ELYRIA — A slow leak in the interior gas lines of a Columbia Avenue house led to a Dec. 20 explosion that shook the city and neighboring communities, according to an Elyria Fire Department report made public this week.
Elyria Fire Marshal Carl Keith wrote that the leaking gas was ignited by pilot lights in either the furnace or hot water heater in the basement of the house at 116 Columbia Ave., causing the explosion, which destroyed the house and damaged nearby homes, including two that had to be demolished.
“The burned area is directly over the area containing the water heater and furnace,” the report said. “Notice also that the debris is thinnest in this area, likely indicating that the epicenter of the explosion was directly below.”
Keith concluded that the gas slowly accumulated over a period of time between Dec. 2, when the gas to the house was turned on following a period of being off, and the day of the explosion. He said Thursday it’s impossible to know exactly when the leak started.
He wrote that he eliminated a catastrophic failure of the gas line as a possibility, which meant that as the gas built up over time, it mixed with surrounding air. As the mixture of gas and air became heavier, it slowly settled from the ceiling to the floor until there was enough gas to cause the explosion, the report said.
Because the temperatures were in the 50s on the day of the explosion, the report said the furnace likely would have been cycling on and off throughout the day.
Once the gas ignited, it caused a “high order” explosion.
“High order explosions result in the total destruction, splintering, etc., of the structure’s components,” the report said.
Although the blast would have radiated out from the point of detonation with the same force in all directions, the report said, walls and other structural factors in the house directed the majority of the blast upward.
Keith said the build-up of gas would have been detected had anyone been living in the house, but because the house was vacant and for sale, no one was around to smell the odor that gas companies add to natural gas to alert residents to a leak. Natural gas is colorless and odorless.
“The reason this got to that point was there was no one there to smell the mercaptan,” Keith said.
Ray Frank, a Columbia Gas spokesman, said mercaptan, which smells like rotten eggs or rotten cabbage, is designed as a warning system and should be taken seriously.
“The appropriate action if there’s a gas leak is to contact Columbia Gas so we can respond and investigate and determine the seriousness of the leak,” Frank said.
Although he said residents in the area told investigators they had smelled gas the day of the explosion, no one called to report it. There had been a call to a nearby Stanford Avenue home that day, which resulted in a leak in that house being repaired, the report said.
After the explosion, Columbia Gas workers capped gas lines, including the one leading into 116 Columbia Ave, according to the report. Following that, the company conducted pressure tests, including in the presence of investigators, to show that the lines leading into the house weren’t leaking.
The report said the gas company is responsible for maintaining the lines running into the house, but once the gas passes the interior gas meter, the lines become the responsibility of the homeowner.