Environmental Design + Construction - September 2008 - (Page S14)

CONCRETE PERVIOUS PAVEMENT SPREADS AS SOLUTION BY JENNI PROKOPY PRIME OUTLETS EMPLOYS PERVIOUS AS PART OF A MALL RECONSTRUCTION, PRIME OUTLETS IN WILLIAMSBURG, VA., RECENTLY COMPLETED A PARKING LOT REPLACEMENT THAT EMPLOYED APPROXIMATELY 7.5 ACRES OF PERVIOUS CONCRETE PAVEMENT AND 3.5 ACRES OF CONVENTIONAL CONCRETE PAVEMENT. (TITAN VIRGINIA READY MIX SUPPLIED ITS ENVIRA BRAND OF PERVIOUS PAVEMENT.) THE SYSTEM DIVERTS WATER INTO THE SOIL INSTEAD OF THE MALL’S OLD STORMWATER MANAGEMENT APPROACH: A DETENTION POND. THE POND HAS BEEN PAVED OVER, CREATING MUCH MORE LAND FOR DEVELOPMENT, AND ADDITIONAL WATER-HARVESTING TECHNOLOGY HELPS CAPTURE WATER FOR LANDSCAPE IRRIGATION. At the Prime Outlets, conventional concrete was used for traffic lanes, while pervious concrete was used for parking stalls. Image courtesy of Titan Virginia Ready Mix. ground fast. “The U.S. Environmental Protection Agency recommends pervious concrete as a Best Management Practice with compliance with federal stormwater law, and that’s a very powerful thing to say,” he says. “We should be using greywater water all over the place; we waste so much water and we just don’t have to,” he argues. KEEPING IT CLEAN The material not only helps manage runoff and capture water, but cleans it as well, according to Stew Waller, executive director of the Arizona Cement Association. “Some heavy metals and contaminants you find in the first flush of a rain storm, hydrocarbons…it washes off all the dirt and contaminants from the pavement,” Waller says. In fact many pervious pavements develop a microbial system in the voids that attacks and consumes these pollutants, so water flowing into the soil is cleaner. Unilock’s Eco-optiloc precast permeable concrete pavers were used to create the largest permeable parking lot on record at Chicago’s U.S. Cellular Field. The park’s drainage capacity is 1.15 million gallons—or 9.25 million 16-oz. sodas. Image courtesy of Rose Paving and Unilock. s14 WWW.EDCMAG.COM One of the most pressing concerns for city planners today is stormwater. In some cities, new regulations dictate the management of stormwater from the minute the first raindrop falls; Chicago, one of the U.S. cities at the forefront of the sustainable movement, enacted a new stormwater management ordinance this year that requires any regulated development to have a city-approved plan in place that manages the rate and volume of runoff, among other things. That’s a lot to swallow for some, but in many cities pervious concrete pavement is helping meet new stringent stormwater management requirements. HOW IS PERVIOUS CONCRETE PRODUCED? Unlike conventional concrete, pervious concrete mixes contain limited or no fine aggregates, producing concrete with approximately 20 percent voids. Those spaces allow water to flow through the pavement, then a bed of uniformly sized aggregate below, and into the soil—reducing or eliminating stormwater runoff. Average strengths of pervious concrete are from 500 to 4,000 psi, but can go higher depending on the application; percolation rates average from 288 to 770 inches per hour. Dan Huffman, managing director of national resources for the National Ready Mixed Concrete Association, says pervious concrete is gaining USING LEAST-COST ANALYSIS TO DETERMINE VALUE Waller points to new pervious pavement at the Glendale, Ariz., Park-and-Ride as an example of the technique at its best. While pervious pavement was more expensive than conventional asphalt pavement upfront, a leastcost analysis considering 20-year service life maintenance costs for both systems proved pervious concrete to be equal in cost in (the city chose to also incorporate additional subdrainage systems and retention ponds). In http://www.edcmag.com

Table of Contents Feed for the Digital Edition of Environmental Design + Construction - September 2008

Environmental Design + Construction - September 2008 Contents Web TOC Editor's Note Newsline New and Notable Announcing the 2008 Excellence in Design Awards Award Winner: Yale Sculpture Building Snapshots: College and Universities Teach Sustainability Color ISH North America Green Continuing Education Special Section: Concrete Product Focus Marketplace and Classifieds Advertiser's Index Underwater Adventures

Environmental Design + Construction - September 2008

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