Lesson Learned: Anchor Strike Of Underwater Pipeline Results In Oil Spill

• NTSB ​has released an investigation report on an incident where an anchor struck an underwater pipeline resulting in crude oil release.
• NTSB found that the release of crude oil occurred as a result of fatigue failure that manifested over a period of time

The National Transportation Safety Board (NTSB) has released an investigation report on an incident where an anchor struck an underwater pipeline in October 2021, resulting in crude oil release in San Pedro Bay, California, reports Safety4sea.

The incident

On October 1, 2021, at 1610 local time, San Pedro Bay Pipeline controllers received the first of a series of leak detection system alarms for their underwater pipeline, which was located in San Pedro Bay, 4.75 nautical miles off the coast of Huntington Beach, California. Over the next 13 hours, NTSB conducted seven pipeline shutdowns and restarts during troubleshooting of the alarms.

At 0604 on October 2, NTSB shut down the pipeline for the eighth and final time. A pipeline contractor vessel crew visually confirmed a crude oil release at 0809, and Beta Offshore, the pipeline operator, then initiated an oil spill response. An estimated 588 barrels of oil leaked from the pipeline. Damage, including clean-up costs, was estimated at $160 million. There were no injuries.

A postaccident underwater examination of the pipeline found a crack along the top of the pipeline within a section of the pipeline that had been displaced from its originally installed location. Additionally, scarring consistent with anchor dragging was identified on the seafloor near the crack location. Postaccident investigation determined that the containerships MSC Danit and Beijing had dragged anchor near the pipeline months before the oil release, on January 25, 2021.

Investigation

​NTSB found that the release of crude oil occurred as a result of fatigue failure that manifested over a period of time in an area of local deformation to the San Pedro Bay Pipeline caused by an external force that resulted in progressive cracks initiating and growing through the pipe wall until the pipe wall ruptured.

Postaccident examination of vessel traffic in the area determined that on January 25, 2021, vessels anchored nearby were subjected to high winds and seas generated by a strong cold front. As a result, the containerships Beijing and MSC Danit dragged anchor, and the anchors struck, displaced, and damaged the San Pedro Bay Pipeline. NTSB determined that the MSC Danit anchor’s contact with the pipeline was the initiating event that led to the eventual crude oil release.

NTSB also found that, because of the proximity of the anchorage positions that the Beijing and MSC Danit were assigned to and the pipeline, the crews had insufficient time and space to heave in their dragging anchors in high winds and seas before the anchors contacted the pipeline. The southeast boundary of the anchorage and the location of contingency anchorage positions southwest of the anchorage did not leave a sufficient margin of safety between anchored vessels and the pipeline.

Following the anchor dragging events, the pipeline operator was not notified by either the vessels or Vessel Traffic Service (VTS) Los Angeles-Long Beach. The VTS watchstanders did not recognize the danger presented to the San Pedro Bay Pipeline by the Beijing and MSC Danit dragging anchors because they lacked a visual indicator of the location of the pipeline, and they were attending to exceptionally high vessel activity due to weather; a visual and audible alarm when an anchored vessel encroaches on a pipeline would increase their awareness. Had the pipeline operator been made aware of the Beijing and MSC Danit anchor dragging, the company could have conducted an underwater survey of the pipeline, identified the damage, and made repairs, preventing the eventual release of crude oil. Further, defined procedures for informing pipeline and other utility operators when possible pipeline incursions have occurred within the VTS area of responsibility would improve the pipeline or utility operator’s ability to identify and respond to any damage.

NTSB also explored the reasons for the pipeline controllers’ delay in properly responding to the pipeline leak following the first alarm. NTSB found that abnormal operating conditions contributed to the pipeline controllers’ incorrect determination that the leak alarms were false. Had the controllers responded in accordance with company procedure for a leak by shutting down and isolating the pipeline, they would have significantly reduced the volume of crude oil released and the resulting environmental damage. NTSB also concluded that the insufficient training of the pipeline controllers contributed to the 14-hour delay in stopping the pipeline’s shipping pumps, which consequently increased the volume of crude oil released, following the first leak alarm.

Finally, as a result of this investigation, NTSB found that Beta Offshore was not in compliance with regulations when the company did not drug-test the pipeline controllers following the accident. NTSB also found that pipeline safety would be enhanced if pipeline companies implemented safety management systems, and that Beta Offshore may have further evaluated their operations, identified continuous improvement opportunities, and better positioned their staff to respond and react to a leak had they implemented a pipeline safety management system.

Probable cause

NTSB determined that the probable cause of the damage to and subsequent crude oil release from the San Pedro Bay Pipeline was the proximity of established anchorage positions to the pipeline, which resulted in two containerships’ anchors striking the pipeline when the ships dragged anchor in high winds and seas. Contributing to the crude oil release was the undetected damage to the pipeline, which allowed fatigue cracks to initiate and grow to a critical size and the pipeline to leak nearly 9 months later. Contributing to the amount of crude oil released was Beta Offshore’s insufficient training of its pipeline controllers, which resulted in the failure of the controllers to appropriately respond to leak alarms by shutting down and isolating the pipeline. Contributing to the pipeline controllers’ inappropriate response to the leak alarms was the water buildup in the pipeline, an incorrect leak location indicated by Beta Offshore’s leak detection system, and frequent previous communication-loss alarms.

Recommendations

​NTSB recommended that the US Coast Guard implement the proposed VTS Los Angeles-Long Beach restructuring of the San Pedro Bay federal anchorages to increase the margin of safety between anchored vessels and the pipeline. In addition, NTSB recommended that the Marine Exchange of Southern California, which jointly operates VTS Los Angeles-Long Beach with the Coast Guard, work with its vessel monitoring system provider to add audible and visual alarms for the system that alert the watchstander when an anchored vessel is encroaching on a pipeline.

Furthermore, NTSB recommended that the Coast Guard implement this capability on all VTS vessel monitoring systems nationwide. Additionally, NTSB recommended that the Coast Guard develop procedures for all VTSs to notify pipeline and utility operators following potential incursions on submerged pipelines within the VTSs’ areas of responsibility.

To address the lack of drug testing of the pipeline controllers following the crude oil release, NTSB recommended that the Pipeline and Hazardous Materials Safety Administration (PHMSA) audit Beta Offshore’s drug-testing program to ensure compliance with postaccident drug-testing regulations.

Finally, to enhance pipeline safety, NTSB recommended that PHMSA issue an advisory bulletin to all PHMSA-regulated pipeline owners and operators, promoting the benefits of pipeline safety management systems and asking them to develop and implement such a system based on American Petroleum Institute Recommended Practice 1173.

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Source: Safety4sea

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