Sign Up for Our Newsletter


How Safe are America's 2.5 Million Miles of Pipelines?

image of Lena Groeger
The explosion of a pipeline in San Bruno was so violent that people nearby thought a plane had crashed. The accident killed eight people and injured 50 more.

This story was originally published by ProPublica.

At 6:11 p.m. on September 6, 2010, San Bruno, California 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 8 people, and injured more than 50.

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 (see "The Whistleblower" series).

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 47 billion 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, Pennsylvania, 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.

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 7 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.

image of Lena Groeger
Lena Groeger is a news application developer at ProPublica. She has previously worked at Scientific American, where she wrote about topics in science and health. Prior to that she was at Wired, where she designed infographics and reported on technolo... READ MORE >