2017 Arkema plant explosion

10:00am, Central Daylight Time (CDT), following warnings from the National Hurricane Center that predicted widespread flooding with rainfall of 15–25 inches (380–640 mm).[7] In the town of Crosby, where the plant was based, forecasts expected 15–18 inches (380–460 mm) in the town of Crosby. Using experiences from past storms, staff at the facility determined that a 'ride-out crew'[lower-alpha 1] would likely be needed at the plant, as the flooding predicted 1 to 2 feet (0.30 to 0.61 m) of floodwaters would render local roads impassible. However, it was believed that while the facility would suffer some flooding that would make travel between buildings difficult, the safety, refrigeration and standby electrical systems would be unaffected by the flooding.[3]

Revisions to weather forecasts raised the expected rainfall to 15–25 inches (380–640 mm) with some areas seeing rainfall amounts of 35 inches (890 mm).[8] With flooding of local roads now certain, the ride-out crew was activated. Staff were still confident the facility would have no issues with maintaining refrigeration of organic peroxides on site. During the day, production was discontinued, and staff prepared the facility for Harvey's arrival, securing loose materials, moving portable equipment that could be damaged by flooding, preparing storm equipment, such as an off-road forklift, ensuring fuel tanks were filled and reducing waste water levels in expectation of the significant rain.[3]

At 10:00pm CDT, Harvey made landfall 30 miles (48 km) northeast of Corpus Christi, Texas. At this time, the National Hurricane Center released another forecast, which now called for rainfall of 15–30 inches (380–760 mm) with isolated amounts up to 40 inches (1,000 mm).[9]

Gauge station 1740 recorded a 13 feet (4.0 m) increase in the Cedar Bayou Stream's water level, during the day.[lower-alpha 2] Meanwhile, the ride-out crew monitored the facility. Towards the end of the day, they determined preempted electrical shutdowns would be needed to reduce danger of equipment damage and electrocution. During the evening, landline phones failed and water continued to rise, surrounding the Low Temperature Warehouses, where the organic peroxides were stored.[3]

At 10:00am CDT, the National Hurricane Center updated its forecast, calling for an additional rainfall 15–25 inches (380–640 mm) and up to 50 inches (1,300 mm) over the next several days.[9][3]

Early in the day, the ride-out crew shut down electricity to several Low Temperature Warehouses. Organic peroxides in these warehouses were transferred into refrigerated trailers. The ride-out crew was optimistic that flooding would crest. In addition to the Low Temperature Warehouses, power was also cut off to other structures, the water supply and fire suppression pumps. Additionally some of the backup electrical generators were also compromised by floodwaters, along with the piping for the emergency liquid nitrogen tank that was on hand should the mechanical (electrically powered) refrigeration fail. Workers were able to restore this temporarily, however the piping was later submerged again by floodwaters.[3]

By the end of the night, only one Low Temperature Warehouse was still operational, with the organic peroxides from the other six warehouses now stored in six refrigerated trailers, now being stored in the 'laydown area' one of the highest points in the facility.[3]

At 2:00am CDT, commercial power was lost, when transformers were flooded. The two remaining standby generators were activated to continue providing electricity to the last Low Temperature Warehouse. However, one of these generators was quickly flooded. At 3:00am CDT, the ride-out crew began transferring the organic peroxides in the last warehouse into two refrigerated trailers, fearing loss of the last remaining generator. Two hours later, at 5:00am CDT, the last generator was turned off by the ride-out crew. Later that morning, they also discovered that the nitrogen tank was also now inoperable after the piping had become submerged again.[3]

Throughout the morning, the forklift and two trucks were lost to rising floodwaters, stranding three trailers by the Low Temperature Warehouses. Water in this area had reached chest height on the ride-out crew. This left around 50 pallets of organic peroxide in the last warehouse. The ride-out crew hand carried the small containers to refrigerated trailers at an adjacent building to keep them cool, finishing this task around midnight.[3]

At this point, three trailers, containing 4,000 containers were still sitting in the floodwaters. The ride-out crew was concerned that these trailers would fail and the organic peroxide would begin to warm.[3]

The ride-out crew discovered one of the refrigerated trailers that could not be moved from the warehouses had started to lean, and likely going to fail. Additionally, the Arkema corporate crisis team suspected there would be at least one fire caused by decomposition of the organic peroxides, and decided to have the ride-out crew evacuate the facility. After a final inspection by boat, the ride-out crew was evacuated by Harris County emergency responders by boat around 12:00pm CDT.[3]

At some point during the day, the secondary containment dikes around the wastewater tanks were overcome by floodwaters, and two tanks released approximately 23,000 pounds (10,000 kg) of organic materials mixed with floodwaters and escaped the facility.[3]

Due to the likelihood of a fire from the decomposing organic peroxides, emergency personnel established a 1.5 miles (2.4 km) evacuation zone around the plant, and evacuated approximately 205 residents from this area. Notably, this evacuation area included U.S. Highway 90, one of the few major roads that remained not impacted by flooding.[3]

Image released by the CSB showing the final flood level

A Unified Command was set up at the Crosby fire station, to coordinate the response to the eventual fire at the facility, consisting of Arkema personnel, various environmental agencies, and fire departments. Roadblocks and air monitoring stations were put into place at the edges of the evacuation zone.[3]

Due to the flooding of Interstate 10, emergency personnel continued to use U.S. Highway 90, as closing the U.S. 90 would have resulted in a multi-hour detour, effectively cutting off Houston from Beaumont.[3]

Near midnight, two police officers traveling along U.S. 90 entered the evacuation area at the northern end, and eventually entered a "large cloud of gas" near the Arkema plant. The officers turned around, and retreated back to the northern edge of the evacuation zone, having irritation to their eyes, skin and respiratory systems. The officers closed the highway, and reported the cloud to the Unified Command.[3]

Just after midnight, Arkema personnel reviewed data from sensors from six of the nine trailers.[lower-alpha 3] The data showed no indications of a temperature increase within these six trailers. Firefighters were sent out to the facility, but failed to observe any signs of organic peroxide decomposition. At 12:30am CDT, U.S. Highway 90 was reopened by Unified Command. CSB investigators suspect that the chemical cloud may have originated in one of the three trailers not fitted with equipment to remotely report temperature data.[3]

Several police officers drove U.S. 90 from the northern edge of the evacuation zone, and entered a cloud of gas. Upon reaching the southern end of the evacuation zone, multiple officers reported nausea and headaches. Additionally, emergency medical technicians called to assist the police officers, drove through the cloud. Twenty-one first responders were taken to a local hospital for examination due to exposure to smoke. Unified Command closed U.S. 90 until 4 September.[3]

At 2:00am CDT, the contents of the refrigerated trailer that had tipped, decomposed and ignited the trailer.[3]

At 10:00am CDT, Harris County helicopters surveyed the facility and noticed the eight remaining trailers were stable and showing no signs of decomposition. However, around 5:00pm CDT two more trailers caught on fire, both of which were located in floodwaters near the Low Temperature Warehouses. The six remaining trailers, all located in the higher 'laydown area' showed no signs of decomposition.[3]

The six trailers in the 'laydown area' were still intact. A survey flight conducted around 1:20pm CDT determined a trailer had lost its cooling capacity. Infrared images determined one of the trailers was leaking a substance that was at an elevated temperature, that was suspected to be a byproduct of decomposition of the organic peroxides.[3]

At 7:00pm CDT Unified Command and Arkema decided to carry out a controlled burn of the remaining trailers. However, a storage tank filled with isobutylene was located about 40 yards (37 m) away. It was decided that the burn would be conducted with the trailer closest to the tank being left until last, to use it as a heat shield while burning the other trailers.[3]

A survey flight in the morning revealed more materials leaking from the trailers. Responders met at 10:00am CDT to reevaluate the plan, and ultimately decided to move forward with it. At 12:45 the plan was started, with an entry team confirming no leaking decomposed organic peroxides were near the isobutylene tank. It was confirmed the leaking material was not near the tank, and at 3:40pm CDT, the controlled burn was started.[3]

At 9:00pm CDT air monitoring was conducted in the evacuation zone, which showed no elevated readings of hazardous gases.[3]

At 1:00am CDT, Unified Command ended the evacuation order, allowing residents back into their homes and reopened U.S. Highway 90.[3][10]

On Thursday, August 31, 2017, the same day as the first fire, the U.S. Chemical Safety Board announced an investigation.[12] This report concluded on 24 May 2018.[3]

The report made five recommendations, directed at four entities:

• Reduce flood risk to as low as reasonably practicable (ALARP). Ensure that any safeguards for flooding meet independent layer of protection requirements. (Arkema Crosby Facility)
• Within 18 months, develop a policy requiring that Arkema and its subsidiaries that manufacture organic peroxides or that have processes which involve more than the threshold quantities of highly hazardous chemicals (HHC) periodically (corresponding with PHA cycle), analyze such facilities to determine whether they are at risk for extreme weather events such as hurricanes or floods. (Arkema Inc.)
• Establish corporate requirements for its facilities that manufacture organic peroxides or that have processes which involve more than the threshold quantities of highly hazardous chemicals (HHC) to ensure that critical safeguards, such as backup power, function as intended during extreme weather events, including hurricanes or floods. (Arkema Inc.)
• Develop broad and comprehensive guidance to help companies assess their U.S. facility risk from all types of potential extreme weather events. Guidance should address the issues identified in this report and cover actions required to prepare for extreme weather, resiliency and protection of physical infrastructure and personnel during extreme weather, as well as recovery operations following an extreme weather event, where appropriate. (Center for Chemical Process Safety (CCPS))
• Update your emergency operations training using lessons learned from the Arkema incident to help ensure that personnel enforcing evacuation perimeters are not harmed by exposure to hazardous chemical releases. Update existing protocols and revise training curricula to include the use of analytical tools, air monitoring, and personal protective equipment, to provide appropriate protection when emergency equipment or personnel need to be moved through an evacuation zone during a hazardous materials release. Include a process for periodic refresher training. (Harris County, Texas)

As of January 2020, the Chemical Safety Board classifies the three recommendations made to Arkema Inc/Arkema Crosby Facility as 'Open - Awaiting Response or Evaluation/Approval of Response (O - ARE/AR)'.[lower-alpha 4] The recommendations sent to Harris County and CCPS are marked as 'Open - Acceptable Response or Alternate Response (O - ARAR)' [lower-alpha 5]

The Environmental Protection Agency began formally asking questions of Arkema on September 7, 2017.[13]