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How deciding not to fix a pipe in Kansas 10 years ago led to the Keystone pipeline's biggest spill

Crews isolated four miles of Mill Creek and drained more than two miles of it during the months-long cleanup.
Environmental Protection Agency
Crews isolated four miles of Mill Creek and drained more than two miles of it during the months-long cleanup.

Independent investigators paint a very different picture from what oil company TC Energy has said publicly about events that led to the Keystone pipeline’s biggest oil spill ever.

Their report says, for instance, that the company dug up the section of pipe nearly a decade before it burst because it knew the pipe had warped. Yet it reburied the spot without fixing it.

The consultants’ 240-page report also sheds light on how the Keystone — with its beefed up safety features that won it a special federal permit to operate at high stress levels — burst open in Kansas last year while operating under much less pressure than it was designed for.

It ruptured, in fact, under run-of-the-mill pressure that normal, less rigorously designed oil pipelines regularly withstand.


Investigators found gaps in TC Energy’s standards and controls for how it designs bends in the pipeline and how it judges whether to repair warped pipes.

“Other (similarly designed bends in the Keystone) may also be susceptible,” they wrote. That includes more than 100 pipe fittings installed in 2010 that “could have similar (welding) imperfections.”

The investigators also found lapses in construction oversight and pointed to ways the Canadian company underestimated key risks that paved the way for more than 500,000 gallons of tar sands crude oil to spill onto a hillside and into a stream in Washington County in north-central Kansas.

TC Energy knew for a decade that the section of pipeline that eventually ruptured had warped from perfectly round to an oval shape. Yet the company didn’t look into how that had happened or what risks accompanied the deformities.

In fact, workers dug up the buried pipe in 2013 to check how much it had warped.

TC Energy then considered fixing the section, but opted to rebury it as it was.

Investigators concluded that was just one of the problems that combined to lead to the pipeline failure.

TC Energy said Monday it has “robust practices and policies” and that the spot that ruptured was up to code.

“We are confident in our ability to continue to safely deliver the energy North Americans rely on,” the company said in an email. “We will examine how we can further our overall safety and integrity.”

TC Energy says that it is running extra checks on its system and that it ran inspection tools through 300 miles of pipe in Nebraska, Kansas and Oklahoma.

It is looking into other spots in the pipeline that investigators said could suffer similar problems.

“Thus far, we have not found any similarities,” the company said. “We anticipate this work to carry into 2024.”

A workaround

The Keystone burst at an elbow, a spot where the 36-inch-wide pipeline took a 30-degree turn.

TC Energy had bought the elbow with an adjoining section of pipe on either end, pre-assembled and pre-welded.

Investigators see evidence that the fusion was not complete in some areas.

But this wasn’t the only trouble brewing.

The bend was shipped to Washington County, Kansas, and installed in 2010.

That’s when installers warped it during construction, most likely by subjecting it to too much weight — perhaps while burying it and compacting the soil around it.

They squeezed the round pipe into an oval and created a wrinkle in one of its adjoining sections.

TC Energy discovered the oval shape in 2012, when it became difficult to run cleaning and inspection tools through the pipeline. The warped pipe was a barrier.

 EPA workers watch pipeline repair work at the site of the Keystone oil spill in December.
Environmental Protection Agency
EPA workers watch pipeline repair work at the site of the Keystone oil spill in December.

So crews dug up the bend to see exactly how warped it was.

Then, instead of fixing it, TC Energy had the inspection contractor modify its tools to pass through the warped spot more easily.

But the warped pipeline piled onto an already imperfect weld job.

And so did engineering decisions, the investigators concluded. The specific way the bend’s design transitions from thicker walls at the elbow to thinner walls for the adjoining pipes on either end increased the stress on the welding seams.

Investigators say the welding work, though flawed, complied with codes. But, they say, that wasn’t enough for this kind of higher-stress scenario.

Under all this stress, one of the weld seams on the inside of the elbow pipe started to crack.

The pipeline held — at first. But over the years, the cyclical rise and fall of pressures and temperatures in the Keystone battered the weld further.

Dec. 7, 2022, brought the final straw in the form of an ordinary procedure at relatively low pressure levels.

Half an hour before the Keystone burst open, TC Energy slowed the oil flow from Nebraska through Kansas to Oklahoma as it prepared to bypass a pump station in Hope, Kansas, to run an inspection tool through the pipeline.

It bypassed the station at 8:59 p.m. Just two minutes later, as the flow of oil increased again, the warped elbow’s long-failing weld finally gave way.

Just 90 feet upslope from Mill Creek, a crack split open across the top of the pipeline, stretching nearly one-quarter of its circumference.

The pressure in the pipeline at the time was well below what the Keystone is designed to handle, and well below even the thresholds set for less rigorously designed pipelines.

Extra sticky crude oil erupted into the night air. Some rocketed over a steep slope and into cropland on the other side, but most of it poured into Mill Creek, coating it in diluted bitumen.

During a months-long cleanup, at times with 800 workers on site, crews isolated and bypassed four miles of the sullied creek and drained more than two miles of the most heavily polluted stretch to excavate the oil.

Diluted bitumen, often called dilbit, poses trickier cleanup problems than other crude oils when it spills into water because it gradually sinks below the surface.

The U.S. Environmental Protection Agency said last week that Mill Creek has now passed visual inspections for oil. Work to restore the habitat and dispose of contaminated soil is ongoing.

The EPA praised cleanup crews for reaching this point in just five months.

The Kansas Department of Health and Environment oversees lab testing of earth and water at the site. It didn’t respond to questions about whether lab work from the creek bed back up the visual inspections.

TC Energy expects to continue working at the site into this fall.

Could it happen again?

The investigators recommend that TC Energy check other bends that it installed with similar designs in case they’re gradually failing, too.

They also urge the company to check for warping.

The fact that TC Energy didn’t discover until 2012 that an elbow had become warped during installation in 2010 “points to lapses in construction oversight and control of construction quality processes,” they wrote.

They also questioned TC Energy’s decision not to run inspection tools through the pipe immediately after it was installed, which would likely have revealed the warping early enough to make the contractor who installed it redo the work at no extra cost.

The report indicates TC Energy identified at least four other warped elbows in Nebraska, Kansas or Oklahoma in 2021 while working to increase the pipeline’s flow rates.

An excerpt of the 240-page investigative report produced by RSI Pipelines Solutions.

It also says this stretch of the Keystone includes 108 other pre-assembled elbows dating to 2010 that came from the same manufacturer as the one that cracked open. Those joints, it says, could have the same incomplete welding fusion.

TC Energy and the federal government’s pipeline regulatory agency got the investigators’ report last month, but the document was only made public last week in response to federal open records requests.

The Canadian company put out its own summary of the independent findings last month.

Its summary doesn’t mention lapses in oversight, risk assessment and company standards. Nor does it explain that the company knew since 2012 that this section of pipe was warped and that investigators concluded that played a key role in the pipeline eventually splitting open.

TC Energy wrote that “a unique set of circumstances” caused the oil spill in Kansas.

But it also announced that it would investigate other spots on the Keystone with characteristics similar to the spill site and review design and construction practices.

The independent report by RSI Pipeline Solutions was commissioned by TC Energy under orders from the Pipeline and Hazardous Materials Safety Administration, part of the U.S. Department of Transportation.

That agency released the report with redactions imposed by the oil company.

Federal law allows companies to block the public from reading details that would reveal trade secrets to competitors, put people in danger or violate their privacy. TC Energy cited those reasons for its redactions.

It blacked out, for example, some of the manufacturers and contractors involved in producing and installing the specific section of pipeline that split open more than a decade later.

It also blacked out details of projects since 2016 aimed at increasing the flow of oil running through portions of the Keystone system that are redacted but that appear to include Kansas.

The night of the rupture

The report reveals other details not previously disclosed by TC Energy, including a more detailed timeline of events.

The Keystone ruptured at about 9 p.m. on Dec. 7.

It triggered a leak alarm at 9:01 p.m., and over the next six minutes, pressure in the pipeline fell by one-fourth.

Emergency shutdown procedures started at 9:07 p.m.

In total, it took 19 minutes from the initial alarm to cut off oil flow to the 96-mile stretch of pipeline that lies between Hope, Kansas, and Steele City, Nebraska.

Crews emptied parts of Mill Creek to clean up the streambed.
Environmental Protection Agency
Crews emptied parts of Mill Creek to clean up the streambed.

The spot where tar sands oil was spewing into rural north-central Kansas lay between those two pump stations.

The Kansas News Service has filed records requests for various documents related to the pipeline, the spill and how TC Energy handles ruptures of this nature.

The federal government has so far produced two records.

One shows stress levels in the pipeline at the time of the incident. The second is the consultant’s investigative report.

The Keystone’s design

In 2007, while planning to build the Keystone system, TransCanada (now TC Energy) received permission from U.S. pipeline regulators to eventually operate most of it at higher stress levels than typically allowed.

But that permit came in exchange for dozens of requirements that would make the massive pipeline system extra safe.

The Keystone had to feature extra rigorous design, inspections and oversight, from the very creation of its myriad pieces to the date of their installation and beyond.

The oil company had to “more closely inspect and monitor the Keystone Pipeline over its operational life” than other pipelines that don’t qualify to operate at its extra high stress levels, the independent investigators note.

The Keystone stretches from Alberta, Canada, to the Texas coast, and over to Illinois. It can transport more than 27 million gallons of oil daily.

TransCanada laid the nearly 300 miles of 3-foot-wide pipeline (with walls about half an inch thick) that run from Steele City, Nebraska to Cushing, Oklahoma in 2010. The oil started flowing a few months later.

TransCanada, or TC Energy, never actually operated the leg at the higher stress levels allowed in its federal permit.

Despite that, and fulfilling the federal requirements for better-than-ever safeguards on this leg, it burst.

Celia Llopis-Jepsen is the environment reporter for the Kansas News Service. You can follow her on Twitter @celia_LJ or email her at celia (at) kcur (dot) org.

The Kansas News Service is a collaboration of KCUR, Kansas Public Radio, KMUW and High Plains Public Radio focused on health, the social determinants of health and their connection to public policy.

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Celia comes to the Kansas News Service after five years at the Topeka Capital-Journal. She brings in-depth experience covering schools and education policy in Kansas as well as news at the Statehouse. In the last year she has been diving into data reporting. At the Kansas News Service she will also be producing more radio, a medium she’s been yearning to return to since graduating from Columbia University with a master’s in journalism.