Permeable pavement, also referred to as porous concrete or pervious concrete, is a highly porous pavement that allows rainwater to pass through it and soak into the ground beneath it. It is a LID strategy and the perfect choice for areas where planting options are limited. Permeable concrete mimics the ground’s surface, allowing water to move through it freely and flow to underground water sources, while at the same time blocking suspended solids/pollutants and reducing runoff. Permeable concrete has many applications which may include:
- residential driveways and streets
- parking lots
- sidewalks
- swimming pool decks
- outdoor sporting courts
- patios
- well linings
- low-water bridges
- low-volume pavements
Permeable concrete has a rough and uneven appearance. It has a typical flow rate ranging between two to eighteen gallons per minute. Although it can be used in light traffic areas, permeable concrete cannot be used for certain streets, highways and heavy loading areas.
Listed below are types of permeable concrete and their suggested applications:
- porous asphalt – highways
- porous turf – areas of occasional parking such as churches and stadiums
- single-sized aggregate (loose gravel with no binder) – low-speed applications such as pathways and driveways
- resin-bound paving – walkways, driveways and parking lots
- plastic grids – used to reinforce gravel parking lots, driveways and fire lanes; can also be planted with grass
- bound, recycled glass, porous pavement – pedestrian and vehicular traffic
- permeable interlocking concrete pavers – used in public areas due to their high architectural appeal
- permeable clay brick pavers – pavers composed of fired clay that is similar to interlocking concrete pavers
The benefits of permeable concrete are both environmental and financial. They include:
- elimination of runoff
- suspended particles and pollutants are trapped
- groundwater is recharged
- reduction of surface temperatures
- elimination of the need for water collection areas and retention basins
- during freezing weather, generally requires less de-icing when compared to its traditional counterparts
- due to its pervious nature, it requires no storm drains, no underground piping and no grading/sloping of the surface at installation which reduces installation costs when compared to traditional paving installations
- eliminates the need for other LID strategies to control runoff such as curbs, gutters, retention basins and other stormwater management strategies
When correctly installed, permeable concrete has the same life expectancy as that of regular concrete – 20-40 years. Permeable concrete can run two to three times the price of regular concrete or asphalt; however, the need for additional stormwater management strategies is reduced or eliminated, thereby saving money in the long run. Frequent maintenance is required with impermeable concrete, to remove the solids and particulates it filters from the runoff. Without proper maintenance, permeable concrete eventually assumes the traits of regular, impermeable concrete.
