State environmental officials say an explosion and fire last month at the Westlake Chemical Corp. complex in Geismar was the fifth and most significant release of chemicals at the plant since the beginning of 2010.

The Advocate ( reported that the March 22 fire primarily released hydrochloric acid, chlorine and vinyl chloride monomer. Records of the Louisiana Department of Environmental Quality say those release exceeding the one-hour permit level for those chemicals and at least three other compounds.

No one was injured in the explosion. The cause is still under investigation.

Fifteen compounds are estimated by DEQ to have been released during the fire, which sent a large plume into the air and over the Mississippi River in Ascension Parish. The other nine pounds of those compounds were in amounts of less than a pound, DEQ said.

DEQ said that some of the chemicals may have been consumed in the fire.

The fire shut down Westlake's vinyl chloride monomer plant probably until mid-May and the entire Geismar Vinyls Complex remains out of production, the company has said.

Vinyl chloride monomer, which has been listed as a possible carcinogen by federal health officials, is used to make polyvinyl chloride, a common plastic used in a variety of household building products, such as pipe and siding.

Westlake Chemical spokesman David Hansen each of the four prior incidents involved different parts of the plant than the tower involved in the March 22 fire. Company officials do not believe those past incidents are related to the fire, Hansen said.

DEQ spokesman Rodney Mallett said the agency cannot say yet whether any of the equipment issues from the prior releases are related to last month's fire.

The Geismar complex is one of about 300 facilities in Louisiana under an enhanced DEQ inspection effort, called the Chemical Accident Prevention Program, said Peter Ricca, DEQ emergency response manager. In 2011, an inspection under the CAP Program found no problems at units that make ethylene dichloride, Ricca said.

But a prior inspection dating back to 2005 under CAP turned up areas of concern at the VCM plant that were later corrected. Also, 2009 inspections under the complex's operating permit resulted in 2010 compliance orders, primarily stemming over record-keeping, DEQ officials said.

One of the orders is still pending in dispute resolution, said Celena Cage, administrator of DEQ enforcement.

PVC plants have long drawn the critique of environmental groups because of the suspected carcinogenic properties of vinyl chloride, even in relatively small amounts.

The complex was built in the mid-1970s and was owned by Borden Chemical until 2002, when Westlake Chemical bought the complex. Since then, the company has spent about $20 million for environmental and safety improvements, Hansen said.

"We take the safety of our employees and the surrounding community very seriously, and we are proud of our safety and environmental record at the site," Hansen said in a statement.



Information from: The Advocate,