This information is preliminary and subject to change.
On November 15, 2023, about 7:00 p.m. local time, control room operators observed a pressure drop in an underwater crude oil pipeline that is part of the Main Pass Oil Gathering (MPOG) pipeline system, owned by Third Coast Infrastructure LLC (Third Coast) and located within Main Pass 69, about 20 miles southeast of Venice, Louisiana, in the Gulf of Mexico.[1] About the same time, the metered volume entering the pipeline became larger than the metered volume exiting the pipeline at its delivery point, possibly indicating a leak. On November 16, 2023, shortly after the start of the 6:00 a.m. shift, control room personnel reviewed the information from the previous shift and isolated the pipeline as a precaution. By this time, the leak had released about 1.1 million gallons of crude oil into an unusually sensitive area in the Gulf of Mexico.[2] Third Coast reported a leak of unknown volume to the National Response Center at 10:52 a.m. on November 16, 2023. No injuries were reported, and the crude oil did not ignite.
On November 16, 2023, the US Coast Guard Command Center reported up to 1.1 million gallons of crude oil was released by Third Coast. After learning of the estimated release volume, the National Transportation Safety Board (NTSB) launched an investigation on November 16, 2023, and the investigation team was on site the following day.
The US Coast Guard, the Louisiana Oil Spill Coordinator’s Office, and MPOG Company LLC established the Unified Command on November 17, 2023, to direct the response to the crude oil release.[3] Over a period of 4 weeks, remotely operated vehicles and divers inspected the pipeline and on December 21, 2023, found indications of oil in the seabed above the pipeline.
While on scene, the NTSB monitored the search for the source of the release, monitored the oil recovery operations, recovered physical evidence, gathered documentation, and completed interviews. On December 28, 2023, divers performed an in-situ test of a collet grip fitting near the leak indications discovered on December 21, 2023.[4] The fitting, installed in 2004 during a repair of the 18-inch diameter steel pipeline, failed the in-situ test. This fitting was among the physical evidence recovered for examination by the NTSB.
The NTSB’s investigation is ongoing. The NTSB’s preliminary report on this accident was postponed until the Unified Command-directed integrity testing was completed on April 5, 2024. Future investigative activity will focus on evaluation of the recovered collet grip fitting, and on Third Coast’s integrity management program, control room management, operator qualifications, incident reporting practices, and pipeline safety management systems.
Parties to the investigation include:
- the US Coast Guard,
- the Pipeline and Hazardous Materials Safety Administration,
- the Bureau of Safety and Environmental Enforcement,
- Third Coast, and
- Oil States Industries.
[1] (a) All times in this report are local times. (b) Main Pass 69 indicates where in the Gulf of Mexico the section of pipe was located.
[2] Title 49 Code of Federal Regulations (CFR) 195.6 defines an unusually sensitive area as a drinking water or ecological resource area that is unusually sensitive to environmental damage from a hazardous liquid pipeline release. Unusually sensitive areas are a type of high-consequence area, as defined in 49 CFR 195.450.
[3] MPOG Company LLC is a wholly owned subsidiary of Third Coast.
[4] A collet is a segmented metal collar that can be tightened to grip a component. (b) In-situ tests are performed on equipment in its original position.
