SOUTHWEST LOUISIANA (KPLC) - Like many Southwest Louisiana residents Wednesday night, Margie Dailey was left wondering what the loud boom was.
"I thought we were going to get knocked out of our chairs," Dailey said. "It scared us to death."
The loud noise and vibrations occurred when the Westlake Chemical Polymer Unit experienced a controlled decompression at the lab.
Residents throughout Southwest Louisiana - and even into Texas - reported hearing, seeing or feeling the effects of the incident.
"My house shook and it was really scary," Dailey said. "We both had to take more Xanax because it really shook us up."
Westlake Chemical reported no off-sight impact and no one was injured on-site.
Westlake Chemical spokesman Joe Andrepont said that vent stacks have rupture discs that are set at a certain pressure, usually over 30,000 pounds of pressure per square inch. When the pressure rises above that set pressure, the disc ruptures, causing gas to flow through the vent stack.
When the gas comes out of the vent stack and into the atmosphere it ignites creating a large fireball.
Once all of the gas is out, there is a loud boom heard from the vent stack.
"At some point, particularly on a cool night like we have tonight, static electricity is the ignition source," Andrepont said. "So, as this gas is coming out through the stacks into the atmosphere, it ignites. That's what the fireball (is) that people may have seen and reported. From here, all the gas, once the content is out, then you have the loud boom, the gas is igniting, kind of like a sonic boom from a jet plane."
Once the gas burns out, the fireball is through. In this particular case, the fire lasted longer than usual, around three minutes.