NTSB says company failed to shut down oil pipeline for nearly 13 hours after pressure dropped

Key Points

• The NTSB found that operators at Third Coast failed to shut the pipeline for nearly 13 hours after pressure first dropped, resulting in a 1.1 million-gallon crude spill into the Gulf of Mexico.
• The leak was triggered by underwater landslides—geohazards like hurricane-induced land movement that Third Coast did not properly assess despite industry warnings.
• Third Coast missed multiple opportunities in the years before the accident to evaluate and mitigate threats from known hurricane-related land movement to their 18-inch pipeline.
• Control-room staff dismissed abnormal gauge readings as equipment glitches and only began shutting down the pipeline the next morning, significantly delaying response.

Roughly 1.1 million gallons of crude oil spilled from a pipeline into the Gulf of Mexico in November 2023 because operators failed to shut it down for nearly 13 hours after their data first hinted at a problem, the National Transportation Safety Board said Thursday.

The NTSB said the leak off the coast of Louisiana was the result of underwater landslides, caused by hazards such as hurricanes, that pipeline owner Third Coast failed to address even though the threats were well known in the industry.

“In the years leading up to the accident, Third Coast missed several opportunities to evaluate how geohazards may threaten the integrity of their pipeline. Information widely available within the industry suggested that land movement related to hurricane activity was a threat to pipelines in the Gulf of America, including the MPOG (Main Pass Oil Gathering) 18-inch pipeline,” the NTSB said in its final report, using the new name assigned to the body of water by the Trump administration.

Third Coast did not immediately respond to phone and email messages seeking comment about the report Thursday afternoon.

Environmental groups raised alarm at the time about the leak and its impact on wildlife and the Gulf. NTSB estimated that the spill caused $30 million in damage.

The amount of oil spilled was far less than the 2010 BP oil disaster, when 134 million gallons were released in the weeks following an oil rig explosion, but it could have been much smaller if workers in the Third Coast control room had acted more quickly, the NTSB said.

The pipeline operator first noticed pressure changes about 45 minutes after he started his shift at 6 p.m. on Nov. 15, 2023. The gauges showed that the volume of oil exiting the pipeline was less than the amount entering, with the output eventually dropping to zero around 12:30 a.m. the next morning.

The controller said his supervisor recommended not shutting down the pipeline as the pressure dropped throughout the evening. Even after the flow went to zero, the controller and his colleagues decided not to shut it down because they believed the data were the result of equipment issues.

It was only after day shift workers started the next day and noticed the trend data and lack of output that Third Coast started to shut down the pipeline, around 6:30 a.m. It was fully shut down by 9 a.m., and the leak was reported to the Environmental Protection Agency less than an hour later.

In a different instance in late April, federal authorities were forced to clean up tens of thousands of gallons of crude from another, smaller oil spill from a decades-old well in southeast Louisiana.

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Associated Press writer Jack Brook in New Orleans contributed.