The National Transportation Safety Board determined that a failure of mooring arrangements during high-water conditions caused two barges to break free and strike a terminal on the Ohio River.
Evansville Marine Services crews originally moored the vessels at the Marathon Petroleum terminal on the evening of April 15, 2024. MPC 907 and MPC 644 were secured using six lock lines and four winch wires while carrying over 50,000 barrels (7.9 million litres) of fuel.
The NTSB found that the river current was approximately three miles per hour (4.8 kilometres per hour) and rising at the time of the mooring.
The two barges broke free from the terminal dock at approximately 04:45 on April 16, 2024. Evidence indicated that a drift pile of debris measuring 100 feet (30.5 metres) by 200 feet (61 metres) followed the barges, likely increasing the strain on the mooring lines.
The drifting vessels contacted mooring cells at the TransMontaigne terminal approximately 1,500 feet (457.2 metres) downstream. This impact resulted in physical damage to the dock structure estimated by TransMontaigne to exceed $2.5 million.
Marathon Petroleum terminal personnel discovered the barges were missing at 06:00 and performed a visual inspection of the site. This inspection revealed that all ten mooring connections used to secure the vessels had broken during the night.
Evansville Marine Services tugs recovered the barges near mile 802 at approximately 07:00 and returned them to the terminal.
Marathon Petroleum reported that the discharge of cargo from the two barges was expected to take place the following morning before the breakaway occurred.
As a result of the accident, Marathon Petroleum refined its procedures to require a verbal handoff regarding barge conditions and mooring arrangements.