A thermal decomposition event in common cleaning agents caused the massive chemical explosion at the Bio-Lab facility in Conyers
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A chemical reaction triggered the massive fire and toxic smoke plume at a Georgia lab in September, endangering nearby communities and metropolitan Atlanta, according to findings released by the U.S. Chemical Safety Board (CSB).
Photo by the US Chemical Safety Board
The CSB published its report on Friday, detailing the events surrounding the September 29 chemical fire at the BioLab facility in Conyers, Georgia.
According to the safety board, the primary substances involved in the incident were chemicals commonly used for cleaning and disinfecting:
bromochloro-5,5-dimethylimidazolidine-2,4-dione (BCDMH), trichloroisocyanuric acid (TCCA), and sodium dichloroisocyanurate (DCCA). These chemicals, stored in the plant's warehouse, generated heat as they degraded, ultimately breaking down and releasing toxic vapours that ignited the fires, the CSB stated in its report.
Federal US authorities have provided an update on their investigation into the fires at the BioLab chemical plant near Atlanta, which created a toxic chemical cloud and forced nearby residents to shelter in place.
The fires, which occurred on September 29 at the BioLab facility in Conyers, produced a massive plume of orange and black smoke visible across the area. On Friday, the U.S. Chemical Safety and Hazard Investigation Board released details about the incident.
BioLab, a subsidiary of Lawrenceville, Georgia-based KIK Consumer Products, manufactures chemicals used to kill algae and bacteria in swimming pools and hot tubs.
In a statement, the company emphasized its “strong track record of working constructively” with regulators and pledged full cooperation with the federal investigation. “We remain firmly committed to understanding the causes of the incident and to making things right for impacted area residents and business owners,” the statement read.
According to the report, a BioLab employee assigned to fire watch at the Plant 12 storage warehouse heard a “popping sound” at around 5 a.m. while leaving a break room for a routine check. The employee immediately noticed that a water-reactive product had become wet and contacted the only other staff member on-site. Despite no initial flames, the employee’s attempts to isolate the chemical were unsuccessful. By 5:10 a.m., they called 911 after noticing “large toxic vapor plumes” forming inside the building.
By 6:30 a.m., flames were visible through the roof where the reaction occurred, prompting an initial shelter-in-place order at 7:40 a.m. Rockdale County firefighters extinguished the fire about 30 minutes later. However, a second fire ignited around noon, producing “thick black smoke, followed by multicolour plumes,” according to the report. Evacuations began at 12:30 p.m., and the fire chief confirmed that the blaze was extinguished by 4 p.m.
The fire caused significant structural damage, with parts of the building collapsing. The Plant 12 warehouse, a bulk storage facility spanning an area larger than five football fields, was completely destroyed. The site remained an “active emergency response scene” for nearly four weeks, according to investigators.
The Plant 12 warehouse was separated from the main warehouse by a firewall and fire shutters. BioLab informed investigators that a permanent fire watch had been implemented two to three months earlier due to "strong odours from oxidizers" in Plant 12 and another storage building.
The incident also disrupted transportation, as Interstate 20, running parallel to the facility, was closed shortly after the building’s collapse at around 1 p.m. The highway reopened the next morning at 7 a.m., but nearby roads and a two-mile shelter-in-place zone enforced by the Rockdale County Emergency Management Agency remained in effect for weeks, lifting only on October 17.
Smoke from the fire drifted toward Atlanta, creating a haze and chlorine-like odor in parts of the city and surrounding areas.
The disaster has led to over a dozen lawsuits being filed against the company.
Read More:
Coverage from September 30th:
CNN:
https://www.cnn.com/2024/09/29/us/rockdale-county-biolab-fire-georgia/index.html
The Guardian: ‘Pattern of negligence’: a chemical plant fire in Georgia forces tens of thousands to take shelter
https://www.theguardian.com/us-news/2024/oct/01/georgia-biolab-chemicals-smoke-evacuation
More on the CSB report:
https://roughdraftatlanta.com/2024/11/25/biolab-chemical-fire-investigation/
https://www.nbcnews.com/news/georgia-chemical-fire-investigation-rcna181541
What is a thermal Decomposition?
When common cleaning agents containing reactive chemicals, such as oxidizing agents, undergo thermal decomposition, their molecules break down into simpler compounds due to high temperatures. This process is often exothermic, meaning it releases heat, which can accelerate further decomposition and potentially lead to an explosion.
Here's a breakdown of the chemical events:
-
Oxidizing Agents as Key Components:
Many cleaning agents contain chemicals like:- Sodium dichloroisocyanurate (DCCA)
- Trichloroisocyanuric acid (TCCA)
-
Hydrogen peroxide
These substances release oxygen or other reactive gases when heated.
-
Thermal Breakdown of Bonds:
When heated, the chemical bonds in these compounds weaken and break, producing:- Reactive gases (e.g., oxygen, chlorine, or nitrogen oxides)
- Heat energy that can accelerate the reaction
- Build-Up of Gas Pressure:
As gases are released rapidly, pressure builds up in a confined space, such as a storage container or warehouse.
4. Combustion or Explosion:
If the gases are flammable or reactive (e.g., chlorine or oxygen), they can ignite in the presence of a spark or heat source, resulting in:
- A fire, fuelled by the oxidizing properties of the chemicals
- A thermal explosion, caused by rapid gas expansion and ignition
5. Chain Reactions:
The heat and reactive gases produced can cause surrounding materials to decompose, amplifying the intensity of the fire or explosion.
Example: TCCA Thermal Decomposition
TCCA breaks down under heat to release chlorine gas (Cl₂) and oxygen (O₂), which are both highly reactive. These gases can cause:
- Combustion when combined with flammable materials
- Toxic fumes, adding a secondary hazard to the explosion
Key Safety Concern
The risk of thermal decomposition and explosion increases when these chemicals are:
- Stored improperly
- Exposed to high temperatures
- Contaminated with moisture, which can accelerate decomposition reactions
Sources on Thermal Decomposition:
Chemical & Engineering NewsDMSO poses decomposition danger - Chemical & Engineering News
Thermal Decomposition for Heat Exchanger Cleaning - Inspectioneering
The fire toxicity of polyurethane foams - Fire Science Reviews
Potential Explosion Hazards with Using DMSO and DMF in Chemical Reactions
Clean Agent Total Flooding Fire Extinguishing Systems
THERMAL DECOMPOSITION PRODUCT RESULTS UTILIZING PFC-410 (3M BRAND PFC ...
A REVIEW OF THERMAL DECOMPOSITION PRODUCT TESTING OF HALOCARBON FIRE ...
Thermal decomposition - Wikipedia
Processes in the thermal degradation of organic matter at atmospheric pressure.. Thermal
Observations:
- Initial Chemical Reaction:
- The "popping sound" and visible wetting of water-reactive chemicals suggest a likely failure in containment or protection against moisture.
-
Early detection but failure to isolate the product reflects both the employee's diligence and potential inadequacies in contingency procedures.
-
Fire Progression and Response:
- Toxic vapour plumes and visible flames indicate a rapid escalation from a chemical reaction to a full-blown fire.
- Multiple fire events within hours point to a potential lack of adequate suppression systems for the stored chemicals.
- Environmental and Public Health Impact:
- Shelter-in-place and evacuation orders, combined with prolonged emergency response, highlight the severity of the situation.
- Chlorine-smelling smog drifting toward Atlanta raises questions about air quality monitoring and communication with affected communities.
4. Facility Management and Oversight:
- The permanent fire watch due to "strong odors" implies ongoing issues with the storage conditions of oxidizers.
- The separation of bulk storage by a firewall and shutters may have helped contain the damage somewhat but was insufficient to prevent the catastrophic outcome.
Lessons and Questions:
- Prevention:
- Could earlier intervention, such as addressing the strong oxidizer odours, have prevented the incident?
- Are the facility's storage and environmental controls adequate for the types of chemicals handled?
- Response:
- Were local firefighters equipped with the specialized training and resources needed to combat a chemical fire of this magnitude?
- Was the delay in observing flames (over an hour) due to the initial reaction being contained within the building, and could advanced detection systems have improved response times?
- Accountability:
- The company's statement about cooperation is promising, but the lawsuits may pressure BioLab and regulators to adopt stricter safety protocols industry-wide.