The National Transportation Safety Board has now released the accident report into the fire onboard cutter suction dredge Jonathon King Boyd on the evening of 17 April 2018. It determined that the probable cause was RLB Contracting’s failure to inform the crew about utilities in the area due to ineffective oversight, which led to dropping a spud onto a buried submarine pipeline, causing natural gas to release and ignite.
The vessel punctured a submarine natural gas pipeline with the spud during dredging operations in Matagorda Bay, Texas. A gas plume ignited and engulfed the dredge and its accompanying towboat, the Bayou Chevron. All 10 crew members abandoned the vessels uninjured. Damage to the pipeline was estimated at USD1.7 million. The Jonathon King Boyd and the Bayou Chevron were constructive total losses, valued at USD5.5 million and USD125,000 respectively.
Turn of events
While making a round on the dredge in the evening of the accident, the deckhand noticed bubbles rising from the water off the stern. He notified the leverman, who stopped operations and went to the stern to investigate. The mate joined him and examined the discharge line for signs of damage and found none, but still noticed bubbles rising to the surface off the stern. He asked if a pipeline was present at the location.
None of the crew recalled smelling natural gas at that time. The leverman and engineer went to the galley to look at the nautical charts where they discovered a charted submarine pipeline at their location. They informed the captain, who then ordered the mate and deckhandto pick up the anchors and move the dredge away from that location for the safety of the crew and vessel. As the crew
prepared to move the dredge and as the leverman was raising the port spud, a geyser of gas and water―35–40 feet high by crew accounts―erupted from the stern of the vessel.
The crew immediately smelled gas and shortly thereafter, fire erupted near the stern of the dredge port side.
The crew of the Jonathon King Boyd utilised HYPACK, a commercially available software used by the hydrographic and dredging industry. HYPACK provides user interface between hydrographic surveys, data files, project files, and tracking of dredge operations. In addition, DREDGEPACK―a module in the HYPACK software―enabled the crew to monitor and track digging operations and the position and depth of the cutterhead in real time.
Pipeline positions could, and as per company policy should, have been entered into the HYPACK software, but according to the crew, the positions were not displayed in the software they had. According to the crew, the production engineer was responsible for entering the location of utilities and that information was typically provided to them at the beginning of the project.
The captain and both levermen told investigators that the channel area in which they were operating did not have signage or pilings identifying the pipeline crossing on either side of the channel. Investigators confirmed that regulations did not require signage marking the pipeline. In addition, they mentioned that although nautical charts (NOAA charts) kept in the lever room and crew galley marked the pipelines in the area, the crew did not use them during dredging (because they did not provide the level of detail needed for dredging operations), nor was there any company policy to do so. The captain and crew did not have a copy of the USACE contract or drawings on board the vessel that identified the locations of the pipelines.
The captain and the levermen told investigators that had they known a pipeline was present they would not have allowed the spuds to freefall from their stowed position. Instead they would have pinned the spud higher and performed a controlled lowering of the spud over the pipeline, if required, to limit the spud’s penetration into the channel bottom. The cutterhead would have been secured and the jet pump would have been used when crossing over the pipeline. Also, the dredge would have been repositioned to the other side of the pipeline. According to the company’s safety officer, this was the first accident of this magnitude for RLB Contracting in 18 years of dredging.
Read the full report here.