Explosions from gas lines being bored through sewer lines are rare, but it is enough of an issue that Puget Sound Energy is warning people about the danger. (Melissa Davis / For HBJ)

‘We nearly blew up your house’: Gas line skewers sewer pipe

The plumber shocked me with what he said: “Oh s—-! We nearly blew up your house.”

I was standing in the basement bathroom of my Shoreline home. I thought I had a plugged toilet. That was only a symptom of a much larger problem.

And what I learned could affect any number of thousands of homeowners in Snohomish County and the rest of the Puget Sound area.

I had tried using a plunger on my clogged toilet on that hot July day but didn’t get anywhere.

Then I noticed sewage had backed into a rarely used shower.

This was no ordinary clog. It was time to call a professional. I lit a candle on the bathroom counter to stave off the smell.

The plumber and his supervisor informed me that it could possibly be a tree root or a broken pipe. They removed the toilet and used a motorized auger to clear the line. I sat in our living room with my 12-year-old son.

Once the clog was cleared, the plumber asked me to watch while his supervisor used a pipe inspection camera to determine the problem.

He snaked the camera about 40 feet down the line until they found that a yellow PVC pipe had penetrated my sewer line.

It’s not easy seeing professionals panic. The yellow pipe was most likely a gas line. Had they nicked the line, there could have been a fire or an explosion like the one that destroyed several businesses in the Greenwood neighborhood of Seattle in March 2016.

I went pale. I scrambled my son out of the house to a nearby neighbor’s home, outside of what I figured would be the blast radius.

The two plumbers conferred. Usually a gas line has writing along the side. They couldn’t see any writing. Maybe it was a water line or a communications line. Was the line yellow or was it white? Was this a false alarm? They brought in a crew to dig several feet down to expose the lines. Yes, it was a yellow gas line. The plumbers called PSE and an emergency crew was on hand 30 minutes later.

That afternoon was a blur of trucks with flashing lights, traffic cones and yellow caution tape. They tied off the gas line and fixed the sewer line.

The plumbing problem was clearly caused by the gas line, a PSE supervisor said, and I’ve filed a claim to be repaid for the replaced sewer pipe.

PSE replaced gas lines in the neighborhood in 2016. Contractor InfraSource did something that’s called directional boring, a way to install underground pipe without digging trenches. It aims to cause the least amount of damage to lawns, streets and sidewalks. Unfortunately, directional boring can sometimes go through sewer lines and cause other problems. That’s what happened to my home.

Explosions from this are rare, said Charlie Gadzik, customer safety communications manager.

In his research, there have only been about a dozen explosions since the 1970s in the U.S. when plumbers hit gas lines that had speared sewer lines, Gadzik said.

“The incident of accident or injury is really rare,” Gadzik said. “There has never been an explosion in Washington state that we know of.”

Still, there have been other natural gas explosions where the exact cause wasn’t determined, he said. And two explosions in Minneapolis, Minnesota, in 2010 focused attention on the risk.

One of the explosions was a similar situation where a plumber using a motorized auger hit a cross-bored gas line. No one was killed, but the plumber suffered burns to his face, neck and hands and the house burned to the ground.

“This is a high priority for us,” Gadzik said. “It’s something, when we became aware of the risk, we acted quickly to put together a program to mitigate the risk.”

About twice a year, PSE gets called out to a home where a plumber has cut a gas line that’s speared a sewer line, but hasn’t caught fire.

“And we have shut off the gas before there was a calamity,” Gadzik said.

PSE will come out to send a camera down a backed-up sewer line to make sure that a gas line isn’t causing the problem. I asked Gadzik why would a homeowner think about calling the gas company over a clogged toilet.

“You wouldn’t,” Gadzik said. “It’s the most unlikely thing you might to expect, which is why we’re trying hard to get the word out.”

PSE has been running advertisements to make customers aware that this could be an issue. They’ve had news organizations do stories on cross-bored pipes. They’ve worked with plumbers and plumbing businesses to make them aware.

PSE has 800,000 customers in the Puget Sound area including 140,000 in Snohomish County. The utility company replaced or installed 17,000 gas lines in 2016, Gadzik said. The utility discovered 138 gas lines that were bored through sewer lines. Of those, 94 came from reports of blocked sewers.

Contractor InfraSource is supposed to work with homeowners to locate sewer lines and avoid them. Depending on the job, the contractor could ask to go into a home and use a camera to determine the sewer’s pathway.

Even if that doesn’t happen, a second company, Hydromax, is supposed to come around to the neighborhood shortly after to use a pipe inspection camera to make sure new lines hadn’t penetrated the sewer lines. That didn’t happen with my neighborhood.

When I called Gadzik, he said they had been having meetings about my house. He said information about replaced gas lines wasn’t always being shared between the two companies. PSE is still doing an analysis on how many homes and neighborhoods may have been missed.

“As a result of your incident, we have changed our process to add a cross-checking step to make sure this doesn’t happen again,” he said.

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