Nov. 15–The largest oil spill in state history was reported a year ago Friday when the Keystone Pipeline leaked an estimated 407,400 gallons of crude oil into a field in rural Marshall County.
The symptoms have been mitigated, but what cracked the pipe has yet to be determined, at least with certainty.
The pipeline carries crude oil more than 2,600 miles from eastern Alberta, Canada, to Oklahoma and Illinois. There have been 14 leaks since it was commissioned in 2010, according to a federal spill database. Most have been fairly minor.
TransCanada, the company that built and owns the pipeline, deployed hundreds of workers to the scene within a day of the Marshall County leak being confirmed. Within two weeks, the pipeline had the go-ahead to start back up.
In less than six months, the spill site was free of oil contamination and seeded — just in time for spring.
But a year after the leak, a final investigation report from the federal Pipeline and Hazardous Materials Safety Administration has yet to be released.
“While we firmly believe no incident is acceptable and deeply regret that this occurred, our teams executed our emergency response and cleanup procedures effectively, in close cooperation with regulatory agencies, community members and landowners,” said Robynn Tysver, a spokeswoman for TransCanada.
“Today, the site has been cleaned. Going forward, we remain committed to achieving our goal of zero incidents and we are focused on finding ways to reach that level of performance in all areas of the organization,” Tysver added.
TransCanada has taken measures to improve control over the Keystone Pipeline’s quality. For example, it unearthed a section of the line 15 miles north of the rupture site in order to perform maintenance on the its coating.
Workers also unearthed other sections of the pipeline in the area to perform similar maintenance work.
Oil started flowing through the pipeline on Nov. 28, 2017. Before Nov. 16, 2017, the pipeline had not been inspected for potential leaks or cracks using in-line tools that pass through the pipeline, according to a National Transportation Safety Board report issued in July. It notes pressure in the pipe increased when an inspection device passed through.
According to he safety board report, which is different than the expected Pipeline and Hazardous Materials Safety Administration report, the pipeline’s strength was compromised because it was damaged during installation in 2008. It’s suspected that happened when a vehicle drove over it, and it caused the pipeline to fatigue and crack over time until the TransCanada inspection tool passed through.
The weakened section of pipeline gave out and ruptured around 5:33 a.m. near Amherst.
The field is not near a populated area, and the land was enrolled in the Conservative Reserve Program, which means the landowner did not suffer any crop losses.
The rural setting and dry weather conditions allowed TransCanada clean up crews to begin removing any contaminated soils relatively easily.
The report indicates that the pipeline’s control center, in Calgary, Alberta, noticed an increase in pressure while the inspection device passed a pump station. The pressure had increased to 1,352 pounds per square inch. The maximum pressure allowed by a state permit is 1,440 pounds per square inch.
Then, a significant decrease in pressure and an increase in the flow rate prompted a shutdown of the pipeline at 5:36 a.m., according to the report.
TransCanada officials didn’t contact local emergency officials or nearby residents about the leak for another four hours.
It wasn’t until the TransCanada employees confirmed the oil leak at the scene that they notified the Marshall County Sheriff’s Office. Local law enforcement arrived minutes after they were noticed of the spill, which had gone unnoticed and unreported by passersby, according to the report.
The South Dakota Department of Environment and Natural Resources did not investigate the cause of the leak, rather focused on remediation efforts, said Brian Walsh, an environmental scientist manager for the department.
“In response to the spill, DENR required TransCanada to identify and excavate the contaminated soil and properly dispose of it. The soil was disposed of at the Sawyer Landfill in North Dakota. The excavation was backfilled with clean soil, the top soil was replaced and the site was reseeded. These activities were completed in early 2018,” Walsh wrote in an email.
“In addition, DENR required TransCanada to install wells and conduct quarterly groundwater sampling to monitor the shallow groundwater for potential impacts,” he said.
Three have been completed so far and none have revealed problems, Walsh said. All contaminant levels were either nonexistent or below what is allowed by South Dakota ground water quality standards, he said. A fourth sample will be taken yet this year.
“After (we) review the results of the upcoming sampling event, DENR will determine what, if any, additional action is needed to move this case toward regulatory closure,” Walsh said.
Some state lawmakers have wanted to change pipeline regulations during legislative sessions since the leak. One bill aimed to place a moratorium on pipeline construction in South Dakota, but it was killed during a committee hearing. Walsh said he’s not aware of any ongoing efforts to change pipeline regulations.
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