Written by: Samantha Justice, P.E.
Green infrastructure incentive programs have become commonplace for new construction and redevelopment regulations. Five of the most common incentives include:
- Development incentives such as expedited permitting, decreased fees, zoning upgrades and stormwater requirement reductions.
- Rebates and installation financing
- Awards and recognition programs
- Stormwater fee discounts
A subset of green infrastructure, stormwater management usually includes the consideration of pervious and porous pavements. Traditional asphalt and concrete parking lot surfaces create significant stormwater runoff, and in many municipalities, cannot be used in expansion or new build situations.
When the paved area is constructed completely with a porous pavement, stormwater concerns are greatly reduced. Depending upon the choice, pavements that return rainwater to the aquifer not only nearly eliminate stormwater runoff – they also reduce sheet flow and point load erosion problems at the pavement edges, and reduce need for additional stormwater infrastructure to convey the water away from the area. Porous pavement systems can be directly integrated with asphalt and concrete surfaces to reduce such failures and reduce or eliminate the need for stormwater conveyance channels, pipes, and swales. As a result, downstream stormwater pipe systems see less silt and less water which requires less maintenance and less capital expenditure for upsizing stormwater pipes.
Increase Parking Capacity
Expanding parking areas with porous pavement can have a neutral effect upon the existing stormwater loading or in some cases can even decrease existing loading.
- In cases where existing parking areas drain to internal inlets, additions self drain, but seldom offer any benefit to existing hard surfaces.
- In cases where parking areas sheet drain in the direction of the parking capacity addition, the new porous surface can go beyond self-draining and can cut off sheet flow and absorb hard surface runoff. Of course, one has to be careful not to overload the new porous system with sediment.
Integrating Permeable with Impervious Pavements
Not all new build parking lots need to be 100% porous. A mix of pervious and impervious surfaces can solve both stormwater concerns and heavy traffic loading expectations. Using asphalt or concrete surfaces in the drive lanes of parking lots alleviates stresses on the system from repetitive passes from vehicles, and ensures that all types of vehicles can use the lot. Joined to these drive lanes can be adjacent porous parking stalls, controlling stormwater runoff and eliminating the need for inlets and conveyance systems. While permeable infill promotes fast infiltration, the base depth may be designed to suit the stormwater needs of the site–allowing for storage and natural percolation.
Semi-rigid resin based porous pavement units may be filled with either aggregate or topsoil, allowing for customization of parking lots for aesthetic appeal while considering intensity and frequency of use. The permeable paver units are easily cut to seamlessly align with hard pavements (permeable pavers, asphalt, concrete), even along curved lines. Impervious surfaces can be painted for centerlines and turning lanes. Porous pavement units offer delineators, allowing parking stall lines and other separation markers. Parking stops and signs can be easily installed over porous pavement units, so there are no limitations when it comes to fully outfitting parking areas for a project’s needs.
The Benefits of Porous Pavements in Pavement Design
Whether porous pavements are included in all or part of a green infrastructure pavement project, the benefits they offer for reducing runoff and stormwater infrastructure size/need, protecting watersheds, and reducing cost are significant.
Presto Geosystems offers the GEOBLOCK® grass and GEOPAVE® gravel porous pavement systems to help control stormwater, meet load requirements and suit landscape plans.
See our Myth Busters Blog Series for how the units eliminate typical concerns about using porous pavements.
For more information on porous pavements, visit our web page: Porous Pavements.