Where does the Merrimack Valley gas crisis stand now? Here's what we know.

[Rhiannon12866]

"People have been able to go back to their homes, but there remains a long road ahead," Gov. Charlie Baker said Tuesday.

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Here’s what what we know about the crisis as of Tuesday afternoon:

How did it happen?

While state officials have said the emergency involved over-pressurized gas lines, a definitive reason could take some time to investigate.

“The investigation, as I understand it, will not be focused on the end users of the gas but on the distribution system and the origin of the pressure,” Kurt Schwartz, director of the Massachusetts Emergency Management Agency, said Friday as the review was just getting underway.

Still, in a letter to Columbia Gas and its Indiana-based parent company, NiSource, Inc., Monday, U.S. Sens. Elizabeth Warren and Ed Markey wrote that the pressure in the system read 12 times higher than what it was meant to hold, based upon a report from the federal Pipeline and Hazardous Materials Safety Administration.

Pressure in the gas lines should have been approximately 0.5 pounds per square inch, or PSI, but instead came in at at least 6 PSI, according to the letter, which sought answers to questions surrounding the company’s response to the crisis and information about pre-planned upgrades to gas lines that were announced ahead of when the fires broke out.

“We have requested a hearing in the Senate Commerce Committee on this incident and we hope that you will cooperate fully and transparently with federal investigators,” the letter said. “We write to request that you provide us with information in order to help the American people understand why this terrible disaster occurred, whether the company was sufficiently prepared to respond to an incident of this magnitude, and how we can prevent any similar tragedy in the future.”


Much more: https://www.boston.com/news/local-news/2018/09/18/merrimack-valley-gas-explosions-fires-update



The house owned by Lawrence Police Officer Ivan Soto sits nearly burned to the ground on Jefferson Street, in Lawrence Friday. –Bob Salsberg / AP

[RockRaven]

1. Recently helped a relative w/ remodel project; learned about the gas lines/codes re his house...

when they build the house new, or in his case completely replace all the gas lines, they pressure-test the entire house system (downstream of the gas meter) at 15 psi -- just with regular air of course -- for a length of time to check for leaks before they hooked the gas meter back up. And their gas meter then delivers 0.5 psi of natural gas.

One can see that there's a big buffer there which allows for degradation of the system before it causes a problem. Indeed on the first pressure test of my relative's new gas lines there was a tiny leak detected -- which only manifested when the pressure was above about 5 psi -- which required some re-working to pass the 15 psi test. If they had never tested the system it still would have functioned safely under normal operating conditions... but would have been brittle when confronted with extreme conditions.

While that anecdote was a badly done new system, the same is likely to be true of an aged system -- there are silent vulnerabilities which only manifest when stressed. An unnecessary stressor is certainly a villain, but perhaps we ought to recognize, as a society, that it is in all of our interests to bear the costs of building and maintaining robust systems which can withstand such villains.

[Rhiannon12866]

2. After all this, it sounds like a good idea to pressure test systems

This really has to be as scary as it gets, a horrible tragedy without any warning. The blame - and a lawsuit - in MA has fallen on Columbia Gas, but they operate in 7 states:

NiSource operates seven local utilities in its service region.

Northern Indiana Public Service Co. ( NIPSCO)
Columbia Gas of Massachusetts (Previously Bay State Gas)
Columbia Gas of Ohio.
Columbia Gas of Kentucky.
Columbia Gas of Pennsylvania.
Columbia Gas of Maryland.
Columbia Gas of Virginia.

NiSource - Wikipedia
https://en.wikipedia.org/wiki/NiSource