Residents witness how DuPage's water works

The Elmhurst Quarry can hold an estimated 2.7 billion gallons of water if it needs to.

It's needed to only once since it began functioning as a flood storage facility back in 1996.

Nineteen years later, the quarry rocks on as DuPage County's first line of defense against massive flooding when too much rain dumps on the region.

"The losses from flooding would be hundreds of millions of dollars," DuPage County Stormwater Management Committee Chairman Jim Zay said. "Some places still flood today, but I can't imagine what it would be if we didn't have this facility."

How interesting can a stony chasm be?

It's an epic combination of Mother Nature and an engineering feat on a scale that would impress designers of a high-tech 007 villain's lair.

The public got to see just how complex and impressive the Elmhurst Quarry is on Saturday when an estimated 300 people signed up for tours of the facility along Route 83 in Elmhurst. Every half-hour from 9 a.m. to 1:30 p.m., four buses transported people from the Elmhurst Historical Museum, 120 E. Park Ave., to the Quarry Control Center about a mile west.

Sarah Hunn, chief project engineer, came equipped not only with an intimate knowledge of how the anti-flooding system works, but also with a pair of lungs powerful enough to speak above the wind and din created by the rushing waters in the background.

"We're pumping the water out of the quarry right now so you can see how it works," she said, almost in a shout. "We pump water along the side of the quarry, underneath Route 83, through the tunnel into this area. This is the aeration area here that slows down the water before it's put back into Salt Creek."

And guess what? The water is actually cleaner, with less silt and flushed with oxygen, than when Hunn's co-workers pumped it out.

"We have a completely redundant system built up," Hunn told a group of about 15. "We can operate everything from home remotely. If for some reason we couldn't do that, we would mobilize a person on the site."

What does it take to open the floodgates and let the swollen Salt Creek water relieve itself? Just the push of a button.

Well, most of the time.

"In August of 2007, the actuators were struck by lightning and we had loss of power," Hunn said. "So we had to mobilize people to come out and hand-crank the gate open. But it takes like 100 times to crank it to raise the gate about an inch, so it takes forever."

Now, the facility has been retrofitted with a "drill motor" to speed things along.

The Stormwater Committee is also studying the possibility of converting the Elmhurst Quarry into a hydropower site.

"We would dump it (water) down into a turbine, creating electricity, down into the underground mine," senior project engineer Chris Vonnahme told the crowd. "They would do that during the day when electricity rates are very high, then at night, they would pump the water back into the surface mine when the electricity rates are lower."

But that's still in the feasibility stage.

"I grew up in Elmhurst, so I know a lot of people know the quarry is here, but they don't know a lot about it," Zay said. "It's great for the residents to see this big hole in the ground and understand how it works."

What's the best part about being a Stormwater Management Committee chairman?

"The days it doesn't rain." Zay said.

Quarry: The entire system can be operated remotely, if necessary