Fire investigators for the Town of Normal said they are puzzling over why an explosion blew the roof off a well house early Tuesday morning on East Cherry Street.
It was a big boom, and the explosion damaged the cement block wellhouse in addition to collapsing the roof onto the pump.
Town water superintendent John Burkhardt said there's no natural gas service to the building. Heat is electric. Nicor tested the air after the fact and found no traces of anything odd.
"That's what's making this hard and we're all scratching our heads. We obviously know something happened. But there's zero evidence there saying what it is," said Burkhart.
Fire department investigators said there's no indication of foul play.
Burkhart said the pump itself doesn't appear to be damaged. Neither is the well casing that goes 200 feet down. This is the kind of mystery that draws water cooler speculation. One idea, Burkhart said, is that some sort of flammable gas underground seeped into the well itself and a spark in the wellhouse set things off.
"There is airspace between the top of the water and the bottom side of that well cap. There is a vent to that well casing into the building," said Burkhart. "It's possible. I'm not sure about giving it a probable number, but it is something that is possible."
Burkhart said the Environmental Protection Agency likes it that way.
"The problem with venting a well to the outside is somebody could contaminate the well because that vent goes right into the well," said Burkhart.
Usually it's not a problem. Burkhart said an EPA staffer, 15 years into his career, told him he'd never heard of something like this. Neither has Burkhart after 18 years with the town.
There was heavy damage to the roof and masonry and to some electrical equipment the roof landed on when it collapsed.
"A new well today, if we started completely from scratch, would cost $600,00-$700,000. From what we appear to know today it's just the building structure. My best guess is about $200,000," said Burkhart, adding the town will remove the roof rubble and secure the well.
"We will get our well contractor to pull all the well out and assess the pump, equipment, and piping. And then we'll assess the well itself with specialized cameras they can send down that well," said Burkhart.
The town has 12 wells. At any given time, Burkhart said four to seven of them are running, depending on demand. He said there are no worries for residents who want to take a shower.
