What is pervious pavement? It's the latest in green construction, being used on projects from Beijing to Park City, and it helps solve one basic question: Where does water go when it rains?

With most concrete, when water falls on it, it simply runs off down the street and eventually down the storm sewer system. But what if water could be absorbed directly into the soil through the pavement?

The new Swaner EcoCenter in Park City aims to be Utah's greenest building, with solar heat and hot water, even the concrete. A slab of pervious pavement was also recently installed at a new building at the University of Utah.

David Mitchell, with Bunyan Industries, said, "This is not just concrete pavement. It's a storm-water management system. And it's taking the storm water, giving it a place to hold under the slab. We can actually hold 10 inches of storm water in that detention basin underneath this pavement."

West Jordan-based Bunyan Industries recently helped install 2.7 million square feet of the stuff in time for the Beijing Olympics.

The concrete resembles a Rice Crispie treat and is highly porous. "Essentially it's concrete that's made with no sand," Mitchell said.

With 6 inches of concrete laid over 18 inches of gravel, it essentially filters the water, prevents storm runoff problems and recharges the underground water table.

Dave Maurer, a senior project manager with Big-D Construction, said, "What this allows you to do is create your detention pond. You can fill it with gravel and then pervious pave over it and park cars on it. So you don't lose any space when you do this."

Going pervious is a big plus toward coveted LEED, or green building certification. "It's really the pavement of the future," Mitchell said.

The key to this method is that it requires some special training and treatment when it's installed, like placing plastic over the top to keep the moisture in. That makes it a little more expensive to install.

E-mail: jdaley@ksl.com