Types of Pervious Pavement

December 10, 2012 at 2:53 pm
pervious paver parking lot
A pervious paver parking lot

The scope of many of the commercial landscaping projects designed, installed, and maintained by our crews here at E-Landscape often requires the use of pervious pavement. This material consists of concrete, asphalt, or pavers that contain air pockets, which allow rain and snowmelt flows to permeate the surface. Precipitation streams into a basin underneath the pavement that consists of layers of crushed stones, sand, and soil. The underlayment allows the runoff to seep into the ground. While pervious paving materials are virtually indistinguishable from regular pavement, they offer significant benefits from an environmental standpoint. With more and more commercial buildings seeking LEED certification and being designed and built with sustainability in mind, it is no wonder that the use of pervious pavers is on the rise!

Types of Pervious Pavement Materials

There are three main categories of pervious pavement materials. They include:

1) Pervious concrete consists of a mixture of Portland cement, open-grade course aggregate, and water. The consistency of the materials – which have a stiff, dry texture – permits water to soak into the material quickly.

2) Pervious asphalt refers to a pavement material made of coarse stone aggregate combined with an asphalt binder. The binder consists of tiny, fine aggregate. Water seeps into the tiny air pockets present in the finished asphalt surface. Pervious asphalt has a similar appearance to traditional asphalt but has rougher features.

3) Pervious pavers are comprised of concrete or composites. Joints between the pavers are filled with small stones that allow water infiltration.

 Advantages of Pervious Pavement

The environmental benefits of pervious pavement make it an attractive alternative to conventional materials. The Environmental Protection Agency reports that the first 1-1/2 inches of rainfall results in stormwater runoff deposits containing approximately 90% of the surface’s contaminants (dirt, debris and hydrocarbons). Most of these pollutants end up in our local waterways. The use of pervious pavement can significantly reduce runoff, thereby improving water quality.

In addition to helping the environment, pervious pavement also offers several economic benefits:

  • Sewer System: Pervious materials reduce the volume of runoff into sewer systems, which decreases the need for municipal governments to construct larger stormwater systems to handle new residential and commercial projects.
  • Maximum Land Utilization: Previous pavement enhances storm water management.  This eliminates the need to buy adjacent land to build large retention ponds or other systems employed for retaining and filtering water. The result is that governments, developers and property owners are better able to maximize land use and, ultimately, realize a greater return on investment.
  • Reduce Installation Costs: As a low-impact strategy for water runoff management, pervious pavement eliminates the need to install expensive, conventional drainage solutions, such as curbs, gutters, storm drain inlets, and retention reservoirs.

Disadvantages of Pervious Pavement

Although it has substantial environmental and economic benefits, pervious pavement is not suitable for all commercial environments. A landscape designer must first determine if the site is adequate for pervious pavement. One factor that must be considered is grading, which cannot exceed a 20 slope when pervious pavement is used. Some other drawbacks to using this material include:

  • Clogging: Improper installation and failure to maintain previous paving can cause it to become clogged. However, small surface areas can be easily cleaned or replaced.
  • Limits on Installation:Pervious pavers are well suited to areas such as driveways, patios and walkways (only where the slope is gentle). Traffic on pervious pavements needs to be limited to automobile parking areas, highways with low traffic patterns, axel and speeds, and other light volume traffic areas.
  • Maintenance: The surface requires regular maintenance to prevent a buildup of grit or gravel in the pores. Failure to maintain the surface may result in drainage issues usually associate with impervious pavements.

Design/Installation of Pervious Pavement

Designers of pervious pavement must consider a variety of factors, such as grades, subsoils, drainage characteristics, and groundwater when deciding whether and how to use them for commercial properties.  Other design elements include traffic loadings and the desired operational life.

The best use of pervious concrete is on sidewalks, parking lots, driveways, and residential roadways. It is essential that the installer has the necessary experience with the material and required specifications. The designer can choose to color the concrete to contrast or blend the surface with the existing surroundings.

Pervious pavers are typically installed on sidewalks, driveways, patios, and parking lots. Many of our clients here at E-Landscape select pavers instead of the other pervious material options  because pavers offer greater design flexibility, can be colored, and have a long life-span.

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