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The vessel within a unit processing Glycol -- a chemical commonly used in antifreeze -- ruptured around 8 a.m., creating a loud explosion that shook homes and rattled the windows in the area. People reported hearing the blast up to 35 miles away in Prairieville and Zachary, according to Facebook users. ORG XMIT: ebhnxqFvOPi2ujzVZ_r1

An explosion at the Dow Chemical plant that rumbled across the Baton Rouge region and rattled homes in Plaquemine on Sunday came after workers were rebooting the facility's systems following an overnight power outage, an Iberville Parish official said Monday.

A tank, or vessel, at a glycol processing unit burst open Sunday morning, sending a shock wave that shook nearby homes and resonated miles away, according to officials in Iberville and neighboring parishes. Dow has been monitoring air quality since the blast but said it hasn't detected any contaminants that would be harmful to workers or the nearby community.

"There is no ongoing emergency at the site. The site is stable and we are in recovery mode at our Glycol 2 unit," Dow wrote in a recent statement. "The rest of our production units continue to run safely and reliably."

The plant was trying to regain power Sunday, which required them to restart their systems and likely contributed to the explosion, said Sheriff Brett Stassi.

Company officials haven't said what they believe caused the tank to rupture but have been communicating with state and local agencies. Crews stabilized the tank shortly after it burst and plan to investigate what led to the malfunction.

Dow directed its more than 3,000 employees and contract workers to report to their normal duties at the 1,500-acre facility just outside of Plaquemine.

The blast sent a plume of white steam into the air, and several people in neighboring parishes reported hearing the bang, including some who posted on social media about hearing it in Zachary, as far as 35 miles away from the plant.

No one was injured in the blast.

"If someone would have been outside that vessel, it would have been bad," Stassi said.

The tank contained water and small amounts of sulfuric acid, ethylene oxide and nitrogen, which are used for a variety of manufacturing purposes, including coolants and polyesters, a Dow spokeswoman said.

Depending on the level, exposure to the chemicals can cause dizziness, skin rashes, eye irritation and difficulty breathing. Parish and company officials didn't report anyone experiencing signs of those symptoms.

Dow reported the maximum amount of ethylene oxide that could have escaped the ruptured tank, roughly 28 pounds, to the state Department of Environmental Quality. But they believe it was far less because monitoring didn't detect the chemical in the air even though a small amount combusted.

The same unit at the Dow plant reported a similar leak to the DEQ following a power outage in May that led to the release of 334 pounds of ethylene oxide over 26 hours. Though the leak didn’t exceed hourly limits, state agents noted in their report that the amount of chemical release surpassed the annual allowable amount under its permit.

DEQ records show Dow filed a request to change their permit earlier this year at the glycol unit but requested part of their request be confidential and cited it would reveal trade secrets.

In 2016, Iberville emergency officials complained that Dow didn’t immediately notify them following a chlorine leak from one of the Olin Corporation facilities operating on the plant site.

Dow said at the time they believed the leak was contained within the plant’s borders but nearly an hour later discovered it had extended beyond the facility.

The Iberville Parish emergency management office sounded a shelter-in-place warning after residents near the plant reported having eye irritation and trouble breathing.

Parish officials said they've been in constant contact with Dow since Sunday morning, and, aside from the startling boom, there is no danger to the public.

“They were really forthcoming with us and called us immediately,” Stassi said.

Email Youssef Rddad at yrddad@theadvocate.com.