What Really Happened During the Gas Explosions in the Merrimack Valley?

🌌Get Nebula using my link for 40% off an annual subscription: go.nebula.tv/Practical-Engineering 🛠What engineering disaster would you like to see me cover nex

Thank you for this video. I was one of the many firefighters from New Hampshire that responded down there. Was one of the scariest days in my career.

I can't say I remember hearing about this back then. Imagine being a gas utility worker* doing that job and you realize the whole town started blowing up, that must be awful. Seeing that map of all the locations that were on fire was frightening.

Considering how many leaks and resulting fires there were, The fact only 1 person died is actually insane.

I often have the same fear in my work as a helicopter mechanic. My thoughts run something like this, “What if I do this work order completely correctly but the guy before me cut a corner I couldn’t even know about without me doing his already completed work again for him?” The end result is that in safety critical jobs, we, the workers doing the actual work in the field, have to be able to trust that the people before us did the job correctly. Otherwise, nothing gets done.

I was one of the electricians who worked on restoring all this and making sure houses were safe. All over Lawrence and Andover. It was crazy times

As a former controls programmer, I am a bit surprised that there were no high pressure shutdowns (measurement and valves) built into the discharge side of the regulators.

Massachusetts resident here. This was HUGE news. I remember seeing dozens of houses on fire, and blown apart houses. Massachusetts is such a quiet and safe state so this really rocked us. The company that bought out Columbia Gas is called Eversource and they seem to be taking things exceptionally seriously, which is good to see.

I live nearby and watched this unfold on the local news. When fires appeared all over the area it was apparent that they had over pressurized the gas system. People reported stove pilot lights shooting flames out/up several feet. Every gas stove, heater, water heater and clothes dryer in the area had to be replaced, as did most of the underground piping and meters. The person that was killed was a teenage boy who had just received his driver's license. He was in a driveway and was crushed by a chimney when the house blew up (see @13:50).

It is good to see the NTSB didn't try to throw the trades under the bus and showed that management totally dropped the ball.

I can’t imagine being the guys installing the pipe and just hearing and seeing explosions in the distance and just know that something went wrong

This is seriously up there with Tacoma Narrows and Hyatt Regency walkway collapse in terms of cautionary tales to teach engineering students. It's easy to explain what happened, and it's a mistake anyone could see themselves making if it slid across their desk on an off day. It has so many implications about proper documentation, multiple levels of scrutiny, making sure you fully understand the system you're working with, the importance of risk analysis...

I live in North Andover MA, one of the towns impacted by this. Thankfully, my family was not impacted, but the day was very surreal. Fires, power turned off, traffic from evacuations, school closures, schools turned into shelters were all experienced. Thank you to all the firefighters and other first responders who helped that day. And, Grady, thanks for making this video. I never really understood the cause until now.

As an oil and gas operator, this is one of my biggest fears. Not tying in the sensing instruments to the control loop. Especially dangerous when commissioning a new line/equipment. Really not sure how this would be missed though. Hot Taps usually have very intensive oversight.

The scary part is that there are still up to 30 states that haven't fixed the insufficient oversight by removing the excemptions.

I remember discussing this immediately after the NTSB released the information about it. I’m an Instrumentation and Electrical Technician for a major pipeline company. We discussed this in a safety meeting even though we don’t operate low pressure systems. This video was so good that I might show it in this month’s safety meeting.

As an hvac tech in the Boston area I can honestly say this was the most stressful day of work I ever had. Our phones were ringing off the hook and every service tech where I worked pulled a 10+ hr day running calls

I lived in Andover during the explosion. We finally got heat and hot water back at Thanksgiving and it was another 2 months to get our stove replaced. Thanks for covering this one.

As a MechE who is going for his PE, this is so absolutely chilling. Really puts into perspective my complaints about how annoying 16 hours of testing is. Such a simple oversight shook tens of thousands of people's faith in the systems that are meant to keep them safe. Really makes you wonder what other everyday devices we normally just take for granted as being safe are one simple oversight from upending our lives. Truly horrific.

I have worked in job environments where asking questions was discouraged. My supervisor's attitude was, "If it isn't in our scope of work it isn't our concern." I caught many problems by asking questions. I saw many others miss things because they were too focused on only the scope of the project. Everyone make mistakes. When we insist on not helping other prevent mistakes things get bad.