Porous pavement offers environmental edge, advocates say

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Capital News Service
LANSING –Rainwater flows through porous pavement, allowing it to quickly reach soil.
That helps keep pavement clearer from ice and snow in the winter. And it reduces the pollutants that rain can wash off of streets and into surface water.
Stormwater acts more naturally, like it did before so much ground was covered with city streets, said David Drullinger, an environmental quality professional with the Department of Environmental Quality.

Detroit, Grand Valley State University, Michigan State University, Battle Creek and Ann Arbor all have porous pavement installations.
Porous pavement may sound like a great idea, but it isn’t widely used although it’s been around for a long time.
“It works about 50 percent of the time” because it gets clogged with dirt, sand and debris, Drullinger said. Clogged pavement must be vacuumed, and few machines are available to do that
“If you don’t have one of those, don’t even think about putting it in because you have no way of keeping it clean,” he said.
Also, few Michigan contractors are experienced with porous pavement, and that may be the problem, Drullinger said. As more contractors work with it, the more effective the technique may become.
“If it’s done right, it would be a good thing to use. Where it does work, it is amazing,” Drullinger said. “Water just sucks right through.”
Despite some problems, several communities are trying porous pavement.
For example, in 2006, Battle Creek designed a driveway access and parking space using porous pavement at Willard Beach Park, said Todd Everson, a city project engineer.
“The only issue is there are a lot of trees, lots of silt. Sweeping and vacuuming needs to happen often,” Everson said.
Battle Creek cleans its porous pavement at least once a year, but every six months is more desirable, Everson said.
Daniel DeGraaf, executive director of the Michigan Concrete Association, said, “It’s being used in the more environmentally sensitive areas in Michigan.”
The Detroit Medical Center’s parking lot uses both porous and regular pavement and is designed so that water runoff drains into the small strips of porous pavement, DeGraaf said.
Grand Valley has installed porous pavement in some of its sidewalks throughout campus, DeGraaf said.
The association, an industry group based in Okemos, is training and certifying contractors to install porous pavement.
“One thing is, it’s nice to have a new product that works but it’s terrible to have it done wrong and it doesn’t work,” DeGraaf said.
The method of installing porous pavement is different than installing regular pavement. It needs to be above a layer of rock to allow water to drain through. If the base layer is done wrong, it could back up in heavy rain, he said.
When constructing a parking lot, the whole thing generally won’t be covered with porous pavement. Instead, developers install strips of porous pavement throughout the lot, allowing water running off the concrete to drain into it, DeGraaf said.
That enables developers to use more land because they don’t have to set aside space for drainage ponds that building codes normally require, DeGraaf said.
Porous pavement also greatly reduces the need for snow clearing and salting in the winter because it doesn’t let water remain on the surface, so ice cannot form. Such areas in parking lots are noticeably clearer of ice and snow than the areas paved with regular concrete, DeGraaf said.
As for cost, it’s generally not much more expensive than regular pavement, although installation costs a little more because of the water storage space required below the surface. However, he said it’s difficult to accurately compare costs because the use of porous pavement is still somewhat specialized.
People are starting to see the benefits of porous pavement, and that’s why it’s gaining traction in the Midwest, DeGraaf said.
Justin Anderson writes for Great Lakes Echo.

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