Permeable pavements allow stormwater runoff to filter through surface voids into an underlying stone reservoir where it is temporarily stored and/or infiltrated. The most commonly used permeable pavement surfaces are pervious concrete, porous asphalt and permeable interlocking pavers. Permeable pavements have been used for commercial and residential sites to replace traditionally impervious surfaces. These include roads, parking lots, driveways, sidewalks, plazas and patios.
While the designs vary, all permeable pavements have a similar structure, consisting of a surface pavement layer, an underlying stone aggregate reservoir layer, optional underdrains and geotextile over uncompacted soil subgrade.
From a hydrologic perspective, permeable pavement is typically designed to manage rainfall landing directly on the permeable pavement surface area. While designers and regulators often discourage it, permeable pavement surface areas may accept runoff contributed by adjacent impervious areas such as driving lanes or rooftops, or from adjacent vegetated areas. Sediment in runoff from adjacent areas increases clogging of the permeable pavement, especially at the edges. This should be considered when determining the size of the contributing drainage area. Additionally, the capacity of the underlying reservoir layer will limit the size of the contributing area.
The individual articles comprising this section on permeable pavement may be viewed as a single article.
A one page fact sheet for permeable pavement provides overview information, a short summary of design, construction and maintenance considerations, and information on stormwater volume and pollutant removal.