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Update, 9:45 a.m. Sunday: Two victims are now in good conditions, and one is in serious condition, according to a Baton Roiuge General spokesperson.

Update, 9:40 a.m. Saturday: One of the three victims remains in criticial condition while another is in serious condition, according to a Baton Rouge General spokesperson. The third victim is listed in good condition.

Original story

GEISMAR — A once financially troubled biofuels plant in Ascension Parish still recovering from an April blast again exploded and caught fire late Thursday, injuring four workers and temporarily forcing highway closures and workers in at least one other plant to shelter in place, authorities said.

The explosion at the Renewable Energy Group plant about 11 p.m. Thursday was sparked from a hydrogen line undergoing maintenance, parish sheriff’s deputies said.

The April 2 fire also involved equipment that had undergone maintenance and was being restarted. Two workers were injured in that fire.

The latest fire at the REG plant off La. 30 in the heart of Ascension’s Geismar industrial complex took five hours to extinguish completely and included among the injured Nick Matassa, who deputies said was badly burned. He is the son of Kenny Matassa, a Gonzales city councilman, longtime parish government employee and candidate this fall for parish president. Other injured workers have not been identified.

The U.S. Occupational Safety and Health Administration opened an investigation into the latest blast and an investigator was on scene Friday, Juan Rodriguez, an agency spokesman in Dallas, said in an email.

Production at the REG Geismar LLC plant had only restarted in October after a two-year hiatus. The complex’s former joint partners had idled the facility on standby in fall 2012 and never restarted production but sold out to REG of Ames, Iowa, in mid-2014.

REG describes itself as a leading advanced biofuels producer and developer of renewable chemicals, with 10 other active biorefineries across the country.

But production stopped again at the Geismar complex, REG’s largest, less than six months later after the April fire. According to financial filings, REG was still trying to repair the $11 million in damage that resulted from the April 2 fire when the latest blast happened.

“They were in process of restarting,” said Rick Webre, director of the parish Office of Homeland Security and Emergency Preparedness.

REG and sheriff’s deputies identified the injured as one company employee and three contract workers. Ascension Parish officials said early Friday that the injuries are not life-threatening.

Officials at Baton Rouge General Medical Center said later Friday morning that while one worker was discharged already and one is good condition, the two others are in critical condition and serious condition.

Roy Fletcher, Kenny Matassa’s campaign consultant, said Matassa’s son had gone through surgery, but Fletcher said he did not know much else and had not inquired further Friday afternoon.

“The family’s dealing with a real disaster here, but all we can do is pray,” Fletcher said.

An attempt to reach Councilman Matassa was unsuccessful Friday, but a post appeared on his Facebook page Friday evening asking for privacy and prayers until more can be learned.

“We are extremely blessed to have so many people concerned for our son. We are grateful to God for each and everyone of you,” the post says.

Nick Matassa’s injuries hit particularly close to home in local government circles. Besides his years on the City Council, Kenny Matassa is a personal friend of Parish President Tommy Martinez, while Parish Councilman Randy Clouatre works as a maintenance manager at REG Geismar.

Clouatre could not be reached for comment Friday.

Ascension Parish sheriff’s deputies said Friday that investigators have determined the line under maintenance had become pressurized with hydrogen, a highly flammable gas. An unidentified source ignited the gas as it was released from the line.

Calls to 911 Thursday night reported that the high-pressure line had exploded, deputies said in a news release. REG officials said firefighters were able to put the fire out by 4:20 a.m.

Nick Matassa and the other injured workers were extracted from the plant and taken to Baton Rouge General Medical Center or St. Elizabeth Hospital, deputies said.

Those initially taken to St. Elizabeth were later transported to Baton Rouge General’s Regional Burn Center, said Meghan Parrish, the hospital’s spokeswoman.

The fire prompted roadblocks for a time Friday morning on roads near the plant. Additional protective measures included a shelter in place order at the nearby Rubicon facility and an order to cease all rail traffic in the area, deputies said.

The April fire started after a seal on a hydraulic pump failed while it was being put through startup procedures.

According to a State Police report released in May, the pump had just undergone regular maintenance.

Workers near the pump told authorities that they had heard a noise, possibly a hissing sound, moments before the pump caught fire and a fireball exploded from the equipment.

That fire also took about five hours to extinguish, State Police reported.

The Geismar facility, which can produce up to 75 million gallons per year of synthetic fuel, is the first to use REG’s proprietary technology. Trademarked as Bio-Synfining, the process turns a wide range of feedstocks, such as animal fat, inedible corn oil, used cooking oil and vegetable oils, into renewable fuel, the company said late last year.

In addition to biodiesel, the Geismar facility makes renewable naphtha and liquefied petroleum gas, the company has said.

Once known as Dynamic Fuels LLC, a joint venture of Syntroleum Corp. and Tyson Foods of Springdale, Arkansas, the $160 million biodiesel facility opened in 2010 with the help of $30 million in state tax breaks.

By October 2012, Dynamic Fuels was idled, though the plant had delivered 450,000 gallons of biodiesel to the U.S. Navy. The complex was left on standby for two years at a cost of $1 million per month.

In 2013, a financial analyst called Syntroleum “snake-bit” in connection with the plant as the company announced it was considering a possible sale of its stake. The company had previously cited mechanical issues, hydrogen supply disruptions and higher-than-expected operational costs with the plant.

Syntroleum, which was low on cash at the time, was staring at $10 million for its share of the costs to restart the plant, analysts said at the time.

REG bought out both partners in back-to-back deals in May and June of 2014 for up to $105 million combined.

REG then announced it would spend $15 million on upgrades and restarted production in October. At the time of a grand opening ceremony in mid-November, the company said the plant employed 45 full-time employees and 30 contract maintenance workers.

Follow David J. Mitchell on Twitter, @NewsieDave.