NTSB: Deteriorated Dock Collapsed After Normal Contact With Barge
When a Louisiana refinery's mooring dock collapsed upon contact with a barge in 2023, allision damage might have been suspected - but the National Transportation Safety Board has determined that it was the dock to blame, not the vessel. A structural inspection had discovered serious deterioration of the dock six years before the accident, and no progress was made in making repairs in the year and a half before the casualty.
In the early hours of April 25, 2023, the towing vessel Ovide J was arriving at the Chalmette Refinery crude oil dock with two laden barges and a cargo of 50,000 barrels of crude. The refinery is on the Lower Mississippi near mile 89, just downriver from New Orleans. The dock was built in 1967 out of wood and steel pilings, dolphins, and access bridges. The transfer platform was located on dolphin number three, along with a boom crane and the pipe manifold.
The relief captain was at the helm as the towboat approached the dock from downriver, using the current to guide the tow slowly towards the pier. The relief captain made his final approach at 0001-0004, maneuvering slowly to make contact with the dock at about 0.3 knots.
When the tow made contact with dolphin number 3, part of the dock fell off into the river. The relief captain put the starboard side engine in neutral in order to avoid fouling the propeller with any debris from the collapse. The other two dolphins remained intact, so the crew moored to the surviving portions of the dock and notified the company of the casualty. Luckily, no one was injured.
The Ovide J and her barges sustained no damage from the incident, and the timber fendering around the dock was undamaged. Video from the pilothouse showed no signs of a hard contact (like jarring, vibration or movement of objects). The relief captain later told investigators that the maneuver - which he had performed at the same dock 20 times in the past year - had gone perfectly to plan.
"When you come in, you touch up stern first. . . . So, when I came in, I lightly touch on the stern. . . . As soon as I touched up, the dock collapsed," he said. "If I had to do it again, I would do it the same way over again. I would not change a thing."
The dock sustained about $7 million worth of damage: 150 feet of the structure collapsed, and the support piles for dolphin number three were sheared off below the waterline. But the damage may have started long before the casualty event, based on past inspection reports. In 2017, a third-party engineering inspection found major deterioration of the braces between the dolphin's pilings. Six years before the collapse, three horizontal braces on the dolphin were broken, one more was damaged and two pilings were "severely deteriorated." The dock owner informed NTSB that the recommendations from this inspection had "not been progressed" before the dock collapsed.
"Because a portion of the dock collapsed from what appeared to be a low-impact contact during docking, it is likely that the dock’s dolphin no. 3 transfer platform structure was compromised to the extent that it could not sustain the forces from a typical docking. The dock owner was aware that the dock had structural integrity issues before the collapse but had not yet taken steps to address them," NTSB concluded.