Investigators examine the pipeline rupture site in May 2015 after the Refugio Oil Spill.  (Bruce Reitherman / Santa Barbara County photo)

Plains All American Pipeline failed to detect and prevent the external corrosion that caused the Refugio Oil Spill, federal regulators concluded in a final investigative report released Thursday.

The company also failed to detect and respond to the rupture in the 24-inch crude oil pipeline in a timely way, as the pipeline continued to operate for 35 minutes after the spill started.

External corrosion caused the spill, and the in-line inspections of the pipeline failed to accurately measure the extent and depth of corrosion.

The pipeline runs along the mountain side of Highway 101 in southern Santa Barbara County and the oil flowed downhill, under the freeway through the culvert, and onto the shoreline and into the ocean.

“The consequences of the spill were additionally aggravated by an oil spill response plan that did not identify the culvert near the release site as a spill pathway to the Pacific Ocean,” the report stated.

That culvert is what funneled crude oil under Highway 101 and the railroad tracks into the ocean, and the company’s oil spill response plan didn’t even mention the culvert.

Federal regulators at the Pipeline and Hazardous Materials Safety Administration will now consider whether Plains violated federal pipeline safety regulations, according to the report, which was released on the one-year anniversary of the spill.

An estimated 123,228 gallons were spilled May 19, 2015 and Plains was indicted of 46 criminal charges related to the spill on Monday. Charges include accusations of not notifying authorities fast enough and knowingly discharging a pollutant into state waters.

Discharge estimates have ranged from 100,000 to 142,800 gallons, but the PHMSA report estimate is at 2,934 barrels of crude oil. Plains has recovered 1,100 barrels of crude oil, as of November.

The Santa Barbara dispatch center notified the National Response Center of an unknown sheen off Refugio State Beach at 12:43 p.m., an hour after someone first reported a petroleum smell in the area.

Plains called the NRC to report the spill at 2:56 p.m., 89 minutes after the leak was discovered by Plains staff.

According to PHMSA, federal regulations require operators to notify the NRC at the earliest practical moment following the discovery of a hazardous materials spill, later defined as within one hour. Plains notified the NRC 29 minutes late.

The report also details the failure of Plains staff to recognize the leak and quickly shut down the pipeline. 

Plains control room staff didn’t recognize signs of a pipeline rupture and restarted Line 901 after the spill started, according to the investigative report. 

Control room operators didn’t respond to the low pressure alarms, which should be high priority safety alarms, the PHMSA report concludes. 

“Neither the pipeline controller nor step-up shift supervisor detected the initial abnormal conditions as the release occurred. There was an indication of decreased pressure and increased flow between 10:53 and 10:58 a.m., which is consistent with a pipeline release. This resulted in a delayed shutdown of the pipeline.”

A shift supervisor shut down the pipeline leak monitoring system alarms since staff anticipated alarms due to Sisquoc Station maintenance activity that day and after the fact, an analysis determined the alarms would have been generated two minutes before the controller finally shut down the pipeline. 

The ruptured piece of pipeline was dug out and taken to an Ohio firm, Det Norske Veritas Inc., which concluded the leak happened at a spot thinned by external corrosion.

“The results of the metallurgical analysis indicate that the leak occurred at an area of external corrosion that ultimately failed in ductile overload under the imposed operating pressure. The morphology of the external corrosion observed on the pipe section is consistent with corrosion under insulation facilitated by wet-dry cycling.”

The spot where the pipe burst – it wasn’t a slow leak, but one rupture, according to experts – had metal loss of 89 percent in the wall thickness. 

PHMSA inspectors also found moisture trapped in pipe insulation on four sections of pipe during digs, compromising the pipe coating.

Operational events of that morning, including a Sisquoc pump shutting down uncommanded, were abnormal but “this should not have caused the release if the pipeline’s integrity had been maintained to federal standards,” the report said. The pipe failed while operating at 56 percent of its maximum pressure. 

Not only was Plains’ system of corrosion control ineffective, but methods for detecting it were inconsistent, according to the report.  

The PHMSA report found that in-line inspections of the pipeline often underestimated and overestimated the wall thickness of pipe, compared to confirmation digs to examine the pipe in person.

Plains never discussed those discrepancies with the third-party inspectors and an increasing frequency of these corrosion anomalies were found on Line 901 and Line 903 for inspections in 2007, 2012 and 2015. Inspections had been conducted on May 6, 2015, just two weeks before the spill.

The ruptured spot of the pipe was detected by the in-line inspection tool in 2012, estimated at 45-percent depth of normal wall thickness. Even though Plains policy says to add 10 percent (making this one 55 percent) to provide a predicted failure time, Plains did not excavate that section of pipe, according to the PHMSA report. 

Since the spill, PHMSA ordered Plains to shut down and purge both Santa Barbara County pipelines – the ruptured Line 901 and connecting 130-mile Line 903 that heads north from Gaviota to Kern County. 

Plains will not comment on the report, saying there are ongoing investigations and pending litigation over the spill. 

“Plains sincerely regrets the accidental Line 901 release and the resulting impact on the community, the environment and wildlife,” the company said in a statement Thursday.

“Since the release, we have worked tirelessly and relentlessly to do the right thing and do it as quickly and effectively as possible by cleaning up the beaches and other affected areas, compensating those who were impacted by the release and working with the various governmental and other organizations responding to the incident.”

Noozhawk managing editor Giana Magnoli can be reached at Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.

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Giana Magnoli, Noozhawk Managing Editor

Noozhawk managing editor Giana Magnoli can be reached at