CEDAR FALLS - Two years ago Scott Ernst, manager of Benton's Concrete, took a class that mentioned concrete that lets water flow through it into the ground.

Both students and instructors alike shrugged it off, thinking the idea may be there, but they won't see it any time in the foreseeable future.

On Friday, Ernst and his crew mixed up truckloads of the pervious concrete to pour a 14-foot-wide, 400-foot-long strip at the University of Northern Iowa.

"I see more of it coming," Ersnt said.

Water quality professionals see pervious concrete as a great way to keep water from flowing quickly off of parking lots and into streams and rivers, helping to reduce sediment, pollutants and temperature variations in waterways.

At UNI, a new parking lot just west of the McLeod Center drains east toward the arena. The pervious concrete was poured in a low spot.

Pervious concrete is a mix with aggregate materials for the concrete ingredients to bind to. When poured, it leaves voids that water can penetrate, soaking down to the ground below.

"You create more of a Rice-Crispie-bar-like pavement," said Wayne Petersen, urban conservationist with the Natural Resources Conservation Service. "It has a different look to it, but for walking on or plowing snow, it will be the same."

The pervious concrete is brown in color, and the voids that allow drainage are noticeable.

The mixture at the McLeod Center should handle all but the heaviest of rains. A subdrain tile serves as a backup and carries away anything the concrete can't soak up so parking lots don't flood and water doesn't stay on the surface to freeze in the winter.

So far, pervious concrete isn't widespread. Petersen knows of projects in North Liberty, Coralville and Arnold's Park. Other communities have tried pervious asphalt.

Ernst said the pervious concrete is both more expensive and more labor intensive to install than traditional concrete. The process uses more and higher quality rock than regular concrete, adding to the cost.

Petersen came to Cedar Falls from Des Moines to monitor the installation and continue gathering information. He said there has been some concern pervious concrete could be less durable than traditional. He suspects that may be wrong.

"I think there's a chance it may have longer life than traditional concrete," Petersen said, noting the porous concrete should leave less water to freeze and thaw and less damage.

Rebecca Kauten, Dry Run Creek watershed coordinator, hopes pervious concrete starts to gain steam.

"We have been talking to local developers that are interested," Kauten said. "Having these projects in the public sector can lead to more attention and more private sector interest."

Contact Jon Ericson at (319) 291-1461 or jonathan.ericson@wcfcourier.com.