New Jersey gas leak explosion: Does this happen often?

On early Tuesday morning, a smell of natural gas in the air (and authorities directing them to evacuate) alarmed some residents in Patterson, N.J. At close to 9:30 a.m., they felt a shockwave – and witnessed a house in the neighborhood blow up.

Two houses were flattened in the explosion that was believed to be caused by a natural gas leak, as reported by NJ.com. No serious injuries have been reported and it is still unknown whether the cause was from leaking pipelines, faulty appliances, or other factors.

"We have shut off the gas mains and electric service. At this time we do not know the cause of the explosion but will work with local officials to fully investigate," The Public Service Electric and Gas Company that maintains gas service in the area said in a statement, according to ABC News.

The reasons leading up to natural gas accidents can vary and not all are tied to leaking pipelines. Digging excavations that hit a pipeline, for instance, can cause an accident. But one factor has received increasing attention over the past decade: the role of aging pipelines, especially in the northeast where pipe infrastructure can be more than 100 years old.

"When it [natural gas] is in a confined space such as a basement or manhole and fills up to a level of 4 percent, all you need is a spark [for it to explode,]" Nathan Phillips, professor at Boston University tells The Christian Science Monitor in a phone interview. "A leak-prone pipe is largely made up of cast iron … these are issues that we have with the infrastructure across aging cities."

Natural gas leaks and accidents are not uncommon, although federal data shows there hasn’t been a clear trend in the number of accidents occurring. For example, in August, a gas leak in Silver Spring, Md., killed seven and destroyed a four-floor apartment. In April, a gas transmission line exploded next to a man’s house in Pennsylvania. Winter might see more such incidents: leaks are more prone to be pushed into homes and buildings as frost covers the soil outdoors, Popular Mechanics reports.

In 2016, 206 significant pipeline incidents have been reported so far in 2016, and 46 occurred during gas distribution, which is where natural gas is delivered from main pipelines to local homes and businesses, according to the Pipeline and Hazardous Materials Safety Administration (PHMSA). Natural gas is widely used as a heating fuel in households and businesses and its use is quickly growing.

Professor Phillips, together with a group of scientists, conducted a study in September 2015 that found 3,400 natural-gas pipeline leaks across Boston and 5,900 leaks in Washington, D.C. Many of the cast-iron pipes were installed in the 1800s, and according to Robert Jackson, one of the study’s authors, pipe age is the first indicator of "determining risk for leaking natural gas pipes," as reported by Popular Mechanics.

An often-used solution replaces the old cast-iron pipes and bare steel pipes with plastic pipes, a strategy that the same study found effective. In Durham, N.C., and Cincinnati, the likelihood of a leak was 0.22 and 0.47 per mile compared to 4.3 leaks per mile in Boston, Washington, and New York. Durham and Cincinnati are similar in that the two cities had replaced all its cast-iron and unprotected steel pipes in separate programs in the past decade.

After a deadly 2010 gas explosion in San Bruno, Calif., the Department of Transportation and PHMSA called for an acceleration of repair, rehabilitation, and replacement of high-risk pipeline infrastructure in 2011. Since then, many utility companies have started pipeline replacement programs, although consumers may sometimes have to wait for years and face higher bills to fund the process, as reported by Detroit Free Press in 2014.

Christina Sames, vice president of operations and engineering for the American Gas Association, tells the Monitor in a phone interview that the time required depends on where the pipeline is. Replacing a pipeline on a busy street would obviously require more permits and take a longer time. Kyle Rogers, AGA vice president of government relations, said up to 40 states have mechanisms that accelerate the replacement process.

According to PHMSA data, 19 states so far have completely eliminated these old iron gas pipes, and from 2005 to 2014, there has been a 26 percent decrease in mileage of iron main pipes and 66 percent in service lines that go to customers. New Jersey still has the most miles of cast-iron main pipelines while New York has the most for service lines. 

The American Gas Association anticipates the cost to retire, replace or recondition these pipes to be upward of $82 billion. They point out that with the current low natural gas prices, it might be a good opportunity to engage in these efforts without passing the burden on to customers.

In his research, Phillips drove around greater Boston, detecting where the greatest leaks were. He was surprised to see the extent of the problem and how people were unaware of it. To him, patching leaks and replacing gas pipelines may not be the best long-term measure.

The pipelines are "better simply because they're newer," he says. "We need to move out of gas altogether and to electrify our building heating system."

In the meantime, he is working on a project that can speed up the pipe-replacement process.

"We notice that we're losing lots of opportunities in saving money when we do things like pave new streets but we leave leaking gas lines under the street, or when we replace broken sewer lines," Phillips says. "We could have replaced the gas pipeline at the same time – that is one way we're thinking of solving the problem."