Explosions and smoke were reported early on Aug. 31 at the storm-flooded site of a plant making plastic catalysts in Crosby, Texas, said plant owner Arkema Inc., although local emergency officials referred to the reaction as a "pop" rather than an explosion.
In a news release on its website, Arkema said that at approximately 2 a.m. Central time, the firm "was notified by the Harris County Emergency Operations Center of two explosions and black smoke" coming from the plant.
But in a news briefing posted by the Harris County Sheriff's Department on its Facebook page at about 6 a.m. Central time, Sheriff Ed Gonzales said it was a non-toxic "pop" rather than an explosion.
"This event had been expected and planned," Gonzales said in a news briefing posted on the department's Facebook page. "There were different organic peroxides of different grades that were released and it created a pop in the containers where they were being stored, and some gray smoke initially emanated from it and it turn into black smoke."
Gonzales said deputies on site experienced some eye and throat irritation, but that was because of the smoke rather than a chemical reaction.
"It was not an explosion. I want to be clear that it was not an explosion," he said.
Bob Royall, assistant chief of emergency operations for Harris County said the word "explosion" wasn't appropriate for what was happening on the site because the work implies a massive reaction.
"Everything that we've seen and been told doesn't indicate that is going to happen," he said.
What did happen were small expected reactions in one of nine containers holding organic peroxides on the site. Royall added. Overhead monitoring of the site has shown that there is a fire inside that container, Royall said, and firefighters and emergency responders will let that fire burn itself out.
Local officials had previously established an evacuation zone in an area 1.5 miles from our plant, based on their assessment of the situation, they added. "We continue to work closely with federal, state and local authorities to manage the situation," they said.
Company officials added that the site followed its hurricane preparation plan in advance of the recent hurricane and had redundant contingency plans in place. However, they said, "unprecedented flooding" overwhelmed the site's primary power and two sources of emergency backup power.
As a result, Arkema lost critical refrigeration of the products on site. Some organic peroxides made there burn if not stored at low temperature. Organic peroxides are extremely flammable, officials said, and agreed with public officials that the best course of action was to let the fire burn itself out.
"We want local residents to be aware that product is stored in multiple locations on the site, and a threat of additional explosion remains," they added. "Please do not return to the area within the evacuation zone until local emergency response authorities announce it is safe to do so."
The facility lost power late Aug. 28 from both its primary supply and its backup generators due to flooding. Hurricane Harvey made landfall on the Texas coast Aug. 25, bringing with it heavy rains that have resulted in at least eight deaths and shut down most plastics and petrochemicals plants in the area.
Arkema's Crosby plant makes liquid organic peroxides that are used primarily in the production of polystyrene, polyethylene, polypropylene, PVC and acrylic resins, as well as polyester-reinforced fiberglass, according to the firm's website.
The plant shut down in anticipation of the storm, and at first a crew of 11 people stayed at the site. Late in the afternoon of Aug. 29, however, the situation became serious when backup generators were inundated with water.
The Crosby Fire Department evacuated one employee Aug. 28 and the rest of the staff was evacuated Aug. 29 when the refrigeration in some of the back-up containers also started to fail, according to the Houston Chronicle.