Frequently Ask Questions
What is Impervious Coverage?
Impervious coverage is any surface in the urban landscape that cannot effectively absorb or infiltrate water.
What is Permeable Pavement?
The Permeable Pavement system is defined as an engineered hard surface with porous areas which captures and temporarily stores stormwater runoff. The captured stormwater is then exfiltrated through an underdrain system, or allowed to infiltrate in to the sub-soil, thus recharging the water table. These systems including but are not limited to Porous Concrete, Permeable Interlocking Concrete Pavers, Permeable Concrete Paver Systems, Concrete Grid Pavers, and Plastic Turf Reinforcing Grid.
What is Stormwater Runoff?
Stormwater runoff is the portion of rainfall that does not infiltrate into the soil. As the amount of impervious surfaces increases in an area, the stormwater runoff coming from that area increases as well.
Why is it important to reduce Stormwater Runoff?
Stormwater runoff is a conveyance system for surface pollutants to stormwater collection systems, and is a main component of land erosion and flooding.
How can we reduce Stormwater Runoff?
Permeable pavement systems are now recognized as Best Management Practice (BMP) by the EPA and North Carolina Department of Environmental and Natural Resources (NCDENR), and are a recommended solution to reducing stormwater runoff by the Leadership in Energy and Environmental Design (LEED) Green Building Rating System. NCDENR now offers impervious credits to builders/homeowners for using pervious surfaces. Visit the NCDENR website.
Where can permeable Pavements be used?
Permeable pavements are ADA compliant and can be used for a surprising number or applications. Permeable pavements are ideal for parking areas, sidewalks, patios, tennis courts, roads and driveways.
Permeable or pervious pavements are an environmentally safe alternative to conventional concrete and asphalt paving materials. Traditional paved surfaces, such as asphalt and concrete, do not allow water to infiltrate and convert almost all rainfall into runoff. If designed and implemented correctly, permeable pavement systems allow at least a portion of stormwater to infiltrate, thus reducing peak runoff volumes and flows, and allow for infiltration of stormwater into a storage area. Permeable paving materials include, but are not necessarily limited to, porous concrete, permeable interlocking concrete pavers, concrete grid pavers, and porous asphalt. Compacted gravel is not considered as permeable pavement by NCDENR.
Helpful Links
NCDENR - Up Close - Who owns the Stormwater?