POROUS ASPHALT PAVEMENTS
Imagine a parking lot without puddles, a bike trail that requires less salt to keep it ice-free in winter. Roads that redirect storm water and filter in back into local aquifers. Porous asphalt pavements can do all of this and more.
Porous asphalt pavements with stone reservoirs are a multi-functional low-impact development technology that integrates ecological and environmental goals for a site with land development goals. They are constructed using the same equipment and techniques as conventional asphalt pavements, and provide a cost-effective means for improving the sustainability of facilities.
Porous asphalt pavements have been used successfully since the 1960’s and have performed well in all climates zones. It is constructed over a sub-service reservoir filled with larger stones, topped by one or two layers of porous asphalt. The asphalt mix is much like typical asphalt mixtures except that it lacks finer material, allowing water to flow through the pavement and into the subsurface reservoir where it soaks into the ground, reducing or eliminating storm water runoff from the paved surface. This means porous asphalt pavements can reduce or eliminating the need for traditional bio-retention facilities and extensive piping and storm drains. They can also help increase available space for parking or save green space that may be lost to other storm water management methods.
Once a porous asphalt pavement is completed, maintenance and upkeep differs from traditional asphalt pavements. The biggest difference is that porous asphalt pavements should not be sanded in the winter. Studies have shown that there is less refreezing with this application, and a much lower amount of deicing chemicals that are needed to melt snow and ice.
Ideally, porous pavements should be cleaned with a vacuum or regenerative-air sweeper once or twice a year to help ensure that the pavement drains as it was designed to do. In some instances power washing may be advisable to clear clogged portions of the porous pavement.
Over their life cycles, porous asphalt pavements tend to not experience the sort of cracking issues that can manifest with other pavement types. This can mean reduced life-cycle costs thanks to the reduced need to crack filling and patching.
The Environmental Protection Agency (EPA) classifies porous asphalt pavements as a “cool Pavement” technology. The evaporation cooling effect means porous asphalt pavements can have lower surface temperatures than impervious pavements, and they can play a role in mitigating the urban heat island effect.