Permeable Pavement and Porous Asphalt:
These Surfaces Let Water Soak In
Runoff from 3 inches of rain. Image courtesy of landscapesforlife.org.
Permeable surfaces allow water to infiltrate and soak into the ground. Soils naturally let rain water soak in. Impermeable surfaces do just the opposite. When the water hits this kind of surface, instead of soaking in, it runs off across the surface. This is what creates stormwater runoff. The more impermeable surface area there is, the more stormwater runoff.
The image to the left shows that as percent cover of impervious surface increases, so does the percent of associated runoff. As impervious cover increases, it goes from most of the water being evaporated or infiltrated, to most of the water running off. This drastic alteration of the natural water cycle creates many changes that must be managed as a result. Proper stormwater management practices must accompany development. The key to decreasing stormwater runoff and the pollution associated with it is to decrease the amount of impermeable surface area! Here are some ways that you can do that on your own property.
Ways to lessen your impermeable footprint on your property:
• Keep paved driveways as small as possible. Use permeable surfaces for overflow parking areas that aren’t needed on a regular basis. While gravel driveways may start off permeable, over time the compaction makes them just as impermeable as regular asphalt.
• Rooftops are impervious too - so keep your home a modest size (which will save you money on utilities as well) and build up - not out - on lake shore lots.
Examples of permeable pavement. The center photo shows interlocking concrete pavers on a residential driveway in Lake George. Homeowner John Kearney estimates the pavers capture as much as 3/4 of the stormwater coming from streets and properties uphill from his property. The photo at right illustrates the dramatic difference in the stormwater absorption ability of porous asphalt (in the foreground) vs. traditional asphalt (in the background.) This product's strength and durabiity have increased, while its cost has decreased. It offers many advantages for commercial applications, including parking lots, driveways and roadways. Read more in the LGA's Jan/Feb 2011 newsletter.
• Use stone pathways or stepping stones across your lawn instead of poured concrete or asphalt paths.
• Consider trying one of the newer permeable pavement technologies. (See the story on permeable pavement on page two of the LGA's Jan/Feb 2011 newsletter - pdf.) There are permeable paver systems, asphalt, and concrete - so you can get just about any look you want. Prices vary - and while all options are generally more expensive than traditional pavements, some are more affordable than others, and it is definitely money well spent.
Permeable Pavement Systems
• The Interlocking Concrete Pavement Institute (ICPI) is a good place to look for info about new permeable technologies.