Small spark grew to 500-foot flames
Something as simple as static electricity or a couple of rocks bumping together likely caused the massive natural gas fire that lit up northern Colorado on Sunday.
No one lit the fire or cut the pipe, investigators said Tuesday. The Weld County Sheriff's Office has concluded its work after determining no crimes were committed.
Now, workers from the U.S. Department of Transportation's office of pipeline safety will do the tedious work of examining the pipe to determine what triggered the big boom that caused a 500-foot tower of flames.
Pipeline safety investigators are zeroing in on a handful of possible causes for the gas leak and the immense fire that followed, said Jim Mitchell, spokesman for the office.
Most gas explosions are started when heavy construction equipment cuts into a buried gas line. But with this incident, Mitchell said the cause was more likely a problem with the pipe.
The 24-inch pipe may have had an inherent flaw in the metal, a construction error could have caused a defect, or elements could have corroded it. In all these scenarios, the flaw would have led to a breaking point where pressure shifted and gas leaked or exploded out of the ground.
But the gas leak itself did not cause the catastrophe, Mitchell said. Something else had to happen to ignite the gas. "The chain of events included something giving a spark," Mitchell said.
Static electricity is a common cause of gas fires in high, Western climates, he added. In these areas, cautious workers wet themselves down before working on a gas pipeline to prevent static from jumping between their body and the gas.
Another possibility would involve the pipeline exploding from too much pressure. The pipe was buried about 6 feet underground and would have pushed all the earth above it upward in the explosion. In that upward push, rocks could have slammed together, sparked and detonated the gas.
A third possibility is that the electric current from an underground phone line found at the edge of the blast's crater could have ignited the gas.
For now, those possibilities will have to remain as speculation. Investigators say it may take several months to finally determine the cause.
Copyright The Greeley Tribune