If it had exploded, the 8,500 cubic feet of natural gas that leaked into the former Kroger grocery store on South Illinois Avenue on Tuesday could have had a devastating impact on the shopping center and blown out windows in nearby businesses, possibly even across the street, a city official said Wednesday.
“Had it exploded, we would have been on national news,” Oak Ridge Fire Department Chief Darryl Kerley said. “It could have been devastating for all the businesses in that complex.”
Authorities suspect that the gas slowly flowed into the 30,000-square-foot grocery store starting Tuesday morning through an uncapped gas line that was once connected to an oven.
By the time emergency workers responded to a report of a gas leak on Tuesday afternoon, Kerley said, “the store was almost completely filled with a dangerous concentration of natural gas.”
But at that point, the gas mixture was actually too rich to burn, Kerley said. Still, firefighters and utility workers had to be cautious as they worked to remove the natural gas because they moved through the flammable range as they reduced the concentration.
“You have to be real careful that you don’t have an ignition source when you start ventilating a structure like that,” Kerley said.
The gas leak was reported at about 3:45 p.m. Tuesday. After smelling gas and doing some detective work to determine the source, workers at Mr. K’s Used Books and CDs reported the leak to the Oak Ridge Utility District, which immediately alerted the Oak Ridge police and fire departments. Nearby stores were quickly evacuated, and the shopping center’s parking lot was temporarily closed.
Kerley said the leak appeared to be the result of a series of events, and not the fault of one person. At some point, he said, someone apparently turned off the gas meter at the back of the former Kroger store, possibly to remove ovens inside. The meter was left off, and after a few months without any gas use, ORUD stopped by to put a seal over the meter to show that they had been there and the meter was off.
But then at about 9:30 a.m. Tuesday, someone turned on the meter, apparently to turn on the heat in preparation for cold weather. However, that person didn’t realize that gas-powered equipment had been disconnected, and gas slowly flowed into the building through the uncapped gas line, Kerley said.
Firefighters worked with ORUD, the Oak Ridge Electric Department, and Kroger representatives to contain the gas leak on Tuesday afternoon, eliminate ignition sources, and ventilate the building. Kerley said they had to ensure that the power was turned off at Kroger and surrounding businesses, and grills—potential ignition sources—were turned off in nearby restaurants, including China Wok and Nixon’s Deli.
Eventually, firefighters used a ladder truck to climb onto Kroger’s roof to open vents. They used high-powered fans at the front of the store to push in fresh air and push out the gas, which is lighter than air and will rise.
Kerley said firefighters and ORUD did not go into the store but used meters stuck through the entryways to measure gas levels.
But they had to put their own safety in jeopardy to get close enough to the building to make sure it was safe, Kerley said. A thermostat or a little spark could have ignited the gas, he said.
“You can’t fix it unless you get close enough to it,” Kerley said. “The good thing, it was too rich when (they) got there.”
He said he was very proud of his team. There was no fire, and there were no injuries.
The fire chief urged anyone who smells natural gas or propane to call 911.
Emergency workers remained at the former grocery store until about 8:30 p.m. Tuesday, when store owners and evacuated staff were called back to their businesses.
Kerley praised Mr. K’s employees for probably saving the shopping center from damage. He said ORFD Battalion Commander Todd Derrick did a fantastic job of getting the situation under control immediately. And he gave credit to the help from ORUD, the Oak Ridge Electric Department, and Kroger.
“Everybody did exactly what they were supposed to do,” Kerley said.
Note: Asked to put the 8,500 cubic feet of natural gas into context, Kerley said a December 2009 natural gas explosion in West Knox County that leveled a house, killed one person, and flung debris and two residents, among other things, occurred in a 3,500-square-foot home.