Pervious Pavement
Type of Development
New Development, Redevelopment
Topography
Hills, Valley, Baylands
Longevity
Medium Term
Environment
Urban
Maintenance
High
Cost
Pervious pavement is 10-15% more expensive than regular asphalt and 25% more than concrete. Maintenance is about $200 per acre per year. However, there is less need for storm drains and curbs. Constructing curb cuts will have more expenses.
Overview
Pervious pavement is designed to slow percolation of storm runoff into the groundwater system. Impervious surfaces like ashpalt and concrete in roads and buildings create flooding and stormwater runoff, which can carry trash and pollutants into stormwater management systems, often clogging them along the way. Pervious pavement can be used instead of concrete on low traffic areas to allow percolation and filtration of water runoff without storm drains. Pervious pavement comes in many forms depending on where it is used. For example, tiled pavement can be used on walkways, but finer grain material like pervious asphalt should be used on bike paths and parking lots. The primary types of pervious material include porous asphalt, pervious concrete, permeable interlocking concrete pavers, and grid pavers.
Function
Pervious pavement allows the efficient percolation and filtration of stormwater, which recharges groundwater and reduces flooding over impervious surfaces.
Benefit
Pervious pavement reduces flooding by absorbing water as it makes contact. Pollutants are successfully removed during the percolation process and groundwater recharge becomes significantly less polluted. Similarly, water draining into the Bay will be cleaner and will carry less trash. Less flooding and runoff will make driving safer, improve community health, and make biorientation areas like bioswales and rain gardens much more effective.
Dependency
Low traffic
Development Considerations
Ensure that the surface is not too close to groundwater, as the water needs to be fully filtered before it reaches water table or it will contaminate the groundwater. The type of soil needs to be considered, as does percolation ability of the ground. These surfaces work best on a 5% or less slope for spreading out water and efficient filtration. Select a mix that has a lower water content, cementitious ratio, and smaller aggregate. (NACTO)
Environmental Considerations
Natural percolation of soil in area. Water table needs to be considerably below the level of the bioswale.
Maintenance Consideration
Long term maintenance is required: sweeping, washing, or vacuuming to remove grease, oil, and other sediment. The pervious pavement must be well executed and maintained in order to avoid failure. Without proper maintenance, development, and construction materials, the project will not be successful. Therefore, the materials, location, implementation, and maintenance are all vitally important.
Cost Considerations
Pervious pavement is 10-15% more expensive than regular asphalt and 25% more than concrete. Maintenance is about $200 per acre per year. However, there is less need for storm drains and curbs. Constructing curb cuts will have more expenses.
