant 12 Storage Warehouse at the Conyers facility when water from a failed sprinkler system component contacted chlorinated isocyanurates stored in the warehouse.
Chlorinated isocyanurates are chemicals used in products for treating pools and spas. The reaction generated heat and activated other sprinkler heads in the warehouse, wetting more chlorinated isocyanurates and other chemicals, including cyanuric acid, aluminum sulfate, and sodium bromide, some of which also reacted.
Black plume of smoke and fire venting through a large hole in the center of the building’s roof (left) and thermal image of building (right) at 12:13 p.m.
Source: RCFR
The multiple reactions generated substantial additional heat, which further led to a domino effect of decomposition of products and, subsequently, caused significant plumes of smoke, toxic vapors, and fires within the building.
Plant 12 Storage Warehouse contained four primary chemicals: Trichloroisocyanuric acid (TCCA) (and formulations thereof), sodium dichloroisocyanurate (NaDCC) (anhydrous and dihydrate), and Bromochloro-5,5-dimethylimidazolidine-2,4-dione (BCDMH), which are National Fire Protection Association (NFPA) Class 1 and Class 2 oxidizers.
The warehouse also contained various commodities and packaging materials, such as corrugated cardboard, plastic bottles, containers, and labeling supplies.
Warehouse Documentation
Plant 12 Storage Warehouse ended up constructed in 2019. In June 2019, prior to the construction of the warehouse, Bio-Lab Conyers’ design-build contractor, ARCO Design/Build (ARCO), prepared and submitted documentation to local authorities on behalf of Bio-Lab, Inc./KIK, stating they anticipated storing an “average inventory” of 6.2 million pounds of raw materials, including oxidizers, in the warehouse.
At the time of the incident, however, the warehouse contained nearly 14 million pounds of various formulations of TCCA, NaDCC, NaDCC dihydrate, and BCDMH combined, more than twice the amount initially indicated to local officials.
Inventory records indicate at the time of the incident, approximately 5,000 “super sacks” containing between 2,205 to 2,805 pounds of chlorinated isocyanurates each were present inside the Plant 12 Storage Warehouse. There also were numerous other bags of BCDMH in the warehouse, each weighing approximately 200 pounds.
Prior to the incident, components of the sprinkler system in the Plant 12 Storage Warehouse had been experiencing significant corrosion and leaking since shortly after Bio-Lab Conyers began storing chlorinated isocyanurates there in 2019.
The warehouse did not have air conditioning, and its ventilation system was insufficient to effectively manage humidity (moisture) levels inside the building in light of the large quantities of oxidizer chemicals in the building.
Sprinkler inspection reports conducted in 2021 and 2022 identified hundreds of “deficiencies” each year due to corroded or rusty sprinkler system heads in an area of the warehouse called the “Powder Storage,” also referred to as “the bunker,” where the company stored most of the chlorinated isocyanurates.
Sprinklers Replaced
In November 2022, following these observed deficiencies, Bio-Lab Conyers replaced the original brass-finish sprinkler heads inside the bunker with wax-coated corrosion-resistant sprinkler heads. The facility also upgraded the bolts and couplings in the bunker in 2023. Sprinkler heads outside the bunker ended up replaced with brass-finish heads, not wax-coated corrosion-resistant heads.
During 2023, Bio-Lab Conyers started storing chlorinated isocyanurates outside of the bunker (in addition to inside the bunker) as the company increased the volume of material in the warehouse.
A subsequent inspection conducted in December 2023 did not identify any deficiencies in the bunker (which now had corrosion-resistant sprinklers), but a large number of deficiencies ended up reported in the sprinkler system outside the bunker, which had brass-finish sprinkler heads. Overall, 1,124 sprinkler heads outside the bunker suffered from corrosion according to the December 2023 Annual Sprinkler Inspection.
Corrosion damage to the sprinkler system components at the Plant 12 Storage Warehouse resulted in a high number of abnormal events recorded by the building’s fire protection alarm monitoring system. Between January 1, 2023, and September 29, 2024, the fire protection system registered abnormal status in at least 60 of the 637 calendar days, or 9.6 percent. At the time of the incident in September 2024, most of the sprinkler heads outside the bunker were still brass-finish heads.
Rockdale County Fire Rescue (RCFR) responded to the incident, along with 14 additional mutual aid units from neighboring counties and cities. Although the first building fire ended up extinguished at 8:10 a.m., the elevated temperatures inside the building from additional decomposing super sacks of materials continued to affect other areas of the warehouse.
Sprinklers Activated
Heat emitted by the decomposing oxidizers also activated the sprinklers in other areas of the warehouse. The water from the sprinklers, in turn, caused decomposition of materials in these other areas, generating even more heat. Additionally, the volume of decomposing material stored outside the bunker, in racks and on the floor, continued generating sufficient heat to ignite combustible materials (wooden pallets and packing materials) throughout the warehouse, resulting in a second fire that ignited at noon.
Portions of the warehouse roof and several walls started collapsing at 12:40 p.m. Although the fire was out at 4 p.m., the remaining roof and wall sections collapsed that evening by 8 p.m.
The emergency response phase lasted 17 days, during which nightly shelter-in-place warnings for a 12-hour period from 7 p.m. to 7 a.m. ended up issued to residents and the surrounding community within a 2-mile radius. There also were school closures for nearly two weeks.
Ultimately, the warehouse ended up destroyed. There were no injuries in the incident or in the subsequent emergency response. The estimated property damage was $50.5 million.
As a result of the incident, on May 15, 2025, after completing remediation of the facility, KIK decided to cease operations at the Bio-Lab Conyers facility and subsequently listed the property for sale on January 27, 2026. As of June 2026, the property was still available.
Operations previously conducted at the Conyers facility moved to Bio-Lab’s facility in Ontario, California, and third-party manufacturing facilities and warehouses.
Incident Timeline
In the CSB report the timeline to the incident started at 5 a.m. on September 29. One of the two employees onsite at Bio-Lab
Conyers (Employee A), assigned to fire watch in the Plant 12 Storage Warehouse, reported hearing a popping sound after stepping out of the breakroom to begin a surveillance round.
Employee A initially attributed the sound to the nearby ice maker in the warehouse. However, based on previous experience and training, Employee A immediately concluded product in the warehouse was wet and called the other employee (Employee B) on fire watch on-site, who also was a member of the Bio-Lab Conyers Emergency Response Team (ERT). Employee A then notified offsite management by phone.
At 5:04 a.m., Employee B arrived at the warehouse and donned a full-face respirator before entering the warehouse building.
Employee A left the building to retrieve their respirator from their vehicle and returned to the warehouse to assist Employee B in attempting to remove super sacks that were off-gassing.
Neither employee reported seeing fire, but both observed several super sacks “putting off” dense white fumes, referred to as “off-gassing.” The off-gassing super sacks were immediately outside the bunker adjacent to the fire barrier wall, with three rows of double-stacked super sacks stored in front of them.
Initial off-gassing observed in the warehouse outside the bunker by a KIK employee assigned to fire watch.
Source: KIK
After assessing the situation, Employee B directed Employee A to call 9-1-1. Employee A did not report a fire when they called 9-1-1 at 5:10 a.m., but they reported a “sprinkler head burst” and that “chemical smoke is everywhere.” On October 3, four days later, the employee told the CSB, “I think it could’ve been water off the ceiling. I don’t know…but I know water…”
Fumes Taking Over
Employee B was able to remove only four super sacks of material from the area in front of the off-gassing super sacks before both employees had to leave the building due to the increasing fume density affecting visibility.
Furthermore, employee B also encountered difficulty moving the super sacks because there was “no visibility and floors [were] too slick for forklift” due to the water from the sprinkler flow. Employee B took a picture and video of the dense white fumes before leaving the building.
RCFR first responders and additional KIK employees arrived at the Plant 12 Storage Warehouse by 5:30 a.m., within 30 minutes of the event’s discovery.
KIK and RCFR personnel recounted to the CSB that upon arrival, they observed large volumes of water running out of the dock doors before RCFR had sprayed any water, indicating an activated fire protection system. However, the timing and extent of fire protection system activations cannot end up determined from alarm system logs because the heat generated by the off-gassing event exposed and shorted wiring, causing system status communication loss at 5:32 a.m. and full system failure at 5:37 a.m.
At 6 a.m., Employee B accompanied RCFR personnel for reconnaissance in an attempt to take them to the location of the initial off-gassing super sacks. RCFR reconnaissance attempt ended up limited, however, due to the thick fumes that hindered visibility and rendered RCFR’s thermal imaging cameras unusable. RCFR and Employee B had to physically feel their way back out of the building after becoming “disoriented and lost for a few minutes” because they could not see the exit doors through the fumes.
Flames Appear
At 6:30 a.m., shortly after the reconnaissance attempts, RCFR personnel observed small flames inside the building near the area where the two KIK employees had first observed the material popping and off-gassing.
RCFR personnel described the fire to the CSB as “very small… very contained,” and located up against the concrete wall separating the bunker from the main warehouse area.
The heat from the fire inside the building was intense enough to initiate a fire on the roof of the building. RCFR informed the CSB they contained the fire on the roof and remained limited to the roof membrane, which overlayed the metal roof decking. As it turned out, the fire charred and burned the roof membrane
Although firefighters observed the flames on the roof at 6:30 a.m., it was not until 8:10 a.m. when the responders extinguished the roof membrane fire by applying a relatively small stream of water, estimated by fire rescue personnel as only a “couple gallons.”
RCFR personnel told the CSB they wanted to use the minimum amount of water necessary and not wet additional material based on their experience with previous TCCA (TCCA-based formulation) incidents at Bio-Lab Conyers, such as the 2020 Plant 6 decompositions.
RCFR responders performing external reconnaissance also looked into the bunker through the open dock door and reported minimal fumes and no signs of sprinkler activation within the bunker area.
First Fire Out
After RCFR extinguished the roof fire, KIK employees were able to safely enter the bunker area, which had no fuming/off-gassing material and no signs of sprinkler activation. In the several hours after extinguishing the roof membrane fire, RCFR personnel focused on increasing ventilation to the rack storage area in the warehouse to remove fumes, improve visibility, and reduce exposure hazards enough to allow KIK employees to safely reenter the bunker area with forklifts to remove super sacks.
KIK employees entered the bunker to remove super sacks of material to reduce the potential for additional off-gassing events in the building. However, they could only remove 59 out of the 4,000 super sacks containing chlorinated isocyanurates stored inside the bunker before RCFR noticed a second fire on the roof of the building and ordered everyone to evacuate the building immediately.
Inventory records indicate 5,000 super sacks, each containing between 2,205 to 2,800 pounds of chlorinated isocyanurates, were present inside the Plant 12 Storage Warehouse, in the bunker and the rack storage area. Additionally, there were a large number of smaller bags containing BCDMH inside the Plant 12 Storage Warehouse bunker.
Second Fire
The second roof fire occurred at noon, with black smoke initially observed rising from the center of the Plant 12 Storage Warehouse. When an RCFR responder went up in the aerial ladder of a firetruck to investigate the extent of the second fire, they described seeing: “a gigantic hole… the entire center, almost dead center of the building had vented through the fire. And if I had to estimate it, it probably was 100 ft by 100 ft… and shooting 40-50-foot flames in the air.”
Because the building ended up constructed from concrete slabs raised into place and supported by a roof and truss system, the walls lacked the support to remain standing once the roof began collapsing shortly after the second larger fire broke out. By 12:40 p.m., some of the warehouse’s exterior had already collapsed from the loss of roof support.
Multicolor plumes of smoke observed during the second fire at Bio-Lab Conyers on September 29, 2024.
Source: Ross/11Alive
RCFR personnel described that the second fire as initially consisting of a large plume of black smoke, thick white fumes and large flames, before changing over to multicolored plumes of smoke.
Safety Issues
The CSB’s investigation identified the safety issues below.
Run To Failure: Most incidents are preceded by warning signs related to asset integrity. The Bio-Lab Conyers facility did not proactively maintain its corroding sprinkler system in the warehouse. Instead, the facility replaced or repaired corroded sprinkler heads and piping after they had failed and begun to leak.
Identification of Storage Hazards: Failure to identify hazards in chemical manufacturing facilities can result in fatalities, injuries, significant property damage, and negative environmental impacts. Early identification enables a structured evaluation of potential safeguards to prevent serious incidents. The Bio-Lab Conyers facility did not identify the hazards associated with storing chlorinated isocyanurates with multiple hazardous characteristics and other oxidizers.
Risk Management and Oversight: KIK had an obligation to thoroughly understand the hazards and risks associated with the stored chlorinated isocyanurates and to effectively assess and manage the risks inherent in Bio-Lab’s storage and handling of these materials. Despite having the potential to learn lessons from two other incidents involving Bio-Lab within five years, KIK failed to acknowledge and address the risks in storing quantities of chlorinated isocyanurates.
NFPA Guidance for Pool-Treatment Chemicals: Clear and comprehensive guidance is essential when storing materials with multiple hazardous properties, especially pool-treatment chemicals such as TCCA, NaDCC, and BCDMH, which are corrosive and water reactive under certain conditions.
PSM and RMP Coverage of Reactive Hazards: TCCA, TCCA-based formulations, NaDCC, and NaDCC dihydrate can undergo a decomposition reaction when heated or exposed to water/moisture. These reactions may release toxic vapors and lead to fires. Yet, these and other such reactive chemicals do not end up regulated under the Occupational Safety and Health Administration’s (OSHA’s) Process Safety Management (PSM) Standard or the U.S. Environmental Protection Agency’s (EPA’s)Risk Management Program (RMP) Rule.
Click here to read the full report.