Porous Concrete Catching On

By Scott Harper

The Virginian-Pilot

NORFOLK

It looks like a giant batch of gray Rice Krispies treats and acts like a sponge.

It is concrete, a porous type of concrete called Envira , that developer Joe Covington is trying out for the first time in Norfolk as part of a condo project near Wards Corner .

Covington hopes the alternative building material will save money, lessen regulatory hassles and better protect the environment - in this case, the Lafayette River .

"I don't understand why it hasn't been tried before," said Covington, watching a thick, pebbled slurry slide from a mixer truck last week.

His company, Covington Contracting , is investing in Envira for a parking lot at the Grantham Square Condominiums off Little Creek Road.

Titan America , the concrete company that makes Envira, is closely monitoring the project. Titan hopes other builders will embrace the technology for construction sites elsewhere in Hampton Roads, where flooding and storm water runoff are major considerations in the development process.

"Everyone thinks it's a great idea," said John Connolly , Titan's local sales manager, "but they're reluctant to try it until more people use it."

Porous concrete is not new. The material has been used for almost 20 years, and is becoming popular on the West Coast, the Midwest and in Florida. But it has not caught on yet on the East Coast.

Envira can be found at some scattered parking lots and driveways in Hampton Roads, and in Poquoson after severe flooding in the waterfront town after Hurricane Isabel.

Unlike regular concrete, Envira soaks up water, letting it filter back into the ground naturally instead of rushing off toward a nearby storm drain, storage pond or directly into a waterway.

Such storm water runoff is considered a major pollution source, carrying dirt, fertilizers, oil, antifreeze and other contaminants to rivers, streams and the Chesapeake Bay.

Envira also is more expensive - about $160 per yard, compared to about $100 per yard for regular concrete, Covington said. But his savings will come from avoiding costs for building a storm water pond or connecting to a storm drain, as required by local building codes and environmental regulations.

Because Covington's lot was so small and so close to other homes, he said he did not have space for a storage pond. So his son, Graham, and a consulting engineer started looking for an alternative. They settled on Envira.

Unlike concrete or asphalt, Envira needs to be covered with wet burlap tarps for several days so it sets correctly. Workers also must use a wide roller to compress the slurry into place, and some training is required. An improper set can cause chipping or sinking.

In all, crews poured about 100 yards of Envira within the parking lot last week. On one completed section, a worker let water gush from a hose to display the lot's newfound sponginess.

As the water soaked in immediately, leaving the surface nearly dry, Covington smiled.

"Isn't that something?"

Scott Harper, (757) 446-2340, scott.harper@pilotonline.com

(c) 2007 Virginian - Pilot. Provided by ProQuest Information and Learning. All rights Reserved.