Permeable paving
Permeable pavement surfaces may be composed of; pervious concrete, porous asphalt, paving stones, or interlocking pavers.
In addition to reducing surface runoff, permeable paving systems can trap suspended solids, thereby filtering pollutants from stormwater.
[4] Polymer based grass grid or cellular paver systems provide load bearing reinforcement for unpaved surfaces of gravel or turf.
The infiltration capacity of the native soil is a key design consideration for determining the depth of base rock for stormwater storage or for whether an underdrain system is needed.
[9] The goal is to control stormwater at the source, reduce runoff and improve water quality by filtering pollutants in the subsurface layers.
A "structural-soil" pavement base combines structural aggregate with soil; a porous surface admits vital air and water to the rooting zone.
During large storm events, the water table below the porous pavement can rise to a higher level, preventing the precipitation from being absorbed into the ground.
Since porous pavement is an infiltration practice, it should not be applied at stormwater hot spots due to the potential for groundwater contamination.
All contaminated runoff should be prevented from entering municipal storm drain systems by using best management practices (BMPs) for the specific industry or activity.
[15] Reference sources differ on whether low or medium traffic volumes and weights are appropriate for porous pavements due to the variety of physical properties of each system.
However, given the variability of products available, the growing number of existing installations in North America and targeted research by both manufacturers and user agencies, the range of accepted applications seems to be expanding.
Working examples exist at fire halls, busy retail complex parking lots, and on public and private roads, including intersections in parts of North America with quite severe winter conditions.
[18] Pervious concrete and asphalt designed to reduce frost heave and spalling damage has been used successfully in Norway and New Hampshire.
[19] Furthermore, experience suggests that preventive measures with rapid drainage below porous surfaces be taken in order to increase the rate of snow melt above ground.
Permeable paving systems, specifically pervious concrete pavers, have shown significant cost benefits after a Life Cycle Assessment was performed, as the reduction in total weight of material needed for each unit is reduced by nature of the porous design.
Some permeable paving products are prone to damage from misuse, such as drivers who tear up patches of plastic & gravel grid systems by "joy riding" on remote parking lots at night.
Traditional permeable concrete paving bricks tend to lose their color in relatively short time which can be costly to replace or clean and is mainly due to the problem of efflorescence.
These systems have been used readily in Europe for over a decade, but are gaining popularity in North America due to requirements by government for many projects to meet LEED environmental building standards.
The remaining large, single-sized aggregate particles leave open voids that give the material its porosity and permeability.
[28]: 2 More recently manufacturers have introduced styles with smaller joint allowing for better ADA compliance and still capturing a significant amount of stormwater.
They give an architectural appearance, and can bear both light and heavy traffic, particularly interlocking concrete pavers, excepting high-volume or high-speed roads.
Clay pavers provide a durable surface that allows stormwater runoff to permeate through the joints[citation needed].
Resin bound paving provides a strong and durable surface that is suitable for pedestrian and vehicular traffic in applications such as pathways, driveways, car parks and access roads[citation needed].
Stabilized decomposed granite provides a strong and durable surface that is suitable for pedestrian and vehicular traffic in applications such as pathways, driveways, car parks and access roads.
[33] Black Locust Lumber wood pavers exceed 10.180 PSI (pounds per square inch) and have a Janka Hardness 1,700 lbf.
