Deadly Dangers Lurk In Natural Gas Distribution Lines

A deadly gas explosion in Massachusetts underscores a hidden danger in the nation’s gas distribution system.

We accept a lot of risks in life. In every year since 1946, at least 30,000 people have been killed in car accidents on U.S. highways. In some years, that number exceeded 50,000. Yet we continue to drive, even though more than 100 people are killed on average each day. Why? Because driving makes life easier and more convenient for us, and so it’s a risk that we accept.

The same is true in the production, transportation, and consumption of energy. There are risks involved. When 47 people were tragically killed in the Lac-Mégantic rail disaster in Quebec, we didn’t stop transporting crude oil by rail. We may change regulations, but we continue to live with these risks because of the value we place on cheap and affordable energy.

There is no free lunch with any source of energy. There are risks and trade-offs.

Disaster in Massachusetts

Last week one person was killed, over 25 were injured, and dozens of homes were damaged or destroyed following a series of natural gas explosions in Massachusetts. The incident remains under investigation, but thus far investigators are focusing on the possibility of overpressurization of a gas main owned by natural gas utility Columbia Gas of Massachusetts.

Columbia Gas of Massachusetts services more than 300,000 customers in three areas in northwestern Massachusetts. Columbia Gas is one of seven regulated natural gas subsidiaries of NiSource, whose combined utility operations serve nearly 4 million customers in seven states. NiSource operates about 60,000 miles of distribution pipelines, and saw its shares drop by nearly 12% following the incident.

This incident underscores an unappreciated risk that exists across the U.S. There are more than 300,000 miles of natural gas pipelines buried beneath every state in the Lower 48:

U.S. natural gas pipeline system.

According to the American Gas Association, steel is used in most natural gas transmission systems pipes, while plastic pipe has predominated in gas utility distribution systems over the past 30 years.

Ticking Time Bombs

The problem lies in the older pipelines. During the first half of the 20th century, cast iron was used in many utility systems. Steel replaced cast iron as the material of choice in the 1950s, but that means that there are a lot of older cast iron pipelines still in service.

2014 report by USA Today found that there is “at least 85,000 miles of aging cast-iron and bare-steel gas pipes still operating in U.S. communities”, with many in heavily-populated areas. Most of these aging pipelines can be found in the Northeast. The report also found that these pipelines are involved in a disproportionate share of gas leaks.

The National Transportation Safety Board (NTSB) and the Pipeline and Hazardous Materials Safety Administration have been warning utilities that these aging pipelines need to be replaced, but it isn’t required by law. The cost of replacing these pipelines can exceed more than $1 million a mile, with the costs passed on to consumers.

Columbia Gas has reported that it has 471 miles of cast- and wrought-iron gas distribution lines. This is more than all about 15 of the nation’s 1,000-plus gas utilities. These lines are vulnerable in a couple of ways. As old as they are, they will begin to corrode and crack. They are vulnerable to shifts in the earth that put additional stress on the pipeline.

But they are also vulnerable to overpressure, which is suspected as the cause. In order to deliver gas to customers, it must be compressed to a certain pressure. There are protections in place to prevent overpressure (e.g., pressure regulators), but those protections can fail. A pressure surge into aging pipeline can easily result in a leak or catastrophic failure.

Pressure Problems

Over the past year, I have experienced an analogous situation with my local water utility. The water pressure into my home is supposed to be no more than 60 pounds of pressure per square inch (PSI). After dealing with numerous leaky faucets and multiple ruptured lines in my sprinkler system, I learned that the pressure sometimes surges to as much as 120 PSI. That was far too much pressure for my aging sprinkler lines, and I found myself having to dig up and replace ruptured sprinkler line just about every week.

Finally, I put in my own pressure regulator on the incoming water line to keep the pressure at 60 PSI regardless of any pressure surges from the utility. I haven’t had any problems with leaky faucets or in my sprinkler system since.

It is conceivable that this sort of pressure surge is behind the incident. A incident investigation may reveal something like a failure in a pressure regulator. Or it may simply be that another aging pipe gave way, and the resulting leak found an ignition source.

Inadequate Response

Columbia Gas reported that they are in the process of visiting 8,600 affected customers so they can shut off gas mains and conduct safety inspections. But their response has been broadly criticized. So much so, that Massachusetts Governor Charlie Baker declared a state of emergency and called in another utility, Eversource, to manage the process of ensuring that any remaining gas leaks are repaired, so the electricity and gas can be turned back on.

This incident is just one of a string of many similar incidents in recent years, and it will certainly increase the pressure on utilities to upgrade their aging pipelines. Despite the high cost of upgrading the pipelines, if natural gas is to continue serving as the home heating fuel of choice in these communities, utilities must do everything they can to ensure that these sorts of preventable accidents don’t happen.

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