Journalism in the Public Interest

Pipelines Explained: How Safe are America’s 2.5 Million Miles of Pipelines?

While pipelines are generally regarded as safe, critics blame insufficient oversight and old pipes for the hundreds of accidents that occur every year. We explain how pipelines fail.

Map of major natural gas and oil pipelines in the United States. Hazardous liquid lines in red, gas transmission lines in blue. Source: Pipeline and Hazardous Materials Safety Administration.

Update, Dec. 6, 2016: In 2012, we detailed safety issues in the U.S.’s more than two million miles of natural gas and oil pipelines. Following months of protest at a section of the Dakota Access Pipeline near the Standing Rock Sioux Reservation, the Department of the Army decided to look at alternative routes. Our explainer remains a useful bit of context in light of this fight.

At 6:11 p.m. on September 6, 2010, San Bruno, Calif. 911 received an urgent call. A gas station had just exploded and a fire with flames reaching 300 feet was raging through the neighborhood. The explosion was so large that residents suspected an airplane crash. But the real culprit was found underground: a ruptured pipeline spewing natural gas caused a blast that left behind a 72 foot long crater, killed eight people, and injured more than fifty.


Over 2,000 miles away in Michigan, workers were still cleaning up another pipeline accident, which spilled 840,000 gallons of crude oil into the Kalamazoo River in 2010. Estimated to cost $800 million, the accident is the most expensive pipeline spill in U.S. history.

Over the last few years a series of incidents have brought pipeline safety to national – and presidential – attention. As Obama begins his second term he will likely make a key decision on the controversial Keystone XL pipeline, a proposed pipeline extension to transport crude from Canada to the Gulf of Mexico.

The administration first delayed the permit for the pipeline on environmental grounds, but has left the door open to future proposals for Keystone’s northern route. Construction on the southern route is already underway, sparking fierce opposition from some landowners and environmentalists.

The problem, protesters say, is that any route will pose hazards to the public. While pipeline operator TransCanada has declared that Keystone will be the safest pipeline ever built in North America, critics are skeptical.

“It's inevitable that as pipelines age, as they are exposed to the elements, eventually they are going to spill,” said Tony Iallonardo of the National Wildlife Federation. “They’re ticking time bombs."

Critics of the Keystone proposal point to the hundreds of pipeline accidents that occur every year. They charge that system wide, antiquated pipes, minimal oversight and inadequate precautions put the public and the environment at increasing risk. Pipeline operators point to billions of dollars spent on new technologies and a gradual improvement over the last two decades as proof of their commitment to safety.

Pipelines are generally regarded as a safe way to transport fuel, a far better alternative to tanker trucks or freight trains. The risks inherent in transporting fuel through pipelines are analogous to the risks inherent in traveling by airplane. Airplanes are safer than cars, which kill about 70 times as many people a year (highway accidents killed about 33,000 people in 2010, while aviation accidents killed 472). But when an airplane crashes, it is much more deadly than any single car accident, demands much more attention, and initiates large investigations to determine precisely what went wrong.

The same holds true for pipelines. Based on fatality statistics from 2005 through 2009, oil pipelines are roughly 70 times as safe as trucks, which killed four times as many people during those years, despite transporting only a tiny fraction of fuel shipments. But when a pipeline does fail, the consequences can be catastrophic (though typically less so than airplane accidents), with the very deadliest accidents garnering media attention and sometimes leading to a federal investigation.

While both air travel and pipelines are safer than their road alternatives, the analogy only extends so far. Airplanes are replaced routinely and older equipment is monitored regularly for airworthiness and replaced when it reaches its safety limits. Pipelines, on the other hand, can stay underground, carrying highly pressurized gas and oil for decades – even up to a century and beyond. And while airplanes have strict and uniform regulations and safety protocols put forth by the Federal Aviation Administration, such a uniform set of standards does not exist for pipelines.

Critics maintain that while they’re relatively safe, pipelines should be safer. In many cases, critics argue, pipeline accidents could have been prevented with proper regulation from the government and increased safety measures by the industry. The 2.5 million miles of America’s pipelines suffer hundreds of leaks and ruptures every year, costing lives and money. As existing lines grow older, critics warn that the risk of accidents on those lines will only increase.

While states with the most pipeline mileage – like Texas, California, and Louisiana – also have the most incidents, breaks occur throughout the far-flung network of pipelines. Winding under city streets and countryside, these lines stay invisible most of the time. Until they fail.

Since 1986, pipeline accidents have killed more than 500 people, injured over 4,000, and cost nearly seven billion dollars in property damages. Using government data, ProPublica has mapped thousands of these incidents in a new interactive news application, which provides detailed information about the cause and costs of reported incidents going back nearly three decades.

Pipelines break for many reasons – from the slow deterioration of corrosion to equipment or weld failures to construction workers hitting pipes with their excavation equipment. Unforeseen natural disasters also lead to dozens of incidents a year. This year Hurricane Sandy wreaked havoc on the natural gas pipelines on New Jersey’s barrier islands. From Bay Head to Long Beach Island, falling trees, dislodged homes and flooding caused more than 1,600 pipeline leaks. All leaks have been brought under control and no one was harmed, according to a New Jersey Natural Gas spokeswoman. But the company was forced to shut down service to the region, leaving 28,000 people without gas, and it may be months before they get it back.

One of the biggest problems contributing to leaks and ruptures is pretty simple: pipelines are getting older. More than half of the nation's pipelines are at least 50 years old. Last year in Allentown Pa., a natural gas pipeline exploded underneath a city street, killing five people who lived in the houses above and igniting a fire that damaged 50 buildings. The pipeline – made of cast iron – had been installed in 1928.

A fire rages through Allentown, PA, after a gas line explosion in Feb. 2011

Not all old pipelines are doomed to fail, but time is a big contributor to corrosion, a leading cause of pipeline failure. Corrosion has caused between 15 and 20 percent of all reported “significant incidents”, which is bureaucratic parlance for an incident that resulted in a death, injury or extensive property damage. That’s over 1,400 incidents since 1986.

Corrosion is also cited as a chief concern of opponents of the Keystone XL extension. The new pipeline would transport a type of crude called diluted bitumen, or “dilbit.” Keystone’s critics make the case that the chemical makeup of this heavier type of oil is much more corrosive than conventional oil, and over time could weaken the pipeline.

Operator TransCanada says that the Keystone XL pipeline will transport crude similar to what’s been piped into the U.S. for more than a decade, and that the new section of pipeline will be built and tested to meet all federal safety requirements. And in fact, none of the 14 spills that happened in the existing Keystone pipeline since 2010 were caused by corrosion, according to an investigation by the U.S. Department of State.

The specific effects of dilbit on pipelines – and whether the heavy crude would actually lead to more accidents – is not definitively understood by scientists. The National Academies of Science is currently in the middle of study on dilbit and pipeline corrosion, due out by next year. In the meantime, TransCanada has already begun construction of the southern portion of the line, but has no assurance it will get a permit from the Obama administration to build the northern section. (NPR has a detailed map of the existing and proposed routes.)


Little Government Regulation for Thousands of Miles

While a slew of federal and state agencies oversee some aspect of America’s pipelines, the bulk of government monitoring and enforcement falls to a small agency within the Department of Transportation called the Pipeline and Hazardous Materials Safety Administration – pronounced “FIM-sa” by insiders. The agency only requires that seven percent of natural gas lines and 44 percent of all hazardous liquid lines be subject to their rigorous inspection criteria and inspected regularly. The rest of the regulated pipelines are still inspected, according to a PHMSA official, but less often.

The inconsistent rules and inspection regime come in part from a historical accident. In the 60's and 70's, two laws established a federal role in pipeline safety and set national rules for new pipelines. For example, operators were required to conduct more stringent testing to see whether pipes could withstand high pressures, and had to meet new specifications for how deep underground pipelines must be installed.

But the then-new rules mostly didn’t apply to pipelines already built – such as the pipeline that exploded in San Bruno. That pipeline, which burst open along a defective seam weld, would never have passed modern high-pressure requirements according to a federal investigation. But because it was installed in 1956, it was never required to.

"No one wanted all the companies to dig up and retest their pipelines," explained Carl Weimer, executive director of the Pipeline Safety Trust, a public charity that promotes fuel transportation safety. So older pipes were essentially grandfathered into less testing, he said.

A burned out car and charred remains of a home in San Bruno, C.A. after a pipeline explosion in Sept. 2010

Later reforms in the 1990’s mandated more testing for oil pipelines, and today PHMSA requires operators to test pipelines in "high consequence" areas, which include population centers or areas near drinking water. But many old pipelines in rural areas aren’t covered by the same strict regulations.

Some types of pipelines – such as the “gathering” lines that connect wells to process facilities or larger transmission lines – lack any PHMSA regulation at all. A GAO report estimates that of the roughly 230,000 miles of gathering lines, only 24,000 are federally regulated. Because many of these lines operate at lower pressures and generally go through remote areas, says the GAO, the government collects no data on ruptures or spills, and has no enforced standards for pipeline strength, welds, or underground depth on the vast majority of these pipes.

The problem, critics argue, is that today’s gathering lines no longer match their old description. Driven in part by the rising demands of hydraulic fracturing, operators have built thousands of miles of new lines to transport gas from fracked wells. Despite the fact that these lines are often just as wide as transmission lines (some up to 2 feet in diameter) and can operate under the same high pressures, they receive little oversight.

Operators use a risk-based system to maintain their pipelines – instead of treating all pipelines equally, they focus safety efforts on the lines deemed most risky, and those that would cause the most harm if they failed. The problem is that each company use different criteria, so "it's a nightmare for regulators," Weimer said.

However, Andrew Black, the president of the Association of Oil Pipe Lines, a trade group whose members include pipeline operators, said that a one-size-fits-all approach would actually make pipelines less safe, because operators (not to mention pipelines) differ so widely.

"Different operators use different pipe components, using different construction techniques, carrying different materials over different terrains," he said. Allowing operators to develop their own strategies for each pipeline is critical to properly maintaining its safety, he contended.


Limited Resources Leave Inspections to Industry

Critics say that PHMSA lacks the resources to adequately monitor the millions of miles of pipelines over which it does have authority. The agency has funding for only 137 inspectors, and often employs even less than that (in 2010 the agency had 110 inspectors on staff). A Congressional Research Service report found a “long-term pattern of understaffing” in the agency’s pipeline safety program. According to the report, between 2001 and 2009 the agency reported a staffing shortfall of an average of 24 employees a year.

A New York Times investigation last year found that the agency is chronically short of inspectors because it just doesn’t have enough money to hire more, possibly due to competition from the pipeline companies themselves, who often hire away PHMSA inspectors for their corporate safety programs, according to the CRS.

Given the limitations of government money and personnel, it is often the industry that inspects its own pipelines. Although federal and state inspectors review paperwork and conduct audits, most on-site pipeline inspections are done by inspectors on the company’s dime.

The industry’s relationship with PHMSA may go further than inspections, critics say. The agency has adopted, at least in part, dozens of safety standards written by the oil and natural gas industry.

"This isn't like the fox guarding the hen house," said Weimer. "It's like the fox designing the hen house."

Operators point out that defining their own standards allows the inspection system to tap into real-world expertise. Adopted standards go through a rulemaking process that gives stakeholders and the public a chance to comment and suggest changes, according to the agency.

Questions have also been raised about the ties between agency officials and the companies they regulate. Before joining the agency in 2009, PHMSA administrator Cynthia Quarterman worked as a legal counsel for Enbridge Energy, the operator involved in the Kalamazoo River accident. But under her leadership, the agency has also brought a record number of enforcement cases against operators, and imposed the highest civil penalty in the agency’s history on the company she once represented.


Proposed Solutions Spark Debate

How to adequately maintain the diversity of pipelines has proved to be a divisive issue – critics arguing for more automatic tests and safety measures and companies pointing to the high cost of such additions.

One such measure is the widespread installation of automatic or remote-controlled shutoff valves, which can quickly stop the flow of gas or oil in an emergency. These valves could help avoid a situation like that after the Kalamazoo River spill, which took operators 17 hours from the initial rupture to find and manually shut off. Operators use these valves already on most new pipelines, but argue that replacing all valves would not be cost-effective and false alarms would unnecessarily shut down fuel supplies. The CRS estimates that even if automatic valves were only required on pipelines in highly populated areas, replacing manual valves with automatic ones could cost the industry hundreds of millions of dollars.

A worker on the Kalamazoo river, helping to clean up an oil spill of almost a million gallons from a ruptured pipeline in July 2010

Other measures focus on preventing leaks and ruptures in the first place. The industry already uses robotic devices called "smart pigs" to crawl through a pipeline, clearing debris and taking measurements to detect any problems. But not all pipelines can accommodate smart pigs, and operators don’t routinely run the devices through every line.

Just last month, a smart pig detected a “small anomaly” in the existing Keystone pipeline, prompting TransCanada to shut down the entire line. Environmentalists pointed out that this is not the first time TransCananda has called for a shut down, and won’t be the last.

“The reason TransCanada needs to keep shutting down Keystone,” the director of the National Wildlife Federation contended in a statement, “is because pipelines are inherently dangerous.”

Last January, Obama signed a bill that commissioned several new studies to evaluate some of these proposed safety measures, although his decision on extending the Keystone pipeline may come long before those studies are completed.

Image credits: The Associated Press, Thomas Hawk, Kevin Martini

Those of us dealing with Hurricane Sandy also learned that pipelines apparently need electricity, too, meaning they’re worthless in an emergency.  So when looking at the damage caused, that might be an interesting issue to consider.

Steven JF Scannell

Nov. 15, 2012, 4:15 p.m.

My track-pipe system is the answer.  We will use composite, and multiple conduit pipes to ship energy and utilities, and the pipes will serve well as rail and monorail systems.  It’s a mega system design, and it’s the answer to the conversions needed of sustainable sources into more congruent existing systems.  The system relies on CAES and hydrogen produced offshore, or anywhere, to deliver more energy than we will need.

Maybe some things like this are better not spoken much about in the media—particularly with diagrams/pictures of locations. I’m concerned that this kind of exposure could inspire terrorists.

Tim, any terrorists already have this information, or they can get it easily.  Nothing published here is remotely hidden, because it’s impossible to do so.

Anybody official looking to hide it is looking out for their own security (by hiding the truth from people who live nearby), not the country’s.

Steven JF Scannell

Nov. 15, 2012, 4:51 p.m.

John, Tim has a good point about security.  But I don’t know what the official answer would be. The controversy could be an open invitation.  My personal feeling is that these systems should be discussed somehow informally but securely, which of course makes no sense. There are so many vulnerability issues like this one.

John, it’s just that putting ideas out there about vulnerable infrastructure can inspire terrorists. At least ProPublica is not a mass medium - yet. But I worry that a major media could pick up on this and generate mass exposure….and BOOM.

Just ‘cause it’s on line does not make it accurate. It does resemble the map of How Obama Won the Election, lol.

Gregg Stoerrle

Nov. 15, 2012, 5:56 p.m.

If your wondering how safe then just read what this whistleblower has posted on youtube under my former employers videos.Go to Trico Lifts youtube videos and start reading and also go to the U.S department of labors’ youtube channel and read what i posted there.Just a hint a top OSHA offical does not risk his career to provide me inside OSHA documentation if doesen’t think there is a serious safety problem.This is just the tip of what i uncovered at Trico Lift and this has cost 3 of us our careers,

Andy Warrener

Nov. 15, 2012, 9:42 p.m.

BP settled to pay 4.5 billion and admitted criminal wrong doing for the Deep Water Horizon disaster. BP made 25 billion profit in 2011. Nuff said?

Just as US journalism stopped: PHMSA 80% SMYS special permits hit six new mills (and numerous re-opened OLD mills) 7 Russian owned, using Ukrainian steel, Mittal, Jindal & PSL took over, 1099 undocumented temps replaced experienced workers forced into early retirement and contract buy-outs, contract surveillance & auditors largely untrained novices and the gas companies had all new people… crank replaced booze; regulation, whistle-blowing and oversight became terrorist acts and Bush was President. Of COURSE it’s all just fine.

Steven and Tim, please point to one historical incident where “the enemy” (as in any enemy we’ve fought) got an attack idea by reading the news for vulnerabilities.

Every time someone reports on someone’s ineptitude, fear-mongers come out of the woodwork to decry it.  It’s always a potential catastrophe, whether it’s lousy computer security at a bank website, fraud through voting machines, pipelines, or nuclear weapon schematics.  Yet, there’s never a problem as a result..

On the other hand, times where secrets have been kept?  That’s where the damage shows up, since there’s no public outcry to fix the problem, so the people responsible let it go unfixed.  We won’t pursue war crimes against the Bush administration officials, because that would give an advantage to terrorists, so we continue to run black sites and violate human rights at home and abroad.  The Japanese downplay the danger of Fukushima and the other reactor meltdowns to prevent a panic, and a lot of people are going to die of cancer as a result.  The government protected the banks from investigation of their over-leveraging and giving so many NINA (no income, no assets) loans, and it almost collapsed the global economy.  Everybody turned a blind eye to BP’s problems at Deepwater Horizon, and that led to a dozen deaths and cost billions and billions of dollars.

I’m having a hard time imagining a group of terrorists topping what we’ve done to ourselves by shielding the people from the truth.  Secrecy never protects you and I.  It only ever protects those in power from scrutiny.

And also, let’s be perfectly honest:  If a terrorist really wanted to make the news and kill a lot of people, they’d blow up a mall or release nerve gas in one near Christmastime.  People show up in masses, they pay attention to absolutely nothing around them, and at worst, you might have to shoot some dude chasing you on a Segway.  In other words, next to no risk, and a guaranteed newsworthy atrocity.

I’m not saying that to scare anybody or suggest we deploy the FBI to every mall in the country (the New York suburbs alone would bankrupt the country…).  It’s not to disparage security guards, either.  I’m pointing it out because everybody knows this is the case (including all the terrorists who allegedly specifically hate our materialism) and it still never happens.

So, you can be terrified if you want, but the best path for the country is to force the companies to clean their own houses and take the one in a billion risk (which existed regardless of the report!) of a terror strike.

My jaw dropped at that map.

Aging infrastructure is scary stuff: corrosion over time may be only one dangerous factor. This effects every small town, city, and metropolitan area!

The Keystone pipeline that transports dirty oil to refineries, and then to export, can easily be viewed as corporate greed incarnate, or as an environmental disaster waiting to happen.

Steven JF Scannell

Nov. 16, 2012, 5:32 p.m.

John,  I salute you for your patience with the worriers and for your diligence.  All your arguments are sound. Your logic is excellent, impeccable I think.  I much appreciate the trouble you went through to make the case for transparency, which is arguably a strong defense in and of itself. Transparency is a strength, within reason.

I wonder how long it will take for the gas well casings themselves to corrode, too, or whether they are more durable than the pipelines. The same goes for the injection wells where toxic chemicals are being dumped/stored. There is so much going on in the ground underneath our feet.

Somewhere on ProPublica website, an earlier article is posted on that topic. Leaks are already happening… and may be from poor capping techniques or corrosion or both.

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