The Massachusetts Gas Disaster

Being one of the longest-settled regions of the U. S., the Commonwealth of Massachusetts has been home to gas utility companies for close to a century and a half.  Unfortunately, some of the pipes installed in the 19th century are still in use in older parts of the state, notably around Lawrence, Andover, and North Andover in the Merrimack Valley north of Boston.  So earlier this month, Columbia Gas of Massachusetts, the gas utility serving the area, announced that it was going to start replacing some older gas lines. 

On Thursday afternoon, Sept. 13, residents of these towns would have been justified in thinking that they had suddenly been transported into the midst of a bad horror movie.  House after house exploded and caught fire.  The Massachusetts State Police logged over 30 calls reporting fires, and by Saturday authorities counted over 60 suspected gas fires in the area.  When one house exploded, its chimney toppled over onto a car, and one teenager in the car later died of his injuries.  Twenty-five people suffered injuries, some serious.

As soon as the scope of the disaster was known, authorities shut off gas and electric utilities to the areas affected and ordered an evacuation, which lasted in some cases until Saturday.  Citing Columbia Gas’s lack of cooperation, Massachusetts Governor Charlie Baker said he was replacing Columbia Gas with another utility, Eversource, to lead recovery efforts, and declared a state of emergency in the region. 

A thorough understanding of what went wrong in Lawrence will have to wait for the results of investigations by local, state, and Federal officials, including members of a National Transportation Safety Board team that were dispatched to the scene.  Nevertheless, similar incidents have happened before, and their history is better known.

In the early days of gas utilities, gas was manufactured typically by the destructive distillation of coal and stored in large accumulator tanks at close to atmospheric pressure.  Only enough pressure to send it through distribution pipes and gas meters was used, and the delivered pressure was so low it was measured in inches of water, rather than pounds per square inch (PSI).  About 7 inches of water was the standard delivery pressure then, and it remains so today—equivalent to about 0.25 PSI.  Such a low pressure reduces requirements on residential piping and means that even a wide-open pipe is not going to leak enough gas to form anything more than a moderate flame.  I have seen a gas utility worker at a work site in my neighborhood street leave a delivery pipe open and unattended for a few minutes, with no apparent concern.

But by the same token, systems designed for such low pressure behave badly if by some mishap a higher transmission-line pressure reaches them.  For transmission over long distances, pressures ranging in the 50 to 100 PSI range are used to deliver gas to substations, where pressure regulators lower the pressure to the low levels needed at customers’ houses. 

Experts agree that somehow, a pressure greatly in excess of the normal 0.25 PSI was mistakenly connected to the distribution system in Andover, North Andover, and Lawrence.  The exact effects on each home depended on what kind of appliances were connected and operating at the time.  Fortunately, the weather was mild—highs in the 70s, lows in the 60s—so probably few domestic heating systems were being used.  Still, older furnaces and stoves use pilot lights, and one official was quoted as saying with enough pressure, a pilot light can turn into a torch.  Minor flaws in piping that would withstand 0.25 PSI may give way under higher pressures, resulting in major leaks of gas that can be triggered by an electric spark, a burning candle, or other source of ignition.  Out of the many hundreds of homes serviced by Columbia Gas in that region, some 60 or so suffered either major leaks or fires and explosions as a result.

When I lived in Massachusetts for a time after growing up in Texas, I noticed a rather widespread prejudice against gas for domestic heating, as opposed to either electricity or heating oil.  I encountered more than one person who said they would never buy or rent a place with gas, simply because of the danger.  Having grown up in a house heated with gas floor furnaces and space heaters (most of which would be too dangerous to install in new construction today), this attitude struck me as strange.  But Columbia Gas has not done its industry’s reputation any good by first allowing this accident to happen, and then by failing to take quick, decisive public actions to mitigate the disaster.  Columbia Gas’s parent company NISource saw its stock price fall 12 percent on the Friday following the disaster, an unusual occurrence for a generally conservative investment such as a fully-regulated utility firm. 

Environmentally speaking, the use of natural gas for domestic heating is more efficient than electric heating, even if natural gas is used to power the electric generation plants.  It can be argued that in making so many new natural-gas discoveries over the past decade, the U. S. has done more in recent years to replace higher-carbon-emission oil with natural gas than any other nation, thus decreasing the world’s carbon footprint. 

But these arguments will not console those who have lost loved ones or property in the Massachusetts gas explosions.  I wouldn’t blame them if some of them return to what is left of their homes and rip out all the gas lines completely.  I can also imagine the troops of lawyers who must be descending upon the region to file lawsuits against Columbia Gas and anyone else with deep pockets who might have been involved.  There is justice in compensating victims for their losses to the extent possible.  A trust has been betrayed when a utility’s normally benign facilities suddenly turn into engines of fire and destruction.  It will be interesting to learn what combination of mechanical failure, lack of understanding, and management errors led to this tragedy.  But even if we learn everything there is to know, that won’t fix the death and damage that resulted from it. 

Sources:  I referred to articles carried by CNN on Sept. 14 at https://www.cnn.com/2018/09/14/us/massachusetts-explosions-fires/index.html, the Boston Globe at https://www.bostonglobe.com/metro/2018/09/13/explosions-cause-unclear-but-specialists-point-gas-pressure/1EyRYFCahN7rZbqodpSxBM/story.html, and Fortune (a Bloomberg News story) at http://fortune.com/2018/09/14/gas-explosion-massachusetts/, as well as Wikipedia articles on natural gas and Lawrence, Massachusetts.