st. paul

The destruction of a St. Paul house in a fireball on Monday was set in motion 19 years ago by an unlikely collision of pipes -- a potential unseen danger on any property where an underground gas line has been moved, officials said Tuesday.

The explosion of Trista Meehan's house at 2014 Villard Av., in the Highland Park neighborhood, was triggered when a contractor breached an Xcel Energy Co. gas pipeline that he did not know had accidentally been laid crossways through the inside of the sewer pipe he was trying to unclog, investigators have found.

"This a very, very low-frequency event -- the problem, of course, is that it has such high consequences," said state Fire Marshal Jerry Rosenthal. There have been five similar incidents resulting from gas pipelines getting crossed with sewer lines in the past 10 years in the state.

But investigators acknowledge that there is a potential for more. In three separate programs, Xcel Energy has scanned hundreds of sewer lines with cameras searching for misplaced gas lines, said Elizabeth Skalnek, chief engineer for the state Office of Pipeline Safety.

It's a costly process because the city also has to flush the sewers to clear the way for cameras to see. The problem is not so much scanning the main sewer lines as it is thousands of lateral lines to houses and businesses.

The scans identified 27 instances where a gas line was inserted into a sewer line, Stalnek said. Most were in St. Paul, but a couple were north of the city and one was in Rochester. Most of the Highland Park area was checked in 2003, but not Villard Avenue. It will be checked now -- "I can guarantee that," she said.

"We are very intent on getting to the bottom of this, along with Xcel," Stalnek said. "We want to know, why did we miss this one back in 2003, because there was a very aggressive project to try to uncover these."

The 2-inch gas line was apparently installed in 1991 as part of a storm-water and sanitary sewer separation project, Stalnek said. The gas main had to be moved from the center of the street to the sides. The 8-inch sewer line that led to the home is about 50 years old.

During that process, the gas line was moved by a process called "directional boring." "When they did that, they went right through the sewer," she said.

It works like this: Instead of digging a trench to lay pipe, a boring pipe system is used to tunnel an underground path. Once the tunnel is done, the gas pipeline is inserted inside the boring pipe and the boring pipe is removed, leaving the gas line in its place. Problems happen when the boring pipe hits things it's not supposed to, such as sewer lines.

According to a 2003 "alert notice" from the Office of Pipeline Safety sent out to Twin Cities plumbers, such crossed lines pose "a limited risk to public safety so long as a gas line is not penetrated by the equipment used to unclog the sewer." The agency sent the notice after it was found that utility lines being installed and reinstalled had done so with directional boring, and that some had been installed through sewer lines.

While acknowledging that there are more such breaches out there, Stalnek said accidents are preventable. "If your gas main has never been moved, it will not affect you," she said. "The best way to know whether or not your gas main has ever been moved is to call your gas pipeline operator."

Rosendahl credited quick action by Lee Moey, the contractor working on the sewer, once he smelled gas, alerting Meehan and helping her get out of the house with her two dogs. "It could have been a lot worse," he said.

Moey was treated at Regions Hospital in St. Paul for burns to his face, neck and hands, and is home recovering, said his father, Ron Moey, owner of Ron the Sewer Rat, a business that specializes in clearing sewers. "He's still pretty traumatized."

Ron Moey said his son was the third person to have tried to unclog the sewer in the past week. Roto-Rooter had tried for several hours, as had Meehan's boyfriend.

"This is such a rarity, but it can happen," said Ron Moey, who has been in business since 1973. "I'm sure there could be another one out there."

Jim Anderson • 612-673-7199