Other Grimes customers are the Polk County Conservation Board, a high school, the Central Iowa Expo (an agricultural trade fair), a manufacturing firm, and a new townhome developer.
The townhome project is noteworthy because the porous asphalt drive, through the center of the development, allowed the developer to build one or two more townhomes instead of taking the space for a storm water retention facility. "That made it feasible for the developer to build the project," says Moyna.
Moyna is Grimes Asphalt's lead marketer of porous asphalt pavements. Last year alone, he made 56 presentations explaining porous asphalt to:
Both Moyna and Jill Thomas, the associate director of the Minnesota Asphalt Pavement Association (MAPA), host "Lunch and Learn" sessions that seek to educate specifiers about porous asphalt.
Consultants typically work on a billable-hours basis, says Thomas, but they're expected to take lunch, which is non-billable. So the state asphalt association buys the engineers a box lunch, which they can eat while Thomas talks to them about porous asphalt. Thomas estimates that she has done some 70 to 75 "Lunch and Learn" sessions for various design firms and agencies.
In a "where", "when" and "why" format, the simple one-page flyer elaborates on how porous asphalt systems temporarily store runoff and eliminate the need for retention basins. Plus, the flyer directs readers to Grimes' website, which features a video clip of porous asphalt in action (www.grimesasphalt.com).
Thomas says MAPA created an 11-page draft specification for porous asphalt. "An agency can put that spec right into a contract," says Thomas. "It covers everything from the geotextile to the mix design to the stone recharge bed."
Porous asphalt is catching on in Minnesota - with 15 to 20 projects constructed since 2005 - in part because groundwater infiltration is being promoted by environmental agencies.
Thomas says watershed districts limit the impervious area that a new building can create. But if, for example, a new Target store can build a porous parking lot, it helps offset the amount of impervious area that would have been included in the project. Plus, the porous parking lot eliminates the need for a retention basin - and the space it would occupy.
"Paving with porous asphalt is no different from paving dense-graded asphalt," says Huddleston. "You mix it in the same plant, haul it with the same trucks, and pave it with the same pavers. There are some minor differences, but they're not huge. I tell our members to develop good porous mix designs, and to make sure they avoid poorly designed jobs.
"Don't skimp on quality in any way," adds Huddleston. "Porous pavement is like going to a new restaurant. You'll try it once, and if the food is bad, you won't go back. You have to make sure the project works so that the technology will promote itself."
Education of internal contractor personnel is a key to success. "You need to make sure your dispatchers, your estimators, your plant people understand what porous asphalt is," Huddleston says. "So when the call comes from somebody who wants a porous pavement, your people know how to answer."
And it's critical for a contractor to know how to dispel the common myths about porous asphalt, Huddleston says. Myth number one is that the water will seep through the pavement, saturate the subgrade, and wreak havoc with the asphalt. It's not so. Water passes through the asphalt and into the stone recharge bed where it is stored until the uncompacted subgrade can absorb it. The stone recharge beds make outstanding structural bases and perform equally well whether dry, wet or saturated.
Secondly, freeze-thaw cycles are no problem for porous asphalt. That's because snow and ice form, then melt on the surface, and the water passes completely through the asphalt. Snow and ice don't build up the way they do with dense-graded asphalt.