Marathon’s St. John refinery has recent history of accidents and chemical leaks, records show

Company has consistent track record of reporting incidents promptly, even when not required

By: - August 31, 2023 5:00 am
Plumes of smoke rise into the sky over the Marathon Petroleum refinery in Garyville on Aug. 25, 2023.

Plumes of smoke rise into the sky over the Marathon Petroleum refinery in Garyville on Aug. 25, 2023. (WVUE-TV screen capture)

The Marathon Petroleum refinery in Garyville, where a large chemical fire forced evacuations last week, has had more than a dozen emergency incidents within the past five years, state records indicate. While several were minor, two of the events injured workers and most began with leaks from pipelines or storage tanks. 

A review of Louisiana Department of Environmental Quality (LDEQ) records show the Marathon refinery in St. John the Baptist Parish has reported 14 emergency incidents since 2019, not including the most recent fire that burned for seven hours Friday after a naphtha liquid leaked from a storage tank and ignited. 

According to the records, half of the occurrences were last year, and nine involved chemicals leaking from containment vessels or pipelines, which LDEQ classifies as solid waste pollution incidents. 

One recent event occurred Feb. 20 when a heated asphalt tank lost 4.6 barrels (193 gallons) of liquid asphalt into the soil over a 50-foot area. In Louisiana, the reportable quantity — the threshold at which facilities must report an unauthorized release — for asphalt is one barrel.  

On Nov. 20, 2022, a diesel pipeline ruptured, spilling 2.2 barrels (92 gallons) of diesel fuel onto the ground. The rupture occurred during hydrostatic testing, a process in which a pipe or tank is subjected to high pressures to test for leaks. 

Perhaps the most severe accident occurred last fall when a chemical fire burned two workers, one of whom had to be airlifted to a New Orleans hospital. The fire ignited Oct. 5, 2022, after a leak developed in the casing of a chemical pump, releasing butane and alkylate, a high-octane gasoline additive. It burned for over 10 hours before it was extinguished.  

Seven months earlier, on Feb. 21, 2022, there was a pipe explosion and fire that injured four people and prompted road closures and a shelter-in-place order within the Marathon facility. The incident caused the company to revise some of its unit startup procedures. 


The refinery experienced no emergency incidents during 2021 and mostly minor incidents in 2020 except for an asphalt leak similar to the one earlier this year. In that May 19, 2020, incident, a storage tank leaked 11 barrels (462 gallons) of liquid asphalt onto the soil. 

In 2019, the facility saw one significant event, on Oct. 14 of that year, when the valve on a railroad tank car failed as workers filled it with liquid asphalt, spilling roughly 50 barrels (2,100 gallons) onto the ground surrounding the tracks.  

Only a few of the incidents resulted in unauthorized air pollution. In one case, the refinery lost oxygen to its thermal oxidizers, causing a release of sulfur dioxide, a poisonous gas. The emission levels did not exceed the state’s reportable quantities, but LDEQ inspectors detected a chemical odor and small levels of sulfur dioxide and volatile organic compounds while monitoring the air at the facility shortly after the incident.  

Most other air pollution incidents were either minor or caused by power failures that were the fault of the utility company. The records appear to indicate Marathon has had a consistent track record of promptly reporting incidents. In some cases, facility personnel reported small leaks that wouldn’t normally require reporting just “as a courtesy,” the records show. 

Friday’s fire involved both a release of solid waste and air pollution. Marathon has said air monitoring has so far shown no impact to the nearby community, though LDEQ’s air monitoring results have not yet been finalized and released to the public. 

Marathon has not responded to the Illuminator’s requests for comment, but the company has issued statements on social media regarding Friday’s fire, saying its cause remains under investigation. 

“Marathon Petroleum’s main priority continues to be the safety of those on-site, our neighbors, first responders, and to limit environmental impact,” the company said in a statement Monday. “As a precautionary measure, the refinery has operated at reduced rates during the response effort. A plan is being developed to return the refinery to normal operations, with safety as our core focus.”

Friday’s incident comes just over a month after a separate large fire and explosion at the Dow Chemical plant in Plaquemine, the cause of which remains under investigation. That facility had a similar number of emergency incidents over the same time period but many more that resulted in high levels of air pollution.

LNG export terminals pose a growing and invisible threat: air pollution

Our stories may be republished online or in print under Creative Commons license CC BY-NC-ND 4.0. We ask that you edit only for style or to shorten, provide proper attribution and link to our web site. Please see our republishing guidelines for use of photos and graphics.

Wesley Muller
Wesley Muller

Wes Muller traces his journalism roots back to 1997 when, at age 13, he built and launched a hyper-local news website for his New Orleans neighborhood. In the years since then, he has freelanced for the Times-Picayune in New Orleans and worked on staff at the Sun Herald in Biloxi, WAFB-9News CBS in Baton Rouge, and the Enterprise-Journal in McComb, Mississippi.