(TNS) - Pressure valves on one or more containers of volatile organic peroxides "popped" late Thursday at the flooded Arkema plant in Crosby, according to the company.
Leaders are on high alert for explosions like the ones that shot plumes of smoke into the air and caused an hours-long fire at the chemical plant early Thursday.
"You could call this a warning sign that more explosions or fires could be coming soon," said Jeff Carr, Arkema spokesperson.
Darryl Roberts, a safety official with the company, said the company expected additional fires to take place in a matter of days.
One local resident reported hearing the popping sounds overnight, and officials confirmed the noise came from the 18000 Crosby Eastgate plant swamped earlier this week by a murky deluge that cut off power.
Previously, the county said the popping sound indicated more organic peroxide exploding. Carr disagreed, blaming the pressure valves releasing instead.
The company said temperatures are slowly rising in the six containers it can track. There are no temperature gauges in the remaining two containers.
Company officials have said they expected the refrigeration to fail in all the trailers and that additional explosions are inevitable.
Hurricane Harvey's winds and floodwaters have created emergencies at chemical facilities across the Houston area, from an Exxon Mobil roof collapse at its massive Baytown complex to the risk of an explosion at a chemical plant northeast of Houston. We combined our Chemical Breakdown risk map, based on a facility's potential for harm, with the region's 100-year floodplains. Type in a Harris County address in the search bar above to view which sites with "potential for harm" fall within a two-mile radius of that address.
The Arkema plant lost power earlier this week, knocking out the primary supply and back-up generators and forcing employees to move the organic peroxides into 18-wheeler box vans with cooling systems.
One employee was evacuated Monday night. Eleven other employees were evacuated Tuesday when the nitrogen refrigeration in the back-up containers also began to fail.
Company leaders on Thursday morning said they had initially considered relocating the chemicals but deemed that process too risky.
"For us to be in a position where we were going to put that material into trailers and try to move it, it runs the risk of not being able to get it out of the area or getting it stuck in traffic, or having a fire or an explosion at a highway or at a public area, versus in the rural area where this site is," Roberts said.
The company instead decided to leave the material on site with backup generators and a cooling system. The company could not say how elevated these generators were.
Arkema said neutralizing the material was not practical and that "at no point" did they intend to destroy it.
"Those were our levels of contingency," Roberts said. "Clearly that wasn't enough."
Local officials ordered the evacuation of residents after seeing the chemical inventories for the facility, which the company has not publicly released.
The Crosby site has a history of regulatory problems.
In 2006, the Texas Commission on Environmental Quality cited Arkema for a fire caused by improperly stored organic peroxides. In 2011, the same plant was cited for failing to maintain proper temperatures of its thermal oxidizer.
In 2016, the Occupational Safety and Health Administration fined Arkema $91,724 after finding 10 violations at the Crosby site, many involving the mishandling of hazardous materials.
Arkema's CEO Richard Rowe said earlier this week that the company spent millions of dollars on upgrades after the fines and believed all issues cited in the inspections had been addressed.
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